220 xlpe under ground cable

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



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



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



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



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



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



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


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


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


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


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


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)


Thermal resistance T2=0


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


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


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


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


b) 76/132 kV,1200mm2:

Emin=U 0

0 .5 Di Ln（Di /D ci）=

3.21kV/mm


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


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

http://wapedia.mobi/en/Lightning

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

220 xlpe under ground cable

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