Construction Exe 09 August SR I 2010 Module Stringing

FOR INTERNAL CIRCULATION ONLY

user’s manual of

construction(part one)

Transmission LinesVolume-5Stringing

Construction ManagementPower Grid Corporation of India Limited

(A Government of India Enterprise)

DOCUMENT CODE NO. : CM/TL/STRINGING/ 96 NOV. 1996

Vol.5 : Page #

CHAIRMAN&

MANAGING DIRECTOR’S MESSAGE

It gives me immense pleasure to learn that Construction Management Deptt. has come

out with further 3 volumes of User’s Manual of Construction of transmission line

(Stringing) & Sub-station (Mechanical) and Electrical auxiliary packages).

For quite sometime a need was also being felt in the organization to develop and

prepare standard procedures, norms and guidelines for execution of various

construction activities as the different regions were following different practices. It is

with this background the construction management department was conceived at

Corporate Centre and entrusted with the task of developing and providing such user’s

manuals of construction and to bring in uniformity. These manuals shall serve as a

useful reference to our field engineers and site managers to accomplish a task in given

time, cost & quality.

I would like to congratulate Construction Management team for its sincere efforts in

preparation of these manuals wherein the main focus has been to bring together all the

theoretical and practical knowledge acquired during the years in the domain of

construction of overhead transmission lines and s/stn. More such user’s manuals

covering the other related fields in the lines/sub-station construction should be

prepared for the benefit of the ultimate users at our remote sites as well as for the

younger generation inducted in the POWERGRID.

(R.P. SINGH)

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CONTENTS

CHAPTER 1

CONDUCTOR AND EARTHWIRE SELECTION

CONDUCTOR CREEP AND SAG-TENSION CALCULATION

PAGE NO.

1.1 SELECTION OF CONDUCTOR 1

1.1.1 POSSIBLE TYPES OF CONDUCTORS 1

1.1.2 SUB-CONDUCTOR SPACING 4

1.1.3 ELECTRICAL CONSIDERATION 7

1.1.4 STRUCTURAL CONSIDERATION 9

1.2 SELECTION OF EARTHWIRE 10

1.2.1 FUNCTION OF GROUND WIRE 10

1.2.2 HOW GROUND WIRE PROTECTS 12

1.2.3 SHIELDING ANGLE AND MID SPAN CLEARANCE 13

1.3 ORIGIN OF CONDUCTOR CREEP 14

1.3.1 PRIMARY AND SECONDARY CREEP 14

1.3.2 EFFECT OF CREEP 15

1.3.3 CREEP ALLOWANCE 16

1.3.4 COMPARISON OF METHODS 17

1.3.5 PRECAUTIONS DURING STRINGING 17

1.4 SAG TENSION CALCULATION 18

1.4.1 CATENARY AND PARABOLIC FORMULAE 18

1.4.2 COORDINATION OF SAGS 21

1.4.3 STRINGING CHARTS 22

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CHAPTER 2

DEFINITIONS AND TERMINOLOGY

PAGE NO

ACSR CONDUCTOR 24

BLOCK 25

BULL WHEEL 27

CLIPPING IN 29

CONDUCTOR CAR 30

CONDUCTOR GRIP 33

RUNNING GROUND 35

TRAVELLER GROUND 36

COMPRESSION JOINT 37

PROTECTOR JOINT 38

PILOT WIRE 40

BULL WHEEL PULLER 43

REEL STAND 46

RUNNING BOARD 47

BULL WHEEL TENSIONER 53

TRAVELER 54

UPLIFT ROLLER 55

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CHAPTER 3

STRINGING METHODS AND GENERAL ASPECTS

3.1 METHODS OF STRINGING 57

3.1.1 MANUAL METHOD 57

3.1.2 TENSION METHOD 58

3.2 GROUNDING DURING STRINGING 59

3.2.1 INTRODUCTION 59

3.2.2 SOURCE OF HAZARDS 61

3.2.3 GROUNDING PROCEDURE 61

3.3 COMMUNICATIONS 62

3.4 SPECIAL REQUIREMENTS FOR 63

MOBILE EQUIPMENT

3.4.1 DRUM OR REEL STAND 63

3.4.2 TENSIONER BULLWHEEL 64

CHARACTERISTICS

3.4.3 PULLER AND TENSIONER OPERATING 66

CHARACTERISTICS.

3.5 TRAVELERS 68

CHAPTER 4

STRINGING PROCEDURE

4.1 STEPS OF STRINGING 78

4.2 STRINGING OF EARTHWIRE 78

4.2.1 PAYING OUT OF EARTHWIRE 78

4.2.2 JOINT OF EARTHWIRE 79

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4.2.3 SAGGING AND FINAL TENSIONING 81

4.2.4 CLIPPING 83

4.2.5 FIXING OF HARDWARE 84

4.3 STRINGING OF CONDUCTOR 85

4.3.1 GUYING OF TOWERS 85

4.3.2 INSULATOR HOISTING 86

4.3.3 PAYING OUT OF PILOT WIRE 90

4.3.4 POSITION OF TENSIONER AND PULLER 90

4.3.5 PAYING OUT OF CONDUCTOR 92

4.3.6 REPAIRING OF CONDUCTOR 96

4.3.7 JOINTING OF CONDUCTOR 97

4.3.8 ROUGH SAGGING OF CONDUCTOR 100

4.3.9 FINAL SAGGING OF CONDUCTOR 101

4.3.10 REGULATION 104

4.3.11 CLIPPING OF CONDUCTOR 105

4.3.12 FIXING OF LINE SPACER 106

4.3.13 INSTALLATION OF DAMPERS 108

4.3.14 JUMPERING 108

4.3.15 PAYING OUT THROUGH ANGLE TOWERS 110

4.3.16 TRANSPOSITION ARRANGEMENT 111

4.4 STRINGING OVER RIVER CROSSING 113

4.5 STRINGING OVER POWER LINE CROSSING 116

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CHAPTER 5

GUIDE LINES

GL - 1 PRE STRINGING CHECKS 119

GL - 2 PAYING OUT OF EARTHWIRE 125

GL - 3 PAYING OUT OF CONDUCTOR 128

GL - 4 FINAL TENSIONING OF EARTHWIRE AND CONDUCTOR 135

GL - 5 CLIPPING AND FIXING OF EARTHWIRE ACCESSORIES 140

GL - 6 CLIPPING AND FIXING OF CONDUCTOR ACCESSORIES 143

ANNEXURE S/1 REQUIREMENT OF TOOLS AND PLANTS

FOR STRINGING 149

ANNEXURE S/2 REQUIREMENT OF MANPOWER

FOR STRINGING 153

CHAPTER 6

CHECK FORMAT 154

BIBLIOGRAPHY 170

RESUMES

(v)

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______________________________________________________________________

CHAPTER ONE

______________________________________________________________________

CONDUCTOR AND EARTHWIRE SELECTION

CONDUCTOR CREEP AND SAG-TENSION CALCULATION

Back to Contents Page

1.1 Selection of Conductor


1.1.1 Possible Types of Conductors :


(i) Up to 220 kv lines, the basic criteria for selecting

the size of conductor is its continuous and short-term

current carrying capacity both under normal and short

circuit conditions. However, for EHV lines this

criteria does no longer hold good, as corona and its

effects come into picture which are function of line

voltage. For 400 kV lines, therefore, size of

conductor is determined not only from current carrying

capacity considerations but also from corona and radio

interference considerations. The experience has

established that the size of conductor which gives

satisfactory corona and RI performance would have

adequate current carrying capacity also. The size of

conductor so determined would normally be larger than

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Chapter-1

Conductor & Earthwire Selection Conductor

Creep & Sag-Tension Calculation

that selected from considerations of power

transmission capability.

(ii) One of the methods to achieve this would be to have a

single conductor with large diameter. However, due to

heavier weight of such a conductor, its manufacture,

handling, transportation and stringing would be

difficult and expensive. Use of single conductor was,

therefore, not considered for 400 kv lines.

(iii) Another method of increasing the size of conductor,

which some utilities in America have tried, is to use

expanded conductor, in which minimum amount of

aluminum necessary to carry the power is retained,

and inert low cost filler material is stranded around

the aluminum portion to increase the overall diameter

of the conductor. However, its use has not found

popular support even in America, due to manufacturing

and other problems. This conductor was also,

therefore, not considered for 400 kv lines.

(iv) The only other alternative was to use bundle

conductors consisting of 2,3 or 4 small size sub-

conductors to obtain required effective overall

diameter of the conductor. For EHV lines, this is the

most technically suitable, economical and commonly

adopted method to transmit bulk power over long

distance. The bundling reduces the inductive reactance

loading and improves the stability of the line. The

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voltage gradient is reduced to acceptable limit,

thereby improving the corona and radio interference

performance. Studies indicated that for the 400 kv

lines 2 or 3 sub-conductors in each bundle would be

sufficient.

Table 1.1 gives the number, size and other physical

properties of various conductors.

Table 1.1: Number, Size and Physical properties of Conductors ------------------------------------------------------------------------------------------------ Code No. of Sub- Stranding Overall Unit wei- U.T.S. Approximate Name conductors (mm) dia. ght (kg/m) (kg) current carry- (mm) ing capacity 40°C ambient temperature------------------------------------------------------------------------------------------------Goat 3 30/7/3.71 25.97 1.492 13780 680 Sheep 3 30/7/3.99 27.93 1.726 15910 745 Deer 2 & 3 30/7/4.27 29.89 1.977 18230 806 Zebra 2 & 3 54/7/3.18 28.62 1.625 13316 795 Elk 2 & 3 30/7/4.50 31.50 2.196 20240 860 Camel 2 54/7/3.35 30.15 1.804 14750 - Moose 2 54/7/3.53 31.77 2.002 16450 900

Bersimis 2 & 4 42/4.57 35.10 2.181 15715 -

7/2.54

AAAC 2 61/3.55 31.95 1.666 16307 - -----------------------------------------------------------------------------------

1.1.2 Sub-conductor Spacing


(i) After having selected the conductor with twin bundle

arrangement, the sub-conductor spacing had to be

decided. Sub-conductor spacing influences the surge

impedance loading (SIL) of the line, corona and radio

interference performance, line losses and the weight

of towers. The cost of series and shunt compensation,

due to change in the reactance of the line, is also

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affected to some extent. A phenomenon known as sub-

span oscillation is also related to sub-conductor

spacing. All the above factors when combined affect

the cost per MW capability of line.

(ii) From the experience and practices adopted by

different countries for 400/500 kv lines, it was found

that the optimum sub-conductor spacing would vary

between 30 to 45 cm. However, a wider range of sub-

conductors spacing form 20 to 50 cm was considered.

(iii) Figure 1.1 shows the surge impedance loading of twin

'Moose' conductor bundle with different sub-conductor

spacings varying from 20 to 50 cm, and inter phase

spacing from 10 to 16 m. With increased interphase

spacing and reduced bundle spacing, the transmission

capability is reduced due to increased inductive

reactance and reduced capacitive reactance of the

line. Accordingly, the amount of series and shunt

compensation of line is also influenced.

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(iv) The tower weights are influenced with the change in

the sub-conductor spacing due to following reasons:

(a) With given configuration of towers, and specified

angle of shield, the cross-arm length increases with

the increase in sub-conductor spacing. This involves

an increase in the height and hence the weight of

towers.

(b) With increase in cross-arm length, the torsional load

increases under broken wire conditions, resulting in

increase in the weight of bracings.

(v) The I²R and corona losses also get affected with

change in sub-conductor spacing due to change in SIL

and surface gradient.

(vi) Apart from the above, sub-conductor oscillations have

also been found to be related to sub-conductor

spacing. These are low frequency and high amplitude

oscillations which may be so severe under certain wind

conditions as to cause clashing of sub-conductors in

the mid sub-span, and thus resulting in damages to the

suspension fittings, spacers and subsequently to

conductors. Through extensive research and

experience, it has been found that the amplitude of

sub-conductor oscillations is reduced as the sub-

conductor spacing is increased, and these can be

controlled considerably by keeping a sub-conductor

spacing-to-diameter ratio more than 14-15. The 400 KV

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lines constructed by CEGB in U.K. with 300 mm sub-

conductor spacing with twin "Zebra' bundle have

experienced trouble due to such sub-conductor

oscillations. Subsequently, they are reported to

have increased the sub-conductors spacing to 500mm

(20 in.) increasing the spacing-to-diameter ratio

from 10.4 to over 17.

(vii) For twin 'Moose' bundle, the optimum sub-conductor

spacing was lying between 45 and 50 cm as shown in

Figure 1.2. The decision, however, went in favour of

45 cm sub-conductor spacing in view of the following

reasons.

(a) For most of the European and American utilities the

sub-conductor spacing for 400/500 kv lines was

varying from 30 cm to 45.7 cm, and a spacing of 45

cm was most commonly adopted (Details in Table 1.2).

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(b) As the spacing of 45 cm was most common, the design Vol.5 : Page #

and performance of spacers and hardwares at this

spacing were well-known.

(c) The corona and radio interference performance was

found satisfactory.

(d) The sub-conductor spacing-to-diameter ratio is more

than 14.

(viii) The horizontal configuration of bundling was

selected, as it is the most common arrangement for

twin bundle conductors, although in some cases for

lower voltages upto 345 Kv, vertical bundling has also

been adopted.

1.1.3 Electrical Considerations :


(i) Current Carrying Capacity

The conductor selected for EHV lines should be

capable of carrying currents under normal as well as

peak loads, without getting overheated. The stability

of the line should not be disturbed, both under

steady state and transient conditions. The surge

impedance loading, in which reactive power consumed by

the line reactance equals the reactive power generated

by the line capacitance, has been calculated as 505

MW (in Figure 1.1) for twin bundle, 'Moose' conductor

with 45 cm sub-conductor spacing, which meets the

normal load requirements of our system. By providing

necessary compensation for reactive power, the

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emergency peak load can also be transmitted without

affecting the stability of the line.

The excessive temperature rise over the ambient

temperature under full load conditions, some time,

may impose a limit of the MVA which can be

transmitted. However, in case of 'Moose' ACSR, the

maximum current carrying capacity for a temperature

rise of 35°C on an ambient temperature of 40°C is

about 900 amps. This provides a limit of power

transmission of 1250 MW from thermal considerations,

which is much more than normal and peak load

requirement of our line.

(ii) Corona and Radio-Interference

When the electric field on the surface of the

conductor exceeds the disruptive field of surrounding

air, corona effect takes place with discharges

emitting from the periphery of the conductor. This

phenomenon produces additional loss of power, radio

disturbance and audible noise. The surface gradient

is proportional roughly to the under root of line

voltage and inversely proportional to diameter of

conductor for a fixed line voltage. It is, therefore,

necessary to limit the surface gradient by increasing

the diameter of conductor. The bundling of conductor

is the most suitable choice, as already stated in

para.1.1.1

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TABLE 1.2: Particulars of EHV lines of some foreign countries

----------------------------------------------------------------Items Italy France Finland Sweden U.S.A. U.S.A U.K.

----------------------------------------------------------------Line Voltage 380 kv 380 kv 400 kv 380 kv 500 kv 500 kv 400 kv

Year of cons-truction 1963 1963 1960 1965 1965 1966 1965

Nature of Conductor ACSR ACSR ACSR ACSR AL-alloy ACSR ACSR

No. of sub-condu ctorsper phase 2 2 2 2 2 2 2

Al/st area of conductor 7.9 4.87 7.9 7.7 - 12.5 7.71

Sub-conductorctor spac- 40 40 45 45 45.7 45.7 30.4 ing(cm)

----------------------------------------------------------------

1.1.4 Structural Considerations :


The electrical advantages of bundle conductors are

counteracted to a great extent by the structural

disadvantages. The mechanical loadings on the

supporting structures increase considerably with

bundle conductors which result in heavier towers and

foundations. The bundling of conductors also

necessitates complicated hardwares and accessories,

thereby increasing the cost of line. However, we have

to reach to the compromise for optimum choice of

conductor.

1.2 Selection of Ground wire

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1.2.1 Function of Ground wire :


(i) As is well known, groundwires are the conductors

arranged above the phase conductors and grounded at

every tower. They mainly afford the protection

against direct strokes and distributing the current

in two or more paths, thus reducing the voltage drop.

Another function of the groundwire, of a minor

nature, is to reduce voltage induced on the

conductors from nearby strokes. In case of Extra High

Voltages, the over voltages due to direct or induced

lightning strokes are not the governing factors and

the insulation selection is based on switching

overvoltage, the ground wire still protects the line

and equipment from damage due to direct or induced

lightning strokes by shielding. It also reduces strain

across the insulator string, in case of stroke, due

to its inherent coupling with the conductor. To

perform this, it must meet the following requirements:

(a) It must be able to carry the maximum lightning

current, without undue overheating.

(b) It must be strong mechanically.

(c) It must be high enough to afford protection to all

the line conductors at mid-span to prevent a side

flash to a line conductor during the interval

required for reflections from the towers to return to

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mid-span and relieve the voltage stress there.

(d) Tower footing resistance should be low.

Size of Earthwire for EHV lines : G.S. 7/3.66mm,

overall dia. 10.98mm, wt. 0.583 Kg/m, UTS 6980 Kgs.

(ii) In addition groundwires exercise a number of

subsidiary effects, some of which are:

(a) Telephone and radio interference.

(b) Corona.

(c) Relaying possibilities.

(d) Zero sequence impedance of the line.

(e) Attenuation of travelling waves.

(f) Reduction in surge impedance.

1.2.2. How Groundwire Protects:


(i) In case of lightning stroke on a transmission line,

the line can be struck either at tower point or at mid

span. When the ground wire is struck at mid - span

the current divides in two parts and flows towards

both towers and at the tower the current again

divides into two parts, one going to the tower and the

other to outgoing portion of the ground wire. If

the tower is struck and there is one overhead ground

wire, the current divides into three parts, one in the

tower and two in the groundwire on either side of the

tower. The strokes on the tower and within a quarter

span on either side of it, are assumed to be on

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tower and treated as such. The strokes on the

middle half span are supposed to be on the mid-span

and dealt with as such.

(ii) In case of stroke, the lightning surge voltage

travels from the point struck to the ground

through tower. From the tower footing the wave is

reflected, and this reflected wave, though reduced in

magnitude depending on footing resistance, cancels

out to a great extent, the incident wave. The

lightning surge, therefore, remains on the point

struck, at tower top or mid-span, for a time taken by

the incident surge to reach the tower footing and

for the reflected surge to reach the point struck.

During this time the point struck will be stressed

by the voltage of surge wave and should not

flashover, i.e., there should be no insulation

flashover for tower strokes and no mid span flash

over for mid span strokes. The insulation level

of a line is, therefore, decided on this basis (for

EHV lines, insulation level is decided based on

switching surges). Similarly, the mid-span

clearance is also kept such that no flashover occurs

during the time, the surge voltage is impressed on

the mid-span.

1.2.3 Shielding Angle and Mid-Span Clearance:


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(i) Shielding Angle

The shielding angle afforded by a groundwire is

defined as the angle between a vertical line through

the groundwire and the slanting line connecting the

earthwire and conductors (outer conductors in case of

bundles). The protective zone of groundwire is the

cone with the groundwire at its apex and the shield

angle as its slanting angle. The earthwire is

supposed to protect all the conductors within this

zone from direct strokes. In actual practice,

however, the probability of flashover is less with

lower shield angle and high with higher shield angle.

On the other hand, lower the shield angle, higher is

the tower, and hence higher the cost of line. So a

compromise has to be reached between the line cost and

protection afforded.

(ii) Mid - span Clearance:

In case of stroke on mid-span, very high voltage is

impressed on the groundwire. The voltage remains on

the groundwire, till such time the reflection of the

wave returns. The voltage on the groundwire may,

therefore, cause flashover from groundwire to

conductor or what is known as "back flashover", if

sufficient clearance is not provided between the

earthwire and conductor at mid-span. This clearance

is, therefore, kept such that the voltage surge may

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not cause flashover during the time it is impressed

on the earthwire.

1.3 Origin of Conductor Creep


1.3.1 Creep is time-dependent strain occurring under stress.

A bare overhead line conductor will suffer a permanent

increase in sag from non-elastic stretch caused by

following:

(a) Short time loading such as from wind and/or ice loads,

or after being subjected to tension during conductor

installation. In these cases the difference of

initial and final modulus of elasticity is involved.

(b) Long time loading at any tension and temperature

level, which is known as 'long-term tensile creep' or,

simply as 'Creep'.

(c) The first stage [para-(a)] is generally known as

'Primary Creep' in which the conductor initially

creeps quite quickly with a rapid decrease in creep

rate. This mainly represents a considerable amount of

strand tightening and settlement, adjustment of load

between layers, stress shifting between components of

a composite (e.g., ACSR) conductor, and partial

metallurgical creep.

(d) The second stage [para (b)] is known as 'Secondary

Creep' in which the creep is more stable and is mainly

metallurgical. In this case the creep and the decrease

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in creep rate are both very slow.

1.3.2 Effect of Creep


As mentioned above, creep results in permanent

increase in conductor sag and, if not properly

controlled, can cause irregular bundle sags, smaller

electrical clearance to ground and to earthed metal

parts; and may require re-sagging operation at a later

stage. The amount of this creep during the estimated

or considered line life will depend upon everyday

stress and everyday temperature operating.

1.3.3 Creep Allowance :


There are two methods of creep adjustment as

mentioned below. Both are in regular use and are

equally popular. It is most convenient to express

creep or permanent sag increase in terms of a

temperature-increase above the ambient.

(i) Overtensioning :

In this first method, allowance for creep during

sagging is made either by including creep correction

in the stringing charts thereby producing 'Erection'

or Initial Stringing Charts, or by reading the sag

from 'final or design' Stringing Charts (hereafter

referred as design stringing charts) at ambient

temperature minus the established temperature

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correction for creep.

(ii) Allowance in Design :

In the second methods, sagging is done to design

stringing charts and the permanent sag increase is

allowed for in the tower design by providing

equivalent extra clearance from the bottom cross-arm.

1.3.4 Comparison of the Two Methods :


The first method will initially result in some tower

overloading though it also results in savings from

reduced tower height.

The second method finally results in lower tower

loadings with age, which means the line life and

stability can be expected to be more than that

achieved with the first method due to reduced tension

and vibration effects. At the same time, there is no

chance of design tensions being exceeded. Further,

lighter and cheaper tensioning equipment will be

required.

The first method normally requires erection stringing

charts, whereas the second method requires furnishing

of only design stringing charts which have to be

furnished in either case.

1.3.5 Precautions during Stringing


Prestressing as per stringing charts effectively

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stabilizes the conductor from creep during its

installation. It is important that all the conductors

in a sagging section are handled uniformly as regards

tension and time during stringing, prestressing and

sagging. The subconductors of a phase should be of

the same make out of the same process of manufacture

(e.g. wire drawn from either hot-rolled rod, or

extruded and drawn rod.)

1.4 Sag-Tension Calculations


1.4.1 A proper evaluation of sags and tensions is necessary

at the design stage for fixing up the ruling span and

structural requirements of line supports. During

erection of the overhead lines, the sags and tensions

to be allowed for various spans under the ambient

conditions will also have to be properly evaluated,

so that the lines may give long and trouble-free

service. Various methods, analytical and graphical

have been devised to determine the sag and tensions.

If the flexible conductor, whose weight is distributed

uniformly along its length, is suspended between two

rigid supports at the same level and is in

equilibrium, its contour lies along a curve which

conforms quite closely to a catenary the longer

the span, the greater the degree of conformity.

The transmission line conductor is usually subjected

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to the following external forces:

(i) a horizontal force due to wind pressure,

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(ii) a vertical force due to the dead weight of the

conductor, and

(iii) A vertical force due to the deposit of ice on the

conductor (in areas subject to snow fall)

If w is the weight of conductor per metre length

(including the weight of ice deposit, if any) and p

the horizontal force due to the wind pressure acting

on the ice-coated conductor per meter length, the

resultant force q on the conductor per unit length is

q = ( w² + p²)

and the catenary which lies in the plane of the

resultant force is inclined to the vertical plane at

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an angle which is given by the equation.

p Tan = --- w

Figure 1.3 represents a span of transmission line

conductor strung between two points of supports A and

B at the same elevation. The length, sag and tension

of the conductor are given by the following catenary

formulae:

2H aqL = ---- Sin h ----

q 2H

H + aq + b = ---- ¦ Cos h ---- -1¦ q ¦ 2H ¦ + +

T H aq ---- = ---- Cos h ---- q q 2H

T H ---- = b + ---- q q

where,

a = span AB,

b = sag of the conductor at its lowest point

with reference to the points of support.

L = length of the conductor in span.

T = tension at either point of support, and

H = horizontal tension at the lowest point O.

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For spans of the order of 300 meters and less, the above

characteristics of the conductor are given with

sufficient degree of accuracy by the following simpler

parabolic formulae, which can be derived by expanding

the hyperbolic functions in the above equations in the

forms of a series and neglecting all terms except the

first two:

a3q² L = a + ---- 24H²

a²q b = ---- 8H

T a²q H ---- = ---- + ---- q 8H q

The above parabolic formulae are generally used in

sag and tension calculations except in the case of

very long spans.

1.4.2 Co-ordination of Sags


The spacing required between the ground wires and

conductors at midspan to ensure that a lightning

stroke which hits the ground wire does not flashover

to the conductor, is referred to as the midspan

spacing. As a rule, from the lightning protection

point of view, the ground wire is strung with a

lesser sag (by about 10-15 percent) than the

conductor so as to give a midspan separation greater

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than at the supports.

Certain steps are involved in determining the midspan

spacing which, while satisfying the requirements of

factors of safety under the worst condition and the

everyday condition, results also in economical tower

configuration.

1.4.3 Stringing Charts


The initial sag-tension charts give sags and tensions

for new ACSR before it has been subjected to the

assumed maximum loading stresses. The final charts

give sags and tension after the conductors have been

stressed due to the assumed maximum loading

conditions, when sagged initially in accordance with

the initial charts.

The initial charts are used for determining sags for

the use of stringing the conductors in a particular

ruling span, determined for a section of line between

two dead-end points. The final charts are used for

determining clearances. They are also used for

stringing when the conductors are prestressed before

or during erection at tensions which will subject them

to the same stress they would receive with the assumed

maximum loading conditions.

An example of using the sag-tension chart for the

'Moose' ACSR used on a typical 400 KV single circuit

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line is given below.

The initial sag-tension chart for the conductor is

given in Figure 1.4.

Corresponding to the stringing temperature of 32°C (on

the right corner) and a ruling span of 350 meters on

the X-axis, the tension is 4,010 kg. as read off on

the ordinate. Corresponding to this stringing tension

and the actual span of 400 meters (on the top left

hand corner of the chart), the sag is read as 10

meters on the X-axis.

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Chapter-2

Definitions & Terminology

______________________________________________________________________

CHAPTER TWO

______________________________________________________________________

DEFINITIONS AND TERMINOLOGY


Terminology for equipment and procedures associated with the

installation of overhead transmission line conductors varies

widely throughout the utility industry. Therefore, definitions

and terminology have been included to provide a correlation

between the terminology used in this manual and industry

synonyms. Note that the synonyms are terms that are commonly

used, although many are not necessarily good usage and should

not be taken as equivalents to the manual terminology.

Definitions & Terminology for Conductor Stringing Equipment.

AAAC. Concentric-lay-stranded all aluminum alloy conductor.

AAC. Concentric-lay-stranded all aluminum conductor.

Aluminum Conductor, Steel Reinforced (ACSR)


A composite conductor made up of a combination of aluminum and

coated steel wires. In the usual construction, the aluminum

wires surround the steel.

Aluminum Alloy Conductor, Steel Reinforced (AACSR)


A composite conductor made up of a combination of aluminum alloy

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and coated steel wires. In the usual construction, the aluminum

wires surround the steel.

Aluminum Conductor, Aluminum Alloy Reinforced (ACAR)

A composite conductor made up of a combination of aluminum and

aluminum alloy wires. In the usual construction, the aluminum

wires surround the aluminum alloy.

Anchor

A device that serves as a reliable support to hold an object

firmly in place. The general term "anchor" is normally

associated with cone, plate, screw, or concrete anchors. The

terms snub, deadman, and anchor log are usually associated with

pole stubs or logs set or buried in the ground to serve as

temporary anchors. The latter are often used at pull and

tension sites. Syn: anchor log, deadman, snub.

Block


A device designed with one or more single sheaves, a wood or

metal shell, and an attachment hook or shackle. When rope is

reeved through two of these devices, the assembly is commonly

referred to as a block and tackle. A set of fours refers to a

block and tackle arrangement utilizing two 4 in double sheave

blocks to obtain four load-bearing lines. Similarly, a set of

fives or a set of sixes refers to the same number of load-

bearing lines obtained using two 5 in or two 6 in double sheave

blocks, respectively. Syn: Set of fours, set of fives, set of

sixes. (Fig. 2.1, 2.2 & 2.14)

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Hold-down block

A device designed with one or more single groove sheaves to be

placed on the conductor and used as a means of holding it down.

This device functions essentially as a traveller used in an

inverted position. It is normally used in midspan to control

conductor uplift caused by stringing tensions, or at splicing

locations to control the conductor as it is allowed to rise

after splicing is completed. Syn:block, splice release; roller,

hold-down; traveler, hold-down.

Snatch Block

A device normally designed with a single sheave, wood or metal

shell, and hook. One side of the shell usually opens to

eliminate the need for threading of the line. It is commonly

used for lifting loads on a single line or as a device to

control the position or direction, or both, of a fall line or

pulling line. Syn: Skookum, Washington, Western.

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Bonded

The mechanical interconnection of conductive parts to maintain a

common electrical potential. Syn: Connected.

Bullwheel


A wheel incorporated as an integral part of a bullwheel puller

or tensioner to generate pulling or braking tension on

conductors or pulling lines, or both, through friction.

A puller or tensioner normally has one or more pairs of wheels

arranged in tandem incorporated in its design. The physical size

of the wheels will vary for different designs, but 17 in (43 cm)

face widths and diameters of 5 ft. (150 cm) are common. The

wheels are power driven or retarded and lined with single or

multiple groove neoprene or urethane linings. Friction is

accomplished by reeving the pulling line or conductor around the

groove of each pair.

Two-Conductor, Three-Conductor, Four-Conductor, Multiconductor

Bundle

A circuit phase consisting of more than one conductor. Each

conductor of the phase is referred to as a subconductor. A two-

conductor bundle has two subconductors per phase. These may be

arranged in a vertical or horizontal configuration. Similarly a

three-conductor bundle has three subconductors per phase. These

usually are arranged in a triangular configuration with the

vertex of the triangle up or down. A four-conductor bundle has

four subconductors per phase. These normally are arranged in a

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square configuration. Although other configurations are

possible, those listed are the most common. Syn:twin-bundle,

tri-bundle, quad-bundle.

Strand restraining Clamp

An adjustable circular clamp commonly used to keep the

individual strands of a conductor in place and to prevent them

from spreading when the conductor is cut. Syn: block, cable

binding; clamp, hose; clamp, plier; grip, vise.

Clearance

1 The condition in which a circuit has been deenergized to

enable work to be performed more safely. A clearance is

normally obtained on a circuit presenting a source of

hazard prior to starting work. Syn: outage, permit,

restriction.

2 The minimum separation between two conductors, between

conductors and supports or other objects, or between

conductors and ground or the clear space between any

objects.

Clipping-in


The transferring of sagged conductors from the travellers to

their permanent suspension positions and the installing of the

permanent suspension clamps. Syn:Clamping-in, clipping.

Clipping Offset

A calculated distance, measured along the conductor from the

plumb mark to a point on the conductor at which the center

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of the suspension clamp is to be placed. When stringing in

rough terrain, clipping offsets may be required to balance

the horizontal forces on each suspension structure.

Conductor

A wire, or combination of wires not insulated from one

another, suitable for carrying an electric current. It may

be, however, bare or insulated. Syn: Cable, wire.

Conductor car.


A device designed to carry workmen and ride on sagged bundle

conductors, thus enabling them to inspect the conductors for

damage and install spacers and dampers where required. These

devices may be manual or powered. Syn: Cable buggy, cable

car, spacer buggy, spacer cart, spacing bicycle. (Fig. 2.10 &

2.11)

Connector rope

A special high strength steel link used to join two lengths of

pulling rope by means of the eye splice at each end. Although

designed to pass easily through the grooves of the

bullwheels on the puller, it should not be passed under full

load. Syn: Peanut.

Crossing structure

A structure built of poles and, sometimes, rope nets. It is

used whenever conductors are being strung over roads, power

lines, communications circuits, highways, or railroads, and

is normally constructed in such a way as to prevent the

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conductor from falling onto or into any of these facilities in

the event of equipment failure, broken pulling lines, loss

of tension, etc. Syn: guard structure, H-frame, rider

structure, temporary structure.

Deenergized

Free from any electric connection to a source of potential

difference and from electric charge; not having a potential

different from that of the ground. The term is used only with

reference to current-carrying parts that are sometimes alive

(energized). To state that a circuit has been deenergized

means that the circuit has been disconnected from all

intended electrical sources. However, it could be

electrically charged through induction from energized circuits

in proximity to it, particularly if the circuits are

parallel. Syn: dead.

Dynamometer

A device designed to measure loads or tension on conductors.

Various models of these devices are used to tension guys or sag

conductors. Syn: Clock, load cell. (Fig. 2.9)

Energized

Electrically connected to a source of potential difference, or

electrically charged so as to have a potential different from

that of the ground. Syn: alive, current carrying, hot, live.

Equipotential

An identical state of electrical potential for two or more items.

Explosives

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Mixtures of solids, liquids, or a combination of the two that,

upon detonation, transform almost instantaneously into other

products that are mostly gaseous and that occupy much greater

volume than the original mixtures. This transformation generates

heat, which rapidly expands the gases, causing them to exert

enormous pressure. Dynamite and Primacord are explosives as

manufactured. Aerex, Triex, and Quadrex are manufactured in

two components and are not true explosives until mixed.

Explosives are commonly used to build construction roads, blast

holes for anchors, structure footings, etc. Syn: Aerex,

dynamite, fertilizer, power, Primacord, Quadrex, Triex.

Conductor grip


A device designed to permit the pulling of conductor without

splicing on fittings, eyes, etc. It permits the pulling of a

continuous conductor where threading is not possible. The

designs of these grips vary considerably. Grips such as the

Klein (Chicago) and Crescent utilize an open-sided rigid body

with opposing jaws and swing latch. In addition to pulling

conductors, this type is commonly used to tension guys and,

in some cases, pull wire rope. The design of the come-along

(pocket-book, suitcase, four bolt, etc.) incorporates a bail

attached to the body of a clamp that folds to completely

surround and envelope the conductor. Bolts are then used to

close the clamp and obtain a grip. Syn: buffalo; come-along;

Crescent; four bolt; grip; grip, Chicago; Kellem; Klein;

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pocketbook; seven bolt; six bolt; slip-grip; suitcase. (Fig. 2.4)

Woven wire grip

A device designed to permit the temporary joining or pulling

of conductors without the need of special eyes, links, or

grips. Syn: basket; Chinese finger; grip, wire mesh; Kellem;

sock. (Fig. 2.6 & 2.12)

Grounded

Connected to earth or to some extended conducting body that

serves instead of the earth, whether the connection is

intentional or accidental.

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Ground grid

A system of interconnected bare conductors arranged in a

pattern over a specified area either on or buried below the

surface of the earth. Normally, it is bonded to ground rods

driven around and within its perimeter to increase its grounding

capabilities and provide convenient connection points for

grounding devices. The primary purpose of the grid is to provide

safety for workmen by limiting potential differences within its

perimeter to safe levels in case of high currents that could

flow if the circuit being worked became energized for any reason

or if an adjacent energized circuit faulted. Metallic surface

mats and gratings are sometimes utilized for this same

purpose. When used, these grids are employed at pull, tension,

and midspan splice sites. Syn: counterpoise, ground gradient

mat, ground mat.

Personal ground

A portable device designed to connect (bond) a deenergized

conductor or piece of equipment, or both, to an electrical

ground. It is utilized at the immediate site when work is to be

performed on a conductor or piece of equipment that could

accidentally become energized. Syn:ground stick; ground

working; red head.

Ground rod

A rod that is driven into the ground terminal, such as a

copper-clad rod, solid copper rod, galvanized iron rod, or

galvanized iron pipe. Copper-clad steel rods are commonly used

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during conductor stringing operations to provide a means of

obtaining an electrical ground using portable grounding devices.

Syn: ground electrode.

Running Ground


A portable device designed to connect a moving conductor or

wire rope, or both, to an electrical ground. These devices are

normally placed on the conductor or wire rope adjacent to the

pulling and tensioning equipment located at either end of a sag

section. They are primarily used to provide safety for

personnel during construction or reconstruction operations.

Syn: ground, moving; ground roller; ground, rolling; ground,

traveling. (Fig. 2.13).

Structure base Ground

A portable device designed to connect (bond) a metal structure

to an electrical ground. It is primarily used to provide safety

for personnel during construction, reconstruction or maintenance

operations. Syn: ground, butt; ground chain; ground,

structure; ground, tower.

Traveller ground


A portable device designed to connect a moving conductor or

wire rope, or both, to an electrical ground. It is primarily

used to provide safety for personnel during construction or

reconstruction operations. This device is placed on the

traveler (sheave, block, etc.) at a strategic location where

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an electrical ground is required. Syn: ground, block;

ground, rolling; ground, sheave.

Hoist

An apparatus for moving a load by the application of a pulling

force and not including a car or platform running in guides.

These devices are normally designed using roller or link chain

and built-in leverage to enable heavy loads to be lifted or

pulled. They are often used to deadend a conductor during

sagging and clipping in operations and during the tensioning

of guys. Syn: Chain hoist; chain tugger; Coffing hoist;

puller, drum.

Conductor lifting hook

A device resembling an open boxing glove designed to permit

the lifting of conductors from a position above them. It is

normally used during clipping-in-operations. Suspension clamps

are sometimes used for this purpose. Syn: Boxing glove,

conductor hook, lifting shoe, lip. (Fig. 2.5)

Isolated

i) Physically separated, electrically and mechanically, from

all sources of electrical energy. Such separation may not

eliminate the effects of electrical induction.

ii) An object that is not readily accessible to persons

unless special means for access are used.

Compression joint


A tubular compression fitting designed and fabricated from

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aluminum, copper, or steel to join conductors or overhead

groundwires. It is usually applied through the use of hydraulic

or mechanical presses. However, in some cases, automatic, wedge,

and explosive-type joints are utilized. Syn:Conductor splice,

sleeve, splice.

Protector joint


A split sleeve that fits over a conductor compression joint

used to protect the joint from bending or damage if the joint

must pass through travellers. The joint protector usually has

split rubber collars at each end to protect the conductor

from damage where it exits at each end of the sleeve.

Jumper

i) The conductor that connects the conductors on opposite

sides of a deadend structure. Syn: Deadend loop.

ii) A conductor placed across the clear space between the ends

of two conductors or metal pulling lines that are being

spliced together. Its purpose, then, is to act as a shunt

to prevent workers from accidentally placing themselves in

series between the two conductors.

Tower ladder

A ladder complete with hooks and safety chains attached to one

end of the side rails. These units are normally fabricated from

fiberglass, wood, or metal. The ladder is suspended from the arm

or bridge of a structure to enable workers to work at the

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conductor level, to hang travellers, perform clipping-in

operations, etc. In some cases, these ladders are also used

as lineperson's platforms. Syn: Ladder, hook.

Insulator lifter

A device designed to permit insulators to be lifted in a string

to their intended position on a structure. Syn:Insulator saddle,

potty seat.

Bull line

A high-strength line normally synthetic fiber rope, used for

pulling and hoisting large loads. Syn: Bull rope; line pulling;

line, threading.

Finger line

A lightweight line, normally sisal, manila, or synthetic fiber

rope, that is placed over the traveller when it is hung. It

usually extends from the ground and passes through the

traveller and back to the ground. It is used to thread the end

of the pilot line or pulling line over the traveller and

eliminates the need for workmen on the structure. These lines

are not required if pilot lines are installed when the

travellers are hung. Syn: Finger rope.

Pilot rope/line

A lightweight line, normally synthetic fiber rope, used to

pull heavier pilot wire that, in turn, are used to pull the

conductor. Pilot ropes may be installed with the aid of

finger lines or by helicopter when the insulators and

travellers are hung. Syn: Leader; line, lead; line, straw;

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P-line.

Pilot wire / Pulling line


A high-strength line, normally wire rope, used to pull the

conductor. However, on reconstruction jobs in which a

conductor is being replaced, the old conductor often serves as

the pilot wire for the new conductor. In such cases, the old

conductor must be closely examined for any damage prior to the

pulling operations. Syn: Line, bull; line, hard; line, light;

line, sock; pulling rope.

Safety / life line

A safety device normally constructed from synthetic fiber rope

and designed to be connected between a fixed object and the body

belt of a worker working in an elevated position when his/her

regular safety strap cannot be utilized. Syn: Line, life; line,

safety; scare rope.

Tag line

A control line, normally manila or synthetic fiber rope,

attached to a suspended load to enable a worker to control its

movement. Syn: Tag rope.

Threading line

A lightweight flexible line, normally manila or synthetic

fiber rope, used to lead a conductor through the bullwheels of a

tensioner or pulling line through a bull wheel puller. Syn:

Line, bull; threading rope.

Connector Link

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A rigid link designed to connect pilot wires and conductors

together in series. It will not spin and relieve torsional

force. Syn: Bullet, connector, link, slug.

Swivel link

A swivel device designed to connect pilot wires and conductors

together in series or to connect one pulling line to the drawbar

of a pulling vehicle. The device will spin and help relieve the

torsional forces that build up in the line or conductor under

tension. Syn: Swivel.

OPGW

Concentric-lay-stranded composite conductor for use as overhead

groundwire with telecommunication capability. The conductor is

constructed with a central optical fiber core surrounded by

helically laid aluminum-clad wires, aluminum alloy wires,

galvanized steel wires, or combinations thereof.

Overhead Groundwire (OHGW) (Lightning Protection)

Multiple grounded wire or wires placed above phase conductors

for the purpose of intercepting direct strokes in order to

protect the phase conductors from the direct strokes. Syn:

Earth wire, shield wire, skywire, static wire.

Aerial Platform

A device designed to be attached to the boom tip of a crane or

aerial lift and support a worker in an elevated working

position. Platforms may be constructed with surrounding railings

that are fabricated from aluminum, steel, or fiber reinforced

plastic. Occasionally, a platform is suspended from the load

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line of a large crane. Syn: Cage, platform.

Lineperson's Platform

A device designed to be attached to a wood pole or metal

structure, or both, to serve as a supporting surface for

workers engaged in deadending operations, clipping-in,

insulator work, etc. The designs of these devices vary

considerably. Some resemble short cantilever beams, others

resemble swimming pool diving boards, and still others as long

as 40 ft. (12 m) are truss structures resembling bridges.

Materials commonly used for fabrication are wood, fiberglass,

and metal. Syn: Baker board, D-board, deadend board, dead-end

platform, diving board.

Plumb mark

A mark placed on the conductor located vertically below the

insulator point of support for steel structures and vertically

above the pole center line at ground level for wood pole

structures used as a reference to locate the center of

the suspension clamp.

Bullwheel Puller


A device designed to pull pulling lines and conductors during

stringing operations. It normally incorporates one or more

pairs of urethane or neoprene-lined, powerdriven, single or

multiple groove bullwheels in which each pair is arranged in

tandem. Pulling is accomplished by friction generated against

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the pulling line that is reeved around the grooves of a pair

of the bullwheels. The puller is usually equipped with its

own engine, which drives the bullwheels mechanically,

hydraulically, or through a combination of both. Some of these

devices function as either a puller or tensioner.

Syn: Puller.

Drum puller

A device designed to pull a conductor during stringing

operations. It is normally equipped with its own engine, which

drives the drum mechanically, hydraulically, or through a

combination of both. It may be equipped with synthetic fiber

rope or wire rope to be used as the pulling line. The pulling

line is payed out from the unit, pulled through the travellers

in the sag section, and attached to the conductor. The conductor

is then pulled in by winding the pulling line back onto the

drum. This unit is sometimes used with synthetic fiber rope

acting as a pilot line to pull heavier pulling lines across

canyons, rivers, etc. Syn: Hoist, hoist, single drum; tugger;

winch, single drum.

Reel puller

A device designed to pull a conductor during stringing

operations. It is normally equipped with its own engine, which

drives the supporting shaft for the reel mechanically,

hydraulically, or through a combination of both. The shaft, in

turn, drives the reel. The application of this unit is

essentially the same as that for the drum puller. Some of

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these devices function as either a puller or tensioner.

Two drum, Three drum Puller

The definition and application for this unit is essentially

the same as that for the drum puller. It differs in that this

unit is equipped with two or three drums and thus can pull

one, two, or three conductors individually or simultaneously.

Syn: Hoist, double drum; hoist, triple drum; winch, double drum;

winch, three drum; winch, triple drum; winch, two drum; tugger.

Pulling vehicle

Any piece of mobile ground equipment capable of pulling pilot

lines, pulling lines, or conductors. However, helicopters may be

considered as a pulling vehicle when utilized for the same

purpose.

Reel Stand


A device designed to support one or more conductor or groundwire

reel having the possibility of being skid,trailer, or truck

mounted. These devices may accommodate rope or conductor reels

of varying sizes and are usually equipped with reel brakes to

prevent the reels from turning when pulling is stopped. They are

used for either slack or tension stringing. The designation of

reel trailer or reel truck implies that the trailer or truck

has been equipped with a reel stand (jacks) and may serve as a

reel transport or payout unit, or both, for stringing

operations. If the reel stand is not self loading,a crane,

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forklift, or other suitable equipment is used to load the reel

into the stand. Depending upon the sizes of the reels to be

carried, the transporting vehicles may range from single-axle

trailers to semitrucks with trailers having multiple axles.

Syn: Reel Trailer, reel transporter, reel truck.

Ruling Span

A calculated span length that will have the same changes in

conductor tension due to changes of temperature and conductor

loading as will be found in a series of spans of varying lengths

between deadends.

Running Board


A pulling device designed to permit stringing more than one

conductor simultaneously with a single pulling line. For

distribution stringing, it is usually made of lightweight tubing

with the forward end curved gently upward to provide smooth

transition over pole crossarm rollers. For transmission

stringing, the device is either made of sections hinged

transversely to the direction of pull or of a hard nose

rigid design, both having a flexible pendulum tail suspended

from the rear. This configuration stops the conductors

from twisting together and permits smooth transition over the

sheaves of bundle travellers. Syn: Alligator, bird, birdie,

equilizer pully, monkey tail, sled. (Fig. 2.7)

Sag

The distance measured vertically from a conductor to the

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straight line joining two points of support. Unless otherwise

stated, the sag referred to is at the midpoint of the span.

Sag Section

The section of line between snub structures. More than one sag

section may be required in order to sag properly the actual

length of conductor that has been strung. Syn: Pull setting,

stringing section.

Sag Span

A span selected within a sag section and used as a control to

determine the proper sag of the conductor, thus establishing

the proper conductor level and tension. A minimum of two, but

normally three, sag spans are required within a sag section in

order to sag properly. In mountainous terrain or where span

lengths vary radically, more than three sag spans could be

required within a sag section. Syn: Control Span.

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Self-damping Conductor (SDC)

ACSR that is designed to control aeolian vibration by integral

damping. Trapezoidal aluminum wires and annular gaps are

utilized. (Fig.2.3)

Shaped wire compact Conductor(TW)

ACSR or AAC that is designed to increase the aluminum area for a

given diameter of conductor by the use of trapezoidal shaped

aluminum wires.

Sheave

1) The grooved wheel of a traveller or rigging block.

Travelers are frequently referred to as sheaves. Syn:

Pulley, roller, wheel, traveller.

2) A shaft-mounted wheel used to transmit power by means of

a belt, chain, band, etc.

Pull Site

The location on the line where the puller, reel winder, and

anchors (snubs) are located. This site may also serve as the

pull or tension site for the next sag section. Syn: Reel setup,

tugger setup.

Tension Site

The location on the line where the tensioner, reel stands, and

anchors (snubs) are located. This site may also serve as the

pull or tension site for the next sag section. Syn:

Conductor payout station, payout site, reel setup.

Snub Structure

A structure located at one end of a sag section and considered Vol.5 : Page #

as a zero point for sagging and clipping offset calculations.

The section of line between two such structures is the sag

section, but more than one sag section may be required in order

to sag properly the actual length of conductor that has been

strung. Syn: O structure, zero structure.

Wire rope Splice

The point at which two wire ropes are joined together. The

various methods of joining (splicing) wire ropes together

include hand tucked woven splices, compression splices that

utilize compression fittings but do not incorporate loops (eyes)

in the ends of the ropes, and mechanical splices that are made

through the use of loops (eyes) in the ends of the ropes held in

place by either compression fittings or wire rope clips. The

latter are joined together with connector links or steel bobs

and, in some cases, are rigged eye to eye. Woven splices are

often classified as short or long. A short splice varies in

length from 7 to 17 ft. (2 to 5 m) for 0.25 to 1.5 in (6 to 38

mm) diameter ropes, respectively, while a long splice varies

from 15 to 45 ft. (4 to 14 m) for the same size ropes.

Splicing Cart

A unit that is equipped with a hydraulic compressor (press) and

all other necessary equipment for performing splicing

operations on conductor. Syn: Sleeving trailer, splicing

trailer, splicing truck.

Steel Supported Aluminum Conductor (SSAC)

ACSR with the aluminum wires annealed.

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Step Voltage

The potential difference between two points on the earth's

surface separated by a distance of one pace (assumed to be 1

m) in the direction of maximum potential gradient. This

potential difference could be dangerous when current flows

through the earth or material upon which a worker is standing,

particularly under fault conditions. Syn: Step Potential.

Stringing

The pulling of pilot lines, pulling lines, and conductors over

travellers supported on structures of overhead transmission

lines. Quite often, the entire job of stringing conductors is

referred to as stringing operations, beginning with the planning

phase and terminating after the conductors have been installed

in the suspension clamps.

Slack Stringing

The method of stringing conductor slack without the use of a

tensioner. The conductor is pulled off the reel by a pulling

vehicle and is dragged along the ground, or the reel is

carried along the line on a vehicle and the conductor is

deposited on the ground. As the conductor is dragged to, or

past, each supporting structure, the conductor is placed in

the travelers, normally with the aid of finger lines.

Tension stringing

The use of pullers and tensioners to keep the conductor under

tension and positive control during the stringing phase, thus

keeping it clear of the earth and other obstacles that could

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cause damage.

Switching Surge

A transient wave of overvoltage in an electrical circuit caused

by a switching operation. When this occurs, a momentary voltage

surge could be induced in a circuit adjacent and parallel to

the switched circuit in excess of the voltage induced normally

during steady state conditions. If the adjacent circuit is

under construction, switching operations should be minimized

to reduce the possibility of hazards to the workmen.

Sag Target

A device used as a reference point to sag conductors. It is

placed on one structure of the sag span. The sagger, on the

other structure of the sag span, can use it as a reference to

determine the proper conductor sag. Syn: Sag board,target

Bullwheel Tensioner


A device designed to hold tension against a pulling line or

conductor during the stringing phase. Normally, it consists of

one or more pairs of urethane or neoprenelined, power-braked,

single or multiple groove bullwheels in which each pair is

arranged in tandem. Tension is accomplished by friction

generated against the conductor that is reeved around the

grooves of a pair of the bullwheels. Some tensioners are

equipped with their own engines, which retard the bullwheels

mechanically, hydraulically, or through a combination of both.

Some of these devices function as either a puller or

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tensioner. Other tensioners are only equipped with friction

type retardation. Syn: Brake, retarder, tensioner.

Touch Voltage

The potential difference between a grounded metallic structure

and a point on the earth's surface separated by a distance equal

to the normal maximum horizontal reach, approximately 3 ft. (1

m). This potential difference could be dangerous and could

result from induction or fault conditions, or both. Syn: Touch

Potential.

Transit

An instrument primarily used during construction of a line to

survey the route, to set hubs and point on tangent (POT)

locations, to plumb structures, to determine downstrain angles

for locations of anchors at the pull and tension sites, and to

sag conductors. Syn: Level, scope, site marker.

Traveller


A sheave complete with suspension arm or frame used separately

or in groups and suspended from structures to permit the

stringing of conductors. These devices are sometimes bundled

with a center drum or sheave and another traveler, and are

used to string more than one conductor simultaneously. For

protection of conductors that should not be nicked or

scratched, the sheaves are often lined with nonconductive or

semiconductive neoprene or non-conductive urethane. Any one

of these materials acts as a padding or cushion for the

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conductor as it passes over the sheave. Traveller grounds

must be used with lined travellers in order to establish

an electrical ground. Syn: Block, dolly, sheave, stringing

block, stringing sheave, stringing traveller. (Fig. 2.8)

Traveller Sling

A sling of wire rope, sometimes utilized in place of

insulators, to support the traveller during stringing

operations. Normally, it is used when insulators are not

readily available or when adverse stringing conditions

might impose severe downstrains and cause damage or complete

failure of the insulators. Syn: Choker.

Uplift roller


A small single-grooved wheel designed to fit in or

immediately above the throat of the traveller and keep the

pulling line in the traveller groove when uplift occurs due to

stringing tensions. (Fig. 2.15)

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Reel winder

A device designed to serve as a recovery unit for a pulling

line. It is normally equipped with its own engine, which drives

a supporting shaft for a reel mechanically, hydraulically, or

through a combination of both. The shaft, in turn, drives the

reel. It is normally used to rewind a pulling line as it

leaves the bullwheel puller during stringing operations. This

unit is not intended to serve as a puller, but sometimes

serves this functions where only low tensions are involved. Syn:

Takeup Reel.

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Chapter-3

Stringing Methods & General Aspects

______________________________________________________________________

CHAPTER THREE

______________________________________________________________________

Stringing Methods & General Aspects


3.1 Methods of stringing .


There are basically two methods of stringing. These are

i) Slack or Manual methods

ii) Tension method

3.1.1 Manual method :


Using this method, the conductor is pulled along the

ground by means of a pulling vehicle,or the drum is

carried along the line on a vehicle and the conductor

is deposited on the ground. The conductor drums are

positioned on drum stands or jacks, either placed on

the ground or mounted on a transporting vehicle. These

stands are designed to support the drum on an arbor,

thus permitting it to turn as the conductor is pulled

out. Usually, a braking device is provided to

prevent overrunning and backlash. When the conductor

is dragged past a supporting structure, pulling is

stopped and the conductor is placed in travelers

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attached to the structure before proceeding to the

next structure.

This method is chiefly applicable to the construction

of new lines in cases in which maintenance of

conductor surface condition is not critical and where

terrain is easily accessible to a pulling vehicle. The

method is not usually economically applicable in urban

locations where hazards exist from traffic or where

there is danger of contact with energized circuits,

nor it is practical in mountainous regions

inaccessible to pulling vehicles.

3.1.2 Tension Method :


Using this method, the conductor is kept under

tension during the stringing process. Normally, this

method is used to keep the conductor clear of the

ground and obstacles, which might cause conductor

surface damage and clear of energized circuits. It

requires the pulling of a light pilot line into the

travelers, which in turn is used to pull in a heavier

pulling line. The pulling line is then used to pull

in the conductors from the drum stands using specially

designed tensioners and pullers. For lighter

conductors, a lightweight pulling line may be used in

place of the pilot line to directly pull in the

conductor. A helicopter or ground vehicle can be used

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to pull or lay out a pilot line or pulling line.

Where a helicopter is used to pull out a line,

synthetic rope is normally used to attach the line

to the helicopter and prevent the pulling or pilot

line from flipping into the rotor blades upon release.

The tension method of stringing is applicable where it

is desired to keep the conductor off the ground to

minimize surface damage or in areas where frequent

crossings are encountered. The amount of right-of-way

travel by heavy equipment is also reduced. Usually,

this method provides the most economical means of

stringing conductor. The helicopter use is

particularly advantageous in rugged or poorly

accessible terrain.

3.2 Grounding during stringing


3.2.1 Introduction :


For any given situation, the bonding together of all

equipment and electrical grounds in a common array is

of major importance. However, such bonding offers no

assurance that a hazardous potential will not exist

between the bonded items and the earth. It is

impractical to design a grounding system precisely

around available fault currents or calculated effects.

Such a design would require precise knowledge of

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many variables and would result in a different

grounding scheme for each location.

The degree of grounding protection required for a

given construction project is dependent upon the

exposure to electrical hazards that exist within the

project area. For a project remote from other lines

and at a time of low probable thunderstorm activity,

minimal grounding requirements are in order. Minimum

grounding requirements include bonding and grounding

of all machines involved in stringing of the

conductor, pulling line, or pilot line. In addition,

running grounds should be installed on all conductive

lines in front of the pulling and tensioning

equipment.

On the contrary, for a project in congested area with

exposure to numerous parallel lines and crossing

situations, and with probability of thunderstorm

activity and adverse weather conditions, extensive

grounding requirements are called for. Historically,

the most significant hazard results from work in

proximity to energized lines. Under any circumstance,

in addition to open jumpers, grounding and other

protective measures must be employed to ensure

reasonable and adequate protection to all personnel.

In addition to the grounding system, the best

safety precaution is to respect all equipment as if it

could become energized. The degree of protection Vol.5 : Page #

provided for a specific project must be a decision of

project supervision based on a clear understanding

of the potential hazards.

3.2.2 Source of Hazards :


Electrical charges may appear on a line due to one or

more of the following factors.

i) Charges induced on the line by a

neighboring energized line.

ii) A fault caused by an accidental contact or

flashover between the line and a neighboring

energized line.

iii) Induced static charge due to atmospheric

conditions.

iv) An error in which the line is accidentally

energized.

v) A lightning strike to the line.

3.2.3 Grounding procedure :


Grounding cables must be connected to the ground

source first, then to the object being grounded. When

removing grounds, the ground must be removed from the

grounded object first and then from the ground source.

The object being grounded should not be teased with

the ground clamp. The clamp must be poised by the

object, snapped on quickly and firmly, and tightened.

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If an arc is drawn, the clamp should not be withdrawn,

but should be kept on the conductor, thus grounding

the line.

3.3 Communications


3.3.1 Slack stringing requires a minimum of communications.

It is, however, desirable to have communication

between the pulling vehicle and the personnel at the

drum location.

3.3.2 Tension stringing requires good communications

between the personnel at the tensioner end and those

at the puller end and at intermediate check points

at all times during the stringing operation. During

the stringing of bundled conductors with a running

board, it is desirable to observe the running board

as it passes through each traveler. The running

board observer(s) should have reliable communications

with both pulling and tensioning ends. When following

the board from the ground is not practical, this can

be accomplished with the aid of helicopters.

3.3.3 During helicopter stringing of the pilot line or

conductor, reliable radio contact with all ground

work sites is extremely important.

Dual or backup systems of communication, with a

dedicated single-use frequency, should be available in

case one system fails, particularly during the actual

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stringing operation.

3.4 Special requirements for mobile equipment :


3.4.1 Drum or reel Stand.


Drum stands are designed to be used with tensioners to

supply the necessary back tension to the conductor.

The stand(s) are selected to accommodate the conductor

(or groundwire) reel dimensions and gross weight.

Some drums are not designed to withstand the forces

developed by braking during tension stringing

operations. Direct tension stringing from the drum at

transmission line stringing tensions should not be

attempted. The conductor may be pulled directly from

the drum stand when employing slack stringing methods.

If the drum stand is not self loading, a crane,

forklift, or other suitable equipment is used to load

the drum into the stand.

3.4.2 Tensioner Bullwheel Characteristics.


The depth, Dg, and flare of grooves in the bullwheels

are not critical. Semicircular grooves with depths in

the order of 0.5 or more times the conductor diameter

and with flare angles in the order of 5° to 15° from

the vertical generally have been found to be

satisfactory.

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The number of grooves in the bullwheel must be

sufficient to prevent the outer layer of wires of

multilayer conductors from slipping over underlying

layers. The minimum diameter of the bottom of the

grooves, Db, should be 30 to 40 times the diameter of

conductor. Details are shown in fig - 3.1.

Tandem bullwheels should be so aligned that the

offset will be approximately one-half the groove

spacing. For normal conductors having a right-hand

direction of lay for the outer wires, bullwheels

should be arranged so that, when facing in the

direction of pull, the conductor will enter the

bullwheel on the left and pull off from the right side

as shown in fig. 3.1. For any conductors having a

left hand direction of lay for the outer wires, the

conductor should enter on the right and pull off from

the left. This arrangement is necessary to avoid any

tendency to loosen the outer layer of strands as the

conductor passes over the bullwheels. Similarly

stranded conductor or wire should be wound on a drum

according to the lay and direction of travel. Note

the convenient thumb rule as shown in Fig.3.2.Clench

the hand into a fist, with the thumb and index finger

protruding. Use the right hand for right lay and the

left hand for left lay. The clenched fingers

represent the barrel and the index finger the

direction of pull off. The thumb points to the Vol.5 : Page #

proper attachment site.

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The material and finish of the grooves must be such

as not to mar the surface of the conductor. Elast-

omer lined grooves are recommended for all

conductors, but are particularly important for

nonspecular conductors. Should a semiconducting

elastomer be used for lining the grooves, it should

not be relied upon for grounding.

Difficulties have been experienced with single V-

groove type bullwheels on some multilayer and special

construction conductors. These types of bullwheels

should only be used with the concurrence of the

conductor manufacturer.

3.4.3 Puller and tensioner operating characteristics.


The pulling and braking systems should operate

smoothly and should not cause any sudden jerking or

bouncing of the conductor. Each system should be

readily controllable and capable of maintaining a

constant tension.

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Pullers and tensioners may be mounted separately or in

groups for bundled conductor installation. The

controls should allow the independent adjustment of

tension in each conductor. It is recommended that the

tensioner have an independently operated set of

bullwheels for each subconductor when stringing

bundled conductor, particularly when more than two

subconductors per phase are being installed. Pullers

should be equipped with load indicating and limiting

devices. The load limiting device should automatically

stop the puller from acting further if a preset

maximum load has been exceeded. Tensioners should be

equipped with tension indicating devices.

Capacity selection of the puller and tensioner is

dependent upon conductor weight, the length to be

strung, and the stringing tensions. The capacities of

the puller and tensioner should be based on the

conductor, span length, terrain, and clearances

required above obstructions. In general, stringing

tensions will be about 50% of sag tensions. Sag

tensions should never be exceeded during stringing.

There are basically two types of pulling machines

used in the construction of transmission lines being

strung under tension. These are defined as bullwheel

and drum type or reel type pullers. Some drum-type or

reel type pullers are available with level wind

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features to provide uniform winding of the line. Some

drum-type and all reel-type pullers provide easy

removal of the drum (or reel) and line to facilitate

highway mobility. This feature also provides the

advantage of interchangeability of drums. The control

of payout tension of the pulling line is a desirable

feature of many pullers. Mobility of the pullers and

tensioners is important to minimize downtime between

pulls. Also critical are the setup and leveling

features of the units.

3.5 Travelers


3.5.1 Diameter. It is generally recognized that as sheave

diameters are made larger, the following advantages

are gained:

(i) The radius bending of the conductor is increased,

so the amount of strain and the amount of

relative movement between individual wires in

the conductor are reduced. This, in turn, reduces

the amount of energy required to bend and

straighten the conductor as it passes through the

travelers. The force and energy required for

such bending and straightening regards the

passage of the conductor in much the same way as

friction in the bearing of the travelers.

(ii) The bearing pressures between conductor strand

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layers are reduced, thus reducing potential

conductor internal strand damage. This is

commonly known as strand notching.

(iii)The force required to overcome friction in the

bearings is reduced because of the greater moment

arm for turning.

(iv) The number of rotations and speed of rotation

are reduced, so wear on the bearings and grooves

is alleviated.

(v) The obvious disadvantages of larger sheaves are

cost and added weight.

The minimum sheave diameter, Ds, at the bottom of

the groove, as shown in Fig 3.3, should be

satisfactory for typical conductor stringing

operations. However, for stringing conductors in

excess of approximately 3km or over substantially

uneven terrain, the recommended minimum bottom

groove diameter of sheaves is (20 Dc-4) inches

([20Dc-10]cm) orlarger, where Dc stands for

conductor diameter. In exceptionally arduous

circumstances, accurate sagging may some times

be very difficult with sheaves having diameters

of less than 19 Dc or 20 Dc.

3.5.2 Configuration of Groove.

The minimum radius at the base of the groove, Rg, is

recommended to be 1.10 times the radius of the

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conductor as shown in Fig 3.3.

Sheaves having a groove radius as discussed above

may, with limitations, be used with smaller

conductors. The limitations relate to the number of

layer of aluminum wires in the conductor. The more

layers of aluminum wires, the more important it is to

support the conductor with a well-fitting groove.

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The depth of groove, Dg, should be a minimum of 25% greater than

the diameter of the conductor. The sides of the groove

should flare between 12° and 20° form the vertical to

facilitate the passage of swivels, grips etc., and to

contain the conductor within the groove, particularly

at line angles.

3.5.3 Bearings.

The bearings should preferably be ball or roller type

with adequate provisions for lubrication and

shielding against contamination. The lubricant must

be suitable for the temperature range involved; and,

where sealed bearings are not used, care should be

taken to ensure subsequent lubrication with the same

type of grease. Mixing of greases of different types

(that is, lithium base and calcium base) may cause

degradation of the lubricant and subsequent bearing

failure. Bearings should have sufficient capacity to

withstand running or static loads without damage.

Proper maintenance is essential.

3.5.4 Material and Construction.

Travelers may be of any suitable material, with due

consideration given to weight. Unlined sheaves for

stringing aluminum conductors should be made of

aluminum or magnesium alloy, and the grooves should

have a smooth, polished finish. It is recommended

that the manufacturer's safe working load, or other

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identification to enable determination of such load,

be permanently displayed on the traveler. Always

ensure that the manufacturer's safe working load for

the traveler is not exceeded. This is particularly

important for situations in which travelers are used

on heavy line angles or on the first or last towers

at which the conductor comes to ground level.

Maximum loads usually will result when the conductor

is being pulled up to sag tensions.

It is recommended that clearances between the sheave

(s) and frame, particularly in the traveler throat

area, be kept as small as possible. This will prevent

the pilot line from jamming should the pilot line

come out of the pulling line sheave. It is

recommended that the vertical throat opening of the

stringing block be kept as small as possible while

still allowing the safe passage of the pulling line,

swivels, and the running board. This practice will

minimize the distance the conductors need to be

lifted during the clipping-in operation.

For bundle conductor configurations, the traveler

frame and shaft should be sufficiently sized so that

deflection due to load, particularly during the

sagging operation, does not cause adjacent sheaves to

contact. Excessive deflection can cause difficulty

in sagging individual conductors.

3.5.5 Lining. Vol.5 : Page #

While grooves may be unlined or lined, lining with

elastomer provides cushioning to increase bearing area

and precludes damage to the conductor from scratched

or marred groove surfaces. Steel pulling lines are

likely to scratch or mar the surface or unlined

grooves; therefore, when such lines are to be used in

the same groove as conductor, grooves definitely

should be lined. It is generally recommended that all

sheaves be lined. It is recommended that the total

surface of the groove, including the top lip, be

lined to give maximum protection to the conductor.

The elastomer used for sheave linings should be

capable of withstanding all anticipated temperatures

without becoming brittle or developing semipermanent

flat areas. It should be sufficiently hard to

prevent the conductor from climbing up the side of

the groove.

3.5.6 Electrical Characteristics.

Neither lined nor unlined travelers should be relied

on for grounding the conductor being installed.

Greased bearings do not provide necessary conductivity

and may be damaged by relatively small currents

passing from the sheave to the body of the traveler.

Semiconductive linings, commonly referred to as

conductive linings, tested to date are reported burned

with currents as low as 20 mA.

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The induced electrical charges on conductor and

pulling lines, particularly when stringing in the

proximity of energized lines, must be drained off

with traveler grounds that bypass the linings or

greased bearings, or both. Traveler grounds provide a

means to bypass electrically the sheaves and ground

the conductor directly to a ground source. After any

grounding device has experienced fault current, it

should not be used.

3.5.7 Bundled Configurations.

Bundle conductor type travelers for stringing two or

more subconductors simultaneously require special

considerations. When even numbers of conductors are

strung, a symmetrical arrangement may be used with an

equal number of conductors on each side of the

pulling line. An independent center sheave is

provided only for the pulling line and should be of

suitable material to withstand the abrasion of the

pulling line.

When odd numbers of subconductors are strung, the

center one could follow the pulling line in the center

sheave. However, this is usually not desirable

because of the material of the groove or because of

contaminants deposited in this groove by the

pulling line, or because of both. Offset-type bundle

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conductor travelers are used that balance the load by

properly spacing the even and odd number(s) of

conductors on each side of the pulling force.

These travelers are directional and should be color-

coded. Care should be taken to ensure their proper

orientation.

When multiple conductors are strung in bundled

conductor type travelers, reduced horizontal

spacing between grooves can result in conductor

oscillation, even in a very light crosswind, too

severe to permit satisfactory sagging. (For

example, groove spacing of 5.4 conductor diameters

permitted sagging of conductors in a crosswind

condition that repeatedly prevented sagging with a

groove spacing of 2.7 conductor diameters because

of very active conductor oscillation.)

When stringing multiple conductors around line angles

in excess of 5°, bundle conductor travelers are

required until the running board passes through the

traveler, but should be replaced prior to sagging

with single-type travelers to provide proper wire

length in the clipped-in position. It is desirable

during sagging for the horizontal spacing of the

sheaves to match the final subconductor spacing to

aid in preventing subconductor sag mismatch.

Some bundle conductor travelers may be converted to

single conductor type travelers. Vol.5 : Page #

Multisheave bundle conductor type travelers and

running boards must be designed to complement each

other and work in unison. Running boards should only

be used to pull in conductors. They should be not

used to line up the conductors with an anchor (that

is, running boards should be not pulled sideways.)

Running boards should have their safe working load

displayed. It is recommended that all running boards

and swivel links be proof tested to 50% over the safe

working load. During stringing, normal pulling

speeds should be maintained when the running board

approaches a traveler.

3.5.8 Helicopter Travelers.

Helicopter travelers utilize outrigger arms that

guide the pilot line into the throat area of the

traveler. These outriggers are usually brightly

painted to be easily seen from the air. Spring-

loaded gates are employed to contain the line. For

bundle conductor travelers, additional guides may be

utilized to funnel the lines into the proper groove.

The design of helicopter travelers should be such

that personnel are not required on the structure

during placement of the pilot line. After initial

placement of the line by helicopter, normal stringing

practices are employed.

Helicopter travelers are directional, and care must Vol.5 : Page #

be exercised to orient them properly on the

structures. Due to the rotor wash of the helicopter ,

if the attachment method of travelers does not

prevent twisting, yaw bars should be utilized for

this purpose.

Some standard travelers may be converted to

helicopter type by the addition of accessory parts.

3.5.9 Uplift Rollers and Hold-Down Blocks.

Uplift rollers that attach to the traveler or hold-

down blocks that are separate devices must be used at

positions where uplift might occur. Uplift can occur

with the pulling line during the stringing operation,

due to its higher tension to weight ratio and, thus,

much flatter sag. This condition is most likely to

occur in hilly terrain at the towers in the low

points of the pull. Hold-down blocks or uplift

rollers should be used in these cases. Since the

uplift condition will normally stop when the

conductors(s) arrive, hold-down blocks that can be

removed prior to the arrival of the conductor(s)

without stopping the pulling should be used. Uplift

devices that attach to bundle travelers are usually

directional, and are usually positioned towards the

pulling end. These devices should have a

breakaway feature in the event of fouling of the

pulling line or incorrect installation.

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Chapter-4

Stringing Procedure

______________________________________________________________________

CHAPTER FOUR

______________________________________________________________________

STRINGING PROCEDURE


4.1 Steps of stringing :


The stringing procedure is broadly divided into the

following steps.

i) Paying out & stringing of earth wire.

ii) Paying out & stringing of conductor.

iii) Final sagging of earthwire & conductor.

iv) Regulation.

v) Clipping and fixing of accessories.

4.2 Stringing of Earthwire


4.2.1 Paying out of earthwire


Normally stringing of earthwire is done manually

since handling the earthwire is easy and it does not

get damaged easily. First, earthwire rollers are

provided on the earth peaks of all the suspension

towers in the section. Before hoisting of earthwire

rollers, it may be ensured that the rollers are free Vol.5 : Page #

from friction. This will ensure correct sag as

measured during sagging operation to be available

after transferring to the suspension clamp. A

lineman/ fitter may be kept on each tower to

ensure free running of the rollers with a red &

green flag and whistle.

At the starting end of a section, earthwire reel is

mounted on roller jacks or horizontal turn table.

The earthwire is pulled from tower to tower manually

or by using a tractor. After reaching the next tower

the earthwire is passed through the suspended

earthwire rollers with the help of a polypropylene

rope and paying out is continued further. Care should

be taken that the earthwire is not pulled over

rocks, stones, boulders etc. to avid scratches on its

surface.

After one length of earthwire reel is exhausted, the

second length of wire is paid out for the balance

section. Midspan joint for earthwire is compressed

on the ground joining the two lengths.

4.2.2 Jointing of earthwire :


Midspan joints for earthwire consists of a galvanised

MS tube with internal diameter matching with the

outer diameter of earthwire. An aluminum sleeve is

provided over the MS sleeve with end plugs as a

Vol.5 : Page #

protective cover to avoid rusting. Relevant approved

drawings are referred for the details.

The aluminium sleeve and one plug are first inserted

through one end of the earthwire. The other plug and

steel sleeve are inserted to the other end. The

cutting of the earthwire is done after gripping the

earthwire with binding wire say 25 mm away from the

edge. The binding wire shall be removed after the

edge is inserted into the tube.

The cut edge of the wire shall be free from burring of

edges. The ends of the wires are inserted into the sleeve

equal in length from both sides. This can be ensured

by marking half the length of the steel sleeve on

both ends of the earthwire. The compression is done

with the help of a hydraulic compressor using suitable

sized dies to a compression of 100 T/sqare inch. The

compression should start from the centre of the tube

and continued progressively outwards. After

compressing the steel portion, the length & cross

section of the compressed portion shall be checked

for elongation and dia as recommended by the

manufacturer.

All sharp edges on the surface of the joint shall be

filed off and smoothened. The aluminum sleeve is

passed over steel portion and end plugs are inserted

at both ends. The compression is done with suitable

Vol.5 : Page #

size dies similarly as explained above for steel

portion and the surface is smoothened and length &

cross section of the compressed joint verified with

drawings.

Similar practice is used for compression of dead end

cone and earthwire jumper cones. In case any crack in

any one of the 7 strands is observed, a joint should

be provided. Any sharp kink in the earthwire should

be cut and joined with a midspan joint.

4.2.3 Sagging and final tensioning


After paying out the earthwire over the length of the

section, one end of the earthwire is connected to the

earth peak of the tower with compressed dead end

cone.

From the tension tower on the other side of the

section, the earthwire is pulled to a rough tension

less than final tension. By holding the earthwire at

this tension on the ground, bolted come-along clamps

are fixed to the earthwire at a distance of about 60

mtrs (depending on the rough sag condition and height

of tower this may be varied) from the sagging tower.

The come-along clamp is connected with 10 or 12mm

dia steel wire rope through a set of two sheave

pulleys and the wire rope is passed through a set of

single sheave pulleys along the body of the tower to

Vol.5 : Page #

a hand operated winch installed on the leg of the

tower. The earthwire is tensioned by pulling the wire

rope initially by a Tractor until approximate sag is

achieved. Finally, the rope is pulled through the

hand winch to the correct sag of the earth wire. The

free end of the earthwire hanging from the come-along

clamp is picked up and passed through a pulley placed

on the earthwire peak of the tower.

The free end is pulled along the catenary curve of

wire rope from the come-along clamp to the earth

peak making provision for the length of tension clamp

with dead end cone. This point is marked by an

adhesive tape/wire and the free end of the wire

is brought down. The earthwire is cut at the marking

and the dead end cone is compressed. The compressed

cone is hoisted to the earthwire peak by

connecting a polypropylene rope passed through

pulley at the earthwire peak.

The hand winch is further tightened to pull up some

more earthwire length to facilitate bolting of the

tension cone to the earth peak. The hand winch is

released and the pulleys wire ropes and come-along

clamps are removed. Suitable adjustment in the aerial

roller can be done to equalize the length or any

difference can be considered while measuring the sag

board elevation. The method of sagging by placement

of sag board is explained in the sagging operation of Vol.5 : Page #

conductor which in principle is similar and can be

adopted for the earthwire also.

4.2.4 Clipping


After final sagging is completed, the earthwire has

to be transferred from the aerial rollers on the

suspension towers to the earthwire suspension clamps.

The point where the earthwire touches the aerial

roller pulley is marked for fixing the suspension

clamp in correct vertical position.

The earthwire is lifted from roller by means of a

ratchet hoist/pull lift from the earthwire peak of

the tower and roller is removed. The earthwire clamp

is fixed to the tower body by D shackle and then the

centre of the earthwire clamp is matched with the

marked point of the earthwire. The saddle of the

clamp is tightened with U bolts. The lever hoist is

released to let the earthwire freely hang in the

suspension clamp.

It should be ensured that the length of the

suspension clamp from the suspension cotter of the

earthwire peak to the saddle where earthwire finally

rests should be equal to the length of the aerial

roller from cotter of earthwire peak to the top side

groove of the pulley wheel.

4.2.5 Fixing of hardware accessories

Vol.5 : Page #


Earthwire is provided with stock bridge type

vibration dampers. The no. of dampers to be fixed

on either side of the tension/suspension tower and

the distance from the suspension clamp/tension cone

is adopted as per manufacturer's recommendations

depending upon the span length. The operation of

fixing of vibration dampers should be taken up

immediately after fixing of suspension clamps.

Flexible copper bonds are provided to connect the

earthwire to the tower body, to improve conductivity

to earth. For each suspension/tension clamp one FCB

is provided. As copper bond is theft prone, it is

better if this is fixed just before charging of line.

At tension towers, the tension clamps on both sides

of earthwire peak are joined by an earthwire jumper,

compressed at both ends by galvanised jumper cone

for maintaining the continuity of the earthwire

between the two substations.

The length of the earthwire reels normally

manufactured is around 2000 mtrs. For stringing in

normal sections, midspan joints are used in reaches

exceeding 2000 mtrs length. But in river crossing

sections for major rivers, the midspan joint in

earthwire is not recommended due to the difficulty in

restringing in case of failure of joint. Special

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reels of about 4000 mtrs length have to be procured

for this purpose.

4.3 Stringing of conductor


4.3.1 Guying of Towers


Before commencement of stringing, the angle towers

where the stringing is to be started have to be

provided with guy supports for all the three phases.

The guys used generally are 20mm steel wire rope. The

guys are attached to the tower at the tip of the

cross arms and centre of the bridge, to the strain

plates with suitable D shackles.

The guys are anchored in the ground at an angle of 45

degrees or less from the horizon, attached to dead

end anchors. For making dead end anchors in the

ground, pits of 1.5mx0.6m, for a depth of 1.5m can be

dug. A set of steel beam and channels as shown in

fig.4.1 tied in the centre with 16mm wire rope, is

lowered and the pit is back filled while compacting.

The guy wire is attached to the dead end anchor wire

with the help of turn buckles of 10 tonnes capacity.

Alternately, instead of burried ground anchors, a

dead weights of sag 5 to 10 tonnes can be placed on

the ground and sag wire attached to them securely.

After pulling up the slackness in the guy, it is

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tightened by the turn buckle. Excessive tightening of

the guy should be avoided. It is advisable to tighten

the guy progressively at the time of rough sagging of

the conductor.

4.3.2 Insulator hoisting :


4.3.2.1 Transportation of Insulators

The required no. of insulators shall be transported

to the tower locations with the wooden packing.

In case the packing is found to be worn out, fresh

packing has to be done in order to avoid damages

during transport.

The crates shall be opened at the tower location. The

Insulator hoisting is done well in advance of

commencement of paying out operation. Hence,

transport should be completed before commencement of

paying out.

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In 400 KV S.C suspension towers, single suspension I string

120 KN disc Insulators are used. For middle phase,

we use V strings consisting of 2 strings of 90 KN

insulators suspended from both ends of the bridge and

joined in the centre by Yoke plate. Recently, V

strings for all the three phases are being used in

400KV single and double circuit suspension towers.

For tension towers, double tension string is used.

All the insulator strings consist of 23 no. of discs

in series. At major river crossings for suspension

towers double suspension strings are being utilised

for reasons of more safety.

4.3.2.2 Hoisting

After opening of the crates, insulators shall be laid

in series, on wooden planks below the suspension

points. The insulators shall be cleaned with water

and wiped dry with clean cloth free from grease and

oil. Insulators shall be checked for any chipping or

crack and shall be replaced with new one if found

defective. The no. of insulators required for string

shall be joined and `R' clips in the clevis shall be

expanded to avoid slippage of the pin. 4 to 6

insulators are generally joined at the manufacturer's

works and packed in a crate. The joints of all

insulators should be checked and `R' clips should be

expanded. If any `R' clip is missing, the same is to

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be made good. The hardware of the string on the tower

side is assembled and joined to the first insulator

by ball eye. The details of hardware fitting for

suspension fitting are given in fig 4.2. The bottom

insulator is joined to the twin moose aerial roller.

The 3 wheels of the aerial rollers should be checked

for free running.

The neoprene rubber cushion on the outer rollers

shall be checked for any cracks/wearing out and shall

be changed if required.

As mentioned earlier the position of the conductor in

the centre of suspension clamp of the fitting shall

be matching with the position in the roller grooves.

Necessary adjustment shall be made in the length of

the aerial roller connector as required.

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A single sheave pulley is fixed to the cross arm very near to

the suspension hanger. A 20 mm polypropylene rope is

passed through the pulley and both the ends are

brought to the ground. One end of the rope is

firmly tied below the 3rd or 4th insulator. The

complete string with aerial roller is lifted up by

pulling the rope through a pulley attached to one of

the tower legs by using tractor/manually. Fig.4.3

shows the hoisting of insulators with tension

fittings. After reaching the top the string is

attached to the suspension hanger and string is

released slowly to hang free.

In hoisting the V string for centre phase, the method

is in general same but 2 pulleys are to be attached

near the suspension point of the V string and a rope

is attached to pull side ways and keep the string

away from the tower until it is clear of the the

waist level. Before hoisting of the V string, both

the strings are joined in the centre by yoke plate

and the aerial roller is suspended from the centre of

the yoke plate.

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4.3.3 Paying out of pilot wire


In tension stringing, a pilot wire is used to pull

the conductor. The pilot wire is initially laid

through the centre wheel of the aerial roller.

A 12 mm dia pilot wire is generally used for pulling

of twin moose ACSR conductor. The pilot wire can be

laid length by length and joined with pilot wire

connectors or it can be pulled from one side of the

section after each drum is paid out.

At power line crossings, the pilot wire is laid from

both sides and free ends are joined after obtaining

the shutdown of the powerline. Scaffoldings shall be

provided for P&T and road crossings before paying out

of the pilot wire.

4.3.4 Position of tensioner and puller :


The paying out of conductor is done generally between

two tension towers. The puller machine can be

positioned behind the tension tower on one side and

the tensioner in front of the tension tower on the

other side. The entry of the pilot wire into the

bull wheels of the puller machine and running out

from tensioner machine should be as nearly horizontal

as possible. Both the machines should be securely

anchored with two dead end anchors in the ground

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and slackness is removed in the stay. Reel winder

shall be positioned at convenient distance of say 10

to 15 mtrs behind the puller. Conductor drums have

to be transported to the tensioner site as per the

approved drum schedule for the section to avoid

wastage and small bit lengths being left over.

For twin moose stringing of one phase, two conductor

drums are mounted on two roller jacks. The selection

of drum shall be such that no midspan joint will come

within 30 mtrs of any tower.

The placement of drum jacks should be such that the

lateral angle of conductor approach into the bull

wheel through guide rollers is low enough to avoid

rubbing on the sides and creating loosening of the

outer strands and birdcaging. The distance of the

drums from the tensioner shall be at least 25 to 30

mtrs so as to distribute the effect of sliding of

outer strands due to low back tension. The reel

should be positioned so that it will rotate in the

same direction as the bull wheels.

4.3.5 Paying out of conductor :


For passing the conductor through the bull wheels of

the tensioner, a 25 mm polypropylene rope is initially

wound over each bull wheel pair in the same way as the

conductor will pass during running. The ropes are

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connected to the conductors. The conductor run shall

be from the top side of the drum. The rope is pulled

by starting the tensioner at low pay out tension to

pass the conductor through bull wheels and are

brought out through the guide rollers. The sub

conductors are attached to the equalizer

pulley/running board by means of wire

mesh/endsocks and swivel joints. The pilot wire is

attached to the other end of the running board with

swivel joint.

At the puller site, the pilot wire is pulled to

remove all slackness using the reel winder. The wire

is passed through bull wheels of the puller and

connected to the reel winder machine. The tensioner

can be initially set for a tension of 2 to 2.5

tonnes. Caution should be made over the wireless hand

set to all the staff who are at middle points and to

the tensioner operator that pulling is about to be

started so that they can stay clear of pilot wire.

The puller is started to draw up the pilot wire until

the bull wheels of the tensioner start moving.

Fig.4.4 & 4.5 show paying out of Bundle conductors

with tensioner and puller. Care should be taken that

the pilot wire does not get entangled in trees,

scaffoldings, aerial rollers etc. while going up

during tensioning. This can be monitored by the staff

who are posted in between the section and guiding the Vol.5 : Page #

puller operator over the wireless sets. The pulling

of the conductor may be done at a moderate speed

while the running board is passing through the aerial

rollers.

The tension in the tensioner must be adjusted so that

the conductors travel well over the ground. In long

spans where conductor is likely to touch the ground,

ground rollers may be placed so that the conductor

can pass without any scratches.

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The back tension of the conductor behind the tensioner

has to be maintained as per the requirement of the

tensioner deployed. The back tension is adjusted by

means of brakes provided on the drum jack. A running

ground shall be connected to the conductor and pilot

wire before paying out near the tensioner and puller

which shall be earthed at the nearest tower.

Both the sub-conductors of one phase which are to be

pulled should be from the same supplier/manufacturer

and preferably from the same lot. This will help

avoid different conductor sag characteristics.

The speed of pulling of the conductor should be such

that to achieve smooth operation. Slower speeds may

cause significant swinging of the running blocks and

insulator hardware assemblies. Higher speeds can

create greater damage in case of malfunction.

The tension applied during stringing generally is

about half the sagging tension. When long lengths of

conductors are strung, the tension at the puller may

be higher than that at tensioner due to the length of

conductor strung, number and performance of

travellers, differences in elevation of supporting

structures etc.

Light and steady back tension should be maintained on

the conductor reels at all times sufficient to

prevent over-run in case of sudden stoppage.

It must also be sufficient to cause the conductor to Vol.5 : Page #

lie snugly in the first groove of the bull wheel to

prevent slack in the conductor between bull wheels.

It may be necessary periodically to loosen the brake

on the reel stand as the conductor is paid off.

Fig.4.6 indicates paid out bundle conductors.

As the conductor is unwound from the reel and

straightens out, the outer strands become loose, a

condition that is particularly noticeable in large

diameter conductor and can be best observed at the

point at which it leaves the reel. As the conductor

enters the bull wheel groove, the pressure of contact

tends to push the loose outer strands back towards

the reel where the looseness accumulates, leading to

a condition commonly known as bird caging. If this

condition is not controlled, the strands can get

damaged to the extent that the damaged conductor has

to be cut and removed.

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This problem can be remedied by allowing enough

distance between the reel and tensioner to permit the

strand looseness to distribute along the intervening

length of conductor and simultaneously maintaining

enough back tension on the reel to stretch the core

and inner strands to sufficiently tighten the outer

strands.

Sub conductor oscillation or clashing of conductors

may occur in bundled conductor lines. Temporary

spacers or other means may be required to prevent

damage of conductor surfaces prior to installation of

spacers. Temporarily positioning of one sub conductor

above another is to be avoided as different tensions

may produce sub conductor mismatch unless the

tensions are low and duration short enough so that

creep does not set in. Conductor clashing can damage

the strands and produce slivers which can result

in radio noise generation.

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Platforms shall be erected with sturdy bellies, where

roads, rivulets, channels, telecommunication or overhead power

lines, railway lines, etc. have to be crossed during stringing

operations. It shall be seen that normal services are not

interrupted or damage caused to property.

4.3.6 Repairing of conductor :


Repairs to conductors, in the event of damage being

caused to isolated strands of a conductor during the

course of erection, if necessary, shall be carried out

during the running out operations, with repair

sleeves. Repairing of conductor surface shall be done

only in case of minor damage,scuff marks etc. keeping

in view both electrical and mechanical safe

requirements. Repair sleeves may be used when the

damage is limited to the outer most layer of the

conductor and is equivalent to not more than one

sixth of the strands of the outer most layer.

4.3.7 Jointing of conductor :


Just before one length of the conductor paying out is

completed another drum has to be deployed in advance

beside the first drum. The paying out has to be

stopped by braking the tensioner and stopping the

puller simultaneously. The paid out conductor of

first drum is held with bolted come-along clamps at a

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distance of 40 to 50 mtrs from the tensioner. The

come- along clamps are attached to the ground anchor

stays. The conductor of the first drum is held and the

free end is cut. The free end of the second drum is

also prepared.

The two ends are joined with a wire mesh midspan

socks. The paying out is again started by releasing

the come along clamps until the midspan socks emerges

outside the tensioner and pulling is stopped. After

anchoring, the conductor is slowly drawn out from the

two end socks. The midspan socks is removed and

midspan compression joint is made. Various steps in

making compression joints are shown in Fig 4.7.

Maximum conductor length shall be made use of in

order to reduce the number of joints. All the joints

on the conductor shall be of compression type, in

accordance with the recommendations of the

manufacturer for which all necessary tools and

equipments like compressor, die sets of correct size

etc. shall be arranged.

The conductor surface shall be clean smooth and

without any projections, sharp points, cuts,

abrasions etc. Conductor joint shall be coated with

an approved mix of linseed oil and zinc chromate

immediately before final assembly as recommended by

suppliers. Surplus mix shall be removed after

assesbling. Vol.5 : Page #

The aluminum filler holes in the MSCJ should be used

to verify the centering of the joint. It should be

ensured that the filler holes are filled before

starting compression of the Aluminium sleeve. The

conductor joints shall be minimum 30 meters away from

any towers. No joints or splices is allowed in single

spans. Midspan joints shall not be used in any single

span crossings such as major power lines, major

rivers, railway lines etc. Compression type fitting

used shall be of self centering type or care should

be taken to mark the conductors to indicate when the

fitting is centered properly. During compression or

splicing operation, the conductor shall be handled in

such a manner as to prevent lateral or vertical

bearing against the dies.

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After pressing the joint, both the aluminum and steel

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sleeve shall have all corners rounded, burrs and

sharp edges removed and smoothened using smooth

files. Similar practice is used for pressing dead end

cone of the tension insulator hardware.

After making midspan joint, the joint is covered with

joint protector sleeves which is designed to pass

over the aerial roller grooves without damaging the

midspan compression joint. The paying out is

continued until the conductor reaches the puller

end in sufficient length to be connected to the

tension hardware. The conductor is held with come

along clamps on both tensioner and puller ends to

ground anchors. The pilot wire is disconnected and

paying out of next phase can be started or machines

shifted to next reach.

4.3.8 Rough sagging of conductor


Before final sagging the conductor, it is rough

sagged to a tension slightly less than the final

tension. Since final sagging is done from one end of

the section, the conductor is initially attached to

the double tension string assembly on the other end.

For doing rough sagging, initially the double tension

string assembly is assembled with insulators and

hardware and hoisted to the cross arms/bridge as done

in the case of suspension towers. The dead end cones

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are compressed on both the sub conductor ends. The

conductor is held by comealong clamps at a distance

of 5 to 6 mtrs from the dead end cones and with the

help of a pulley connected to a ground anchor, the

conductor is pulled to slacken the free end of

conductor (sufficient length to be attached to the

hoisted insulator string assembly).

By holding the conductor with pulley, the dead end

cones are attached to the tension string. The pulley

is slowly released and the conductor will haul-up

itself to the top. The come along clamps and pulley

etc. are removed.

4.3.9 Final sagging of conductor


The sagging of the conductor shall be done using

sagging winches. After being rough sagged the

conductor shall not be allowed to hang in the

stringing blocks for more than 96 hours before being

pulled to the specified sag.

The tensioning and sagging shall be done in

accordance with the approved stringing charts before

the conductors are finally attached to the towers

through the insulator strings. Only after the

conductor is rough sagged on the adjacent section,

final sagging can be done in the preceding section to

avoid overloading of towers. For doing the sagging

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operation, a span has to be selected in the section to

fix the sag board and check the sag.

In the event of using sag tension charts showing sags

in each of the actual spans and tension in each

section, usual practice is to place the sag boards in

the longest span of the section, and in a span where

the difference of elevation in the two suspension

points is minimum.

In case of referring the general sag tension charts

for spans with 5 mtr increment in length and 2 degree

centigrade raise of temperature, the equivalent span

has to be calculated for all the spans in the

section.

The following formula is used.

¦ L13 + L2

3

+...¦ Equivalent Span (L) = (sq. root of) ¦-------------¦ ¦ L1 + L 2 ¦

L1, L2 - Individual spans in a section

A span in the section is to be chosen which is equal

to the equivalent span with a maximum variation of

plus or minus 2.5 mtrs. The tension and sag required

are to be noted for the prevailing actual temperature

at the time of checking the sag. Sag board is to be

fixed to a tower on one side of the span by measuring

the sag length using steel taps from the cross arm

level after adjusting for vertical insulator and

other hardware lengths. On the other tower (sighting

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end), a thread is to be horizontally tied at the same

measured elevation from the cross arm.

The tension insulator strings are hoisted with all

hardware on the tower. The details of tension

fittings are shown in fig.4.8. The conductors are

held by come-along clamps and attached to separate

four sheave pulleys at sufficient distance of say 40

to 50 mtrs depending upon rough sag condition and

height of the tower. The other ends of the four

sheave pulleys are connected to the line side yoke

plate of the double tension string. The pulling

wires of the four sheave pulley are passed through a

set of single sheave pulleys along the body of the

tower to the ground level. The initial pulling is

done with the help of tractor/truck .Then the

pulling ropes are attached to hand winches mounted on

the legs of the tower or power winches duly

anchored. Wooden cross bars are tied to the body of

the four sheave pulley and held by ropes in a

horizontal position to avoid over turning of the

four sheave pulley and twisting of the pulling wires.

A view of final sagging is shown in fig.4.9.

The conductor is brought into final sag position with

the help of winches and the sag is checked by

sighting far end sag board from behind the near end

sag thread by matching elevation tangent of the

conductor curve. Sighting should be done keeping Vol.5 : Page #

sufficient distance from the sag line to avoid

parallax error.

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After reaching the final sag, the free end of the conductor

is picked up and pulled by rope and pulley

attachment along the line of the string. The

conductor is marked at the point where cutting is to

be done and dead end cone is to be pressed. The

free ends of the conductors are brought down and cut

near the marking and dead end cones are pressed. The

four sheave pulley is slightly tightened to

facilitate attaching the dead end cone to the tension

assembly. After fixing, the four sheave pulley is

slowly released, brought down and all clamps and

pulleys are removed.

4.3.10 Regulation :


If the running blocks/aerial rollers which are used to

string conductor are not frictionless, it can cause

problems during sagging operation. If one or more of

the travellers become jammed, sagging can become very

difficult.

A running block swinging in the direction of the pull

can be an indication of a defective block. If

unforeseen sagging difficulties occur, the block

should be checked. Tensions applied to the conductor

to overcome sticky or jammed blocks can cause sudden,

abrupt movement of the conductor in the sag spans and

quickly cause loss of sag, particularly, if the

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conductor is already very close to final sag.

Care shall be taken to eliminate differential sags in

the sub-conductor as far as possible. However, sag

mismatching more than 40 mm shall not be allowed.

For checking the mismatch of the sub conductors with

horizontal, a theodolite shall be placed in the

alignment of the phase near the tower. The vertical

angle is raised to match the horizontal cross hair to

touch the tangent of the sub conductors. Mismatch can

be corrected by adjusting the sag using the sag

adjustment plates.

4.3.11 Clipping of conductors :


The clipping of the conductor follows sagging

operation. This entails removing the conductors from

the rollers and placing them in suspension clamps

attached to the insulator string. Before taking

up clipping operation, the conductor is earthed

properly on suspension towers. The conductors are

held with hooks at 2 mtrs away from the aerial

roller on both sides. A wire rope is connected to

both the hooks passed through a pulley positioned on

the cross arm tip in series with a pull-lift/ratchet

lever hoist/four or two sheave pulley.

The centre of the aerial roller is marked on the

conductor. The conductor is raised by about 75 to 100

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mm and the aerial roller is removed and lowered by

rope and pulley. The suspension clamp and armoured

rods are fixed with neoprene rubber cushions centered

over the marking.

The suspension clamp is placed over the armored rods

and clamped with U bolts. The suspension clamp is

connected to the string and the lifting device is

released. The insulator string will hang freely with

the conductors suspended in the clamps. The

verticality of the string may be checked with plumb-

bob.

Care should be taken to prevent any damage to the

conductor while being lifted by hooks. Gunny bags or

rubber pads may be used around the conductor to

prevent damage to the outer strands.

4.3.12 Fixing of line spacers :


Following the clipping operations for bundled

conductor lines, spacers are usually installed. This

is done by placing personnel on the conductors with

the use of a conductor cycle normally known as

spacer-cycle to ride from structure to structure.

Depending on the length of line to be spaced and the

equipment available, cycles may be hand powered

or diesel powered.

Care must be exercised to ensure that the concentrated

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load of the man, car and equipment does not increase

the sag sufficiently to cause hazards by obstructions

(spacers, repair sleeves, midspan joints etc.) over

which the cycle will pass.

The installation of the spacers on the conductor

varies with span length, the type and manufacture of

the spacer and is normally done in accordance with

the manufacturer's recommendations duly approved.

The spacer cycle is hoisted on the bundle at one

tension end. In case of engine powered cycles, the

spacer cycle is normally provided with travel meter,

with the help of which the spacers are fixed at re-

quired distances as per the placement chart. In case

of hand powered cycles, the personnel pulling the

cycle with rope measure the distances on ground and

placement is done on the top. A number of models of

spacers are being manufactured and the method of

installation varies with the design of the spacers.

After reaching the next suspension tower, the cycle

is transferred to the next span by crossing the

suspension clamp with the help of crossing ropes

provided in the cycle.

In case of spans crossing HT/LT lines, care should be

taken while drawing the spacer cycle with rope. Safe

electrical clearance should be maintained to the

spacer cycle and rope. For crossing the lines, the

rope shall be drawn up to the cycle, and brought down Vol.5 : Page #

after crossing the line, keeping sufficient clearance

from the line. The person on the cycle can travel

himself to cross over the section above the power

line.

4.3.13 Installation of dampers :


Vibration dampers/spacer dampers are normally placed

on the conductors immediately following clipping to

prevent any possible damage because of vibrations to

the conductors, which at critical tensions and wind

conditions can occur in a matter of hours.

In lines where spacer dampers are installed,

vibration dampers need not be installed. The number

of dampers and spacing are provided as per the

instructions of the manufacturer.

4.3.14 Jumpering


The jumpers at the section/angle towers shall be

formed to parabolic shape to ensure minimum clearance

requirements. Pilot suspension insulator string shall

be used if found necessary (Generally where angle of

deviation is more than 45 degrees), to restrict the

jumper swings to the design values at both middle and

outer phases. Clearance between the conductors and

ground, jumpers and the tower steel work shall be

checked during erection and before commissioning the

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line.

While jumpering is made, a local earthing should be

made to avoid any static discharge that might occur

due to the voltage induced on the line by existing

power lines in the vicinity.

Care should be taken to leave jumpers for one angle

tower in a continuous stretch of 25 to 30 kms, so as

to prevent transmission of electric shock. These left

out jumpering can be taken up during final

inspections. The individual sections jumpered shall be

kept earthed and earth shall be removed only before

commissioning.

The jumpers in general are 10 to 15 mtrs in length.

Hence left over bits of conductor shall be used for

jumpering. For installation of jumpers, the distance

between the jumper pads of dead end cones is measured

by passing a rope in the shape of a jumper and by

checking vertical clearance from the cross arm end.

Conductor is cut after making adjustment in length

for the jumper cone dimension.

The inner and outer conductor of the bundled jumper

are of different lengths, which shall be measured

separately. This will ensure a horizontal plane of

the jumper bundle when installed. After cutting the

conductor, jumper cone is pressed using hydraulic

compressor. The conductors are laid out on the ground

parallelly and spacers are fixed as per the fixing Vol.5 : Page #

instructions. The jumper is hauled up from both ends

of the tension clamps and jumper cone is attached to

the connector of the dead end cone. Clearance to the

tower body shall be checked as per the drawing.

4.3.15 Paying out through angle towers :


In order to reduce wastage of conductor, the

possibility of paying-out of conductor through

angle towers using TSE may be considered.

Here the running blocks or rollers are fixed to the

cross-arm peaks through sufficiently long steelropes

of 20 mm dia measuring maximum 30 cm. care may be

taken that the pulling is done slowly and smoothly

when the equalizer pulley passes the roller, so that

no jerks comes to the cross arm peak. Cross arm

stays may be provided as a precautionary measures.

If substantial line angles are involved, two running

blocks in tandem may be required to reduce the

bending radius of the conductor or load on each

running block or both. Where bundle conductor running

blocks are used at line angle more than 5°, it is

advisable to change to individual single conductor

running blocks after passage of the running board to

facilitate accurate sagging. It is desirable during

sagging for horizontal spacing of the sheaves to

match the final subconductor spacing to avoid

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subconductor sag mismatch.

However, if any noticeable damage is sustained to the

conductor, this procedure should be abandoned.

4.3.16 Transposition arrangement :


In 400 KV S/C and D/C lines, the 3 phases are

transposed in equal lengths of 1/3rd distance of the

line to achieve equal mutual coupling between the

phases and earth.

Normally, C type towers without any angle of

deviation are placed at 1/3rd, 2/3rd and at the end of

the transmission line (about 2 to 3 spans before

the terminal gantry).If possible, transposition tower

should be placed at section tower where B type tower

with 0 degree is already proposed otherwise, to save

the cost. In lines where double circuit portions are

constructed in forest reaches, major river crossing

reaches etc. if it is possible, the transposition can

be done while changing over from double circuit to

single circuit without providing any extra

transposition tower.

The arrangement of transposition involves jumpering to

change the phases in the required position. The centre

phase and one of the side phases is transposed to the

other side of the tower by means of jumper attached

to a pilot insulator suspended from the cross arm

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tips. The 3rd phase is transposed from one side of

the tower to the opposite side of the tower on the

farther phase by jumpering through top of the tower

where a small line is strung between the earthwire

peaks with two single tension fittings with sag

adjustment turn buckle. Compression type T -

connectors are provided on the line conductors and

the jumpers are connected using compressed jumper

cones. Compressing of T connectors on the line

conductors can be done at the time of make up or

final sagging operation as per the drawing.

Compression of T-connectors after saging is completed

will be very difficult since either the line has

to be brought down or the compressor machine has to

be hoisted and joint made at line elevation.

Fig.4.10 is a view of 400 KV S/C transposition tower.

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4.4 Stringing over river crossing.


In major river crossings having multi-span section

with suspension towers, there are special arrangements

and some precautions to be taken during stringing.

It is better to plan stringing activity during the

dry seasons of the year. In rivers where there is

water flow through out the year, extra precautions

have to be taken. The method of stringing in major

navigable rivers having flow of water through out the

year, is explained below. In case of navigable

rivers prior intimation should be given to the local

authorities and boat operators in the nearby areas.

Caution signals shall be raised with red flags about

1 km up and down streams of the alignment.

4.4.1 Earthwire


Paying out of earthwire cannot be done length by

length as is normally done in ordinary sections. As

explained earlier, special drums having full length of

the sections are procured for stringing. Initially, a

polypropylene rope of say 1 km length is passed

through the section over the aerial rollers by

carrying the rope in boats. After paying out the

polypropylene rope the earthwire is attached from one

end of the section and pulled by the rope through the

Vol.5 : Page #

aerial rollers. The earthwire drums are mounted on

horizontal turn tables or rolling jacks which

shall be frictionless. After pulling for each span,

the rope may be passed to the next span manually and

pulling of earthwire may be continued. The T&P

required for sagging also will need longer pulling

wire of four sheave or two sheave pulleys as the

tower heights are very large.

4.4.2 Paying out of conductor


In multispan reaches of major river crossings the

conductor has to be paid out using tension stringing

equipment. The pilot wire has to be initially paid

out from one end of the section as is done in the

case of earthwire by using polypropylene rope. The

total pilot wire reels required have to be kept at

one end of the section and joined with pilot wire

connectors after each length is pulled. Conductor

paying out can be done by normal stringing method. It

is better to procure conductor of larger length than

normally supplied, to avoid midspan joint of conductor

in the river crossing reaches. However, the conductor

reels should not be too heavy and cause difficulty in

handling and transporting.

In case the dead end towers used for the river

crossing reach are also of special type much taller

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than the normal towers, it is advisable to string

the river crossing reach upto the next angle tower

of normal size and do double side sagging at the

Anchor towers. Thus using of long stays which are

difficult in laying can be avoided. Also, long stays

are not reliable keeping in view the large bending

moment experienced by the tower

For long spans in river crossings, the sag is very

high. Care should be taken while checking the sag

with help of sag board so as not to give chance for

any error due to wind load on the conductor. It is

better to carry out the sagging operation in near

still wind condition. Sub conductor mismatch in

large spans shall be avoided completely at the time

of erection itself since differential creepage in the

conductors may cause large difference in the

conductor elevations. In spans exceeding 500 mtrs,

due to the large sag, pulling of spacer cycle

becomes very difficult in approaching the tower from

centre of the span. Also pulling from the ground may

not be possible due to flow of water. Under these

conditions, it is better to use powered cycles with

good braking arrangement.

All bolts & nuts of hardware shall be doubly checked

for tightness, provision of spring washers, cotter

pins etc. to avoid tower failure.

4.5 Stringing over power line crossings Vol.5 : Page #


In the alignment of the Transmission line, many power

line crossings are encountered ranging from LT to

EHV. While crossing major power lines, due to

limitations of the tower spotting requirements and

reasons of economy, the minimum clearance of 6.10

mtrs is provided from the 400 KV line. Sagging has to

be very accurate and physical clearance from the

power line shall be checked after the sagging

operation.

While planning the stringing operation in reaches

where power line crossings are encountered advance

action should be taken to obtain line clear permit to

work from the utility operating the power line. The

line clear can be taken after paying out of pilot

wire, earthwire and conductor in sections which can

be joined after obtaining the shutdown.

In case of power lines upto 33 KV, it is easier and

economical to bring down the LT/HT conductors at two

or three poles. In case of lines of 132 KV and

above, bringing down the conductor is very difficult

and in many cases the utilities will not agree for

doing so. Any damages to the conductor or insulators

of the line to be brought down will cause a lot of

inconvenience and unnecessary outage of the line.

It is suggested to request utility to arrange as a

precautionary measure few hardware fittings and Vol.5 : Page #

insulator in order to replace them, if necessary. In

such cases, special cylindrical rollers fabricated

out of soft wood about 50 cms in length and 30 cms in

dia split in cross section with a groove at the

centre to accommodate the conductor of the line may

be used.

These rollers can be mounted on the conductor or

earthwire of the power line to be crossed and the

conductor to be strung can be drawn over these

rollers. Normally, crossings of major lines is done

in one or two spans only with dead end towers at

both ends and commonly with a special extension tower

of suspension type in the middle. Tension stringing

of these reaches will be very difficult and

unwarranted since the no. of spans is normally limited

to two only.

All the activities of paying out, sagging, placement

of line hardware & accessories shall be completed

during the shutdown period since it will be very

difficult to carry out operations without shutdown

afterwards. In spans using special extensions of 18

or 25 mtrs, the conductor slope is very high making

it very difficult for placement of bundle spacers

using the spacer cycle. Precautions should be taken

by holding a control rope from the spacer cycle to

the tower to avoid any accident.

Vol.5 : Page #

Vol.5 : Page #

Chapter-5

Guidelines

______________________________________________________________________

CHAPTER FIVE

______________________________________________________________________

GUIDELINES


GL-1 PRE-STRINGING CHECKS


NAME OF LINE ...... NAME OF CONTRACTOR ......

SECTION - LOC. NO....... TO LOC. NO.......

Following preparations need to be made before taking up

stringing work.

1.1 Foundation checks

1.1.1 Backfilling of soil of foundation should be done

wherever required since back filled earth might have

settled down with the passage of time. Area should be

fairly levelled within four legs.

1.1.2 Revetment / Benching wherever required shall be comp-

leted so that there is no danger to foundation during

and after stringing work. However, if it is felt

that, non-completion of Revetment / Benching is not

going to harm foundation during and after stringing,

the same may be programmed and executed on later

date.

1.2 Tower checks

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1.2.1 The tower shall be checked by two supervisors starting

simultaneously from the bottom of the tower at two

diagonally opposite legs. The checking shall be

carried out towards the top of the tower and the

supervisors will come down checking through the

other opposite diagonal legs.

1.2.2 It shall be ensured that correct size of bolts/nuts

are used and fully tightened.

1.2.3 It shall also be ensured that all bolts/nuts have been

provided with spring washers.

1.2.4 A torque wrench may be used at random to ensure

sufficient tightness.

1.2.5 Any missing members shall be provided with correct

size member.

1.3 Way leave clearance

1.3.1 In order to maintain cordial relations with the field

owners for smooth completion of stringing, it is

desired that compensation of damage of crops during

foundation and tower erection is paid to the field

owners before taking up stringing work.

1.3.2 Also, wherever possible and if found necessary,

compensation of crop to be damaged during stringing

may be processed in advance for prompt payment.

1.3.3 Advance precautions should be taken to handle way

leave problem. Rough handling of the issue may spread

to nearby villages along the line resulting into total

Vol.5 : Page #

stopage of site activities.

1.4 Tree cutting

1.4.1 Immediately after completion of detailed survey,

issual of notices and valuation of trees by Revenue

Authorities should be taken up. Wherever necessary,

clearance from Forest Authorities may be taken for

tree cutting.

1.4.2 The tree cutting may be carried out alongwith

foundations so that the same is completed before

tower erection.

1.4.3 Any left over tree may be removed well in advance in

order to achieve smooth stringing and requisite

electrical clearance.

1.4.4 Tree compensation should be paid as promptly as

possible to gain confidence of field owners for

smooth completion of balance construction work.

1.5 Line material & drawings

1.5.1 It shall be ensured that all approved drawings of

line material and stringing charts with latest

revision are available at site to facilitate

stringing works. Preferably one set of drawing in

Bound Book shall be available at site with each gang.

1.5.2 All line material shall be available at site as per

requirement.

1.5.3 Though all the line materials are checked for any

defect before entering into stock Register yet it is

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necessary to keep constant watch on line material

during stringing for any other damage. It shall be

ensured that no defective line material is used at

any cost.

1.6 Tools and plants

1.6.1 All the tools and plants required for safe and

efficient stringing shall be available at site. A

list of necessary tools and plants is given at

Annexure-S/1.

1.6.2 All the tools and plants shall be tested as per

approved safety norms and relevant test certificates

shall be available. In addition to above, periodic

testing of tools and plants shall be carried out and

its safe working capacity shall be worked out and

recorded.

1.6.3 It shall be ensured that Tension stringing equipments

and other measuring instruments are properly

calibrated and relevant certificates are available.

1.7 Personal protective equipments

1.7.1 All the persons working on tower or

conductor/Earthwire shall wear safety helmet, safety

belt and safety shoes. Similarly all the persons

working on ground shall wear safety helmet and safety

shoes. List of personal protective equipments is given

at Annexure-S/1.

Vol.5 : Page #

1.7.2 Safety equipments shall be tested as per safety norms

and necessary test certificate shall be available.

Also, a periodic check shall be carried out to ensure

requisite strength.

1.8 Manpower

1.8.1 Manpower engaged for the purpose of stringing shall

be skilled and competent enough to ensure safe,

smooth and efficient stringing activity.

1.8.2 A list of necessary manpower required for stringing

is given at Annexure-S/2.

1.9 Misc

1.9.1 Shutdown of power line crossings shall be planned

well in advance. Shutdown should be obtained in

writing and lines are dismantled if required.

1.9.2 Similarly for Railway crossing, necessary block shall

be planned well in advance. Proper protection /

scaffolding shall be provided before taking up

stringing.

1.9.3 Road and Telephone line crossings shall also be

provided proper scaffolding and warning signals.

1.9.4 Tower vulnerable for one side load shall be guyed

properly both at waist and bridge level so as to

avoid any untoward incident.

1.9.5 Wireless communication (walky - talky ) sets shall be

in proper working condition.

1.9.6 It shall be ensured that tower footing resistance has

Vol.5 : Page #

been measured and found within permissible limit of

10 ohm.

1.9.7 It shall be verified that Drum schedules for

conductor and earthwire have been submitted and

approved well in advance. This is compulsory for

optimum use of conductor and earthwire to minimise

wastages.

Vol.5 : Page #

GUIDELINES

GL-2 PAYING OUT OF EARTH WIRE




2.1 Safety precautions

Safety shall be given utmost importance during

stringing. The following need to be ensured

2.1.1 Safe working conditions shall be provided at the

stringing site

2.1.2 All persons on tower/earthwire shall wear safety

helmet, safety belt and safety shoes and all the

persons on ground shall wear safety helmet and safety

shoes

2.1.3 Immediate Medical Care shall be provided to workmen

met with accident. First Aid Box shall be available

at stringing site.

2.1.4 Traveller ground shall be provided between Earthwire

drum and the section tower to avoid any potential

hazards.

2.1.5 Foolproof communication through walkie talkie shall

exist in order to avoid any danger to workmen or

public on ground while paying out.

2.2 Checking paying out process

2.2.1 General

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a) Relevant approved drawings as mentioned in para 1.5.1

shall be referred to.

b) It shall be made sure that paying out is carried out

as per approved drum schedule.

c) All the pulleys fixed on towers for paying out should

move freely to avoid any damage to earthwire or

pulley and to achieve correct final sagging.

d) One person on each tower shall be available with red

and green flags and whistle for supervision and

communication.

e) Walky-Talky sets shall be in good working condition

for smooth communication between pulling tractor and

unwinding of E/W drum.

f) Earthwire shall be checked constantly as it is

unwound from earthwire drum for any broken, damage

or loose strand. If any defect is noticed then

the defective portion has to be removed and mid

span joint provided. It may be mentioned here that

there is no repair sleeve for earthwire.

g) Necessary arrangement shall be made to avoid any

rubbing of earthwire against ground or hard surfaces

so that earthwire is not damaged.

2.2.2 Details of earthwire

Details of Manufacturer, Drum No., Length and

Location nos. between which earthwire is paid out,

shall be recorded in order to maintain traceability so

Vol.5 : Page #

that any problem encountered during operation and

maintenance can be properly investigated in case of

failure.

2.2.3 Details of M.S. Joint

a) M.S. Joint shall be provided strictly as per approved

drawings and technical specifications.

b) Following details of MS Joint shall be recorded.

i) Manufacturer's name and batch number

ii) Earthwire No.1 or 2 and Location nos. between

which MSJ is provided.

iii) Dimensions of M.S.Joint before and after

compression shall also be recorded and shall be

within permissible limits as per approved

drawings.

c) M.S.Joint shall be provided atleast 30 meters away

from tower.

d) There shall not be any M.S.Joint over Rly/River/Main

Road Crossing.

e) Not more than one M.S.Joint shall be provided in one

span for each earthwire.

Vol.5 : Page #

GUIDELINES

GL-3 PAYING OUT OF CONDUCTOR




3.1 Safety precaution

Safety shall be given utmost importance during

stringing. The following need to be ensured.

3.1.1. Safe working conditions shall be provided at the

stringing site

3.1.2 All persons on tower/conductor shall wear safety

helmet, safety belt and safety shoes and all the

persons on ground shall wear safety helmet and safety

shoes.

3.1.3 Immediate medical care shall be provided to workmen

met with accident. First Aid Box shall be available

at stringing site.

3.1.4 Traveller ground shall be provided between Tensioner/

Puller and section tower to avoid any potential

hazards.

3.1.5 Fool proof communication through walkie talkie shall

exist in order to avoid any danger to workmen or

public on ground.

3.2 Tensioner/puller placing

3.2.1 It shall be ensured that Tensioner and Puller are

placed on firm and levelled ground Vol.5 : Page #

3.2.2 It shall be confirmed that Tensioner/Puller are

firmly anchored with ground with wire rope of atleast

20 mm diameter in order to hold them in place.

3.2.3 It shall be verified that suitable earthing by copper

cable of cross section of atleast 64 mm² is provided

for both puller and Tensioner.

3.2.4 Slope of pilot wire/conductor between Tensioner/puller

and section tower shall be approximately three

horizontal to one vertical as far as possible. This

is essential to restrict the load on traveller

and section towers.

3.2.5 It is also necessary that horizontal angle of pilot

wire/conductor between Tensioner/Puller and section

tower shall be as minimum as possible in order to

avoid damages to pilot wire/conductor and sides of

grooves of bull wheels.

3.3 Conductor drum placing

3.3.1 It shall be ensured that there is enough distance

between tensioner and conductor drum so as to avoid

brid caging and breaking of conductor strands.

Generally a distance of 25 to 30 meters will serve

the purpose.

3.3.2 Horizontal angle of conductor as it approaches

tensioner should be small enough to avoid rubbing

of sides of grooves.

3.3.3 Horizontal angle of conductor as it leaves conductor

Vol.5 : Page #

drum should be small enough to avoid rubbing of

conductor on side flanges.

3.3.4 It shall be verified that braking device is

functioning properly for conductor drum to get desired

level of control during paying out operation.

3.4 Sequence of paying out

3.4.1 It shall be ensured that earthwire is already paid

out before taking up paying out of conductors.

3.4.2 It shall be checked that proper sequence of paying

out is maintained in order to avoid any clashing and

damage to conductors and to avoid any unbalancing of

loads on towers. For this purpose following sequence

shall be maintained.

a) In case of D/C line, sequence of paying out of

conductor shall be from top to downwards.

b) In case of S/C line, sequence of paying out of

conductor is that outer phases are completed

before taking up middle phase.

3.5 Insulator hoisting

3.5.1 Checking of Insulators

a) Insulators shall be completely cleaned with soft and

clean cloth.

b) It shall be verified that there is no crack or any

other damage to insulators.

c) It is very important to ensure that 'R' clips in

insulator caps are fixed properly. This is a security

Vol.5 : Page #

measure to avoid disconnection of insulator discs.

d) Necessary precautions shall be taken so that no

damage to insulators is caused during hoisting. In

case of damage, the same needs to be replaced.

e) Details of insulators (i.e. Type, Make, KN, & Batch

No.), No. of discs, Loc. No. and phase (R, Y or B )

are to be properly recorded.

3.5.2 Checking of Suspension Fitting

a) It shall be verified that necessary hardware fitting

as per approved drawings is provided for insulator

strings.

b) It shall be checked that there is no damage to any

component of hardware fittings.

c) It shall be verified that all nuts and bolts are

tightened properly.

d) It shall be made sure that all the necessary security

pins (split pins) are fixed properly as per approved

drawings.

e) Details of suspension fitting (Type, Make, Batch

No.), Loc. No. and phase (R,,Y or B) are to be

recorded.

3.6 Checking paying out process

3.6.1 General

a) Relevant approved drawings as mentioned in para 1.5.1

shall be referred to.

b) It shall be made sure that paying out is carried out

Vol.5 : Page #

as per approved drum schedule.

c) All the Travellers fixed on tower for paying out

should move freely to avoid any damage to conductor

or Traveller and to achieve correct final sagging.

d) One person on each tower shall be available with red

and green flags and whistle for supervision and

communication.

e) Walky-Talky sets shall be in good working condition

for smooth communication between Tensioner and

Puller.

f) Conductor shall be checked constantly as it is

unwound from Conductor drum for any broken, damage

or loose strand. If any major defect is noticed

then the defective portion has to be removed and mid

span joint provided. However if the defect is of

minor nature i.e. number of damaged strands is not

more than 1/6th of the total strands in outer

layer, a repair sleeve shall be provided.

g) Necessary arrangement shall be made to avoid any

rubbing of conductor against ground or hard surfaces

so that conductor is not damaged.

3.6.2 Details of conductor

Details of Manufacturer, Drum No., Length and

Location nos. between which conductor is paid out,

shall be recorded in order to maintain traceability so

that any problem encountered during operation and

Vol.5 : Page #

maintenance can be properly investigated in case of

failure.

3.6.3 Details of M.S. Joint

a) M.S. Joint shall be provided strictly as per approved

drawings and technical specification.

b) Following details of MS Joint shall be recorded

i) Manufacturer's name and batch number

ii) Conductor No.1 or 2, phase R,Y,B and Location nos.

between which MSJ is provided.

iii) Dimensions of MSJ before and after compression shall

also be recorded and shall be within permissible

limits as per approved drawings.

c) M.S.Joint shall be provided atleast 30 meters away

from tower.

d) There shall not be any M.S.Joint over Rly/River/Main

Road Crossing.

e) Not more than one M.S.Joint shall be provided in one

span for each conductor.

Vol.5 : Page #

GUIDELINES

GL-4 FINAL TENSIONING OF EARTHWIRE AND CONDUCTOR




4.1 General

4.1.1 All the approved stringing charts and other relevant

drawings shall be available at site before taking up

the final tensioning.

4.1.2 Final sagging in a particular section shall be done

only after verifying that conductor and earthwire are

already rough sagged in adjacent sections. This is

very important to avoid overloading of towers due to

one side load.

4.1.3 It shall be ensured that all safety precautions are

being taken as detailed in GL-2 & GL-3.

4.1.4 Final Tensioning and sagging shall be carried out in

a calm weather when rapid changes in temperatures are

not likely to occur.

4.2 Fixing of sag boards

4.2.1 Thermometer shall be installed on tower at the same

elevation as that of conductor and far enough above

the ground to avoid the effect of ground heat

radiation.

4.2.2 The atmospheric temperature shall be read from

thermometer just prior to final sagging. The Vol.5 : Page #

corresponding value of sags for earthwire and

conductor shall be noted from approved stringing

charts. Initial sag tension chart shall be referred

for conductor and Final-Sag-Tension chart shall be

referred for earthwire.

4.2.3(a) In case of earthwire sag length shall be measured by

steel tape from earthwire peak after adjusting for

length of suspension clamps. The sag board shall be

fixed on tower at one side of sagging span. On other

side of sagging span, a thread shall be tied on the

tower at the same elevation as that of sag board.

(b) In case of conductor, sag length shall be measured by

steel tape from cross arm after adjusting for length

of suspension insulators and hardware fittings. The

sag board shall be fixed on tower at one side of

sagging span. On other side of sagging span, a thread

shall be tied on the tower at the same elevation as

that of sag board.

4.2.4 Sag boards are to be fixed as per following

a) For a section having length upto 8 spans, the sag

boards shall be fixed in first and last span.

b) For a section having length more than 8 spans, the

sag boards shall be fixed in first, intermediate and

last span.

4.3 Final sagging of earthwire

4.3.1 Rough sagged earthwire shall be tightened further by

Vol.5 : Page #

winch machine fixed on tower till, the final sagging

position is achieved.

4.3.2 The final sag shall be checked by sighting far end

sag board from behind the near end sag thread by

matching elevation tangent of the earthwire.

Precautions shall be taken to avoid any parallax

error.

4.3.3 Marking of earthwire shall be done correctly after

adjusting for length of tension clamp as per

approved drawings.

4.3.4 The earthwire shall be cut at the marked point and

Tension clamp provided.

a) Following shall be checked in respect of Tension

clamp.

i) All the components of tension clamp are properly

fitted as per approved drawing.

ii) All Nuts and Bolts have been properly tightened

iii) None of the components of the clamp is damaged. In

case of any damage, the same shall be replaced by

good one.

iv) Split pin has been properly provided.

b) Following shall be recorded regarding tension clamp.

i) Earth wire No. and location No. between which it is

provided.

ii) Batch No., Make etc.

iii) Dimensions before and after compression.

Vol.5 : Page #

4.3.5 Sag shall again be checked after fixing tension clamp

in order to ensure that no error is introduced by

fixing tension clamp.

4.4 Final sagging of conductor

4.4.1 Rough sagged subconductors of one phase shall be

simultaneously tightened by winch machine fixed on

tower till the desired final sag is achieved.

4.4.2 The final sag shall be checked as mentioned in para

No. 4.3.2

4.4.3 Marking of conductor shall be done correctly after

adjusting length of Tension fittings.

4.4.4 The conductor shall be cut at the marked point and

Dead end joint provided.

a) Following shall be checked in respect of tension

fittings.

i) Insulators shall be checked as detailed in para

3.5.1

ii) Tension fittings shall be checked in accordance with

para 3.5.2

b) The following shall be recorded in respect of Tension

fittings.

i) Wire No., Phase and location of towers on which it is

provided.

ii) Batch No., Make etc.

iii) Dimension of Dead end joint before and after

compression. It shall be within permissible limit as

Vol.5 : Page #

per approved drawings.

4.4.5 Sag mismatching shall be checked by sighting through

the Teodolite placed on ground near the tower. Any

mismatch shall be corrected by using sag adjustment

plate in Tension fittings. It shall be verified that

sag mismatch is not more than permissible limit of 40

mm.

Vol.5 : Page #

GUIDELINES

GL-5 CLIPPING AND FIXING OF ACCESSORIES OF EARTHWIRE




5.1 Clipping and Checking of Suspension clamps

5.1.1 It shall be ensured that correct marking on earthwire

is done to fix suspension clamp. The suspension clamp

after fixing shall be in exact vertical position.

5.1.2 Following shall be verified in respect of suspension

clamp.

a) Suspension clamp is provided strictly as per approved

drawings.

b) All the components of suspension clamp are properly

fitted as per approved drawings.

c) All Nuts and Bolts have been properly tightened

d) None of the components of the clamp is damaged. In

case of any damage, the same shall be replaced by

good one.

e) Split pin has been properly provided.

5.1.3 Following shall be recorded for suspension clamps:

a) Earthwire No and location No. of tower in which

suspension clamp is provided .

b) Batch No., Make etc.

5.1.4 Sag shall be rechecked to ensure that no error is

Vol.5 : Page #

introduced after clipping operation.

5.2 Checking of vibration Dampers

5.2.1 Following checks shall be carried out for vibration

Dampers:

a) Vibration Dampers are provided as per approved

placement chart.

b) All Nuts and Bolts have been tightened properly

c) There is no damage to V.D.

5.2.2 Following shall be recorded:

a) Make, Batch No. etc.

b) Wire No., Loc. No. of Dampers provided.

5.3 Checking of Earthwire Jumpers

5.3.1 Following shall be checked:

a) Earthwire jumper is provided on all tension towers as

per approved drawings and technical specification.

b) All Nuts/Bolts have been properly tightened

c) Split pin provided properly

5.3.2 Dimensions of jumper cone before and after

compression shall be recorded. It shall be within

permissible limits.

5.4 Checking of Copper Bonds

5.4.1(a) It shall be ensured that one copper bond is provided

for each suspension and tension clamp as per approved

drawing.

b) It shall be verified that there is no damage to

copper Bond. Vol.5 : Page #

c) All the Nuts/Bolts are properly tightened



b) Wire No., Location No. of tower on which it is

provided.

Vol.5 : Page #

GUIDELINES

GL-6 CLIPPING AND FIXING OF CONDUCTOR ACCESSORIES




6.1 Conductor Clipping

6.1.1 Before taking up clipping, the conductor should be

earthed to avoid any electrical hazards.

6.1.2 Conductor shall be marked properly so that after

placing of suspension clamp, the insulator fitting

hangs in exact vertical position.

6.1.3 Following shall be checked in respect of suspension

clamps.

a) Armour rods have been properly provided as per

approved drawings.

b) All the other components of suspension clamps have

been properly provided as per approved drawings

c) None of the components of suspension clamp is

damaged. In case of any damage, the same needs to

be replaced.

d) All Nuts/Bolts have been properly tightened.

e) All the split pins have been provided.

6.1.4 Since, the suspension clamp is part of suspension

fittings, the details of clamp may be clubbed with

that of fitting as per para 3.5.2

Vol.5 : Page #

6.2 Fixing of Vibration Dampers

6.2.1 Following checks shall be carried out for vibration

Dampers:

(i) Vibration Dampers are provided as per approved

placement chart.

(ii) All Nuts and Bolts have been tightened properly

(iii) There is no damage to V.D.


(i) Make, Batch No. etc.

(ii) Wire No., Loc. No. of Dampers provided.

6.3 Fixing of Spacer

6.3.1 Spacers shall be provided as per approved placement

chart.

6.3.2 Necessary precautions shall be taken while crossing

any LT/HT line to avoid any electrical hazards by

accidental touching of ropes.

6.3.3 All components of spacer shall be properly fitted as

per approved drawing.

6.3.4 None of the components shall be damaged. In case of

any damage, the same shall be replaced by good one.

6.3.5 All Nuts/Bolts shall be properly tightened.

6.3.6 The following shall be recorded.


b) Details of span, phase, no. of spacers provided,

distance between spacers.

NOTE - In case spacer dampers are to be provided, the

Vol.5 : Page #

guide line for fixing of spacer as per para 6.3 shall

also be applicable for spacer dampers.

6.4 Fixing of Jumper and Jumper Spacer

6.4.1 Before taking up Jumpering work, necessary earthing

of conductor shall be provided to avoid any potential

hazards.

6.4.2 Length of Jumper shall be carefully selected such

that it is in parabolic shape so as to give live

metal clearance and Jumper drop as per approved

drawing. Length of jumpers of sub-conductors of a

bundle shall be properly co-ordinated so that jumper

spacers lie in horizontal position as far as

possible.

6.4.3 Jumper cone shall be compressed as per approved

drawings. Its dimension before and after compression

shall be recorded and shall be within permissible

limits. Since Jumper cone is part of Tension fitting,

the details of cone shall be clubbed with that of

fitting as per para 4.4.4

6.4.4 All nuts and bolts shall be properly tightened. This

is very essential to ensure tightness of jumpers to

avoid arcing and flashover which may result in damage

of tension fittings and undesirable tripping of line.

6.4.5 Jumper spacers shall be provided as per technical

specification and approved drawings.

Vol.5 : Page #

a) Following shall be checked.

i) All components have been properly provided.

ii) No component is damaged. In case of damage, the same

shall be replaced.

iii) All Nuts and Bolts have been properly tightened

b) Following shall be recorded for Jumper spacer

i) Make, Batch No.

ii) Loc. No., Phase, No. of spacer.

6.5 Pilot Fittings

Following shall be checked in respect of pilot

fittings.

a) Insulators shall be checked as detailed in para

3.5.1

b) Fittings shall be checked in accordance with para

3.5.2

6.6 Checking of Transposition Tower

6.6.1 Before taking up transposition job, the following

documents shall be available at site.

a) The approved phase sequence to be kept on both sides

of tower.

b) The approved drawing of transposition tower having

all the relevant details.

c) The approved drawings of various line material to be

employed for transposition arrangement.

6.6.2 It shall be ensured that jumpers provided for

different phases are as per approved drawing. The

Vol.5 : Page #

point of fixing of jumper on conductor and length of

jumper shall be strictly as per approved drawing. The

live metal clearance of different phases shall be

measured and recorded. The live metal clearance

shall be within permissible limit.

6.6.3 T- Clamp/Jumper Cone

a) T-Clamp and Jumper cone shall be provided as per

approved drawings.

b) Dimensions before and after compression shall be

recorded. It shall be within permissible limit.

c) All Nuts/Bolts shall be properly tightened

6.6.4 Pilot Fitting & Balancing Weight

a) Pilot Fittings

Following shall be checked in respect of pilot

fittings.


3.5.1

ii) Fittings shall be checked in accordance with para

3.5.2

b) Balancing Weight

i) It shall be ensured that Balancing weights have been

provided as per approved drawings.

ii) There shall be no damage to Balancing weight. In

case of damage, the same shall be replaced.

6.6.5 Single Tension Fitting

a) Following shall be checked in respect of tension

Vol.5 : Page #

fittings.


3.5.1

ii) Tension fittings shall be checked in accordance with

para 3.5.2 and 4.4.4 (b).

6.6.6 It shall be ensured that earth mast on earthwire

peaks of tower have been properly provided as per

approved drawing.

Vol.5 : Page #

Annexure - S/1


POWERGRID CORPORATION OF INDIA LTD.(CONSTRUCTION MANAGEMENT)

LINE CONSTRUCTIONSTRINGING ACTIVITY

Tools and Plants required for StringingGang for Tension Stringing

1. TSE Sets. - 1 set

(Tensioner & Puller of 8 t/10 t Cap.)

2. Running Block for conductor. - 100 nos.

3. Running Block for earthwire. - 60 nos.

4. Head Board. - 2 nos.

5. Pilot wire each of 800 m length. - 10 nos.

6. Pilot wire joint. - 12 nos.

7. Grnd. roller for Tension/Manual

Stringing. - 30/100 nos.

8. Wire mesh pulling grip

(One end open of reqd. dia. for

conductor). - 6 nos.

9. Wire Mesh Pulling Grip

(One end open of reqd. dia. For

earthwire). - 2 nos.

10. Wire Mesh Pulling Grip

(Double end open of reqd. size

for conductor.) - 4 nos.

11. Articulated Joint.

Heavy duty (20 t). - 10 nos.

Vol.5 : Page #

Medium duty (10 t). - 10 nos.

Light duty (5 t). - 5 nos.

12. Drum mounting jack for conductor

drum of 10 t capacity. - 4 sets

13. Turn Table (5 t.capacity). - 2 nos.

14. Anchor Plate (1.5 m.x1.0 m. x8 mm) with

15 Nos. Anchor Pins (45 mm dia. And

850 mm long). - 10 sets

15. Hydraulic compressor Machine 100 T

capacity with die sets. - 5 nos.

16. Travelling Grnd. - 12 nos.

17. Dynamometer - 10 T. - 4 nos.

- 2 T. - 2 nos.

18. Pilot wire reel stand. - 4 nos.

19. Four sheave pulley with 9 mm dia.

& 300 m length wire rope. - 6 sets


and 300 m length wire rope. - 2 sets


and 150 m. length wire rope. - 4 sets

22. Equiliser pulley (10 T. capacity). - 16 nos.

23. Conductor Lifting tackle. - 4 sets

24. Winch - Motorised/Manual - 10 T

capacity. - 4 nos.

25. Comealong clamp for conductor

(Bolted type/Automatic). - 50/20 nos.

26. Comealong Clamp for Earthwire Vol.5 : Page #

(Bolted type/Automatic). - 15/10 nos.

27. Trifor (5 T. Capacity) - 6 nos.

28. Aerial Chair for conductor. - 6 nos.

29. Aerial Trolley. - 4 nos.

30. Turn Buckle - 10 T. - 16 nos.

- 3 T. - 6 nos.

31. Tension/Sag PlateFor Tensioning

Purpose). - 6 nos.

32. Sag Board. - 8 nos.

33. Marking Roller. - 4 nos.

34. Mismatch Roller. - 2 nos.

35. Joint Protector. - 6 nos.

36. Walkie Talkie Set. - 4 sets

37. Theodolite with stand. - 1 no.

38. Thermometer. - 3 no.

39. Survey Umbrella. - 1 nos.

40. Hydraulic Wire cutter. - 2 nos.

41. Binocular. - 3 nos.

42. Flag (Red and Green) - 30 nos.

43. Crow Bar (1.8 m Length). - 10 nos.

44. Nail Puller. - 6 nos.

45. Wire Rope.

(19 mm. dia.). - 1000 m.

(16 mm. dia.). - 150 m.

(14 mm. dia.). - 900 m.

46. Polypropylene rope.

(25 mm. dia.). - 500 m. Vol.5 : Page #

(19 mm. dia.). - 500 m.

47. D Shackle.

(190 mm Long). - 40 nos.

(150 mm Long). - 125 nos.

(100 mm Long). - 125 nos.

48. Bulldog Clamp 100 mm Long. - 35 nos.

49. Hammers, spanners,( Both Flat and

ring) round files, flat files,

screw drivers, cutting pliers,

Steel and Metallic Tapes, - As per reqmt.

Hecksaw frames and Blades,

Deadmen, Scaffolding,Slings, etc.

50. Tents, Buckets, water drums,

camping cots, tables, - As per reqmt.

chairs, petromax lamps etc.

51. Safety equipments:

i) Safety helmets - 200 nos.

ii) Safety belts - 40 nos.

iii) Safety shoes - 200 nos.

iv) First Aid Box - 5 nos.

Note: The quantity of safety equipment may be changed as per

manpower engaged.

Vol.5 : Page #

ANNEXURE - S/2

Back to Contents PagePOWERGRID CORPORATION OF INDIA LTD.

(CONSTRUCTION MANAGEMENT)LINE CONSTRUCTION

Man Power Requirement

For Stringing Gang

1. Manpower requirement and average output per gang is given

as under:-

Sl. No. Description of line Manpower Nos. Average output

KM per month

1. 132 KV S/C Line 85 30

2. 132 KV D/C Line 85 15

3. 220 KV S/C Line 110 30

4. 220 KV D/C Line 110 15

5. 400 KV S/C Line 200 15

6. 400 KV D/C Line 200 8

2. Breakup of Manpower is as follows :

400KV S/C 220KV S/C 132KV S/Cor D/C Line or D/C Line or D/C Line

i) Engineer. 2 Nos. 2 Nos. 1 No.

ii) Supervisors. 10 Nos. 6 Nos. 4 Nos.

iii) Skilled Manpower.

(a) Fitters. 30 Nos. 20 Nos. 15 Nos.

(b) TSE operators. 2 NOS. 2 Nos. 2 Nos.

(c) Mechanics. 4 Nos. 3 Nos. 2 Nos.

Vol.5 : Page #

(d) Carpenters. 2 Nos. 2 Nos. 1 No.

(e) Skilled workers for

misc. works. 110 Nos. 50 Nos. 40 Nos.

iv) Unskilled workers. 40 Nos. 25 Nos. 20 Nos.

Vol.5 : Page #

Vol.5 : Page #

Chapter-6

Check Format

______________________________________________________________________

CHAPTER SIX

______________________________________________________________________

CHECK FORMATBack to Contents Page

POWERGRID CORPORATION OF INDIA LIMITED(CONSTRUCTION MANAGEMENT)

LINE CONSTRUCTION

Check Format

NAME OF LINE...... NAME OF CONTRACTOR......

SECTION - LOC. NO....... To LOC. NO.......

----------------------------------------------------------------ITEM CHECKED RESULT OBSERVATION,

IF ANY----------------------------------------------------------------

(A) Pre-stringing checks:

1) Backfilling of soil and

revetment/Benching wherever Yes/No

required is done.

2) Towers are tightened

properly and all the mem- Yes/No

bers, Nut/Bolts are provided.

3) Trees in the corridor

removed to facilitate Yes/No

smooth stringing.

4) All Line materials, tes-

ted T & P, safety equipments Yes/No

Vol.5 : Page #

and relevant drawings are

available for stringing.

5) Shutdown of Powerline/

Railway block if required, Yes/No

is arranged.

6) Necessary Protection/

scaffolding/warning signals Yes/No

provided for Railway/Power

line/P&T line/Road Crossing.

7) Towers vulnerable for one

side load is guyed properly. Yes/No

8) Tower footing resistance is

within permissible limit of Yes/No

10 ohms.

Vol.5 : Page #

(B) Paying Out of Earthwire

1) Work is being carried

out with full safety meas- Yes/No

ures as per guide line.

2) Travelling grounds are

provided Yes/No

3) Paying out is carried out

as per approved drum schedule. Yes/No

4) All pulleys fixed on

towers for paying out are Yes/No

moving freely.

5) Effective communication

exists through walkie-

Talkie and through persons

on towers. Yes/No

6) Earthwire is being con-

stantly checked as it is un- Yes/No

wound. Damaged portion, if

any, is removed.

7) Necessary arrangement

have been provided to Yes/No

avoid rubbing of earthwire

against hard ground.

8) Necessary details of

Earthwire, M.S. Joints Yes/No

Vol.5 : Page #

recorded as per Ann-

CF-I & CF-II.

(C) Paying out of Conductor

1) Work is being carried

out with full safety meas- Yes/No

ures as per guide line.

2) Tensioner/puller are

properly placed, firmly Yes/No

anchored and earthed.

3) Conductor drums are

placed properly to avoid Yes/No

bird caging

4) Sequence of paying out

is such that to avoid un- Yes/No

balanceing of load on tower.

7) Details of insulators

and fitting are recorded as Yes/No

per Ann. CF-III & CF-IV.

8) Paying out is carried

out as per approved drum Yes/No

schedule.

9) Travellers fixed on

towers are moving freely. Yes/No

10) Effective communication

exists through walkie-talkie

and through persons stand- Yes/No

ing on towers for smooth Vol.5 : Page #

and safe paying out.

11) Conductor is checked

continuously as it is un-

wound from drum. Damaged Yes/No

portion, if any, is re-

moved/repaired.

12) Proper arrangements

made to avoid rubbing of Yes/No

conductor on ground/hard

surfaces.

13) Details of conductor

and M.S.J/repair sleeve is Yes/No

recorded as per Ann. CF-I

& CF-II.

(D) Final Sagging and Tensioning of Earthwire and Conductor

1) Sag board is fixed cor-

rectly after taking into ac- Yes/No

count length of suspension

clamp/fittings.

2) No. of sag boards fixed

in a section is as per tech- Yes/No

nical specification.

3) Sag is measured corre-

ctly at prevailing tempera- Yes/No

ture. Details recorded as

per Ann. CF-V.

4) Sag mismatch is within Vol.5 : Page #

permissible limits of 40mm Yes/No

as checked with Theodolite.

5) After measuring sag,

marking/cutting of Earth-

wire/ conductor is done Yes/No

correctly to fix tension

clamp/fittings)

6) Details of tension clamp/

fitting are recorded Yes/No

as per Ann. CF-VI, CF-III,

& CF-IV.

(E) Clipping of Earthwire and Conductor

1) For clipping, the mark-

ing is done correctly so Yes/No

that suspension clamp/

fitting hangs exactly

vertical.

2) Before clipping of con-

ductor, proper earthing is Yes/No

provided.

3) Following line material provided

as per specification. Details

recorded as shown below.

a) Suspension clamp of

Earthwire and conductor Yes/No

as per Ann.CF-IV & CF-VI.

b) Vibration Dampers for Vol.5 : Page #

Earthwire and Conductor as Yes/No

per Ann. CF-VII

c) Details of spacer/spacer

damper/jumper spacer Yes/No

recorded as per Ann. CF-VIII.

d) Jumpers for Earthwire/

Conductor as per Ann. CF-IV Yes/No

& CF-VI.

e) Pilot fitting, wherever

necessary as per Ann. CF- Yes/No

III & CF-IV.

4) Sag/Tension again mea-

sured after clipping and Yes/No

found o.k. Details recor-

ded as per Ann. CF-V.

5) Transposition done as

per specification. Details Yes/No

of line material recorded

properly.

6) All line materials pro-

vided are as per specifica-

tion and approved drawings. Yes/No

All necessary details recor-

ded for traceability.

7) Jumpers tightened prop-

erly. Live metal clearance Yes/No Vol.5 : Page #

are as per specification.

8) Minimum Ground Clearance,

Clearances over Power line/ Yes/No

Railway line/River Crossing

are as per specification.

Certificate: Stringing is completed in all respect.

FOR CONTRACTOR FOR POWERGRID

SIGNATURE SIGNATURE

NAME NAME

DESIGNATION DESIGNATION : E1/E2/E3

DATE DATE

VERIFIED

SIGNATURE

NAME

DESIGN:E4/E5

DATE

APPROVED

SIGNATURE

NAME

DESIGN: E6/E7

DATE

Vol.5 : Page #

ANNEXURECF- I

Details of Earthwire/Conductor

1. Make

2. Batch No.

3. Quantity and Location

Sl.No.

DrumNo.

Lengthmarked on

Drum

Lengthpaid

Paid between

From

Loc. No.

To Loc.

No.

Phase Wire No.

4. There is no damage to Earthwire/conductor before or

during stringing.Strands are in perfect position.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

ANNEXURECF- II

Details of M.S. Joint for Earthwire/Conductor and Repair

Sleeve for Conductor

1. Make

2. Batch No.

3. Location

Sl.No.

Between Loc. No. Phase Wire No.

4. Dimension - Recorded as per Ann.CF-IX

5. M.S. Joint has been provided at least 30 meters away

from tower.

6. There is no M.S. Joint over Railway/River/Main road crossing

7. Not more than one M.S. Joint provided in one span for

each Earthwire/Conductor.

8. Repair sleeve shall be used if number of damaged strands

is not more than 1/6th of the total strands in the outer

layer. If damage is more, then the damaged portion shall

be removed and M.S. Joint provided.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

ANNEXURE

CF - III

Records of Insulators

1. Type - Glass/Porcelain, Suspension/Tension/Pilot2. Make -

Vol.5 : Page #

3. Batch No. -4. Electro Mechanical Strength -5. Quantity and Location -

Sl.No.

Loc. No. Qty. asper drg.

Qty. in CKT-I Qty. in CKT-II

Phases PhasesR Y B R Y B

Remarks

6. Insulators are completely cleaned with soft cloth. Glazing

is proper. There is no crack, scratch or white spot on its

surface.

7. `R' Clips in Insulators are fitted properly.

8. While Hoisting, no damage caused to insulators.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

ANNEXURECF - IV

Details of Hardware Fitting

1. Make

2. Batch No.

3. Type of fitting - I/V, Single/Double, Suspension/Tension.

4. Quantity and Location.

Sl.

No.

Loc. No. No. of fittingsPhases

R Y B

Remarks

5. All Nuts/Bolts properly tightened

6. All components of fittings have been provided as per

approved drawings. Dimensions and galvanizing are O.K.

Fitting is cleaned and there is no damage to any component.

7. All split pins properly provided.

8. In case of Tension fittings, Dimensions before and

after compression recorded as per Ann.CF-IX


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

ANNEXURECF - V

Sag Measurement for Earthwire and Conductor

1. Sag board fixed between Loc. No......... and ....

2. Temperature ........°C

3. Measurement of Sag/Tension.

Item Phase/Wire No. As per Sag/Tension Chart Actual

Sag

Tension

4. During paying out/ rough sagging, tension in

conductor / Earth Wire was as per technical specifications.

5. For final sagging, initial stringing chart for conductor

and final stringing chart for Earth Wire are used.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

ANNEXURECF - VI

Suspension/Tension Clamps for Earthwire

1. Make

2. Batch No.

3. Quantity & Location No.

Sl. No. Wire No. Loc. No. Remarks

4. All components of clamps have been provided as per

Vol.5 : Page #


Clamp is cleaned and there is no damage to any component.

5. All Nuts & Bolts have been properly tightened.

6. Split pins have been properly fixed.

7. In case of Tension clamp, Dimensions before and after

compression recorded as per Ann.CF-IX


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

ANNEXURECF - VII

Records of V.D. for Earthwire/Conductor

1. Make

2. Batch No.

3. Quantity & Location

Sl.

No.

Fixed on

Loc. No.

Fixed towards

Loc. No.

Phase/wire No. No. of V.D.

4. All components of V.D.have been provided as per approved

drawings. Dimensions and galvanizing are O.K. V.D. is

cleaned and there is no damage to any component.

5. Nuts/Bolts tightened properly.

6. V.D. fixed as per approved placement chart.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

ANNEXURECF - VIII

Records of Line spacer/spacer Damper/Jumper spacer

1. Make

2. Batch No.

3. Quantity & Location

Sl. No. Span/Loc. No. Phase No. of Spacer

4. All components of spacer have been provided as per


Spacer is cleaned and there is no damage to any component.

5. Nuts/Bolts tightened properly.

6. Spacer/spacer damper fixed as per approved placement chart.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

ANNEXURE

CF - IX

Dimensions for M.S. Joints/tension sets for earthwire and conductor.

i) Type of joint ACSR (Mid span jt./dead end jt./jumper cone/)/E/W (Mid span jt./ dead end jt./jumper cone)/ACSR Repair sleeve/T-Clamp.

ii) Locn. No. ... ..... ..... ..... ..... iii) Span Loc. No. ..... to .. .. .. .. .. iv) Apprd. drg. Nos......................v) Details of dimensions

Steel portion Aluminium portion

As per drg. Actual As per drg. ActualBef. Comp. Aft. Comp. Aft. Comp. Bef. Comp. Aft. Comp. Aft. Comp.

Length Outerdia

Length C-C F-F Length C-C F-F Length Outerdia

Length C-C F-F Length C-C F-F

C-C : Corner to corner distance.

F-F : Face to face distance.

Vol.5 : Page #

vi) Bores in the sleeves are perfectly clean.

vii) The following may be checked as per approved drawing:

a) Marking and cutting.

b) Correct sizes of dies

c) Centering & fixing of sleeves.

d) Fixing of all the components i.e. Aluminium end

pipes, hole plugs etc.

e) Compression of sleeves at specified pressure.

f) Application of filler paste (Zinc chromate).

viii) All the sharp edges have been filed after compression.

ix) There is no crack, bend or any damage to joint

after compression.


SIGNATURE SIGNATURE

NAME NAME


DATE DATE

Vol.5 : Page #

Vol.5 : Page #

Bibliography

______________________________________________________________________

BIBLIOGRAPHY______________________________________________________________________

(1) "Transmission line structures" by S.S. Murthy and A.R.

SanthaKumar.

(2) "Manual on Transmission Line Towers" - CBI&P - Technical

Report No.9.

(3) "Workshop on transmission line"-CBI&P- Vadodara (29th

Nov.- 2nd Dec.,94).

(4) "Symposium on Design & Protection of 400 kV Transmission

Lines" - CBI&P - Publication No.131 .

(5) "Overhead line Practice" by John Mccombe.

(6) "Guide to the installation of overhead transmission line

conductors" - IEEE Std. -524 - 1992.

(7) "Code of practice for Design, installation and

maintenance of overhead power lines"-IS:5613:1989.

(8) "Transmission line construction"-Electricity

Generating Authority, Thailand - Specification No.C-

2, Rev. 6 .

(9) "Technical Specification Vol.III" - Power Grid

Corporation of India Ltd.

(10) "Accident Report on Tower failure in NR-I"

(April,95)- Power Grid Corporation of India

Ltd.

(11) "List of checks for stringing" prepared by WR

(July,94)- Power Grid Corporation of India Ltd.

(12) "Construction Manual,Part-II, Transmission Line

Construction, Vol.-III, Section-III: Stringing" SRTS.

- Power Grid Corporation of India Ltd.

(13) Indian Electricity rules 1956.

(14) Indian Electricity Act, 1910.

Vol.5 : Page #

_____________________________________________________________________

_

RESUMES______________________________________________________________________

OUR TEAM

(1) Sh. V.C. Agarwal, AGM, is B.E. (Civil) and M.E. (Hons.)

in ‘Soil Mech. and Fndns. Engg.’ From Univ. of Roorkee,

Roorkee.

He has 28 yrs. of vast experience in Construction,

Planning and Monitoring of large Transmission Projects.

(2) Sh. D.K. Valecha, Sr. Manager, is B.Sc. Engg.

(Electrical) from Reg. Engg. College, Kurukshetra.

He has 17 yrs. of varied experience in Planning &

Monitoring, Construction, Operation & Maintenance of

Transmission Lines and Substations.

(3) Sh. J.K. Parihar, Manager, is B.E. Elect. (Hons.) from

Univ. of Jodhpur, Jodhpur.




(4) Sh. R. Nagpal, Manager, is B.E. Elect. (Hons.) from

Punjab Engg. College Chandigarh and MBA from Indira

Gandhi National Open Univ., New Delhi.




(5) Sh. N.K. Rai, Dy. Manager, is B.Sc. Engg. (Mech.) from

Birla Institute of Technology, Mesra, Ranchi.

He has 19 yrs. of varied experience including 8 yrs. in

Indian Army in Stores Management, 11 yrs. in Power Sector

in Planning, Monitoring and Contracts Deptt. at Corporate

Center.

Vol.5 : Page #

(6) Sh. B.K. Jana, Dy. Manager, is B.E. (Civil) from Regional

Engineering College Durgapur and M.Tech. in Applied

Mechanics from I.I.T. Delhi.

He has 14 yrs. of varied experience in Design, Planning &

Coordination of Sub-station works, TL Fndns., Pile Fndns.

& other special heavy Foundations.

(7) Sh. S.K. Niranjan, Engineer is B.Tech. (Civil) from

H.B.T.I., Kanpur (U.P.).

He has 7 yrs. of varied experience in design of

underground structures (Power Tunnels and Shafts) of

Hydro-Electric projects.

Vol.5 : Page #

CONSTRUCTION MANAGEMENT DEPTT.

Vol.5 : Page #

User’s ManualOf

Construction

Transmission Line(Part-1)

Sub-Station(Part-2)

General Support(Part-3)

Vol. 1Line Survey

Vol. 3Soil

Investigation &Foundation

Vol. 2Env. Mgmt.

Vol. 4Tower Erection

Vol. 1Land &Infrastr.

Vol. 3Switchyard

Ercn.

Vol. 2Civil

Construction

Vol. 4Ercn. Of TF,

SR & CB

Vol. 1MB

(Procedures& G. Lines)

Vol. 3Contracts

Mgmt.

Vol. 4Budget

& Finance

Vol.5 : Page #

Vol. 5Stringing

Vol. 5Aux. Pkgs.

(Elect.)

Vol. 5Labour

Regulations

Documents

Construction Exe 09 August SR I 2010 Module Stringing