17190068 Catalogue of EHV Cables

COMPANY

PROFILE

Universal Cables Limited (UCL) was established in the year 1962 as a modern mass production unit for the manufacture of paper insulated power cables in technical collaboration with the world's largest cable producer BICC, UK. Late Shri. M. P. Birla, who had adorned the chair of the company from the day of its inception for over 25 years enabled the company to flourish in a highly competitive world, while distinguishing itself by the latest technological tie ups with the foremost leaders in the world of this industry and the most up-to-date technology.

Universal Cables Limited entered into a collaboration agreement with M/s. ASEA BROWN BOVERI CABLE AB of Sweden in the year 1977 for the manufacture of Crosslinked Polythene Power Cable for the first time in the country. The Company is the foremost manufacturer of XLPE Cable with modern dry cured dry cooled process for voltage range extending from 1.1 kv to Extra High Voltage.

Under the collaboration agreement of M/s ASEA BROWN BOVERI CABLE AB, Sweden, UCL brought in complete know how of compounding of Polymer and produced complete range of dielectrics presently used in all special cables.

UCL emphasizes on in-house Research & Development. R & D programme is mainly directed to applied research for product development, process development and technological upgradation. R & D Laboratory of UCL is a recognized unit of Department of Scientific and Industrial Research of Govt. of India. This Laboratory has developed many new Cables for

special applications such as Flamuni range FRLS Cable, 1.1kv XLPE Cable, etc.

In 1983, UCL embarked on a joint venture with MPAVN for manufacture of Jelly Filled Telephone Cable in technical collaboration with one of the world's leading manufacturers of Telephone Cable, M/s Ericsson Cable AB of Sweden. This unit is named M/s. VINDHYA TELELINKS LIMITED and is situated at Rewa, only 50 KM away from the Power Cable Plant at Satna.

Since 1985, M/s. ASEA BROWN BOVERI CABLE AB, SWEDEN is further assisting this company in manufacture of Fluoro-plastic Cables, specifically for very high temperature operation and high frequency signalling circuitry.

In 1993, UCL & VTL jointly entered into the field of optical communication by way of manufacturing Optical Fibre Cables in technical and financial collaboration with M/s Ericsson Cables AB of Sweden under the name M/s BIRLA ERICSSON OPTICAL LIMITED (BEOL).

UCL also exports its products to various countries of the world, which has earned much recognition for its export efforts.

M/s. Universal Cables Limited is a vibrant progressive company, a leader in its field of activities, serving the aspiration of the nation in the field of Power Development.

1.0 INTRODUCTION:

After a decade of satisfactory experience in the manufacture of high voltage XLPE cables and intensive R&D, Unistar XLPE cables range now includes Extra High Voltage XLPE cables. They are suited to withstand a service voltage range from 66 KV upto and including 145 KV.

This marks a quantum jump both in respect of manufacturing technology and quality assurance techniques. This development has been possible because of very active all round support from our technical collaborator ASEA BROWN BOVERI CABLES AB, of Sweden-acknowledged world leaders in development and manufacture of Extra High Voltage XLPE cables. The manufacturing plant and testing laboratories of the company have been upgraded with large capital investment to adopt the technology.

'Unistar' EHV XLPE cables are designed for bulk trans-mission of electrical energy with minimum transmission losses for an effective service life of 50 years or more.

2.0 CABLE DESIGN:

2.1 Conductor: Conductor is made of stranded copper or aluminium having high compactness and smooth surface finish. 2.2 Conductor Shield: This is applied over the conductor with a semi-conducting compound which not only eliminates the risk of electrical discharge at the interface between conductor and insulation but also presents a very smooth protrusion free interface with the insulation to eliminate any localised stress concentration. 2.3 Insulation: Insulation is composed of a special super-clean grade of crosslinkable polythene and applied over the conductor screen to the desired thickness in a void free manner. 2.4 Core Screen: A semi-conducting layer similar to conductor screen is applied over the insulation for similar purpose and this is followed by a semi-conducting non-woven water barrier tape when required. Over this tape metallic part of the screen is applied in the form of spiral wrapping of copper wires. When the cable is installed in water-logged area or underwater, metallic part of the screen is often impervious metal sheath in place of copper wires. 2.5 Outer sheath for unarmoured cables: This is composed of ST-2 grade PVC to IS: 5831/84/ IEC-840 or black polythene with PE/AL moisture barrier tape depending upon the installation condition. 2.6 Armoured Cables: If required by installation conditions, further protection of on-ferrous metal wire armouring and extruded PVC sheath may be applied.

2.7 Conductive outer layer: A conductive outer layer facilitates testing of the non-metallic outer sheath. This test is important to ensure the physical integrity of the cable from time to time, be it at the factory, after transportation, directly after laying upon completion of the installation, or periodically thereafter. The construction details of three designs of EHV XLPE cables are shown in figure 1 to 3:

Fig. 1 Copper Wire screen, standard design:

Fig. 2 Copper Wire screen, water tight design:

(i) Radial water sealing is achieved by a corrosion resistant metal polyethylene laminate.

(ii) Longitudinal water sealing is achieved by a water swellable tape applied over the copper wire.

Fig. 3 Lead sheath screen: (i) Radial water sealing is achieved by a corrosion resistant-lead sheath.

(ii) Longitudinal water sealing is achieved by a water swellable tape applied under sheath.

3.0 CONSTRUCTION:

Construction details of Unistar EHVXLPE cables are given in tables 1 to 3.

4.0 TECHNICAL PARAMETERS:

Technical parameters of Unistar EHV XLPE cables are given in tables 4 to 8.

5.0 PROCESSING:

Unistar EHV XLPE cables are processed in a modern triple extrusion manufacturing line with 'ASEA' dry cure and dry cooling arrangement. The material handling system is completely mechanised and the plant is air-pressurised with clean air to avoid any contamination. The processing parameters are determined by computer programming and the entire line of processing is controlled, from a central control console with the help of closed circuit TV.

Fig. 4 Catenary continuous vulcanizing extrusion line. 6.0 TESTING & QUALITY ASSURANCE:

Unistar EHV XLPE cables are tested to IEC 840, SS 4241417 and IS - 7098 (III) for routine and type tests. Besides this EHV XLPE cable samples are subjected to long term evaluation testing programme and accelerating ageing for verifying the compliance to the expected designed life.

The Quality Control of EHV XLPE cables during manufacture is very critical and expert supervision is required for raw material testing, in process checks and also for final

Fig. 5. The products are supported by qualified research and development.

testing. A specially trained quality assurance team works round the clock for maintenance of the quality at an optimum level.

The Quality of Unistar EHV XLPE cable also has been verified by independent testing at Central Power Research Institute, Bangalore.

7.0 INSTALLATION & ACCESSORIES:

Service Engineers of the company have been specially trained for installation of EHV XLPE cables together with suitable accessories and they provide all assistance to the customers for this purpose. Accessories for indoor and outdoor termination and also for straight through joint, are being supplied by KABELDON AB of Sweden - a subsidiary company of our collaborator ABB Cables AB. Details of accessories and their installation instructions are available on request.

The Company also accepts complete turn-key jobs for the supply installation, testing and commissioning of EHV XLPE Cables.

Fig. 6. Outdoor termination.

Fig. 7. We can help you to install a maintenance-free cable network. 8.0 TECHNICAL SERVICE:

A team of trained service Engineers will be happy to assist the customers for selection of EHVXLPE cables of the right design and accessories needed for the intended application. They will also provide all necessary after-sales service.

TABLE-1 SINGLE CORE CABLES – 66 KV

Approx Wt/KM Area

(sq. mm.)

Approx. Conductor Diameter

(mm)

Insulation Thickness

(mm)

Screen Area

(sq. mm)

Outer Sheath

Thickness (mm)

Approx. Overall

Diameter (mm)

With Al. Conductor

(Kg)

With Cu. Conductor

(Kg)

185 240 300 400 500 630 800 1000

16.2 18.6 20.6 23.6 26.7 30.2 35.0 38.5

12.0 12.0 12.0 12.0 12.0 12.0 12.0 12.0

35 35 35 35 35 35 35 35

2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2

53.0 56.0 58.0 61.0 65.0 69.0 76.0 79.0

2450 2750 3000 3450 3900 4450 5400 6100

3500 4100 4700 5650 6600 8000

-- --

TABLE-2

SINGLE CORE CABLES – 110 KV

Approx Wt/KM Area

(sq. mm.)


(mm)


(mm)

Screen Area

(sq. mm)

Outer Sheath

Thickness (mm)

Approx. Overall

Diameter (mm)

With Al. Conductor

(Kg)

With Cu. Conductor

(Kg)

400 500 630 800 1000

23.6 26.7 30.2 35.0 38.5

17.5 17.0 16.5 16.0 16.0

95 95 95 95 95

3.2 3.3 3.4 3.4 3.6

75.0 78.0 80.0 86.0 90.0

5050 5400 5950 6900 7650

7200 8150 9500

-- --

TABLE-3

SINGLE CORE CABLES – 132 KV

Approx Wt/KM Area

(sq. mm.)


(mm)


(mm)

Screen Area

(sq. mm)

Outer Sheath

Thickness (mm)

Approx. Overall

Diameter (mm)

With Al. Conductor

(Kg)

With Cu. Conductor

(Kg)

400 500 630 800 1000

23.6 26.7 30.2 35.0 38.5

21.0 20.0 20.0 19.0 19.0

95 95 95 95 95

3.5 3.5 3.6 3.6 3.8

80.0 84.0 87.0 95.0 98.0

5800 6100 6750 7600 8400

7950 8800 10300

-- --

TABLE-4

CONDUCTOR RESISTANCE

Maximum D. C. Resistance at 20ºC (Ohm/KM) Cross Section (Sq. mm) Aluminium Copper

165 240 300 400 500 630 800 1000

0.164 0.125 0.100

0.0778 0.0605 0.0469 0.0367 0.0291

0.0991 0.0754 0.0601 0.0470 0.0366 0.0283 0.0221 0.0176

TABLE-5 APPROXIMATE CAPACITANCE (uF/KM)

Rated Voltage of the Cable Area (Sq. mm) 66 KV 110 KV 132 KV

185 240 300 400 500 630 800 1000

0.16 0.18 0.19 0.21 0.23 0.25 0.28 0.30

- - -

0.16 0.18 0.20 0.23 0.24

- - -

0.15 0.16 0.18 0.20 0.21

TABLE-6 APPROXIMATE INDUCTANCE FOR SINGLE CORE CABLES

LAID IN TREFOIL FORMATION (mH/KM)


185 240 300 400 500 630 800 1000

0.42 0.40 0.39 0.38 0.36 0.35 0.34 0.33

- - -

0.41 0.40 0.38 0.37 0.36

- - -

0.43 0.41 0.40 0.38 0.37

TABLE-7

APPROXIMATE DIELECTRIC LOSSES, WATT/KM/PHASE, AT RATED VOLTAGE


185 240 300 400 500 630 800 1000

73 82 86 95

104 113 127 136

- - -

203 228 253 291 304

- - -

272 290 326 363 381

TABLE-8 APPROXIMATE CHARGING CURRENT, AMPS/KM, AT RATED VOLTAGE


185 240 300 400 500 630 800 1000

1.9 2.1 2.3 2.5 2.7 3.0 3.3 3.6

- - -

3.2 3.6 4.0 4.6 4.8

- - -

3.6 3.8 4.3 4.8 5.0

SCREEN BONDING METHODS

BOTH-ENDS BONDING Both-ends bonding of screens, means that the screens are connected and earthed at both ends of the cable route. In this case a current will appear in the screen. This will cause losses in the screen, which reduces the cable current-carrying capacity. These losses are smaller for cables in trefoil formation than in flat formation.

SINGLE-POINT BONDING Single-point bonding of screens, means that the screens are connected and earthed only at one end of the cable route. In this case, a voltage will be induced between screen and earth, but no current will appear. This induced voltage is proportional to the cable length and current. Single-point bonding can only be used for limited route lengths.

CROSS-BONDING Cross-bonding of screens, means that the screens belonging to adjoining cables are connected as in the figure.

In this case, a voltage will be induced between screen and earth, but no current will appear. The maximum induced voltage will appear at the link boxes for cross-bonding, see figure. This method permits a cable current-carrying capacity as high as with single-point bonding but longer route lengths than the latter. It requires screen separation and additional link boxes, though. CURRENT RATING

The cables should at least have a cross section adequate to meet the system requirements for power transmission capacity. The evaluation of the overall cost of a cable system should include the capitalized cost of losses, both on load and no load losses. Since the cost of losses is normally evaluated based on the marginal cost of energy and installed power, overall optimization may often lead to using larger cable cross sections than the minimum ones meeting current carrying requirements.

On load losses are basically the ohmic losses in the conductor and the metallic screen. The XLPE cables can be loaded continuously to a conductor temp, of 90°C. However, to keep a safety margin, or to keep the losses lower, or to avoid possible thermal instability due to drying out the surrounding soil, it may be advantageous to limit the operating temp, to, say, 65°C. No load losses are basically the dielectric losses. Here it is the choice of dielectric material that counts, especially for application at 100 KV or more. Thanks to its small loss angle, XLPE presents much lower dielectric losses than paper or rubber as cable insulation material. The continuous current ratings given in tables 9 to 12 are calculated according to IEC Publ. 287 on the following conditions. Ground temp. : 30°C

Ambient air temp. : 40°C

Depth of laying (L) :1.0Mtr.

Distance between cable axes

laid in flat formation (S) : 70 mm + De

Thermal resistivity of soil : 150 °C cm/Watt.

TABLE-9 CURRENT RATING FOR 66 KV CABLES WITH ALUMINIUM CONDUCTOR

Cross

Section Cables in Ground Cables in Air

Flat Formation Trefoil Formation Flat Formation Trefoil Formation Cond-uctor

Screen SPB / CB Both Ends SPB / CB Both Ends SPB / CB Both Ends SPB / CB Both Ends

Sq. mm

Sq. mm. 65ºC 90ºC 65ºC 90ºC 65ºC 90ºC 65ºC 90ºC 65ºC 90ºC 65ºC 90ºC 65ºC 90ºC 65ºC 90ºC

185 240 300 400 500 630 800

1000

35 35 35 35 35 35 35 35

235 275 310 355 405 460 525 590

300 350 395 450 515 590 665 745

220 250 280 310 345 380 415 445

280 320 360 400 445 490 545 585

225 260 295 335 385 440 495 545

285 330 375 430 490 560 630 700

225 260 290 330 380 430 485 530

285 330 370 420 485 545 615 685

305 360 415 480 555 650 745 850

410 485 555 645 755 880 10101160

295 335 385 440 505 575 650 720

395 460 525 610 695 795 905 1010

290 340 390 455 525 610 700 785

395 460 525 620 715 830 950 1075

290 340 390 450 520 600 685 770

395 460 525 610 710 820 935 1055

TABLE-10 CURRENT RATING FOR 66 KV CABLES WITH COPPER CONDUCTOR

Cross Section Cables in Ground Cables in Air

Flat Formation Trefoil Formation Flat Formation Trefoil Formation Cond-uctor Screen SPB / CB Both Ends SPB / CB Both Ends SPB / CB Both Ends SPB / CB Both Ends Sq. mm


165 240 300 400 500 630

35 35 35 35 35 35

305 350 395 450 515 580

385 445 505 575 650 740

275 305 335 370 405 435

350 395 435 480 525 570

290 335 375 425 485 545

370 425 480 540 615 595

290 335 370 420 475 530

365 420 475 535 605 675

390 455 525 610 710 815

525 620 715 820 960

1110

365 420 475 535 610 685

500 580 655 740 845 950

375 435 500 575 660 755

505 595 680 780 905

1035

370 430 495 565 650 735

505 590 670 770 890

1015

TABLE-11 CURRENT RATING FOR 110 KV & 132 KV CABLES WITH ALUMINIUN CONDUCTOR

Cross Section Cables in Ground Cables in Air



400 500 630 800

1000

95 95 95 95 95

350 400 455 520 570

445 510 580 665 735

275 300 320 345 360

360 390 420 450 480

335 380 430 490 540

420 485 550 620 690

325 365 415 460 505

415 470 525 590 650

480 555 645 765 845

645 750 875 995

1145

425 475 530 585 645

580 650 735 810 900

450 525 605 690 775

610 705 815 935

1060

440 510 580 660 735

600 690 795 905

1015

TABLE-12 CURRENT RATING FOR 110 KV & 132 KV CABLES WITH COPPER CONDUCTOR

Cross

Section Cables in Ground Cables in Air



400 500 630

95 95 95

445 505 570

560 645 730

320 335 360

415 440 470

420 475 535

535 610 685

405 445 500

515 580 645

610 705 810

815 950

1095

505 555 610

695 775 860

570 655 745

770 890

1020

550 625 710

750 915 975

RATING FACTORS

1. RATING FACTOR FOR CROSS SECTION OF METAL SCREEN: Single core cables in Trefoil Formation, Screen Bonded at Both Ends. For Singe Point Bonding or Crossbonding no rating factor applies. 1.1 Rating Factor for 66 KV Cables:

Conductor Sq. mm. Copper Screen Sq. mm. Al. Cu. 16 35 50 95 150 300

300 500 800

1000

185 300 500 630

1.01 1.01 1.02 1.02

1 1 1 1

0.99 0.99 0.99 0.98

0.98 0.97 0.92 0.94

0.97 0.95 0.92 0.90

0.95 0.92 0.88 0.84

1.2 Rating Factor for 66 KV Cables:

Conductor Sq. mm. Copper Screen Sq. mm. Al. Cu. 16 35 50 95 150 300

300 500 800

1000

- 300 500 630

1.03 1.04 1.06 1.08

1.02 1.03 1.04 1.06

1.01 1.02 1.03 1.04

1 1 1 1

0.99 0.98 0.97 0.96

0.97 0.95 0.92 0.90

2. RATING FACTORS FOR CABLES IN GROUND: 2.1 Rating Factor for Depth of Laying:

Depth (Metre) 0.5 0.7 0.9 1.0 1.2 1.5 Rating Factor 1.10 1.05 1.01 1.0 0.98 0.95

2.2 Rating Factor for Thermal Resistivity of Soil:

Thermal Resistivity (ºC cm/Watt) 70 100 120 150 200 250 300

Rating Factor 1.35 1.19 1.10 1.0 0.88 0.80 0.72 2.3 Rating Factor for Ground Temp.:

Ground Temperature ºC Conductor Temp ºC 10 15 20 25 30 35 40 45

90 65

1.15 1.26

1.12 1.20

1.08 1.13

1.04 1.07

1.0 1.0

0.96 0.93

0.91 0.85

0.86 0.76

2.4 Rating Factor for Groups of Cable in Ground:

Number of Groups Distance cc Between

groups (mm) 1 2 3 4 5 6 7 8 9

100

200

400

600

800

2000

1

1

1

1

1

1

0.76

0.81

0.85

0.88

0.90

0.96

0.67

0.71

0.77

0.81

0.84

0.93

0.59

0.65

0.72

0.77

0.81

0.92

0.55

0.61

0.69

0.74

0.79

0.91

0.49

0.56

0.64

0.71

0.76

0.91

0.49

0.56

0.66

0.72

0.77

0.91

0.47

0.53

0.63

0.70

0.75

0.90

0.46

0.52

0.62

0.69

0.75

0.90

2.5 Rating Factors for Phase Spacing (one group in Flat Formation with Cross Bonded or Single Bonded Screen):

Spacing ‘S’ mm De De + 70 200 250 300 350 400

Rating Factor 0.93 1 1.03 1.05 1.07 1.06 1.10

3. RATING FACTOR FOR CABLES INSTALLED IN PIPES IN THE GROUND Single Core Cables partially installed

in separate Pipes* Single Core Cables in separate

Pipes. Single Core Cables in a common

Pipe.

0.94 0.90 0.90 The rating factor given for single core cables partially installed in separate pipes, applies only when a cable section between screen earthing points are partially laid in pipes under the following conditions - The cables are laid in trefoil formation over the major portion of the section - The pipes are laid in fiat formation - The pipe length is not more than 10% of the section between earthing points - One cable per Pipe - The Pipe diameter is two times the cable diameter. 4. RATING FACTOR FOR CABLES IN THE AIR: 4.1 Rating Factor for ambient air temp:

Air Temp ºC 15 20 25 30 35 40 45 50 55

Rating Factor 1.25 1.21 1.16 1.11 1.05 1.0 0.94 0.87 0.81 OVER LOAD 105°C As infrequently as possible, the cables may be overloaded and the conductor temp. may reach upto 105ºC. Both occurrence and duration of these overloads should be kept to a minimum, though, in the interests of sparing the cable life Cyclic and emergency rating can be calculated through IEC: 833-2 EMERGENCY LOAD 130°C Upon emergency, the conductor temperature is allowed to rise upto 130°C However the duration of the emergency load should be restricted to not more that 50 Hours at a time and 500 Hours per year in order not to shorten the cable life substantially SHORT-CIRCUIT CURRENTS The permissible short-circuit current of a cable is determined by the maximum permissible conductor temperature (250°C), and by the duration of the short-circuit current At high peak currents the dynamic forces between the conductors must be taken into account Thermally maximum short-circuit currents Formula to calculate the thermally equivalent short-circuit current at different durations Where Ik = I1/tk Where Ik = short-circuit current during time tk

I1 = short-circuit current for 1 s from Tables 13 and 14 tk = short-circuit durations.

This formula is valid only in the time interval 0.2 - 5s.

TABLE-13

Max. Short-Circuit on the conductor during 1s. kA Conductor Temperature before Short Circuit

Aluminium Conductor Copper Conductor Cross Section

Mm2 65ºC 90ºC 65ºC 90ºC

185 240 300 400 500 630 800

1000

19.2 24.8 31.1 41.4 51.8 65.2 82.8 104

17.5 22.7 28.3 37.8 47.2 59.5 75.6 94.5

29.0 37.6 47.0 62.7 78.4 98.7 125 157

26.5 34.5 42.9 57.2 71.5 90.1 114 143

TABLE-14

Max. Short-Circuit on the Screen during 1s. kA

Metallic Screen Cross Section mm2 Metallic Screen Temperature before the Short Circuit

Copper Screen Lead Sheath 50ºC 70ºC

16 25 35 50 95

150 300

110 170 240 340 650 1030 2070

3.4 5.4 7.5 11 21 32 64

3.3 5.1 7.1 10 19 30 60

Tablet 13 and 14 are based on the following formula

Mechanical forces from short-circuit currents Formula to calculate the dynamic forces between two conductors F = 0.2 x is2 S Where is = peak current, kA

S = centre – to - centre spacing between conductors, m F = force N/m

Note : All figures given are non-binding and indicative only

Where I = maximum short-circuit current, A i = current density. A/mm2, 1s S = conductor or screen cross section, mm2

t = duration of short-circuit current, s E = 1 0 for conductor = 1 2 typical for metal screens K = 148 for Al, 226 for Cu and 41 for Pb B = 228 for Al. 234 for Cu and 230 for Pb ot = final temperature, ºC oi = initial temperature ºC

17190068 Catalogue of EHV Cables

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