Gen Const Practics

8/22/2019 Gen Const Practics

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CSPDCL, RAIPUR Section 5 Page 1 of 52

RAPDRP Part B

Section5 GCP

GENERAL CONSTRUCTION PRACTICES

A. CONSTURCTIONAL PRACTICES FOR SUB-TRANSMISSION LINE

1.0 DETAILED SURVEY

Successful bidder shall carry out detailed survey and prepare the detailed route of 33 KVlines, location of 33/11Kv Substations on topographical sheets / majmuli maps availablefrom government agencies. The bidder shall make his own arrangements for obtainingthe topographical maps / majmuli maps from the concerned agencies, the final routemap of 33 KV lines shall be prepared and submitted by the bidder showing the proposedpole position, ground clearance, conductor sag and various crossings i.e. railway lines,communication lines, EHT lines, rivers, road and stream crossings on the map to a scaleof 1:25000. All LT lines along with pole locations are to be marked on village / majmulimaps / patwari maps to a scale 1:5000.

1.1 Check Survey of Pole Locations

The detailed survey shall be conducted to locate and peg mark the pole positions on

ground conforming to the approved profile and pole schedule. In the process, it isnecessary to have the pit centers marked according to the excavation marking charts.The levels up or down of each pit center with respect to the center of the pole locationsshall be noted and recorded for determining the amount of earthwork required to meetthe approved design parameters.

Changes, if required, after detailed survey in the preliminary pole schedule shall becarried out by the Contractor and he shall thereafter submit a final pole schedule for theapproval of employer. The pole schedule shall show position of all Poles, type of Poles,span length, type of foundation for each pole and the deviation at all angles as set outwith other details.

(i) Details En-route: All topographical permanent features, such as trees,

telecommunication lines, buildings etc, 5.5 meter on either side of the alignmentshall be detailed on the route plan.

(ii) Clearance from ground building, trees etc.: Clearance from ground buildings,trees and telephones lines shall be provided in conformity with the Electricity Act,2003, as amended up to date. The bidder shall select the height of the polessuch that all the electrical clearances are maintained.

(iii) The minimum planting depth of poles shall be governed by IS: 1678, However, ifdue to the ground conditions e.g. water logged area etc. depth of planting ofpoles shall be suitably increased, with appropriate extension arrangement inorder to maintain the required clearances the vendor will submit the details of thesame on case to case basis.

(iv) Appropriate Guarding arrangement shall be used for crossings of electric line /

telecom line / road / drain / canal crossing and at all points as per statutoryrequirements. The bidder shall provide install anti climbing devise and dangerplates on all poles and DT stations.

1.2 Survey shall be carried out of the existing 33 KV lines net work. The survey shallbe GPS based. It will cover mapping of 33 KV lines poles. The survey shall becarried out existing 33 KV feeder wise.

1.3 Preparation of single line diagram through suitable GIS & Electrical planningsoftware indicating the location of each 33 KV lines poles, size of the conductorsand locations.

1.4 The bidder shall hand over the software in CD media and corresponding licensekey to operate the system to the Employer after the completion of award.

For Existing Line

1.5 Survey should also indicate the numbers of existing poles which are leaning andare required to be straightened. It should also indicate whether proper ground


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clearance is available. In case it is necessary to provide guarding for the 33 KVline crossing the road, it should be indicated.

1.6 It shall also identify the spans where the conductor size is less than Raccoon for33 KV Lines.

For new line work

1.7 Based on the aforesaid survey tapping point of 33 KV lines is to be proposedgiving the location of proposed Substations.

1.8 The survey shall clearly indicate the locations where road crossing guarding oftelephone line is required.

1.9 The detail of survey which include pole location, distance between poles,reference point, size of conductor and other details as per above shall be providedto the Employer in Excel format or text format along with the data field name.

2.0 CLEARANCES - GENERAL

For the purpose of computing the vertical clearance of an over-head line, the maximumsag of any conductor shall be calculated on the basis of the maximum sag in still air andat the maximum temperature, as per REC specifications. Similarly, for the purpose of

computing any horizontal clearance of an over-head line, the maximum deflection of anyconductor shall be calculated on the basis of the wind pressure, as per RECspecifications.Following clearances shall be maintained by the contractor while executing thework, in conformation to the Indian Electricity Rules 1956:-

2.1 Clearance above Ground of The Lowest Conductor

1 No conductor of an over-head line, including service lines, erected across a streetshall at any part thereof be at a height less than

(a) For low and medium voltage lines 5.8 meters

(b) For high voltage lines 6.1 meters

2 No conductor of an over-head line, including service lines, erected along any streetshall at any part thereof be at a height less than

(a) For low and medium voltage lines 5.5 meters

(b) For high voltage lines 5.8 meters

3 No conductor of an over-head line including service lines, erected elsewhere thanalong or across any street shall be at a height less than.

(a) For low, medium and high voltage lines up to Andincluding 11,000 volts, if bare

4.6 meters

(b) For low, medium and high voltage lines Up to andincluding 11,000 volts, if insulated

4.0 meters

(c) For high voltage lines above 11,000 volts 5.2 meters

4 For extra-high voltage lines the clearance above ground shall not be less than 5.2meters plus 0.3 meter for every 33,000 volts or part thereof by which the voltage ofthe line exceeds 33,000 volts: Provided that the minimum clearance along or acrossany street shall not be less than 6.1 meters.

2.2 Clearance from Buildings of Low and Medium Voltage Lines and Service Lines


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Where a low or medium voltage over-head line passes above or adjacent to orterminates on any building, the following minimum clearances from any accessible point,on the basis of maximum sag, shall be observed:-

a. For any flat roof, open balcony, verandah roof and lean-to-roof

(i) When the line passes above the building a vertical clearance of 2.5meters from the highest point; and

(ii) When he line passes adjacent to the building a horizontal clearance of1.2 meters from the nearest point, and

b. For pitched roof

(i) When the line passes above the building a vertical clearance of 2.5meters immediately under the lines, and

(ii) When the line passes adjacent to the building a horizontal clearance of1.2 meters.

The horizontal clearance shall be measured when the line is at a maximum deflectionfrom the vertical due to wind pressure.

2.3 Clearance from Buildings of High and Extra-High Voltage Lines

i. Where a high or extra-high voltage over-head line passes above or adjacent to anybuilding or part of building it shall have on the basis of maximum sag a verticalclearance above the highest part of a building immediately under such line, of notless than

(a)For High Voltage Lines up to andincluding 33,000 volts

3.7 meters

(b) For Extra High Voltage Lines3.7 meters plus 0.3 meters for everyadditional 33,000 volts or part thereof.

ii. The horizontal clearance between the nearest conductor and any part of such

building shall, on the basis of maximum deflection due to wind pressure, be not lessthan:-

(a)For high voltage lines up to andincluding 11,000 volts

1.2 meters

(b)For high voltage lines above11,000 volts and up to andincluding 33,000 volts

2.0 meters

(c) For extra-high voltage lines2.0 meters plus 0.3 meters for everyadditional 33,000 volts or part thereof.

3.0 CONSTRUCTION

The construction of over head-lines may be divided into the following parts:-1. Survey of lines,2. Providing required line materials and shifting of these materials at site,3. Erection of intermediate poles, cut point/ double pole (D.P.) locations.4. Erection of Stay Sets and installation of strut poles as required,5. Testing of line insulators and erection of insulators,6. Execution of temporary jumpering at the terminal points to facilitate uninterrupted

supply of power to the consumers.7. Stringing of new conductor, tying of conductor on insulators, jumping at cut points

locations.8. Earthing of individual supports.9. Provision of cradle guards at locations where possibilities of lines of different voltage

gradient is likely to construct by other agency at a later date. Also providing earth

mat / earthing cradle guard at various crossings as per prevailing rules,


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10. Provision of anti-climbing device through wrapping of Barbed wire,11. Provision of danger notice board,12. Marking of each and every support,13. Special Crossing and its guarding i.e. P&T lines, building, line of other voltage

grading, Road, other than Road/ Street, River crossing, Railway line crossing etc.14. Jumpering of lines to existing system network.

15. Testing & commissioning of line with the existing system.

3.1 Maximum Intervals between Supports

All conductors shall be attached to supports at intervals not exceeding the safe limitsbased on the ultimate tensile strength of the conductors and the factor of safetyprescribed.

Provided that in the case of over-head lines carrying low or medium voltage conductors,when erected in, over, along or across any street, the interval shall not without theconsent in writing of the Engineer in Charge, exceed 65 meters. Average span of HTlines with proposed conductors is given in the table below: -

Sr.

No.

Line

class

Support (height mtrs

/KG)Conductor type

Nominal conductor

size in sq mm

Max span in

mtrs

133 KV,3 ph

PCC (9.1m/280kg) AAAC 100 100

3.2 Pit Marking and Digging Procedure

After surveying, the pole location should be marked with the peg. The pits should not betoo large than necessary, as otherwise, after erection of the pole and filling thereremains a possibility of tilting of poles. For marking the pits, the dimensions of the pitand the centre to centre distance of pits are required. Pits having a dimension of about1.2 mtr x 0.6 m should be excavated with its longer axis in the direction of the line orcircular pit of size 0.6 mtr dia. The planting depth should be about 1/6 length of supporti.e. 1.5 mtr in case of 8 mtr long PCC pole. the Excavation in generally done by using

pickaxe crow bars, and shovel, very hard or rocky soil may require blasting of rock bysmall charges of gun power, etc. For hard rock location pit size of pole shall beexcavated depth of 1 meter and dia is 1.2 times of bottom dimension of pole i.e. appox350mm.

3.3 Erection of Poles and Concreting

After excavation of pits is completed, the supports / poles to be erected may be broughtto the pit location by manual labor or by cart. Then the pole may be erected inside thepit.

Before starting Cement pole erection activities, requisite quantities of constructionmaterials like boulders etc must be brought by the contractor near the pit. Issuance of

Permit to Work (PTW) may be governed on inspection of construction materials inrequisite quantities at site.

Before erection the pole in the pit, concrete base-padding of not less than 75 mmthickness or stone block/ pre-casting of size 450x450x75mm shall be provided for theuniform distribution of the loads of the support on the soil. At least 48 hours should beallowed for setting of base padding concrete before placing the pole on it.

Erection of poles can be done by using Bipod / Wooden horse made of 5 cm G.I. pipeand 6 m long. The spread of the legs should be 10 m. The tie wire for attachment ofbipod to the pole is about 6 m long and is made of 7/10 SWG. Stay wire and this wireshould be attached to the pole at 8 m. The pole is slid along the line route. The pole istied with 3 ropes. The rope at the bottom prevents the pole from being dragged in thedirection of the pull. To prevent the support from moving side in rising, two guy ropes are

fixed on both sides and attached to temporary anchor.


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For smooth sliding and perfect placement of pole in the pit, an inclined trench having15.2 cm (6 in.) width and 10.2 cm (4 in.) length may be dug adjacent to the pit. A pieceof M.S. channel may be placed in the inclined position at the other end of the pit forenabling the pole to slip smooth inside the pit. The trench would facilitate the pole to skidsmoothly into the pit with jerks.

The bipod is placed in position and attached to the pole by means of tie wire. The pull for

lifting the poles is provided by rope pulley. When the pole has reached at an angle of10.7 m to 12.2 m (35 to 40,) the bottom holding rope is slowly released. When the poleassumed the vertical position, the holding ropes should be tightened.

It should be ensured that the time of erection, four men are at the ropes and thesupervisor should be at a distance for guiding correct position so that in the event ofbreaking of rope, if pole falls, it will not result into an accident.

Having lifted the pole the same should be kept in vertical position with the help of manilarope of 20/25 mm dia. using the rope as a temporary anchor. As the poles are beingerected say from an anchor point to the next angle point, the alignment of the polesshould be checked and set right by visual check. The verticality of the poles are to bechecked with a spirit level. After the pole erection has been completed, and havingsatisfied that the verticality and alignments are all right, bolder filling and ramming is to

be done. In case of PCC pole back filling by bolder shall be done.In swamp and special locations, before earth filling, the poles are to be concreted up tothe ground level of the pit.

In existing tilted pole location of line, pole shall require to make vertical by using extrabolder filling & ramming. Guy supports are to be provided wherever found missing oradditionally required.

After poles have been set, the temporary anchors are to be removed.

3.4 Earthing

Earthing shall generally be carried out in accordance with the requirements of IndianElectricity Rules, 1956 and the relevant regulations of the Electricity Supply Authority

concerned and as indicated below:(a) All metallic supports shall be earthed.

(b) For PCC poles the metal cross-arms and insulator pins shall be bonded andearthed at every pole for HT lines.

(c) All special structures on which switches, transformers, fuses, etc., are mounted /likely to mount should be earthed.

(d) The supports on either side of the road, railway or river crossing should beearthed.

(e) All supports (Steel & PCC) HT lines passing through inhabited areas, roadcrossings and along such other places, where Earthing of all poles is considereddesirable from safety considerations should be earthed.

In special locations and special structures, road crossings etc., pipe/rod Earthingshould be done on either side of the construction .

At other locations the coil earthing may be adopted. The coil earthing consists of 10 mlength of 8 SWG. G.I. wire compressed into a coil 450 mm length and 50 mm dia andburied 1500 mm deep as per REC standard J-1.

Following shall be the earthing requirements:

Sl No Description Type of Earthing

1 Single Pole PCC 1 No. Coil Earthing at each SP

2 Double Pole PCC 2 Nos. Coil Earthing at each DP

3 Road Crossing GI Pipe earthing on either side one each


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4 Telephone LineCrossing

GI Pipe earthing on either side one each

5 DP with IsolatingSwitch

Coil earthing 2 Nos. and GI Pipe earthing 1 No

3.5 ERECTION OF DP STRUCTURE FOR ANGLE LOCATIONS

For angles of deviations 10 degrees to 60 degrees, DP structure may be erected. The pitdigging should be done along the bisection of angle of deviation.

After the poles are erected, the horizontal/cross bracings should be fitted and thesupports held in a vertical position with the help of temporary guys of Manila rope 20/25mm dia.

Ensuring that the poles are held in vertical position (by spirit level) or using plumb theconcreting of poles with 1:3:6 @ 0.3 Cmt. per pole for PCC may be done from bottom ofthe support to the ground level. Before erection the pole in the pit, concrete base-padding of not less than 75 mm thickness shall be done for the uniform distribution ofthe loads of the support on the soil. At least 48 hours should be allowed for setting of

base padding concrete before placing the pole on it.

3.6 CONCRETING

The concreting mixture of one Cmt. 1:3:6 ratios would mean 1 part cement, 3 partsCoarse sand and 6 part 40 mm aggregate size stones . It may be noted that whilepreparing the concrete mixture, large quantities of water should not be used as thiswould wash away cement and sand.

3.7 PROVIDING OF GUYS TO SUPPORTS

In spite of careful planning and alignment of line route, certain situations arise where theconductor tries to tilt the pole from its normal position due to abnormal wind pressure

and deviation of alignment, etc. When these cases of strain arise, the pole isstrengthened and kept in position by guys. One or more guys will have to be provided forall supports where there is unbalanced strain acting on the support, which may result intilting/uprooting or breaking of the support.

Guys are braces fastened to the pole. In this work anchor type guy sets are to be used.These guys are provided at (i) angle locations (ii) dead end locations (iii) T - off points(iv) Steep gradient locations and (v) where the wind pressure is more than 50 kg /Sq.mtrs.

The fixing of guys stays will involve (i) pit digging and fixing stay rod (ii) fastening guywire to the support (iii) Tightening guy wire and fastening to the anchor. The marking ofguy pit, digging and setting of anchor rod must be carefully carried out. The stay rod

should be placed in a position so that the angle of rod with the vertical face of the pit is30/45 as the case may be.

Before start of erection of Stay sets, required concreting materials like Cement, Sand,Stone Chips and Construction water need to be made available near the pit.

For double pole structure (DP), four stays along the line, two in each direction andtwo stays along the bisection of the angle of deviation or as required dependingon the angle of deviation are to be provided.

After concreting of 0.2 cmt per stay, back filling and ramming must be done well andappropriate time / days shall be allowed for proper setting. Alternately stone block/ RCCbase anchor plate of size 450x450x75mm as per REC standard K-1/ K-4 may be used.


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The number of RCC base anchor plate / Pre-casting shall be 3 nos. per stay for 11Kvline and 2 nos. per stay for LT line.

The free end of the guy wire/stay wire is passed through the eye of the anchor rod, bentback parallel to the main portion of the stay/guy and bound after inserting the G.I.thimble, where it bears on the anchor rod. If the guy wire proves to be hazardous, it

should be protected with suitable asbestos pipe filled with concrete of about 2 m lengthabove the ground level, painted with white and black strips so that, it may be visible atnight. The turn buckle shall be mounted at the pole end of the stay and guy wire sofixed that the turn buckle is half way in the working position, thus giving the maximummovement for tightening or loosening.

3.8 Guy Stay Insulators

Guy insulators are placed to prevent the lower part of the Guy from becoming electricallyenergized by a contact of the upper part of the guy when the conductor snaps and fallson them or due to leakage. No guy insulator shall be located less than 2.6 m from theground. Guy insulators are to be used in stay wires only. When continuous earth wire isused guy insulator may not be required.

3.9 Fixing of Cross-Arms

After the erection of supports and providing guys, the cross-arms are to be mounted onthe support with necessary clamps, bolts and nuts. The practice of fixing the cross armsbefore the pole erection is also there. In case, the cross-arm is to be mounted after thepole is erected, the lineman should climb the pole with necessary tools. The cross-arm isthen tied to a hand line and pulled up by the ground man through a pulley, till the cross-arm reaches the line man. The ground man should station himself on one side, so that ifany material drops from the top of the pole, it may not strike him. All the materials shouldbe lifted or lowered through the hand line, and should not be dropped.

3.10 Insulators and Bindings

Line conductors are electrically insulated from each other as well as from the pole or

structure by Insulators. Following two types of insulators shall be used for the lineinsulation:

(1) Pin type(2) Strain type

The pin type insulators will be used for straight stretch of line. The strain insulators areused at terminal locations or dead end locations and where the angle of deviation of lineis more than 10.

The pins for insulators are fixed in the holes provided in the, cross-arms and the pole topbrackets. The insulators are mounted in their places over the pins and tightened. In thecase of strain or angle supports, where strain fittings are provided for this purpose, onestrap of the strain fittings is placed over the cross-arm before placing the bolt in the holeof cross-arms. The nut of the straps is so tightened that the strap can move freely inhorizontal direction.

3.11 Tying of Conductor on Pin Insulators

Conductors should occupy such a position on the insulator as will produce minimumstrain on the tie wire. The function of the wire is only to hold the conductor in place, onthe insulator, leaving the insulator and pin to take the strain of the conductor.

In straight line, the best practice is to use a top groove insulator. These insulators willcarry grooves on the side as well. When the conductor is placed on the top groove, thetie wire serves only to keep the conductor from slipping out.


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On corners and angles (below 5 degree deviations) the conductors should be placed onthe outside of the insulators. On the far side of the pole, this pulls the conductor againstthe insulator instead of away from the insulator.

3.12 Kind and Size of Tie Wire to Be Used

Aluminum tie wire should be used with aluminum line conductor. The tie should always

be made of soft annealed wire so that it may not be brittle and injure the line conductor.A tie wire should never be used for second time. Good practice is to use no. 6 tie wiresfor line conductor. The length of the wire varies from 1 m for simple tie of a smallinsulator (11 kV Pin insulators).

3.13 Rules of Good Tying Practice:(i) Use only fully annealed tie wire.

(ii) Use suitable size of tie wire which can be readily handled yet one which willprovide adequate strength.

(iii) Use length of tie wire sufficient for making the complete tie, including anallowance for gripping with the hands. The extra length should be cut from eachend if the tie is completed.

(iv) A good tie should;

(a) Provide a secure binding between line wire insulator and tie wire.

(b) Have positive contacts between the line wire and the tie wire so as toavoid any chattering of the contacts.

(c) Re-enforce line wire in the vicinity of insulator.

(v) Tying to be done without use of pliers.

(vi) Do not use the wire which has been previously used.

(vii) Do not use hard drawn wires for tying.

3.14 Conductor Erection

Conductor erection is the most important phase in construction. The main operationsare:-

(a) Transportation of Conductor to works site.(b) Paying and Stringing of Conductor(c) Jointing of Conductor(d) Tensioning and Sagging of Conductor

The conductor drums are transported to the tension location. While transportingprecautions are to be taken so that the conductor does not get damaged / injured. Thedrum could be mounted on cable drum support, which generally is made from crow-bar

and wooden slippers for small size conductor drums. The direction of rotation of thedrum has to be according to the mark in the drum so that the conductor could be drawn.While drawing the conductor, it should not rub causing damage. The conductor could bepassed over poles on wooden or aluminum snatch block mounted on the poles for thispurpose.

The mid span jointing is done through compressions or if helical fittings are usedthe jointing could be done manually. After completing the jointing, tensioning

operation could be commenced. The conductor is pulled through come-along clamps tostringing the conductor between the tension locations. Sagging of conductor has to be inaccordance to the Sag Tension chart. In order to achieve it, it is preferred to pull theconductor to a tension a little above the theoretical value so that while transferring it fromthe snatch blocks to the pit insulators and to take care of temperature variation. Proper

sag could achieve. Sagging for 11 KV line is mostly done by Sighting. A horizontal stripof wood is fixed below the cross-arm on the pole at the required sag. The lineman sees


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from other end and the sag is adjusted by increasing or decreasing the tension. Thetension clamps could then be finally fixed and conductor be fixed on pin-insulators. Allfittings, accessories like guys, cross-arms, etc., could be checked as they should nothave deform.

The maximum permissible spans for all the lines of 11/0.4 KV are prescribed according

to the design of the supports. Sag-tension charts for these conductors are to befollowed.

3.15 Anti-Climbing Devices

In order to prevent unauthorized persons from climbing any of the supports of HT & LTlines without the aid of a ladder or special appliance, anti-climbing devices are providedto the supports. Two methods generally adopted are (i) barbed wire binding, for adistance of 30 to 40 cm at a height of 3.5 to 4 m from ground level, (ii) clamps withprotruding spikes at a height of 3 to 4 m.

3.16 Testing and Commissioning

When the line is ready for charging, it should be thoroughly inspected in respect of the

following:-(i) Poles-Proper alignment, concerting and muffing.(ii) Cross-arms Proper alignment.(iii) Binding, clamps and jumpers To check whether these are in reach.(iv) Conductor and ground wire Proper sag to check whether there are any cuts,

etc.(v) Guys: To check whether the Guy wire is tight and whether the Guy insulators

are in-tact.(vi) Earthing System: To check whether the earthing connections of supports and

fittings are intact. Measure earth resistance with earth tester.

After the visual inspection is over and satisfied, the conductor is tested forcontinuity/ground, by means of megger. At the time of testing through megger person

should not climb on the pole or touch the guarding, conductor, guy wire etc.

(1) Before charging any new line, it should be ensured that the required inspection feefor the new line is paid to the Electrical Inspector and approval obtained from himfor charging the line.

(2) The line should be energized before the officer who has been authorized by theCompany in this regard.

(3) Before energizing any new line, the officer-in-charge of the line shall notify to theworkmen that the line is being energized and that it will no longer be safe to workon line. Acknowledgement of all the workmen in writing should be taken in token ofhaving intimated them.

(4) Wide publicity, by issuing notice in the local news paper should be arranged, in allthe localities through which the line, that is to be energized passes, intimating the

time and date of energizing and warning public against the risk in meddling withthe line.

(5) The Officer-in-charge of the line shall personally satisfy himself that the same is ina fit state to be energized.

3.17 Special Crossings

(A) In case the lines cross-over the other lines or buildings, safe minimum clearancesare to be maintained as per I E Regulations. These clearances should bemaintained. The crossings could be for

1. Telephone / telegraph lines2. Buildings3. Lines of other voltages

4. Roads, Streets, Other than Roads/Streets. Extra steel structures and GIwire, if needed shall be provided by the agency.


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(B) River Crossing: Data for the highest flood-level should be obtained for previousyears. For medium voltage minimum clearance of 3 m is kept over the highestfloor level. Double pole or 4 pole structure would be required to be speciallydesigned, depending upon the span and conductor size for the river crossing.The structures should be located at such places that they could be approachedunder flood condition also. The foundation of structures should be sound so thatit may not get eroded or damaged due to rain water.

3.18 Guarding

Guarding is an arrangement provide for the lines, by which a live conductor, whenaccidentally broken, is prevented to come in contact with other electric lines, telephoneor telegraph lines, railway lines, roads, and persons or animals and carriages movingalong the railway line or road, by providing a sort of cradle below the main electric line.Immediately after a live conductor breaks, it first touches this cradle guard of G.I. Wiresbefore going down further, this in turn, trips the circuit breakers or H.T. /L.T. fusesprovided for the protection purposes, and the electric power in the conductor or the lineis cut off, and danger to any living object is averted.

Guarding is not required for crossings of 66 KV and higher voltage lines where thetransmission line is protected by fast acting relay operated circuit breaker of moderndesign with a tripping time of the order of 0.25 sec. from occurrence of fault to itsclearance. For all other crossings, guarding is essential for Railway Telecommunicationlines and major road crossing.

The minimum height between any guard wire and live crossing conductor shallnot be less then 1.5 m in case of a railway crossing.

The guarding consists of 2 G.I., bearer wires strung between the two line supports, andG.I. Cross-lacings connecting two-bearer wires at definite intervals. The bearer fixed tothe guarding cross-arms on the line supports by means of threaded eyebolts for proper

tightening.

4.0 DESIGN PARAMETERS:

(i) Factor of safety 2.0 in normal conditions for 2.5 for 33 KV Lines PCCsupports.

(ii) Wind pressure on pole & conductor 75 kg/m2

for 33 KV lines.(iii) In addition to wind load on cross arm insulators guy-wire etc shall be

considered.(iv) Wind load on full projected area of conductors and poles is to be

considered for design.(v) Ground clearance shall be minimum 5.2m for 33 KV Lines for bare

conductor at locations other than road crossings.

(vi) The live metal clearance shall be as per IS: 5613(vii) Pole accessories like danger plates phase plates and number plates

shall be provided.

5.0 STRINGING OF CONDUTOR

i) The works include spreading of conductors or HT/LT cables without anydamages and stringing with proper tension without any kinks / damagesincluding binding of conductor at pin points, jumper at cut points etc, Theground and line clearances at road crossings along roads. LT crossingand others shall be as per the relevant I.E. rules.

ii) While transporting conductors drums to site precautions are to be taken so thatthe conductor does not get damaged. The drum shall be mounted on cable drum

support, The direction of rotation o the drum shall be according to the mark in


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the drum so that the conductor could be drawn, While drawing the conductor, itshall not rub causing damage, the conductor shall be passed over poles onwooden or aluminium snatch block (pulley) mounted on the poles for thispurpose.

iii) The conductor shall be pulled through come-along clamps to stringing theconductor between the tension locations.

iv) Conductor splices shall not crack or otherwise be susceptible to damage in thestringing operation. The contractor shall be used only such equipment/ methodsduring conductor stringing which ensures complete compliance in this regard. Allthe joints including mid span joints on the conductor and earth wire shall be ofthe compression type in accordance with the recommendations of themanufacturer, for which all necessary tools and equipment like compressorsdies, etc, shall be obtained by the contractor, each part of the joint shall becleaned by wire brush till it is free of rust or dirt, etc, and be properly greasedwith anti corrosive compound, before the final compression is carried out withthe compressors. After completing the jointing, tensioning operation shall becommenced.

v) All the joints or splices shall be made at least 15 meters away form thepole No. joints of splices shall be made in spans crossing over main roads,railways and small rivers, spans. Not more than one joint per sub conductorspan shall be allowed. The compression type fittings shall be of the selfcentering type. After compressing the joint the aluminium sleeve shall have allcorners rounded; burrs and sharp edges removed and smoothened.

vi) During stringing of conductor to avoid any damages to the joint the contractorshall use a suitable protector for mid span compression joints in case they are tobe passed over pulley blocks / aerial rollers. The pulley groove size shall besuch that the joint along with protection can be passed over it smoothly.

6.0 PERMITTED EXTRA CONSUMPTION OF CONTRACTOR SUPPLIED MATERIALS

The quantities of conductor, insulator, earth wire, hardware fitting, conductor and earthwire accessories indicated in BPS are tentative and actual quantity will depend upon finalsurvey. The payment for contractor supplied line materials shall be made for thequantities incorporated in the works plus permitted extra quantities as mentioned below:

Contractor shall make every effort to minimize the breakage, losses and wastage of theline material during erection. However the contractor shall be permitted the extraconsumption up to the limit as specified in the table below and shall be permitted todispose of the scrap, if any .

Sr.No.

Item% of permitted extra

consumption

1 Conductor 1

2 HT & LT Cable 1

3 Cable (Power & Service Wire) 1

In case of conductor the permitted extra consumption limit of 1% is inclusive of sag,jumper, damage, losses and wastage.

The contractor shall not be required to return to the purchaser, empty conductor / earthwire left over drums and shall dispose of the same at his cost.

7.0 TENSIONING AND SAGGING OPERATIONS

(i) The tensioning and sagging shall be done in accordance with the approved

stringing charts or sag tables. The initial stringing chart shall be sued for the


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conductor and final stringing chart for the earth wire. The conductors shall bepulled up to the desired sag and left in running blocks for at least one hour afterwhich the sag shall be re-checked and adjusted, if necessary before transferringthe conductor from the running blocks to the suspension clamps. The conductorshall be clamped within 36 hours of sagging in.

(ii) The sag will be checked in the first and the last section span for sections up toeight spans and in one additional intermediate span for sections with more thaneight spans. The sag shall also be checked when the conductors have beendrawn up and transferred form running blocks to the insulator clamps.

(iii) At sharp vertical angles, conductor and earth wire sags and tensions shall bechecked for equality on both sides of the angel and running block. Thesuspension insulator assemblies will normally assume verticality when theconductor is clamped. Tensioning and sagging operations shall be carried out incalm whether when rapid changes in temperature are not likely to occur.

7.1 Clipping in

Clipping of the conductors in to position shall be done in accordance with themanufacturers recommendations, jumpers at section and angle towers shall be formed

to parabolic shape to ensure maximum clearance requirements, Fasteners in all fittingsand accessories shall be secured in position. The security clip shall be properly openedand sprung into position.

7.2 Fixing of conductor and earth wire accessories

Conductor and earth wire accessories supplied by the contactor shall be installed bycontractor as per the design requirements and manufacturers instruction within 24hours, of the conductor / earth wire clamping. While installing the conductor and earthwire accessories, proper case shall be taken to ensure that the surfaces are clean andsmooth and that no damage occurs to any part of the accessories or of the conductors.

7.3 ReplacementIf any replacements are to be effected after stringing and tensioning or duringmaintenance e.g. replacement of cross arms, the conductor shall be suitably tied to thepole at tension points or transferred to suitable roller pulleys at suspension points.

8.0 FINAL CHECKING, TESTING AND COMMISSIONING

After completion of the works, final checking of the line shall be carried out by theContractor to ensure that all foundation works, pole erecting and stringing have beendone strictly according to the specifications and as approved by the Owner. All the worksshall be thoroughly inspected in order to ensure that:

1 Sufficient backfilled earth covers each foundation pit and is adequatelycompacted.

2 All poles are used strictly according to final approved drawing and are free ofany defect or damage whatsoever.

3 The stringing of the conductors have been done as per the desired clearances.

4 All conductor accessories are properly installed.

5 All other requirements for completion of works such as fixing of danger plate andanti-climbing device have been fulfilled.

6 The insulation of the line as a whole is tested by the Contractor throughprovision of his own equipment, labor, etc. to the satisfaction of the purchaser.

7 All poles are properly grounded.8 The line is tested satisfactorily for commissioning purpose.


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9.0 ELECTRICAL SYSTEM DATA

Sr. No. Description of the Parameter 33 kV System 11 kV System

1 System Operating Voltage 33 kV 11 kV

2Maximum operating voltageof the systems (rms) 36 kV 12 kV

3 Rated frequency 50 Hz 50 Hz

4 No. of phases 3 3

5 Rated Insulation levels

(i) Full wave impulse withstandvoltage (1.2/50 micro-sec.)(ii) One minute power frequency dryand wet withstand voltage (rms)

170 kVp

80 KV

75 kVp

28 KV

6 Min. creepage distance25 mm/KV(900 mm)

25 mm/KV(300 mm)

7 Min. clearance

(i) Phase to earth(ii) Phase to phase(iii) Sectional

320 mm320 mm3000 mm

140 mm280 mm

Clearances

8 Rated short circuit current 25 KAfor 1 sec.

25 KAfor 1 sec.

9 System neutral earthing Effectivelyearthed

Effectivelyearthed

10.0 REPAIR TO CONDUCTORS

The conductor shall be continuously observed for loose or broken strands or any otherdamage during the running out operations. Repair to conductors, if necessary, shall be

carried out with repair sleeves. Repairing of the conductor surface shall be carried outonly in case of minor damage, scuff marks, etc. The final conductor surface shall beclean, smooth and free from projections, sharp points, cuts, abrasions, etc. TheContractor shall be entirely responsible for any damage to the poles during stringing.

(B) CONSTRUCTION PRACTICE FOR 33/11KV TRANSFORMER SUB-STATION

Following are the works owner intends to execute with installation of various equipments,apparatus and associated accessories so that all should function properly in co-ordination witheach other.

1. Providing foundation, supporting structures, operation & maintenance platform for eachequipments, apparatus and associated accessories strictly as per recommendation ofOriginal Equipments Manufacturer (OEM) and Indian Electricity Rules,

2. Providing ISMC100 Channel on the cable trench and installation of control panels in theControl Room.

3. Installations and Commissioning of each equipments, apparatus and associatedaccessories with control panels for protection alarm circuits of equipments / feeders atsubstations, which shall invariably include Transformer protection, Feeder Protection andIncomer protection.

4. Installation testing and commissioning of Current Transformers.

5. Testing & Pre - Commissioning checks shall be made in association with representativeof Engineer in Charge as per Original Equipments manufacturer recommendations /standard check list as approved by EIC.

6. Providing control / power cables between Breaker, CT, PT, Power Transformer andIndoor / outdoor control panels. The cable shall be laid in trenches provided by owner.


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Control supply of 30V DC at the substation control room shall be extended to VCBcontrol panels (Out door panel and Indoor panel) by the agency.

7. VCBs are to be connected with substation earthing mesh using 50X6 mm GS flat. Twodistinct connections shall be required for this purpose. Approximately 25 running feet GSflat shall be required for this purpose.

8. For indoor panel earthing, separate 2 Nos. 3 metres long pipe earthing pits shall beprovided with 50X6 mm GS flat. Two distinct earth connections shall be provided in thepanel earthing. Approximately 30 running feet GS flat shall be required for indoor panelearthing.

1. EXECUTION OF CONSTRUCTION WORKS:

Contractor shall jointly conduct a detailed survey site selected for 33/11 kV substations of theCircle with CSPDCL representative and prepare presentable document showing status of workrequired to be executed. This status report shall be examined by SE (O&M) for issuance ofnecessary advice for taking up the work at site. On finalizing the program, agency shall startexecution of work at defined work place in planned manner. Work shall not be executed inhaphazard manner without planning. Record of procured materials for execution of works at siteshall be jointly made by representative of agency, representative of Substation O&M deptt. andthe representative of SE(O&M). Materials shall be properly tagged, documented and stacked inthe store yard. Loading, unloading, cartage and handling of materials in stores etc all shall be inthe scope of the agency.

The REC construction standard practice should be followed while execution of works.

2. 33/11 KV Power Transformer:

a. The power transformer shall be oil immersed, naturally air cooled (type ON), outdoorstype, three phase, 50 Hz, 33/11 KV step down power transformers of 1.6 MVA (as perrequirement) capacity as per the technical specification detailed at vol-II of the BidDocument shall be tested and inspected before dispatch and delivery at places as per

list of sites. The Power Transformer as per technical specifications detailed in vol-II ofthe Bid Document is required to be installed and commissioned alongwith exercising thetest checks as recommended by OEM (original equipment manufacturer).

b. The metallic breathers should be provided. The alignment of breather should be vertical.Breather pipe should be cleaned for proper connection.

c. Transformer neutral should be solidly grounded with two different earth connections. Thetransformer body should be grounded at two different locations.

d. Transformer oil should be tested for insulation resistance, sludge, and acidity and gascontent checks. Results should be compiled and furnished in the o/o concernedExecutive Engineer (STM) and EIC.

e. Operation of Buchholz relay, OTI and WTI are to be checked with representative ofEngineer in Charge. The connecting cable should be checked for healthiness. Thecables are to be neatly dressed, clamped with the transformer, buried in the groundusing protection covering of bricks and sand as per CPWD specifications / laid in thecable trench, provided with ferrules, provided with proper size double compression glandmade of brass at entry points of control panel and marshalling box and lugged.Operation of OTI, WTI and Buchholz relay is to be checked, calibrated thereafter inassociation with the representative of EIC and checked for local & remote alarm andtripping.

f. Cable connection / termination details, equipments details, terminal block details, tagsdetails etc should be prepared and submitted to EIC & STM Division of CSPDCL.

1.1 Power Transformer foundation:Digging of transformer foundation

i) Hard Soil excavation and digging 7.2 x 0.6 x 0.7 = 3.04 cmtii) Black Cotton Soil - excavation and digging 2.0 x 2.0 x 2.0 = 8.0 cmt


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1.2 Concreting of foundation:The concreting shell be provided for foundation with mix ratio of 1:3:6 of cement ,sandand metals.

A total concreting of 7.7 CMT shall be provided in black cotton soil location as per drawing.A total concreting of 5.5 CMT shall be provided in hard rock/hard soil as per drawing .

A masonry work with bricks 1.5x0.3x8.4=3.78 CMT shall be also provided after aboveconcreting as per drawing

A plastering with 15 mm thick bricks of size 1x2.4x4=9.6 CMT of ratio of 1:6 of cement andsand mixture shall also be provided over the above masonry work as per drawing.

1.3 Foundation of 33 kv and 11kv VCBs:-The Excavation for each VCB shall be as per foundation design prescribed bymanufacturer of VCB and as per their foundation drawing.The concreting for each VCB shall have a ratio of 1:3:6 of mix of cement, sand, andmetals for foundation and grouting of structures and foundation bolts as per drawing.

3. Bus Bar.

3.1 Bus Bar arrangement:The Bus Bar arrangement shall be as per drawing enclosed with documents to meet therequirement of the individual substation and shall conform to the IEE rules.

3.2 Structures for 33 kv and 11 KV bus bar :-H-Beam of lenths 8 mtr. Shall be provided for bus bar structures as per drawing. Theconcreting @0.45 cmt per structure is required in ratio of 1:3:6.

4. VCB:The VCBs are required to be installed at the locations listed in this bid. The CTs are also tobe installed by the agency in separate/same locations in accordance with therecommendations of the breakers manufacturer. General arrangement drawings shall besubmitted by the agency for Owners approval before start of work of installation of breakers.

The agency shall install foundations, supporting structures and O&M platform. Requireddrawings shall be provided by agency for owners approval before execution of works at site.

4.1 Current Transformer :Along with the Vacuum Circuit Breakers, Current Transformers are to be provided. CTs areto be erected on suitable structure provided by the bidder. Testing and pre commissioningchecks shall be conducted in accordance with OEM recommendations and as approved bythe owner. Terminal components at HT as well as LT & Earthing side shall also be the partof the CT.

4.2 Control Panels:i. The panels as per the requirement of protection like feeder protection,

transformer protection or incomer protection are to be provided with each

breaker:ii. Panel should be erected on ISMC75 (75x40x6 mm) MS channel duly welded on

MS angle inserted on indoor trench. Panels should then be properly aligned,iii. Cables should enter with double compression glands, codified, lugged, dressediv All alarm, annunciation and trip circuits / indication & alarm circuits should be

tested and made operative,v. The indication should be made operable,vi. Breaker should be remotely operated,vii. Indicating instruments should be calibrated,viii. Grounding of panel at two different locations should be provided.ix. Control relays should be calibrated and checked for tripping and closing

operations.x. Pick up time / trip time and tripping at normal and reduced voltages should be

checked.


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xi. Latching arrangement of relays should be checked for safe operation.

5. Station Battery & Charger:Station battery is to be provided at each substation.

The battery connections / terminals are to be cleaned and provided with petroleum jelly.

Terminals hardware is to be provided with connecting cables. The cable should be neatlydressed, clamped and wired using ferrules, tag marks, double compression glands. Thenew cable supplied should conform to IS: 1554 specification and must be suitable for DCutilization and having current carrying capacity 50 A current rating. Connecting cable andassociated materials needed for commissioning of battery shall be treated as part of thebattery.

The Station battery are to be supplied with wooden racks made of Sal wood planks ofthickness not less than 25mm, support legs made of size not less than 2 inches X 2inches. The battery may be placed on two-tier formation of stand. The construction ofbattery rack should suit site conditions of their placement. The rack should be painted withthree coat of acid proof paint of reputed make as approved by Engineer in Charge. Nometal fasteners / nails should be used for construction of battery racks. The stand should

be supported on insulators to obtain necessary insulation from the earth and there shouldbe insulators between each cell and stand.

The battery sets are to be provided with battery chargers as per detail specificationsenclosed. Interconnecting cables and power supply cables originating / terminating at thebattery charger, should be neatly dressed, clamped and wired using ferrules, tag marks,double compression glands etc as applicable. Connecting cable and associated materialsneeded for commissioning of charger shall be treated as part of the battery charger.

The agency shall provide following equipments at all the substations:1. Two copies of battery instruction sheet duly laminated,2. One cell testing voltmeter 3 0 3 volts,3. Two syringe hydrometers

4. One thermometer with specific gravity correction scale,5. One set of suitable spanners,6. Two acid resistant funnel,7. One acid resisting jar of 2 liters capacity.

6. Isolator / AB Switch / Drop out Fuse:

Isolator, AB switches and DO Fuses should be supplied with base steel structure, terminalsbi metallic connectors / PG clamps / earth connectors. They should be checked for properalignment and free & smooth operation. The insulators should be cleaned beforecommissioning. The linkage of contacts should be checked for free and adequate grip. Theisolator should be checked for fully OPEN / CLOSED positions. Contact between twomovable points should be checked and recorded. The contacts should be adequately

lubricated before commissioning. Connection of terminal connectors shall be checked forproper tightness. Operating handle should be separately grounded. Equipments should besupplied with detail technical specifications enclosed.

7. Lightning Arrester:

LAs should be supplied with base steel structure, terminals bi metallic connectors / PGclamps and earth connectors. LAs are to be connected with separate earth connection usingGS flat. All LA terminals / connections are to be tightened.

8. Lighting:

The substation area inside the fencing should be illuminated with flood light fittings provided

with 250 Watts Sodium Vapory Lamps. Each fitting and its Junction box enclosures shouldbe IP 55 protection type. Water and vermin proof-ness is a must. At least 4 Nos. fittings at all


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the four corners should be provided. Acceptable make of fitting, fixtures and lamp are Philips,Crompton, Alsthom, and Bajaj only.

Area light supply from Substation DB to be extended through 2X16 Sq.mm PVC insulatedPVC Sheathed aluminum stranded armoured power cable laid in underground trench ofwidth 300 mm wide, provided with 2

ndclass brick protection (Approx. 10 bricks per metre

length of laying) and sand protective covering (200 mm thick) and laid at the depth of 750mmminimum. Laying specification of cable shall be as detailed in CPWD specification of layingpower cables. Suitable loop length of 1.5 metre to be kept at the end points.

Pole mounted junction box (and not the Control Gear Box supplied with the fitting) should bemade of 2mm thick CR steel sheet of size 300X450X200mm fitted with SPN terminal block of32A capacity, 10A SPN miniature circuit breaker of ISI mark and reputed manufacture. TheJB should be applied with suitable anti rusting treatment and painted with 2 or more coats ofzinc oxide paint followed by 2 or more coats of enamel paint of approved make and shade.The JB should also conform to IP 55 protection for enclosure. Neoprene gasket should beused in JB. 2 Nos. earthing terminals of 10 mm dia should be provided with 25X6mm sizeof mounting clamps. Bidders shall get JB drawing approved before start of manufacturing.4 Sq.mm, 1100V grade, weather proof three core (One core for phase, one core for Neutraland one core for earthing) aluminum stranded conductor PVC sheathed and PVC insulated

cable conforming to IS 694 should be used for connection of fitting and its Control Gear Boxfrom pole mounted Junction Box. Control Gear box must provide ISI approved components.Copper wound heavy chokes shall be acceptable.

Tubular poles 12m high as per IS: 2713 (Latest Version) embossed with ISI certification markand pole designation shall be used for installation of area light fixtures in Urban as well asRural substations. Pole should be designated as 410 SP - 60. Poles and fitting structuresshould be painted with two coat of anti rusting bitumen paint inside and out side up to theplanting depth and two coat zinc oxide paint followed by 2 or more coats of aluminum paintof approved make, brand and shade on portion of pole which will remain above ground level.

9. Station Transformer &Distribution Boxes:

The Station Transformer should be commissioned with fresh Silica Jel, Breather, Cabling

Network, Bimetallic Clamp, Lugs, Earthing and Lightning Arrester. Station TransformerDistribution Box (DB) is required to be provided with handles, cover, locking arrangements,fixing knobs etc. and shall be free from rust. Approved brand of red oxide paint in two coatsshall be applied followed by two or more coats of approved brand and colour of enamel paintmaking the surface perfect finish. The DBs are required to be provided with neoprenegaskets for making them water-resistant. Entry of cables inside the box shall be throughgland so that no vermin or insects may enter inside the DBs. The cables should beterminated with proper size lugs and gland. Necessary tagging, identification of cores anddressing of cables with nylon cable ties shall be in the scope of work. Locking arrangementshall be provided in all locations. 5 Lever brass Pad- Lock to be provided shall be of Godrejmake and the keys shall be handed over to representatives of Engineer in Charge in writing.

All materials required to perform this work shall be in the scope of agency.

10. Insulators:

All supplied insulators should be clean and without cracks / chipping etc before mounting.Chipped or cracked insulators will not be acceptable.

11. AAA Conductor:

The AAA conductors required for formation of bus, jumpers and interconnection of variousequipments apparatus and associated accessories shall be 100 sq mm AAA DOG conductorand shall be provided with necessary hardware / strain fitting.

12. Steel structure / supports:

The steel supports / structures / clamps shall to be provided with necessary hardware usingfollowing sections:ISMC 100 Channel (100x50x6 mm),


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RAPDRP Part B

Section5 GCP

ISA 65x65x6 mm MS angle,50x8 mm MS Flat

Steel sections are to be fabricated in such a way that no gas cutting, gas drilling, sharpedges workmanship are found on finished items. Properly drilled holes of circular / ellipticalshape, smooth edges are to be ensured. Hardware is to be used as per specifications

enclosed.13. Connections:

Suitable Bi metallic clamps should be provided at bushings of the transformers and circuitbreakers. Also at all those points where joining of two different materials is required, bi metallic clamps should be provided.

T Clamps should be provided on each jumper on bus bars. Line jumpers should beprovided with adequate size of PG Clamps (Two numbers PG Clamps at each end of

jumper). Clamp should be made of aluminium grade T-1F as per IS 8309 having goodelectrical quality aluminum material and should not be brittle in nature.

Suitable PG clamps should be provided on the jumpers of bus bar wherever it is required.

14. Cabling:

The control cables between outdoor breaker panel and indoor control panel, transformermarshalling box and breaker indoor / out door control panels etc shall be provided and laid inthe open trenches. Trenches are to be provided by the agency.

The cable inside control room shall be laid in existing concrete trench. Cables shall beproperly tagged, bunched and tied using cable ties inside trench. At the entry point of trenchin control room, proper sealing arrangement should be provided so as to stop entry ofreptiles and rain water inside control room through trench.

15. Labeling:

All the equipments and circuits should be labeled using yellow base and black indicationmarks (number or name). 40 / 50 mm height digits / words should be used for this purpose.Colour coding of phases at breaker, bus and transformer and feeder end should be markedwith colour circles. Sample should be approved by EIC before execution. Painting andmarking of digits etc should be performed by a skilled / trained painter. Labeling of followinginformations is intended by the owner preferably in local HINDI language:

Transformer capacity and designated name like T - 1 or T 2,VCB designated nameIdentification of CT & PTColour coding of bus bars, transformer terminals, feeders phases,Name of feeder

Warning instruction, if any, of availability of two sources of HT supply on same structure.

16. Earthing of Sub Station :-

Earthing work is to be executed on all the substations. Earthing should be provided with GIearth pipe, GS solid rod 25 mm dia and 50X6 mm GS flat forming earth grid and riser alongwith GI wires / Stay wires as per requirement of Engineer. Engineer shall approvearrangement of earthing network. Following arrangement envisaged for grid/earth rod/ earthpipe: (Indicative drawing is enclosed with the document)

Description of equipment Semi Urban / RuralSubstation

Urban Substation

Earth Pit 3 m long, 40 mm dia 3 Nos. 3 Nos.

Earth rod GS solid 25 mm dia 19 Nos. 16 Nos.


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Section5 GCP

Standard requirements / provisions of earthing of CSPDCL are enclosed herewith.Connections of earth-grid / earth pit with Lightning Arrester and Power Transformer Neutraland Transformer body (at two distinct points) are to be made using 50X6mm GS flat.

Connections of other equipments may be provided with 8 SWG GI wire or GI Stay wire asper approval of Engineer in charge. Following arrangements are envisaged for earthconnection:

Power Transformer Neutral(Two distinct connections) GS FlatTransformer Body GI Stay wireBreaker body / legs (Two distinct connections) GS FlatLightning Arrester GI wireStation transformer Neutral (Two distinct connections) GI Stay wireFencing GI wireControl Panels (Two distinct connections) GI flatIsolator handle GI wireSteel structure of substation GS Flat

Line meters GS wire

Fencing and gate should be grounded. Moving portion of gate should be grounded withflexible braided conductors of equivalent aluminum 25 Sq.mm size of conductors duly luggedand bolted.Substation wise measurement of earth resistance of earth pits/mesh and correspondingdrawing of existing earthing arrangement shall be recorded and submitted by the agency.

17. Painting of Over head structures:

RS joist, tubular pole, fencing, main gate etc shall be done as under:De-rusting shall be performed using wire brush, emery paper etc. The surface shall be

cleaned and painted with two or more coats of red oxide zinc chromate primer paint using

painting brush. On smooth surface finish, two or more coats of aluminium paints usingpainting brush shall be applied till final smooth surface finish and even shade on surfaceappears.

17.1 Enclosure boxes / panels:

The Engineer in Charge shall approve the make of paint. It shall be reputed make andshade. The brush shall only be used for painting. The quality of painting shall beexamined at the time of final handing over of installation and also at the time ofcompletion of defect. In event of detoriation of paint, the surface cleaning and repaintingshall be performed by the agency without any extra cost. After application of two or morecoats of red oxide zinc chromate paint, the installation shall be offered to owner forclearance to apply final finish paint either aluminium paint or synthetic enamel paint.

18. Metering equipments and Line Meters:

33 KV metering units (combined CT & PT unit) for incoming and outgoing 33 KV feeder and11 KV metering units (combined CT & PT unit) on all outgoing 11 KV feeders are to beinstalled along with electronic meters on the substation structures in the substation to recordline parameters of 33 KV and 11 KV incomer as well out going feeders. These meters are tobe installed inside the control room. The work shall involve provision and installation ofmetering unit on substation structure (out side) and meter box and meters in control room,laying, tagging and tagging of control cables. Meters shall be commissioned in associationswith representative of EIC. The installation details needs to be submitted by the agency forapproval of owner before start of work.

19. SITE TESTING AND PRE

COMMISSIONING CHECKS:

Earth mat 50X6 mm GS Flat 50X6 mm GS Flat

Laying of earth mat Below ground 0.5 meter


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Section5 GCP

An indicative list of tests is given below. Contractor shall perform any additional test basedon specialties of the items as per the Field Quality Plan/ instructions of the equipmentsmanufacturer or owner without any extra cost to the Owner. The Contractor shall arrange allinstruments required for conducting these tests alongwith calibration certificates and shallfurnish the list of instruments to the Owner for approval. Detail test certificates duly signed byCSPDCL representative & agency representative of tests jointly carried out at site before

putting the equipments in use, shall be submitted by the contractor in three copies as perfollowing distribution:

A. O/o the STM, Circle headquarters,B. O/o the Executive Engineer (O&M),c. Concern Substation

19.1 GENERAL CHECKS:

Check for physical damages.

Visual examination of zinc coating/ planting.

Check from name plate that all items are as per order/ specification.

Check tightness of all bolts, clamp and connecting terminals using torque wrenches.

For oil filled equipments check for oil leakage, if any. Also check oil level and top up.

Check ground connections for quality of weld and application of zinc rich paint over weld jointof galvanized surfaces.

Check cleanliness of insulator and bushings.

All checks and tests specified by the manufacturers in their drawings and manuals as well astests specified in the relevant code of erection.

19.2 CIRCUIT BREAKERS:

Insulation resistance of each pole.

Check adjustment, if any, suggested by manufacturer.

Breaker closing and tripping time.

Slow and power closing operation and opening.

Trip free and anti pumping operation.

Minimum pick up volts of coils

Contact resistance.

Functional checking of all accessories.

Functional checking of control circuits, interlocks, tripping through protective relays and auto-reclose operation.

Insulation resistance of control circuits, motor etc.

Resistance of closing and tripping coils.

19.3 ISOLATORS:

Insulation resistance of each pole.

Manual and electrical operation on interlocks.

Insulation resistance of control circuit and motors.

Ground connectionsContact resistance

Proper alignment to minimize the vibration to the extreme possible during operation.

Measurement of operating torque for isolator and earth switch

Resistance of operating and interlocking coils.

19.4 CURRENT TRSFORMERS:

Insulation Resistance Test

Polarity test.

Ratio identification test-checking of all ratios on all cores by primary injection of current.

Dielectric test of oil

Magnetizing characteristics test.

19.5 VOLTAGE TRANSFORMERS


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Section5 GCP

Insulation resistance test

Polarity test.

Ratio test

Dielectric test of oil

19.6 SURGE ARRESTER

Grading leakage current

Resistance of ground connection

19.7 PHASING OUT

The phasing out of all supplies in the Sub station system shall be carried out.

19.8 STATION EARTHING

Check soil Resistively

Check continuity of grid wires

Check earth resistance of the entire grid as well as various sections of the same.

Check for weld joint and application of zinc rich paint on galvanised surface.

Dip test on earth conductor prior to use.

19.9 CONDUCTOR STRINGING AND POWER CONNCTORS

Physical check for finish

Electrical clearance check

Testing of torque by torque wrenches on all bus power connectors and other accessories.

Milli volt drop test on all power connectors

Sag and tension check on conductors.

19.10 INSULATORSVisual examination for finish damage, creepage distance, etc.

20. CIVIL WORKS AND SOIL INVESTIGATION

20.1 GENERAL

The provisions of this section of specification shall only be applicable to the extent ofscope of works indicated in Bid Proposal Sheet (BPS). The intent of specification coversthe following:

Design, engineering, and construction of all civil works at sub-station. All civil works shallalso satisfy the general technical requirements specified in other Sections of thisSpecification and as detailed below. They shall be designed to the required serviceconditions/loads as specified elsewhere in this Specification or implied as per National/International Standards.

All civil works shall be carried out as per applicable Indian Laws, Standards and Codes.All materials shall be of best quality conforming to relevant Indian Standards and Codes.

The Contractor shall furnish all design, drawings, labour, tools, equipment, materials,temporary works, constructional plant and machinery, fuel supply, transportation and allother incidental items not shown or specified but as may be required for completeperformance of the Works in accordance with approved drawings, specifications anddirection of Employer.

The work shall be carried out according to the design/drawings to be developed by theContractor and approved by the owner based on Tender Drawings Supplied to theContractor by the Owner. For all buildings, structures, foundations etc. necessary layoutand details shall be developed by the Contractor keeping in view the functionalrequirement of the substation facilities and providing enough space and access foroperation, use and maintenance based on the input provided by the Owner. Certainminimum requirements are indicated in this specification for guidance purposes only.


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In case of R&M of existing substations, Contactor shall visit site to ascertain the amountof repair and strengthening of structures and foundations, dismantling and newconstruction of structures and foundations works are to be done before quoting.Contractor must furnish the design and drawings in support of the activities mentionedabove that are to be carried out in the R&M of existing substation site.

However, the Contractor shall quote according to the complete requirements.

20.2 GEOTECHNICAL INVESTIGATION

20.2.1 The Contractor shall perform a detailed soil investigation to arrive at sufficiently accurate,general as well as specific information about the soil profile and the necessary soilparameters of the site.So that the foundation of the various structures can be designedand constructed safely and rationally.

A report to the effect will be submitted by the Contractor for Owners specific approvalgiving details regarding data proposed to be utilised for civil structures design.

20.2.2 The Contractor should visit the site to ascertain the soil parameters before submitting thebid. The topography is uneven steeply sloping at few places requiring cutting and filling

operations including slope stability and protection measures (if slopes encountered). Anyvariation in soil data shall not constitute a valid reason for any additional cost & shall notaffect the terms & condition of the Contract. Tests must be conducted under all thecritical locations i.e. Control Room Building. Tower locations, transformer etc.

20.3 SCOPE OF WORK

This specification covers all the work required for detailed soil investigation andpreparation of a detailed report. The work shall include mobilisation of necessaryequipment, providing necessary engineering supervision and technical personnel, skilledand unskilled labour etc. as required to carry out field investigation as well as, laboratoryinvestigation, analysis and interpretation of data and results, preparation of detailed Geo-technical report including specific recommendations for the type of foundations and theallowable safe bearing capacity for different sizes of foundations at different foundingstrata for the various structures of the substation. The Contractor shall make his ownarrangement for locating the co-ordinates and various test positions in field as per theinformation supplied to him and also for determining the reduced level of these locationswith respect to the benchmark indicated by the Owner.

All the work shall be carried out as per latest edition of the corresponding IndianStandard Codes.

20.3.1 Bore Holes

Drilling of bore holes of 150 mm dia. in accordance with the provisions of IS: upto 10 mdepth or to refusal which ever occur earlier. (By refusal it shall mean that a standardpenetration blow count (N) of 100 is recorded for 30 cm penetration). For a newsubstation, minimum three (3) bore holes shall be done to find out the geological profileof the area. If any unconformity encountered then more bore holes shall be drilled withthe approval of Engineer-in-charge for the new projects. However in case deep pilefoundations are envisaged the depths have to be regulated as per codal provisions. Incases where rock is encountered, coring in one borehole per bay shall be carried out to1.5 M in bedrock and continuous core recovery is achieved.

Performing Standard Penetration Tests at approximately 1.5 m interval in the boreholestarting from 1.5 m below ground level onwards and at every change of stratum. Thedisturbed samples from the standard penetrometer shall also be collected for necessarytests.


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Collecting undisturbed samples of 100/75 mm diameter 450 mm long from the boreholesat intervals of 2.5 m and every change of stratum starting from 1.0 m below ground levelonwards in clayey strata.

The depth of Water table shall be recorded in each borehole.

All samples, both disturbed and undisturbed, shall be identified properly with the

borehole number and depth from which they have been taken.

The sample shall be sealed at both ends of the sampling tubes with wax immediatelyafter the sampling and shall be packed properly and transported to the Contractorslaboratory without any damage or loss.

The logging of the boreholes shall be compiled immediately after the boring is completedand a copy of the bore log shall be handed over to the Engineer-in-charge.

20.3.2 Electrical Resistivity Test

This test shall be conducted to determine the Electrical resistivity of soil required fordesigning safe grounding system for the entire station area. The specifications for theequipments and other accessories required for performing electrical resistivity test, the

test procedure, and reporting of field observations shall confirm to IS: 3043. The testshall be conducted using Wagners four electrode method as specified in IS: 1892,

Appendix-B2. Unless otherwise specified at each test location, the test shall beconducted along two perpendicular lines parallel to the coordinate axis. On each line aminimum of 8 to 10 readings shall be taken by changing the spacing of the electrodesfrom an initial small value of 0.5 m upto a distance of 10.0 m.

20.3.3 Water Sample

Representative samples of ground water shall be taken when ground water is firstencountered before the addition of water to aid drilling of boreholes. The samples shallbe of sufficient quantity for chemical analysis to be carried out and shall be stored inairtight containers.

20.3.4 Back Filling of Bore Holes

On completion of each hole, the Contractor shall backfill all bore holes as directed by theOwner. The backfill material can be the excavated material and shall be compactedproperly.

20.3.5 Laboratory Test

1. The laboratory tests shall be carried out progressively during the field work aftersufficient number of samples have reached the laboratory in order that the testresults of the initial bore holes can be made use of in planning the later stages ofthe field investigation and quantum of laboratory tests.

2. All samples brought from field, whether disturbed or undisturbed shall beextracted/prepared and examined by competent technical personnel, and thetest shall be carried out as per the procedures laid out in the relevant I.S. Codes.

The following laboratory tests shall be carried out

a) Visual and Engineering Classification

b) Liquid limit, plastic limit and shrinkage limit for C- soils.

c) Natural moisture content, bulk density and specific gravity.

d) Grain size distribution.


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e) Swell pressure and free swell index determination for expensivesoil only.

f) Consolidated un-drained test with pore pressure measurement.

g) Chemical tests on soil and water to determine the carbonates,sulphates, nitrates, chlorides, Ph value, and organic matter and

any other chemical harmful to the concrete foundation.h) C.B.R value

i) Rock quality designation (RQD), RMR in case of rock isencountered

20.3.6 Test Results and Reports

20.3.6.1 The Contractor shall submit the detailed report in two (2) copies wherein informationregarding the geological detail of the site, summarised observations and test data,bore logs, and conclusions and recommendations on the type of foundations withsupporting calculations for the recommendations. Initially the report shall be submittedby the Contractor in draft form and after the draft report is approved, the final report in

two (3) copies shall be submitted. The test data shall bear the signatures of theInvestigation Agency, Vendor and also site representative of CSPDCL.

20.3.6.2. The report shall include but not limited to the following:

a) A plan showing the locations of the exploration work i.e. bore holes, dynamiccone penetration tests etc.

b) Bore Logs: Bore logs of each bore holes clearly identifying the stratification andthe type of soil stratum with depth. The values of Standard Penetration Test(SPT) at the depths where the tests were conducted on the samples collected atvarious depths shall be clearly shown against that particular stratum.

Test results of field and laboratory tests shall be summarised strata wise as wellin combined tabular form. All relevant graphs, charts tables, diagrams andphotographs, if any, shall be submitted along with report. Sample illustrativereference calculations for settlement, bearing capacity, pile capacity shall beenclosed.

20.3.7 Recommendations: The report should contain specific recommendations for the type offoundation for the various structures envisaged at site. The Contractor shall acquainthimself about the type of structures and their functions from the Owner. Theobservations and recommendations shall include but not limited to the following:

a) Geological formation of the area, past observations or historical data, ifavailable, for the area and for the structures in the nearby area, fluctuations ofwater table etc. Slope stability characteristics and landslide history of the areashall be specifically highlighted. Remedial measures to be adopted shall also begiven.

b) Recommended type of foundations for various structures. If piles arerecommended the type, size and capacity of pile and groups of piles shall begiven after comparing different types and sizes of piles and pile groups.

c) Allowable bearing pressure on the soil at various depths for different sizes of thefoundations based on shear strength and settlement characteristics of soil withsupporting calculations. Minimum factor of safety for calculating net safe bearingcapacity shall be taken as 3.0 (three). Recommendation of liquefactioncharacteristics of soil shall be provided.


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d) Recommendations regarding slope of excavations and dewatering schemes, ifrequired. Required protection measures for slope stability for cut & fill slopes ofswitchyard and approach road with stone pitching/retaining walls shall be clearlyspelt out. Calculation shall also be provided for stability adequacy.

e) Comments on the Chemical nature of soil and ground water with due regard todeleterious effects of the same on concrete and steel and recommendations for

protective measures.

f) If expansive soil is met with, recommendations on removal or retaining thesame under the structure, road, drains, etc. shall be given. In the latter casedetailed specification of any special treatment required including specification ormaterials to be used, construction method, equipments to be deployed etc. shallbe furnished. Illustrative diagram of a symbolic foundation showing details shallbe furnished.

g) Recommendations for additional investigations beyond the scope of the presentwork, if considered such investigation as necessary.

20.4 SITE PREPARATION

The contractor shall be responsible for proper leveling of switchyard site as per layoutand levels of switchyard finalised during detailed engineering stage. The Contractor athis own cost shall make the layout and levels of all structure etc from the general gridsof the plot and benchmarks set by the Contractor and approved by the Owner. TheContractor shall give all help in instruments, materials and personnel to the Owner forchecking the detailed layout and shall be solely responsible for the correctness of thelayout and levels. Site leveling shall be in the scope of the contractor. Bidder maydecide the level of the sites. However, the level shall be such that it is 300 mm higherthan the highest flood level (HFL) of the site. If HFL is not available, then nearby roadlevel shall be assumed as HFL.

Whenever for bay extension works the existing substation are to be modified orstrengthen, contractor should keep same as EGL of existing sub-station so that FFL

shall be same for both and all the necessary arrangements are to be carried out in thisregard by the contractor.

20.5 SCOPE OF WORKS

This clause covers the design and execution of the work for site preparation, such asclearing of the site, the supply and compaction of fill material, slope protection by stonepitching/retaining walls depending on the site location & condition, excavation andcompaction of backfill for foundation, road construction, drainage, trenches and finaltopping by brick soling/stone filling.

20.5.1 General

1) The Contractor shall develop the site area to meet the requirement of theintended purpose. The site preparation shall conform to the requirements ofrelevant sections of this specification or as per stipulations of standardspecifications. Contractor shall also carry out necessary protection of slope ofswitchyard area and approach road.

2) The fill material if required shall be suitable for the above requirement. The fillshall be such material and the site so designed as to prevent the erosion bywind and water of material from its final compacted position or the in-siteposition of undisturbed soil.

3) Material unsuitable for founding of foundations shall be removed and replacedby suitable fill material and to be approved by the Owner.

4) Backfill material around foundations or other works shall be suitable for thepurpose for which it is used and compacted to the density described under


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Compaction. Excavated material not suitable or not required for backfill shall bedisposed off in areas as directed by owner upto a maximum lead of 1 km.

20.5.2 Excavation and backfill

1. Excavation and backfill for foundations shall be in accordance with the relevant

code.

2. Whenever water table is met during the excavation, it shall be dewatered andwater table shall be maintained below the bottom of the excavation level duringexcavation, concreting and backfilling.

3. When embankments are to be constructed on slopes of 15% or greater,benches or steps with horizontal and vertical faces shall be cut in the originalslope prior to placement of embankment material. Vertical faces shall measurenot more than 1 m in height.

4. Embankments adjacent to abutments, culverts, retaining walls and similarstructures shall be constructed by compacting the material in successive uniformhorizontal layers not exceeding 20 cm in thickness (of loose material beforecompaction). Each layer shall be compacted as required by means of

mechanical tampers approved by the Owner. Rocks larger than 10 cm in anydirection shall not be placed in embankment adjacent to structures.

5. Earth embankments of roadways and site areas adjacent to buildings shall beplaced in successive uniform horizontal layers not exceeding 20 cm in thicknessin loose stage measurement and compacted to the full width specified. Theupper surface of the embankment shall be shaped so as to provide completedrainage of surface water at all times.

6. The land required for borrowing earth shall be arranged & selected bycontractor. The identified land shall be got approved by site in charge. Thequoted rates shall include cost of earth, taxes, duties, royalty, compensation forthe land identified for borrow earth. The rate shall also be inclusive of all leads,lifts, ascent, descent and testing required for completion of work in all respect.

7. The ground levels for all measurements shall be taken at every 5 meter distancein uniformly sloping ground and at closer distance where pits/undulations aremet with. In fairly leveled area, levels shall be taken at 15 mt. apart at thediscretion of Engineer in Charge. The ground levels shall be recorded andplotted on plans. The same is signed by the contractor and the Engineer inCharge before the earth work is started. All labor, material, tool, equipment etcrequired for the above work shall be arranged by the contractor at his own cost.

20.5.3 Compaction

1. The density to which fill materials shall be compacted shall be as per relevant ISand as per direction of Owner. All compacted sand filling shall be confined as far

as practicable. Backfilled earth shall be compacted to minimum 95% of theStandard Proctors density at OMC. The sub-grade for the roads andembankment filling shall be compacted to minimum 95% of the StandardProctors density at OMC. Cohesion less material sub grade shall be compactedto 70% relative density (minimum).

2. At all times unfinished construction shall have adequate drainage. Uponcompletion of the roads surface course, adjacent shoulders shall be given a finalshaping, true alignment and grade.

3. Each layer of earth embankment when compacted shall be as close to optimummoisture content as practicable. Embankment material, which does not containsufficient moisture to obtain proper compaction, shall be wetted. If the materialcontains any excess moisture, then it shall be allowed to dry before rolling. The

rolling shall begin at the edges overlapping half the width of the roller each timeand progress to the center of the road or towards the building as applicable.


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Rolling will also be required on rock fills. No compaction shall be carried out inrainy weather.

20.5.4 Req

Documents

Gen Const Practics