220KV XLPE U/G CABLE LAYING & GIS SUBSTATION INSTALLATION
A Mini Project Report
Submitted in the partial fulfillment of the requirement for the award of the degree of
BACHELOR OF TECHNOLOGY
in
Electrical and Electronics Engineering
By
JAYA VENKATA PRATAP LAVU (06E11A0214)
K.PRADEEP (06E11A0227)
M.PRASHANTH REDDY (06E11A0230)
Under the esteemed guidance
of
Ms.D.Lohitha
Assistant Professor, Dept. of EEE.
Department of Electrical & Electronics Engineering
BHARAT INSTITUTE OF ENGINEERING & TECHNOLOGY
(Accredited by NBA, Approved by AICTE, Affiliated to JNTUH)
Mangalpalli (V), Ibrahimpatnam (M), R.R.Dist., A.P, 2010
BHARAT INSTITUTE OF ENGINEERING & TECHNOLOGY
Department of Electrical & Electronics Engineering
CERTIFICATE
This is to certify that the project report
entitled “PROGRAMMABLE MINI CIRCUIT BREAKER” N.KARTHIK
[06E11A0216], K.PRADEEP [06E11A0227], M. PRASHANTH REDDY
[06E11A0230] was carried out by in partial fulfillment for the award of the
degree BACHELOR OF TECHNOLOGY in Electrical and Electronics
Engineering, Jawaharlal Nehru Technological University, Hyderabad during the
academic year 2009-2010
Dr. Sukhdeo Sao Ms.D.Lohitha
Head of the Department Internal Guide
ACKNOWLEDGEMENT
We are profoundly thankful to our Dr.P.Padmanabham, Principal,
BIET for his constant encouragement in carrying out our project work.
We express our deep gratitude to Dr. Sukhdeo Sao, HOD, EEE for his
valuable suggestions throughout this work.
We express our sincere thanks to Ms.D.Lohitha, Asst.Professor,
Department of Electrical and Electronics Engineering, Bharat institute of
Engineering & Technology for her valuable suggestions during the project
development without which we couldn’t have completed the project
successfully.
Special thanks to all the teaching and non-teaching staff of EEE
department, and of whole Bharat institute of Engineering & Technology for
supporting us.
Thanks to Vijai Electricals, for introducing this project work to us and
also for guiding us for the initiation of this project.
We also extend our sincere thanks to our parents and friends for their
moral support throughout the project work. Above all we thank god almighty for
his manifold mercies in carrying out the project successfully.
- JAYA VENKATA PRATAP L
- K.PRADEEP
- REDDY
INDEX
Chapter I
1.INTRODUCTION
Scope:-
Design, Engineering supply and laying of 220kv XLPE cable system, facilitating power flow of 200MW minimum in ach cable circuit ensuring sufficient overload capacity and all safety measures.
Electric power can be transmitted or distributed either by overhead system or by underground cables.
1. STANDARDS:
The Design, manufacture and performance of XLPE cables and the associated accessories
shall conform to the following International Standards, as amended /revised till date, as
applicable.
IEC 62067 Power cable with extruded insulation and their accessories related voltage
above l50kV up to 500kV
IEC 60840 Power cable with extruded insulation and their accessories related voltage
above 30 kV up to 150kV
IEC 60228 Conductor for insulated cables
IEC 60229 Tests on cable over sheaths
IEC 60230 Impulse tests on cables and their accessories
IEC 60270 Partial discharge measurements
IEC 60287 Calculation of continuous current carrying capacity and losses
IEC 60502 All cables with extruded insulation and their accessories
2. General Technical Requirement
2.1 Design Considerations
2.1.1 The cable shall be suitable for buried installation with uncontrolled back filling
and laying in the area likely to be flooded by water. The cable shall withstand all
mechanical and thermal stresses, which are likely to occur during its normal
steady state and transient operation conditions.
2.1.2. The metallic screen shall be designed to withstand earth fault current liable to
occur in the system during conductor to ground fault as specified in clause 4.0(vi)
of Techncial Specification APT-76/2007 (Volume – 2C) i.e. 40kA for 1 second
for 220 kV cables and 31.5kA for 1 second for 132 kV cables.
2.1.3 The thermal resistivity of the soil is generally 150oC.cm/watt.
2.1.4 The cable shall be designed to have a minimum useful life of not less than fifty
years.
2.1.5 Each cable length shall be provided with a pulling socket pulling eye, which shall
be fitted to pulling end. The pulling socked eye end shall be able to take the
pulling tension of 7000kgs (1000mm2) and 8400 kgs. (1200mm2), while ensuring
the side pressure on the cable at any bending point should be less than 5000N/m
(pulling force/bending radius), along with a reasonable factor of safety.
2.1.6 The outer sheath of the cable will be given adequate chemical treatment in order
to protect itself from rodent and termite attack.
2.1.7 The conductor will be clean, uniform in size and shape, smooth and free from
harmful effects.
2.1.8 The supplier is providing the design calculation and associated details along with
the offer in order to establish the specified minimum continuous current rating
and short time current rating of the cable.
2.2 Construction Details of Cable
2.2.1 Cable construction and material
i) Conductor: Single core conductor shall consist of stranded, compacted,
five segmental circular, plain annealed copper wires conforming to IEC 60228. The
wires shall be made of high conductivity copper and shall be stranded and
compacted. The copper used for the conductor shall be of highest purity. The
nominal area of conductor shall be 1000 sq mm for 220 kV and 1200 Sq.mm for
132 kV Cable. The minimum number of wires in conductor and DC resistance of
conductor shall be as per IEC 60228.
ii) Conductor screening: Conductor screening shall consist of an extruded
layer of thermosetting black semi conducting compound which shall be
firmly bonded to the outer surface of the conductor and should cover the
whole surface of the conductor and suitable for the operating temperature of
the cable and compatible with the insulating material. The nominal
thickness of the conductor screen is 1.5mm. Semi-conducting tetoron tape is
applied between conductor and the extruded semi conducting layer, the
thickness is 0.8mm.
iii) Insulation: insulation shall be cross-linked polyethylene (XLPE) and shall
conform to the IEC 62067 or IEC 60840 and of very high degree of purity
and radiant cured (i.e., dry curing). This XLPE insulation shall be applied
by extrusion and vulcanized to form a compact homogenous body free from
micro voids and contaminants. The nominal thickness of the insulation
between conductor screen and insulation screen is 24.0mm for 220 kV and
18.0mm for 132 kV Cable. The eccentricity of insulation should not be
more than 10%.
iv) Non-metallic part of insulation screening: The insulation screen shall
consist of an extruded layer of thermosetting of semi-conducting compound
extruded directly over the insulation and shall be continuous and cover the
whole surface of insulation. It should be firmly bonded to the insulation and
suitable for operating temperature of the cable and compatible with the
insulating material. The conductor screening, insulation and insulation
screening shall be extruded in one operation by single common head
process to ensure homogeneity and elimination of voids. The nominal
thickness of insulation screen is 1.0mm. Ovality calculated shall not be
more than 5%.
v) Water blocking tape (longitudinal water barrier): This shall be semi-
conducting synthetic non-woven tape with suitable swellable absorbent for
longitudinal water sealing covering the whole surface area of the non-
metallic part of insulation screening. This barrier shall restrict longitudinal
water penetration under the metallic sheath. The nominal thickness of water
blocking tape is 6.6mm for 220 kV and 5.0mm for 132 kV Cable.
vi) Metallic part of insulation screening (Moisture barrier): This shall
consist of extruded metallic aluminum sheath (corrugated and seamless) and
shall be impervious to moisture, close fitted and free from defects. The
nominal thickness of metallic sheath is 2.7mm for 220 kV and 2.3mm for
132 kV Cable. Anti-corrosive compound (bitumen) shall be applied over the
aluminum sheath.
vii) Outer Jacket: The outer jacket shall consist of extruded, black, heavy duty
HDPE compound conforming to the requirement of type ST7 of IEC 62067.
The nominal thickness of the outer jacket is 5.0mm. The outer jacket will be
anti-rodent and anti-termite. Semi-conducting graphite shall be applied over
outer PE jacket.
2.2.2 Cross Bonding and Earthing of Metallic Sheath:
To eliminate the sheath circulating current losses and consequence raise in potential, the
metallic sheath at cable joints shall be cross bonded and earthed. Please refer section 7.3
on page 12
2.2.3 The maximum charging current per 1000 meters of 220kV and 132kV cables is
6.86 amps and
5.33 amps respectively.
2.3 Cable accessories
a) Outdoor terminations
Cable outdoor terminations: The sealing ends shall conform to the latest
international standards and shall be of thoroughly proven design. The
internal electric stress in the sealing end shall be controlled by the pre-
moulded cone arrangement preferably with epoxy bell mouth. The outdoor
type sealing ends will be suitable for installation in polluted atmosphere
referred to in clause 3.0 of Tender Technical Specification, and shall be
completely weather proof.
Each outdoor type sealing end shall be supplied complete with mounting
plate insulators to insulate the sealing end from the supporting structures
and to control the sheath current. Each sealing end will be provided with
clamp with consumption material such as wiper and solvent for cleaning.
The power cable leading to sealing end will be provided with proper
sunshield cover, while installing the same.
b) GIS terminations: The sealing ends shall conform to the latest
international standards and shall be of thoroughly proven design. The
internal electric stress in the sealing end shall be controlled by the pre-
moulded cone arrangement with epoxy unit. GIS termination shall be of dry
type insulation construction. This construction is compatible to GIS
equipment conforming to IEC 60859.
c) Cross Bonding Joint
Cross Bonding Joint is installed as the connection joint between two cables
of minor section of the cable route. This joint has a pre-molded structure.
The insulation part of the joint consists of one single body comprising of
stress relief cone and silicon rubber insulating part. The whole body of the
joint is encapsulated by a copper cover which is separated by an insulation
flange and the whole assembly is put into a waterproof box. The whole
system has a reliable characteristic of waterproof and anti-corrosion. Both
sides of the Joint are earthed through Link boxes with SVL via earthing
cable with co-axial cores.
d) Straight through joint
Straight through joint is installed as the connection joint between two
cables of major section of the cable route. This joint has a pre-molded
structure The insulation part of the joint consists of one single body
comprising of stress relief cone and silicon rubber insulating part. The
whole body of the joint is encapsulated by a copper cover which is put into
a waterproof box. The whole system has a reliable characteristic of
waterproof and anti-corrosion. The metallic sheath of the Straight through
joint is earthed through earthing cable via earth link box without SVL.
e) Link boxes with SVL and without SVL
The Material of enclosure of all types of Link Boxes is stainless steel.
2.4 Identification
The external surface of the 220 kV and 132 kV XLPE Cable outer sheaths of cable shall
be printed with the following legend:
220kV,1000mm2 XLPE, SFC, China 2010, APTRANSCO.
132 kV 1200 mm2 XLPE, SFC, China 2010, APTRANSCO.
Besides above, progressive sequential marking of length shall also be provided at every one meter
3. Testing Protocol for XLPE cables and accessories:
3.1 Details of the tests to be carried out in respect of 220 kV XLPE cables and
3.1.1 Routine Tests and Special Tests on cable at works3.1.2 The cables shall be subject to all relevant routine and special tests as described in
IEC 62067.
3.1.3 Routine test on cable shall be carried out as per table 1 below :
Sl No.
Item Requirement
1. Partial discharge test The sensitivity is 2pC, test voltage shall be raised gradually to and held at 1.75Uo for 10s and then slowly reduced to
1.5Uo there shall be no detectable discharge from the test object at 1.5Uo.
2. AC Voltage test The test voltage shall be raised gradually to 2.5Uo, which shall then be held for 30 min between then conductor and metallic sheath, no breakdown of the insulation shall occur.
3. Electrical test on outer sheath The test voltage shall be 25 kV (DC). No breakdown of the outer sheath shall occur.
Table 13.1.4 Routine Tests on cable accessories at works
The cable accessories shall be subject to all relevant routine tests as described in IEC 62067, as per table 2 below:
Sl No.
Item Requirement
1a Partial discharge test for end terminations (Stress relief cone & Epoxy Unit)
The sensitivity is 2pC, test voltage shall be raised gradually to and held at 1.75Uo for 10s and then slowly reduced to 1.5Uo there shall be no detectable discharge from the test object at 1.5Uo.
1b AC Voltage Test for end termination (Stress relief cone & Epoxy Unit)
The test voltage shall be raised gradually to 2.5Uo, which shall then be held for 30 min between the conductor and metallic sheath, no breakdown of the insulation shall occur.
2a Partial discharge test on Pre-moulded joint insulation unit.
(This test shall be carried out and witnessed, if required, in Japan)
The sensitivity is 2pC, test voltage shall be raised gradually to and held at 1.75Uo for 10s and then slowly reduced to 1.5Uo there shall be no detectable discharge from the test object at 1.5Uo.
2b AC Voltage test on Pre-moulded joint insulation unit.
(This test shall be carried out and witnessed, if required, in Japan)
The test voltage shall be raised gradually to 2.5Uo, which shall then be held for 30 min between the conductor and metallic sheath, no breakdown of the insulation shall occur.
Table 2
3.2 Tests on the 220 kV and 132 kV cables during installation
10 kV DC test for 1 minute for outer sheath as per IEC 60229, after cable laying for each cable.
3.3 Pre-commissioning Tests on 132 kV and 220 kV cable
systems:
Following tests shall be carried out as Pre-Commissioning Tests, on the installed cable system:
a) Continuity of conductor.b) Absence of cross phasing.c) Insulation resistance test. d) 10 kV DC voltage test for 1 minute on the outer sheath
3.4 Commissioning Test on 132 kV and 220 kV cable systems: 24 Hours AC testing, a voltage of Uo may be applied for 24 hours. APTRANSCO
to make applicable 132 kV or 220 kV (phase to phase voltage) power supply available.
4. Quality assurance plan
The standard SFC quality assurance plan in respect of EHV cables and accessories,
conforming to ISO 9001 is submitted for approval.
5. Packing and forwarding
5.1 After the completion of the preliminary route survey and also total station survey
the cross bonding arrangement drawing shall be prepared and shall be submitted
to APTRANSCO for approval. These cross bonding drawings shall indicate the
drum lengths to be manufactured and supplied for each route. The overall drum
dimensions are given on page no. 17 and 21 in the GTP for 220 kV and 132 kV
cables respectively.
5.2 The cut ends of the cable shall be sealed by means of non-hygroscopic sealing
material so as to protect the cable from moisture and other atmospheric effects
during transit and laying. The following information shall be marked on the drum.
a) Name of the manufacturer i.e. Shenyang Furukawa Cable Co. Ltd., China
b) Nominal cross-sectional area of the conductor
c) Type of cable and voltage
d) Length of cable on the drum
e) Direction of rotation of drum (Arrow)
f) Gross weight of the drum
g) Consignee
h) Order No.
5.3 The drum will be of such construction as to ensure delivery of cable at site free from displacement and damage and will be able to withstand all stresses during handling in transit and laying. Each drum shall be supplied with the steel base frame (drum stand).
5.4 Drums or parts of drums made from ferrous metals will be treated with suitable rust preventive finish or coating to minimize rusting during transit or storage.
5.5 Bolts, screws, nails etc., if used in the construction of drums will be counter sunk so that the heads are below the surface of the flange.
5.6 Drum construction, cable placement on the drum and the installation of protective wrappings etc., will be carefully coordinated to prevent damage to the cable during normal handling, ocean shipment and land transportation of the cable to site. Method of storage of cable drums at site will also be indicated in case the
cables are to be stored for longer periods.5.7 The cable accessories will be packed suitably so as to withstand handling during
transit. We shall be responsible for any damage during transit due to improper and inadequate packing and handling. The easily damageable material shall be carefully packed and marked with appropriate caution symbols. We shall supply, without any extra cost, any material found short inside the packing cases.
5.8 Each consignment of cable accessories shall also be accompanied by a detailed packing list containing the following information:
a) Name of the consigneeb) Details of consignmentc) Destinationd) Total weight of consignment e) Handling and unpacking instructionsf) Bill of material indicating contents of each package
The packing list including bill of material, shall be submitted to APTRANSCO for approval before shipment of the material, after completion of works inspection.
6. Drawings:
Following drawings shall be submitted to APTRANSCO for approval of the same.
6.1 For Equipment Supply from SFC, China
a) 220kV Porcelain Outdoor termination – SFC Type .YJZWC4
b) 220kV Composite Outdoor termination – SFC Type. YJZWC4-F
c) 220kV GIS termination – SFC Type. YJZGG-960
d) 220kV Pre-Moulded (one piece structure) Insulation Straight Through Joint – SFC Type. YJJJI1
e) 220kV Pre-Moulded (one piece structure) Normal Straight Through Joint – SFC Type. YJJTI1
f) 132kV Porcelain Outdoor termination – SFC Type.YJZWC
g) 132kV GIS Termination – SFC Type.YJZGC
h) 3-Phase Cross-bonding Link Box with SVL – SFC Type. CLB-3S
i) 3-Phase Link Box with SVL – SFC Type. PLB-3S
j) 3-Phase Link Box without SVL – SFC Type. SLB-3S
k) 1-Phase Link Box with SVL – SFC Type. PLB-1S
l) 1-Phase Link Box without SVL – SFC Type. SLB-1S
6.2 For Equipment Supply from India:
a) Cross Section drawing for the co-axial earthing cable.
b) Cable route marker,
c) Warning tape,
d) Cable Tie
e) RCC Slab
6.3 Field Drawings:
a) Preliminary route survey drawing
b) The total station survey drawings
c) Cross bonding Drawing no.VEL/AP Transco/Lot-1/002(Sheet 1 to 3) &
VEL/AP
Transco/Lot-2/003(Sheet 1 to 3) under Section.7
d) Detailed trench cross section drawings
e) Position and type of all joints.
f) Drum length chart showing the distance between various joints of each cable
route
g) Details of the joint bays.
h) RCC Link box Pit
i) End termination structure drawings.
j) Monopoles/ Lattice structure drawing for LILO connection including
Foundation details.
k) Earthing details for the equipments
7. Guaranteed Technical Particulars for the Cable Systems
7.1 For 220 kV XLPE Cable System
Sl No
Description Values filled by the
manufacturer are guaranteed
1.
Maker’s Name, address and country of manufacturea) Cableb) Jointsc) Terminationsd) Accessoriese) Steel Structures
Shenyang Furukawa Cable Co., LTD. Hujiadian Dashupu Village Sujiatun District Shenyang China
2. Laying Agency Name and Address JDS Trade Links Pvt. Ltd., A/2D, Kyd Street, Chowringhee
Sl No
Description Values filled by the
manufacturer are guaranteed
Mansion, Kolkata 700016, West Bengal, India
3.
Manufacturer’s type designation / Standards conformed
a) Cableb) Jointsc) Terminationsd) Accessoriese) Steel Structures
Please refer to the
attached drawings
Standard
IEC 62067
4.
Rated voltage(kV)
a) Nominal
b) Highest
220
245
5.Continuous current carrying capacity per cable conductor (Amps) Calculation to be provided.
658A
6.Suitable for earthed or unearthed system Earthed System
7.
Permissible voltage and frequency variation for satisfactory operation
a) Voltage (Volts)
b) Frequency ( Hz)
0~24500049~61
8.Continuous current rating when laid underground under the following conditions of laying in Amps
658A
a)Reference ground temperature of 30 deg.C (below ground level) and maximum of 50 Deg.C at surface.
Yes
b)Maximum conductor temperature of 90 deg.C Yes
c)Depth of laying(to the highest point) of 1500mm Yes
9.Temperature rise for 10% over current deg. C 15 deg. C
10.Emergency overload rating 1226 Amps
11.Rating factors applicable to the current in Sl.No. 8 for the following variations/ conditions of installation.
a) Variation in ground temperature from 25, 30, 35, 40, 686A, 658A, 628A, 598A, 565A,
Sl No
Description Values filled by the
manufacturer are guaranteed
45 and 50 Deg.C, in steps of 5 Deg. C. 531A
b)Variation in thermal resistivity of the soil in the range 100, 120, 150, 200, 250, 300 Deg.C Cm/W
787A, 727A, 658A, 575A, 515A, 470A
c)Group rating factor for different spacing (center to center) of cables installed horizontally (in flat formation).
Not applicable
12.
Short circuit capacity:
a) Short circuit current kA (rms)b) Duration of short circuit (sec)
144.02kA
1sec
13.
Conductor temperature allowed for the short circuit duty with conductor temperature as 90 Deg. C before inception of short circuit (Deg. C)
250 Deg. C
14.The tangent delta at normal frequency and rated voltage.
≤0.0008
15.
Conductor: -
a) Materialb) Normal cross sectional area (sq.mm)c) No.of strands d) Overall diameter of conductor (mm)e) Maximum dielectric stress at the conductor kV/mm
a) Copperb) 1000 sq.mmc) 185d) 38.9mme) 7.85 kV/mm
16.
a) Maximum D.C resistance of conductor for 1000 metres at 20 Deg.C.
b) Maximum A.C resistance of conductor for 1000 metres at 90 Deg.C.
a) 0.0176Ohmsb) 0.0233Ohms
17.
Sequence Impedances of the cable1) Cable positive sequence (Z1) = R1 + jX1
2) Zero sequence conductor Zo = ROC +jXOC
3) Zero sequence sheath Zo = ROS +jXOS
4) Zero sequence Neutral ZoM = ROM +jXOM
And the calculations of the above may also be submitted.
1) 0.0233+j0.1594 /km2) 0.1713+j1. 6462 /km3) Not applicable4) Not applicable
18. Capacitance at 50Hz per 1000 metres0.172 Micro Farads
19.Maximum charging current per 1000 metres at rated voltage
6.86 Amps
20.Conductor screening:
a) Semi-Conductive tetoron tape/Super smooth semi-conductive
Sl No
Description Values filled by the
manufacturer are guaranteed
a) Material b) Extruded/wrapped or bothc) Thickness (mm)d) Maximum dielectric stress at conductor screening
(kV/mm)
cross-linked compound.b) Bothc) 0.8mm/1.5mm.d) 7.70 kV/mm
21.
Insulation:-
a) Composition of insulationb) Dry curedc) Thickness of insulation (mm)d) Tolerance on thickness e) Specified insulation resistance at 90 deg. C (Ohms-
cm)f) Maximum dielectric stress (kV/mm)g) Insulation resistance at 20 deg. C (Ohms)
a) XLPEb) Dry methodc) 24mmd) +1.0/-1.2mme) 1183 M·kmf) 30kV/mmg) 11834 M·km
22.
Non-metallic part of Insulation screening:
a) Materialb) Extruded / wrapped or bothc) Thickness mm
a) Super smooth semi-conductive cross-linked compound.b) Extrudedc) 1.0 mm
23.
Water blocking tape
a) Material
b) Extruded/wrapped or both
c) Thickness mm
a) Semi-conductive cushion water blocking tape.b) Wrappedc) 6.6mm
24. Metallic part of insulation screening (Moisture barrier)
a) Type of screen
b) Normal diameter of cable over metallic screen mm
c) Normal thickness of the screen mm
d) Whether screen is to be earthed at both terminations
e) Screen voltage/KM corresponding to rated current of cable with one end of screen unearthed
f) Screen current corresponding to rated current of
a) Continuously extruded and corrugated aluminum sheath.b) 119.4mmc) 2.7mmd) Yese) 35.0V/kmf) <70Ag) 8314W/kmh) 1674.4V/km
Sl No
Description Values filled by the
manufacturer are guaranteed
cable with both ends of screen earthed. : Amps
g) Screen Loss/KM corresponding to rated current of cable with both ends of screen earthed. : Watts
h) Screen Voltage/KM corresponding to short circuit current in cable for 3-phase fault with one end of screen unearthed. Volts
i) Screen current corresponding to short circuit current
in cable for 3-phase fault with both ends of armour
earthed. Amps/sec
j) Current rating of screen under short circuit dutyAmps
i) 86.78 kA/sj) 86.78 kA/s
25.
Outer jacket (sheath)
(a) Material(b) Details of rodent and termite protection (c) Thickness of sheath mm (d) Tolerance of thickness of sheath(e) Sheath loss of cable per KM of 3 phase circuit at
Watts (f) Normal voltage and frequency at maximum
continuous current rating.
(a) HDPE(b) Appending anti-termite dose(c) 5.0mm(d) +0.5/-0.8mm(e) 0(f) 127/220kV /50Hz
26. Overall diameter of cable mm 129.4mm
27. Weight per metre (Kg/mtr.) 20.78 kg/m
28. Recommended minimum installation radius(mm) 2300mm
29. Safe pulling force when pulled by eye (Kg) 7000kg
30.
Cable drums:
a) Dimensions:-( Flange dia/Barrel dia/thickness)
mm
b) weight of cable drum with cable Kg
c) Maximum length (single length) mtr.
(a)<3600mm(b)<16000kg(c) 600mtr
31. Cable termination kits
a) Maker’s name and country of manufactureb) Typec) Material of the bushingd) Creepage distance (mm)e) Whether cable termination kit is complete with all
a) Shenyang Furukawa Cable Co., Ltd.
Sl No
Description Values filled by the
manufacturer are guaranteed
accessories.
b) YJZWC4 / YJZWC4-F
c) Porcelain/Composite
d) 8070mm/8401mm
e) Yes. (But without supporting structure. The supporting structure would be supplied from India).
32.
Jointing kits:-
a) Maker’s name and country of manufactureb) Type of kitc) Whether straight through jointing kit is complete
with all accessories.
a) Shenyang Furukawa Cable Co., Ltd. China
b) YJJJI1 and YJJTI1
c) Yes. But link boxes and cross bonding earthing cables are additional items, as per the PO.
33.Maximum dielectric power loss of cable per KM of
3-phase circuit laid in ground at normal voltage, frequency and maximum conductor temperature.
2090 Watts
34.Total max. losses per KM of 3 phase circuit at the
above condition with rated current ( Watts )46065 Watts
35.Attenuation to carrier signal operating over a
frequency range of 50-200 kHz.---
36.Phase to ground characteristic impedance at 50-200
kHz0.1634~0.6473 Ohms/km
37. Maximum life50 Years
38. Power frequency withstand voltage318 kV(rms)
39. 1.2/50 microsecond impulse withstand voltage 1050 kV (Peak)
40. Partial discharge magnitude at rated voltage PCNo detectable discharge
41. Max. pulling load for the cable7000 kg
Sl No
Description Values filled by the
manufacturer are guaranteed
42.Any other important particulars for cables and
accessories
43.Maximum single length 220 kV 1000 Sq.mm XLPE
Cable shall be supplied by the bidder.
600 Mts. or more, based on the engineering drawings to be approved by APTRANSCO.
7.2 For 132 kV XLPE Cable System
Sl No
Description Values filled by the manufacturer
are guaranteed
1.
Maker’s Name, address and country of manufacturea) Cableb) Jointsc) Terminationsd) Accessoriese) Steel Structures
Shenyang Furukawa Cable Co., LTD. Hujiadian Dashupu Village Sujiatun District Shenyang China
2.Laying Agency Name and Address
3.
Manufacturer’s type designation / Standards conformed
a) Cableb) Jointsc) Terminationsd) Accessoriese) Steel Structures
Please refer to the attached
drawings
Standard
IEC 60840
4.
Rated voltage(kV)
a) Nominal
b) Highest
132
145
5.Continuous current carrying capacity per cable conductor (Amps) Calculation to be provided.
711 A
6.Suitable for earthed or unearthed system Earthed System
Sl No
Description Values filled by the manufacturer
are guaranteed
7.
Permissible voltage and frequency variation for satisfactory operation
a) Voltage (Volts)
b) Frequency ( Hz)
0~14500049~61
8.Continuous current rating when laid underground under the following conditions of laying in Amps
711 A
aReference ground temperature of 300C (below ground level) and maximum of 500C at surface.
Yes
b)Maximum conductor temperature of 900C Yes
c)Depth of laying(to the highest point) of 1500mm Yes
9.Temperature rise for 10% over current deg. C 150C
10.Emergency overload rating 1298 Amps
11.Rating factors applicable to the current in Sl.No. 8 for the following variations/ conditions of installation.
a)Variation in ground temperature from 25, 30, 35, 40, 45 and 50 Deg.C, in steps of 5 Deg. C.
741A, 711A, 680A, 647A, 613A, 577A
b Variation in thermal resistivity of the soil in the range 100, 120, 150, 200, 250, 300 Deg.C Cm/W
852A, 786A, 711A, 621A, 558A, 510A
c)Group rating factor for different spacing (center to center) of cables installed horizontally (in flat formation).
Not applicable
12.
Short circuit capacity:
a) Short circuit current kA (rms)b) Duration of short circuit (sec)
172.72kA
1sec
13.
Conductor temperature allowed for the short circuit duty with conductor temperature as 90 Deg. C before inception of short circuit (Deg. C)
250 Deg. C
14.The tangent delta at normal frequency and rated voltage.
≤ 0.001
15. Conductor: - a) Copper
Sl No
Description Values filled by the manufacturer
are guaranteed
a) Materialb) Normal cross sectional area (sq.mm)c) No.of strands d) Overall diameter of conductor (mm)e) Maximum dielectric stress at the conductor kV/mm
b) 1200 sq.mmc) 185d) 42.0mme) 5.70 kV/mm
16.
a) Maximum D.C resistance of conductor for 1000 metres at 20 Deg.C.
b) Maximum A.C resistance of conductor for 1000 metres at 90 Deg.C.
a) 0.0151Ohmsb) 0.0204 Ohms
17.
Sequence Impedances of the cable1) Cable positive sequence (Z1) = R1 + jX1
2) Zero sequence conductor Zo = ROC +jXOC3) Zero sequence sheath Zo = ROS +jXOS4) Zero sequence Neutral ZoM = ROM +jXOMAnd the calculations of the above may also be submitted.
1) 0.0204+j0.1501 /km2) 0.1684+j1.6504 /km3) Not applicable4) Not applicable
18. Capacitance at 50Hz per 1000 metres0.223Micro Farads
19.Maximum charging current per 1000 metres at rated voltage
5.33 Amps
20.
Conductor screening:
a) Material b) Extruded/wrapped or bothc) Thickness (mm)d) Maximum dielectric stress at conductor screening
(kV/mm)
a) Semi-Conductive tetoron tape/Super smooth semi-conductive cross-linked compound.b) Bothc) 0.8mm/1.5mm.d) 5.70 kV/mm
21.
Insulation:-
a) Composition of insulationb) Dry curedc) Thickness of insulation (mm)d) Tolerance on thickness e) Specified insulation resistance at 90 deg. C
(Ohms-cm)f) Maximum dielectric stress (kV/mm)g) Insulation resistance at 20 deg. C (Ohms)
a) XLPEb) Dry methodc) 18.0mmd) +1.0/-1.8mme) 911 M·kmf) 30kV/mmg) 9110M·km
22. Non-metallic part of Insulation screening: a) Super smooth semi-conductive cross-linked compound.
Sl No
Description Values filled by the manufacturer
are guaranteed
a) Materialb) Extruded / wrapped or bothc) Thickness mm
b) Extrudedc) 1.0 mm
23.
Water blocking tape
a) Material
b) Extruded/wrapped or both
c) Thickness mm
a) Semi-conductive cushion water blocking tape.b) Wrappedc) 5.0mm
24.
Metallic part of insulation screening (Moisture barrier)
a) Type of screen
b) Normal diameter of cable over metallic screen mm
c) Normal thickness of the screenmm
d) Whether screen is to be earthed at both terminations
e) Screen voltage/KM corresponding to rated current of cable with one end of screen unearthed
f) Screen current corresponding to rated current of cable with both ends of screen earthed. : Amps
g) Screen Loss/KM corresponding to rated current of cable with both ends of screen earthed. : Watts
h) Screen Voltage/KM corresponding to short circuit current in cable for 3-phase fault with one end of screen unearthed. Volts
a) Continuously extruded and corrugated aluminum sheath.b) 106.2mmc) 2.3mmd) Yese) 38.2V/kmf) <10A g) 9733 W h) 1690.1V/km
i) Screen current corresponding to short circuit
current in cable for 3-phase fault with
both ends of armour earthed.
Amps/sec
i) 65.21 kA/sj) 65.21 kA/s
Sl No
Description Values filled by the manufacturer
are guaranteed
j) Current rating of screen under short circuit dutyAmps
25.
Outer jacket (sheath)
(g) Material(h) Details of rodent and termite protection (i) Thickness of sheath mm (j) Tolerance of thickness of sheath(k) Sheath loss of cable per KM of 3 phase circuit
at Watts (l) Normal voltage and frequency at maximum
continuous current rating.
(a) HDPE(b) Appending anti-termite dose(c) 5.0mm(d) +0.5/-0.8mm(e) 0(f) 76/132kV /50Hz
26. Overall diameter of cable mm 116.2mm
27. Weight per metre (Kg/mtr.) 19.77 kg/m
28.Recommended minimum installation radius
(mm)2100mm
29. Safe pulling force when pulled by eye (Kg) 8400kg
30.
Cable drums:
a) Dimensions:-( Flange dia/Barrel dia/thickness)
mm
b) weight of cable drum with cable Kg
c) Maximum length (single length)
mm
(d)<3600mm(e)<15000kg(f) 600m
31.
Cable termination kits
a) Maker’s name and country of manufactureb) Typec) Material of the bushingd) Creepage distance (mm)e) Whether cable termination kit is complete with all accessories.
a) Shenyang Furukawa Cable Co., Ltd.
b) YJZWC
c) Porcelain
d) 4500mm
e) Yes. (But without supporting structure.
The supporting structure would be supplied from India).
Sl No
Description Values filled by the manufacturer
are guaranteed
32.
Jointing kits:-
a)Maker’s name and country of manufactureb) Type of kitc) Whether straight through jointing kit is complete
with all accessories.
Not required as per the BOM for the project.
33.Maximum dielectric power loss of cable per KM of 3-phase circuit laid in ground at normal voltage, frequency and maximum conductor temperature.
1215Watts
34.Total max. losses per KM of 3 phase circuit at the above condition with rated current ( Watts )
45959 Watts
35.Attenuation to carrier signal operating over a
frequency range of 50-200 kHz.---
36.Phase to ground characteristic impedance at
50-200 kHz0.1492~0.5917 Ohms/km
37. Maximum life 50 Years
38. Power frequency withstand voltage 190 kV(rms)
39. 1.2/50 microsecond impulse withstand voltage 650 kV (Peak)
40. Partial discharge magnitude at rated voltage PC No detectable discharge
41. Max. pulling load for the cable 8400 kg
42.Any other important particulars for cables and
accessories--
43.
Maximum single length 132 kV 1200 Sq.mm
XLPE Cable shall be supplied by the
bidder.
600 Mts or more based on the site conditions and later
engineering.
8. Cable cross-section drawings
8.1 Cable Cross-section drawing for 220kV XLPE cable
No. Construction Diameter
(mm)
1 Conductor 38.9±0.4
2 Semi-Conductive tetoron tape 40.5
3 Conductor screen 43.5
4 XLPE insulation 91 .5−2. 0+1 .0
5 Insulation screen 93.5
6 Semi-conducting cushion water-blocking tape 106.7
7 Corrugated aluminum sheath and bitumen 119.4±2.0
8Anti-termite HDPE outer covering and graphite coating 129.4±2.0
8.2 Cable Cross-section drawing for 132kV XLPE cable
No. Construction Diameter (mm)
1. Conductor 38.9
2. Semi- Conductor tetoron Tape 40.5
3. Conductor Screen 43.5
4. XLPE Insulation 91.5
5. Insulation screen 93.5
6. Semi- Conducting Cushion Water- Blocking Tape 106.7
7. Corrugated aluminum sheath and bitumen 119.4
8. Anti-termite HDPE Outer Covering And Graphite Coating
129.4
9. Calculation book for current carrying capacity of 220kV
and 132 kV cable
(a) Continuous current carrying capacity
Condition
No. Item DATA
1 Voltage U0/U 127/220 (kV) 76/132 (kV)
2 The nominal area of conductor 1000mm2 1200mm2
3 Frequency f 50Hz 50Hz
4 The depth of laying 1500(mm) 1500(mm)
5 Relative permittivity of the insulation ε 2.3 2.3
6 Loss factor of insulation tgδ 0.0008 0.0008
7 Resistivity of AL sheath ρsh 2.84×10-8 (Ω.m) 2.84×10-8 (Ω.m)
8 Resistivity of conductor ρcond. 3.93×10-3 (1/ oC) 3.93×10-3 (1/ oC)
9 Temperature coefficient of AL sheath α20AL 4.03×10-3 (1/ oC) 4.03×10-3 (1/ oC)
10 Thermal resistivity of XLPE insulation 3.5 (k.m/w) 3.5 (k.m/w)
11 Thermal resistivity of MDPE outer covering 3.5 (k.m/w)
12 Conductor temperature of operating 90 oC
13 AL sheath temperature of operating 60 oC
14 Soil temperature (assume) 30 oC
15 Earthing type of AL sheathBonded at single point or cross-
bonded
16 Axial separation of conductor 129.4mm 116.2mm
No. of circuits 2 2
Calculation formula:
I=Δθ−W d [0 .5T 1+n (T 2+T3+T 4) ]
R [T1+n (1+λ1 )T2+n (1+λ1+λ2) (T 3+T 4 )]
Where:
I - continuous current rating (A)
θ- conductor temperature rise above the ambient temperature (oC)
R - A.C. current resistance at 90 oC (Ω/m)
n - number of conductor in a cable
Wd-dielectric losses per unit length (w/m)
λ1-ratio of the total losses in metallic sheaths respectively to the
total conductor losses
λ2-ratio of the total losses in armour respectively to the total
Conductor losses
T1-thermal resistance per core between conductor and sheath (k·m/w)
T2-thermal resistance between sheath and armour (k·m/w)
T3-thermal resistance of external serving (k·m/w)
T4-thermal resistance of surrounding medium (k·m/w)
3) Calculation of AC resistance R of conductor
R=R’(1+ys+yp)
R’=Ro[1+α20(θ-20)]
where:
R’- DC current resistance of conductor at maximum operating
temperature (Ω/m)
ys - skin effect factor
yp - proximity effect factor
R0 - DC resistance of conductor at 20 oC (Ω/m)
θ- maximum operating temperature 90 oC
α20-temperature coefficient of conductor at 20 oC
y s=X
s4
192+0 . 8 Xs4
Xs2=
8πfR
ks10−7
where:ks=1
Y p=X
p4
192+0 . 8 Xp4( dc
s )2
{0.312[ dc
s ]2
+ 1 .18X
p4
192+0 .8 Xp
4
+0 .27 }where:dc - diameter of conductor (mm)
s - distance between conductor axes (mm)
kp = 1
4) Calculation of dielectric losses wd
W d=ϖCU
02tgδ
where:ω=2πf
C-capacitance per unit length (F/m)
U0- voltage to earth (V)
C= ε
18 Ln( Di
dc)×10−9
where:
ε-is 2.3
DI-external diameter of insulation (excluding screen) (mm)
dc- diameter of conductor (mm)
5) Calculation of AL sheath losses λ1
λ1=λ’1+λ〃1
where:
λ’1 is eddy-current losses
λ〃1 is circulating current losses
Calculation of λ1〃:
λ1} } } = { {R rSub { size 8{s} } } over {R} } left [g rSub { size 8{s} } λ rSub { size 8{0} } left (1+Δ rSub { size 8{1} } +Δ rSub { size 8{2} } right )+ { { left (β rSub { size 8{1} } t rSub { size 8{s} } right ) rSup { size 8{4} } } over { 12 times 10 rSup { size 8{12 } } } } right ]} { ¿¿ ¿
¿
gs=1+( t sD s)1. 74
( β1 Ds10−3−1 . 6)
β1=√ 4 πϖ107 ρs
where:
ρ - resistivity of AL sheath (Ω.m)
R - resistance of AL sheath (Ω/m)
D - diameter of AL sheath ,D=
Doc+Dit
2+t s (mm)
t - thickness of AL sheath (mm)
Doc- maximum diameter of AL sheath (mm)
Dit- minimum diameter of AL sheath (mm)
a. Trefoil formation
λ0=
3m2
1+m2 ( d2 s )
2
Δ1= (1.14m2. 45+0 . 33 )( d
2 s )(0 .92m+1 . 66)
2=0
b. Flat formation
λ0=6m2
1+m2 ( d2 s )
2
Δ1=0. 86m3 .08( d
2 s )(1. 4m+0. 7 )
2=0
where: m= ϖ
Rs
10−7
6) Losses of armour λ2
λ2=0
7) Calculation of thermal resistance
Calculation of thermal resistance T1
Thermal resistance
T 1=ρT1
2 πLn (1+2 t 1
dc)
where:
ρT1 - thermal resistivity of insulation material (k·m/w)
dc - conductor diameter (mm)
t1- insulation thickness between conductor and AL sheath (mm)
Calculation of thermal resistance T2
Thermal resistance T2=0
Calculation of thermal resistance T3
T 3=ρT 3
2πLn( Doc+2 t 3
( Doc+Dit
2 )+t s ) Where:
ts- Thickness of outer serving
ρT3-thermal resistivity of outer serving (non-metal) (k·m/w)
8) Groups of buried cables (not touching)
T 4=ρT4
2 πLn{(u+√u2−1) [( d ' p1
d p1)( d ' p2
d p2)¿⋅¿( d ' pk
d pk)¿⋅¿( d ' pq
dpq)]}
There are (q-1) items, with the item d′pp/dpp excluded.
Where:
The distances dpkand d'pk are measured from the center of the
dpk cable to the center of cable k ,and to the center of the
Reflection of cable k in the ground-air surface respectively.
u=2L/De
L-distance from the surface of the ground to the cable axis.(mm)
De - external diameter of the cable.
s1 - axial separation between two adjacent cables (mm).
Table 1 Continuous Current Carrying Capacity
Item unit Data
Voltage U0/U kV 127/220 76/132
The nominal area of conductor mm2 1000 1200
Distance mm 129.4 116.2
Soil resistivity k·m/w 1.5 1.5
Conductor resistance (D.C. at 20 oC) Ω/km 0.0176 0.0151
Conductor resistance (A.C. at 90 oC) Ω/km 0.0233 0.0204
Dielectric loss W/m 0.697 0.405
Sheath loss factor --- 0.4542 0.4522
Thermal resistance between conductor and shield k·m/w 0.5842 0.4771
Thermal resistance of jacket k·m/w 0.0851 0.0898
Thermal resistance of surrounding medium k·m/w 3.4266 3.4955
Number of cores --- 1 1
Maximum operating temperature oC 90 90
Ambient temperature oC 30 30
Conductor temperature rise above the ambient temperature
oC 60 60
Current carrying capacity A 658 711
11. Current Carrying Capacity of Metallic Shielding in short circuit
I AD=√ K2 S2Ln (θ f +βθ i+β )
t
where: IAD=short-circuit current calculated on an adiabatic basis, A;
t=duration of short circuit, 1sec.;
K= constant depending on the material of the current carrying component,
148.0A.s1/2/mm2;
S=geometrical cross-sectional area of the current carrying component;
θf=final temperature; 60 oC
θi=initial temperature; 180 oC
Β,228K.
Cross-sectional of metal shield S=3.14
Doc+Dit
2×δ
Where: Din=inner dia.of aluminum sheath, mm; Doc= outer diameter of aluminum sheath, mm;
δ=thickness of aluminum sheath, mm.
Factor M is calculated as follows:
M=√ σ2
ρ2
+√ σ3
ρ3
2σ1δ×10−3F
Where: σ2, σ3 = volumetric specific heat of media either side of the screen and sheath,
2.4×106J/K·m3,2.4×106J/K·m3;
ρ2, ρ3=thermal resistivity of the media either side of screen, sheath or armour,
3.5k·m/W,3.5k·m/W;
σ1=volumetric specific heat of the screen, sheath or armour, 2.5×106J/K·m3 ;
δ=thickness of screen, sheath or armour, mm; F=0.7.
ε=1+0 . 61M √t1−0 .069 (M √ t1)2+0 .0043 (M √ t1 )3
Where: t=duration of short current, 1s
The permissible short-circuit current: I=IAD×ε Where: I=permissible short-circuit current.
Result of metal sheath short current
Item Unit Value
Voltage U0/U kV 127/220 76/132
The nominal area of conductor mm2 1000 1200
Final temperature θfoC 180 180
initial temperature θioC 60 60
Constant β oC 228 228
Constant K A.s1/2/mm2 148 148
Cross-section of metal sheath mm2 945.1 703.8
Inner diameter of aluminum sheath Din mm 102.7 91.6
Outer diameter of aluminum sheath Doc mm 119.4 106.2
volumetric specific heat of media either side of the screen and sheath σ2
J/K·m3 2.4×106 2.4×106
volumetric specific heat of media either side of the screen and sheath σ3
J/K·m3 2.4×106 2.4×106
thermal resistivity of the media either side of screen ρ2 k·m/W 3.5 3.5
thermal resistivity of the media either side of screen ρ3 k·m/W 3.5 3.5
volumetric specific heat of the screen σ1 J/K·m3 2.5×106 2.5×106
thickness of screen δ mm 2.5 2.5
Constant F --- 0.7 0.7
Constant ε --- 1.051 1.061
Factor M --- 0.085 0.101
Duration of short current s 1.0 1.0
adiabatic short-circuit current IAD kA 82.55 61.47
The permissible short-circuit current I kA 86.78 65.21
12. Current Carrying Capacity of Conductor in short circuit
The general form of the adiabatic temperature rise formula which is applicable to any initial
temperature is :
IAD
2 t=K 2S2 Ln( θf +βθi+β )
Factor to allow for heat loss into the adjacent components, ε=√1+X √ t
s+Y ( ts )
Where: X, Y is constant, 0.41 mm2/s and 0.12mm2/s
S= section of conductor, 400mm2.
t= time is 1s
θf=final temperature; 90 oC
θi=initial temperature; 250 oC
The permissible short-circuit current I = IAD×ε
Result of conductor short-circuit current
Item Unit Value
Voltage U0/U kV 127/220 76/132
The nominal area of conductor mm2 1000 1200
Final temperature θfoC 250 250
Initial temperature θioC 90 90
Constant β oC 228 228
Constant K A.s1/2/mm2 148 148
Constant X mm2/s 0.41 0.41
Constant Y mm2/s 0.12 0.12
Constant ε --- 1.007 1.006
Duration of short-circuit t s 1.0 1.0
adiabatic short-circuit current IAD kA 143.08 171.70
The permissible short-circuit current I kA 144.02 172.72
13. Calculation of electric stress
1. Maximum dielectric electric stress at the conductor surface
a) 127/220kV,1000mm2:
Emax=U 0
0. 5 Dci /Ln( Di
Dci)=
7.70kV/mm
U0=127kV Dci=43.5mm Di=91.5mm
b) 76/132 kV,1200mm2:
Emax=U 0
0. 5 Dci /Ln( Di
Dci)=
5.70kV/mm
U0=76kV Dci=46.6mm Di=82.6mm
2. Minimum dielectric electric stress at the XLPE insulation surface
a) 127/220kV,1000mm2:
Emin=U 0
0 .5 Di Ln(Di /D ci)=
3.73kV/mm
U0=127kV Dci=43.5mm Di=91.5mm
b) 76/132 kV,1200mm2:
Emin=U 0
0 .5 Di Ln(Di /D ci)=
3.21kV/mm
U0=76kV Dci=46.6mm Di=82.6mm
14. Max. dielectric power loss of cable per Km of 3 phase
a) 127/220kV,1000mm2:
W d=nωCU02tg δ=3×0 .697=2.090kW /km
C= ε×10−9
18 ln( Di
Dci)=0 . 172μF /km
tgδ:0.0008 U0=127000V Dci=43.5mm Di=91.5mm
b) 76/132 kV,1200mm2:
W d=nωCU02tg δ=3×0 . 405=1.215kW /km
C= ε×10−9
18 ln( Di
Dci)=0 .223μF /km
U0=76kV Dci=46.6mm Di=82.6mm
15. Sheath loss of cable per km. of 3 phase
a) 127/220kV,1000mm2:
W s=nI2Rλ=3×6582×0.02 33×0 .4542 /1000=13 .735kW /km
b) 76/132 kV,1200mm2:
W s=nI2Rλ=3×7112×0. 02033×0 . 4522/1000=13 . 934 kW /km
16. Total loss in cable per km. of 3 phase
a) 127/220kV,1000mm2:
W=Wr+Wd+Ws=46.065kW/km
Wr=nI2R=3×6582×0.0233/1000=30.24kW/km
Wd=2.090kW/km
Ws=13.735kW/km
b) 76/132 kV,1200mm2:
W=Wr+Wd+Ws=45.959kW/km
Wr=nI2R=3×7112×0.02033/1000=30.810kW/km
Wd=1.215kW/km
Ws=13.934kW/km
17. Induced voltage on Sheath
a) 127/220kV,1000mm2:
Sheath induced voltage under normal operating:
Sheath induced voltage under fault conditions:
b) 76/132kV,1200mm2:
Sheath induced voltage under normal operating:
Sheath induced voltage under fault conditions:
18. Continuous current carrying capacity which will permit a further 10% overload for two hours laid in ground
a) 127/220kV XLPE Cable, Size:1x 1000mm2:
Diameter
(mm)
Thermal resistivit
y(k·m/w)
Thermal capacitance(J/k·m)
Losses(W/m)
Conductor 42.0 4140 10.27
Conductor screen
46.6
XLPE insulation
82.6 0.4771 15112 0.405
Insulation screen
84.6
Cushion layer
86.6
Water-blocking layer
94.6
U s=2ϖ ILn( 2 sds
)/10−7=2∗2∗π∗50∗658∗Ln( 2∗129 . 4111. 0 )=35 .0V /km
U s=2ϖ ILn( 2 sds
)/10−7=2∗2∗π∗50∗40000∗Ln( 2∗129 .4111.0 )=1674 .4 V /km
U s=2ϖ ILn( 2 sds
)/10−7=2∗2∗π∗50∗711∗Ln (2∗116. 298 . 9 )=38 . 2V /km
U s=2ϖ ILn( 2 sds
)/10−7=2∗2∗π∗50∗31500∗Ln( 2∗116. 298 . 9 )=1690 . 1V /km
Diameter
(mm)
Thermal resistivit
y(k·m/w)
Thermal capacitance(J/k·m)
Losses(W/m)
Corrugated aluminum sheath
106.4 1828 4.644
PE outer 116.2 0.0898 4192
∑ 0.5669 25272 15.320
Thermal resistance of surrounding medium: In the Soil - 2.502 k·m/w
Conductor resistance (A.C. at 90 ℃):0.02033 Ω/km
The constant of time:τ=T·Q=1432s-1
Material characteristic:Thermal resistivity of outer covering 3.5k·m/w,Thermal resistivity of XLPE insulation 3.5k·m/w。
1. Solve the cable hot road
Thermal capacitance of XLPE insulation Qi =15112J/k·m
Factor for apportioning the thermal capacitance of dielectric:
= 0.3718
TA = T1 =0.1652k·m/w
TB=qsT3 =2496.8k·m/w
QA=p×Qi=9759J/k·m
Qs=1828J/k·m
Qj=4192 J/k·m
= 0.485 1/DD
1-
/DD2ln
1=p
2sese
′
1d/d
1-
d/d2ln
1 = p
2cncn
=12152J/k·m
2. Calculation of cable partial transient
2.1 Buried cables
=3757
= 7378001
= 0.00086
= 0.00016
= 0.0097 J/k·m
Tb = TA+TB-Ta = 0.5978 J/k·m
3 The transient temperature rise of the conductor above the outer surface of the
cable
3.1 Buried cables
θc(t) = Wc×(Ta×(1-e-at)+Tb×(1-e-bt)) =4.2639 ℃4 Calculation of cable environment partial transient
4.1 Buried cables
sj′
siB )/qQp+(Q+Qp-1 = Q
BBBAA0 TQ+T+TQ2
1 = m
BBAA0 TQTQ = n
n
n-m+m = a
0
02
00
T+Tb-Q
1
b-a
1= T BA
Aa
1
1
pk2'
i
pk2
i
2
i
2e
iIT
e δ4t
dE
δ4t
dE-
δt
L-E-
δ16t
D-E-
π4
Wρ=(t)θ
N
k
b= m0−√m02 -n0
n0
Where: ρT - soil thermal resistivity
WI - the total power loss per unit length of each cable in the group
-Ei(-x) – the exponentiation integral function.
De - external surface diameter of cable
δ- soil thermal diffusivity
t – time from moment of application of heating
L – axial depth of burial of hottest cable
Dpk – distance from centre of cable k to centre of hottest cable p
Dpk′ - distance from image of centre of cable k to centre of hottest cable p
N – number of cables
θe(t) =2.2339 ℃
5. The conductor to cable surface attainment factor α(t) for the transient temperature rise between the conductor and outside surface of the cable.
α=θc/Wc/(TA+TB) = 0.6832
6. Calculation of the complete temperature transient
6.1 Transient temperature response
After calculating separately the two partial transients and the conductor to cable surface attainment factor the total transient rise θ(t) above ambient environment.
6.1.1 Buried cable
θ(t) = θc(t)+α(t)θe(t) =5.7901℃
=4.9615℃
7. Calculation of the steady-state conductor temperature rise θ△ d due to the
dielectric loss.
tθ-∞ θα+1
tθ= tθ a
7.1 Buried cable
θ△ d =Wd(0.5T1+T2+T3+T4) = 1.5505 ℃
7. Calculation of emergency ratings
7.1 Buried cables
= 1.1667
t = 7200 -time measured from moment of application of current I2
IR = 711 A –sustained (100% load factor)rated current for the conductor to attain.
I1 =711A –constant current applied to cable prior to emergency loading
h1 = I1/IR = 1
R1=0.00002036Ω/m -a.c resistance of conductor before application emergency current
Rmax= 0.00002033 Ω/m -a.c resistance of conductor at end of period of emergency current
RR = 0.00002118current IR , i.e. at standard maximum permissible temperature.
θmax = 1.5505K -maximum permissible temperature rise above ambient at end of period of emergency loading.
θR(t) = 73.4495K - conductor temperature rise above ambient after application of IR .
θR(t)=θa(t)
The emergency current I2 is given by:
= 1226A
2
1
RR
R12
1max1
max
12
1R 2 ∞θ/tθ
/RRh-rR/R+
R
RhI=I
∞θ
θ=r max
b) 76/132kV,1200mm2:
Diameter
(mm)
Thermal resistivit
y(k·m/w)
Thermal capacitanc
e(J/k·m)
Losses(W/m)
Conductor 38.9 3450 10.08
Conductor screen
43.5
XLPE insulation
91.5 0.5842 20386 0.697
Insulation screen
93.5
Cushion layer
98.7
Diameter
(mm)
Thermal resistivit
y(k·m/w)
Thermal capacitanc
e(J/k·m)
Losses(W/m)
Water-blocking layer
106.7
Corrugated aluminum sheath
119.4 2443 4.578
PE outer 129.4 0.0851 4689
∑ 0.6694 30968 15.355
Thermal resistance of surrounding medium: In the Soil - 2.426 k·m/w
Conductor resistance (A.C. at 90 ℃):0.0233 Ω/km
The constant of time:τ=T·Q=2072s-1
Material characteristic:Thermal resistivity of outer covering 3.5k·m/w,Thermal resistivity of XLPE insulation 3.5k·m/w。
1. Solve the cable hot road
Thermal capacitance of XLPE insulation Qi = 20386J/k·m
Factor for apportioning the thermal capacitance of dielectric:
= 0.3428
TA = T1 =0.1581k·m/w
TB=qsT3 =3222.4 k·m/w
QA=p×Qi=10438 J/k·m
Qs=2443 J/k·m
Qj=4689 J/k·m
1d/d
1-
d/d2ln
1 = p
2cncn
= 0.4866
=16648J/k·m
2. Calculation of cable partial transient
2.1 Buried cables
=4726
= 12567649
= 0.00062
= 0.00013
= 0.0113 J/k·m
Tb = TA+TB-Ta = 0.6968 J/k·m
3 The transient temperature rise of the conductor above the outer surface of the cable
3.1 Buried cables
θc(t) = Wc×(Ta×(1-e-at)+Tb×(1-e-bt)) =4.3278 ℃4 Calculation of cable environment partial transient
4.1 Buried cables
Where: ρT - soil thermal resistivity
sj′
siB )/qQp+(Q+Qp-1 = Q
1/DD
1-
/DD2ln
1=p
2sese
′
BBBAA0 TQ+T+TQ2
1 = m
BBAA0 TQTQ = n
n
n-m+m = a
0
02
00
T+Tb-Q
1
b-a
1= T BA
Aa
1
1
pk2'
i
pk2
i
2
i
2e
iIT
e δ4t
dE
δ4t
dE-
δt
L-E-
δ16t
D-E-
π4
Wρ=(t)θ
N
k
b= m0−√m02 -n0
n0
WI - the total power loss per unit length of each cable in the group
-Ei(-x) – the exponentiation integral function.
De - external surface diameter of cable
δ- soil thermal diffusivity
t – time from moment of application of heating
L – axial depth of burial of hottest cable
Dpk – distance from centre of cable k to centre of hottest cable p
Dpk′ - distance from image of centre of cable k to centre of hottest cable p
N – number of cables
θe(t) =1.7195 ℃
5. The conductor to cable surface attainment factor α(t) for the transient temperature rise between the conductor and outside surface of the cable.
α=θc/Wc/(TA+TB) = 0.6065
6. Calculation of the complete temperature transient
6.1 Transient temperature response
After calculating separately the two partial transients and the conductor to cable surface attainment factor the total transient rise θ(t) above ambient environment.
6.1.1 Buried cable
θ(t) = θc(t)+α(t)θe(t) =5.3708℃
=4.597℃
7. Calculation of the steady-state conductor temperature rise θ△ d due to the dielectric loss.
7.1 Buried cable
tθ-∞ θα+1
tθ= tθ a
θ△ d =Wd(0.5T1+T2+T3+T4) = 2.6498 ℃
7. Calculation of emergency ratings
7.1 Buried cables
= 1.1667
t = 7200 -time measured from moment of application of current I2
IR = 658 A –sustained (100% load factor)rated current for the conductor to attain.
I1 = 658A –constant current applied to cable prior to emergency loading
h1 = I1/IR = 1
R1=0.00002332Ω/m -a.c resistance of conductor before application emergency current
Rmax= 0.0000233 Ω/m -a.c resistance of conductor at end of period of emergency current
RR = 0.0000243current IR , i.e. at standard maximum permissible temperature.
θmax = 2.6498K -maximum permissible temperature rise above ambient at end of period of emergency loading.
θR(t) = 72.7502K - conductor temperature rise above ambient after application of IR .
θR(t)=θa(t)
The emergency current I2 is given by:
= 1298A
As we tapping the current from the over head lines (220kv) in the form of LILO (Line-in
And Line-out) Technology without distributing the existing over head line 220kv
2
1
RR
R12
1max1
max
12
1R 2 ∞θ/tθ
/RRh-rR/R+
R
RhI=I
∞θ
θ=r max
Over view of LILO Technology figure
Contents
1. Scope of work2. Advantages and disadvantages of underground cables3. Construction Details 4. Cable Specifications5. Laying of Cables6. Cross Bonding7. Cables Accessories
Advantages / Disadvantages:
Advantages:-
Conductor protects from storms and thunders Small voltage drop and better general appearance Low physical damage Less subject to damage from severe weather conditions (mainly lightning, wind and
freezing) Much less subject to conductor theft, illegal connections, sabotage, and damage from
armed conflict. Greatly reduced emission, into the surrounding area, of electromagnetic fields (EMF)
Disadvantages:-
Undergrounding is more expensive, since the cost of burying cables at transmission voltages is several times greater than overhead power lines
Underground power cables, due to their proximity to earth, cannot be maintained live, whereas overhead power cables can be
Cable Construction Details:-Cable consists of 7 layers
1. Conductor2. Conductor screening 3. Insulation4. Non metallic part of insulation Screening5. Water blocking tape6. Metallic part of insulation Screening (Moisture Barrier)7. Outer Jacket
1. Conductor: Single core conductor consists of stranded, segmental, compacted circular annealed Cu wires. The wires made of high conductivity Cu and the Cu used for the conductor should have highest purity.Overall diameter of the conductor is 38.9 mm.
2. Conductor Screening: It consists of semi conductive Tetoron tape and smooth semi conductive cross linked compound. The conductor screening should suitable for the operating temperature of cable and compatible with the insulating material.Thickness of the tetoron tape is 0.8mm, super smooth semi conductive compound is 1.5mm.Maximum dielectric stress at the conductor screening is 7.85 Kv/mm
3. Insulation: Insulating material is XLPE of very high degree of purity and dry cured. Thickness of the insulation is 24.0mm. Specified insulation resistance at 90 deg.C is 1183 MOhm-km maximum dielectric stress 30 kV/mm.
4. Non Metallic part of Insulation Screening: The material used is extruded super smooth semi conductive cross linked compound. Thickness is 1.0 mm.
5. Water Blocking Type: wrapped semi conductive cushion water blocking tape. Thickness of the material is 6.6 mm.
6. Metallic part of Insulation Screening (moisture barrier): Continuously extruded and corrugated aluminum sheath. Thickness of the material is 2.7 mm.
7. Outer Jacket: The outer jacket consists of HDPE material. The purpose of this material is to insulate the metallic screen from ground. Thickness is 5.0 mm.
Cable specification
The rated voltage a) Nominal 220Kvb) Highest 245Kv
The continuous current carrying capacity perCable conductor is 658A
It is a earthed system Frequency (49-61) Hz.
Short circuit current capacity 144.02KA/1 sec
Capacitance at 50Hz per 1000m is 0.172 µF
Over all diameter of the cable is 129.4mm
Weight of the cable per meter is 20.78kg per meter
Maximum life is 50 years
Power frequency withstand voltage 318Kv(RMS)
Number of strands 185
Cable Laying:-
For laying of cable, total distance is divided into major sections. Each major section is equally divided into three minor sections. It is double circuit scheme.
Excavation of cable trench:-
Depth and width of the open trench is 1.8m and 1.8m. Clearance Between circuit to circuit is 1.2m. Three single core cables are placed in trefoil formation in each circuit. For every 5m of length there should be nylon tape and for every 20m length there should be a trefoil clamp. Before placing the cables a sand layer of 5cm thickness has to be placed. After placing the cables in trefoil formation, up to 10cm height from the top of the circuit should backfill with sand.
RCC Slabs: - After placing the cables and backfilling with sand we cover each circuit separately with RCC Slabs by length wise. The size of the RCC slab is
Width : 750mmLength : 300mmThickness : 50mm
6mm rods are used for making RCC slabs with cement concrete mix of 1:2:4 After placing the RCC slabs we should backfill with excavated earth
Warning Tape: - For each circuit separate warning tape is used along the length. The thickness of the tape is 50 microns and the width is 500mm
Railway Crossing & Road Crossing:-HDD (Horizontal direct drilling) method to place cables.In this method holes are drilled in trefoil formation, PVC or HDPE pipes are placed in the
holes to pass the cables from it.
Cross Bonding: In order to eliminate the sheath circulating current losses and consequent rise in potential, the metallic sheath at cable joints shall be connected together at every joint and solidly earthed through disconnecting link boxes. The cable sheath covering and sheath insulators provided at the cable terminations shall be capable of withstanding sheath voltage arising from maximum momentary fault current of 40 kA(rms) for 220 kV and 31.5 kA for 132kV. Cable covering protection units (ccpu) with surge voltages induced in the cable circuit. The sheath voltage under normal operating condition shall be around 50 to 60v to ground in any section.
Accessories:
1. Straight through joint:-
The straight joints shall be suitable for underground installation with uncontrollable backfill and for laying in areas likely to be flooded by water. These shall have adequate mechanical protection features.
2. Cross Bonding joint:-
The first 2 minor sections from the feeding end and termination will have to be cross bonded and every major section end (which consists of 3 minor sections) has to be directly earthed. End of every major section end has to be directly earthed. End of every major section shall be of normal type of straight through joints and end of every minor section, which is to be cross bonded, shall be of insulated type of straight through joints. Phase transposition of cable shall be done during laying every 3 sets of joints.
3. SF6 Gas Terminations or GIS Terminations:-
It is used to terminate GIS substation Terminations and
termination enclosures for high voltage gas insulated switchgear
4. Terminations or Silicon Terminations:-
The termination which is done at outdoor
5. Link Boxes:-
Link boxes are made up of
stainless steel plate of sufficient mechanical strength and enclosure links and cable cover protection units (ccpus)
The insulated type straight through joints shall be connected to cross link box by means
of single core cable and through links and surge arresters (ccpu) to be connected to earth. Provision for transpositions of sheath and screen by cross bonding shall be made in cross link boxes.
Top View Joint Bay Under Ground XLPE Cable
Model Layout Joint Bay Section
The normal type of straight through joints also be connected to link box by means of single core cable and through links. The connecting terminals and disconnecting link shall be made of copper.
CCPUS :-
In order to minimize transient over voltages on cables, ccpu units are installed at insulated joints or at either cross bonded section. Ccpu’s shall be protected from moisture in a suitable case shall be enclosed in the water light link boxes.
Megger Test Equipment