Medium Voltage Cables
Medium Voltage Cables to BS 6622 Medium Voltage Cables to IEC 60502 Medium Voltage Cables to VDE 0276

Medium Voltage Cables to IEC 60502

Three Core Cables to IEC 60502

Application

The three core cables are designed for distribution of electrical power with nominal voltage Uo/U ranging from

1.8/3KV to 26/35KV and frequency 50Hz. They are suitable for installation mostly in power supply stations,

indoors and in cable ducts, outdoors, underground and in water as well as for installation on cable trays for

industries, switchboards and power stations.

Standards

IEC 60502 Part 1(1.8/3KV)

IEC 60502 Part 2(3.6/6KV to 18/30KV)

Construction

Conductor: Plain annealed copper or aluminium complying with IEC 60228 class 1 or 2.

Conductor Screen:

The conductor screen consists of an extruded layer of non metallic, semi-conducting compound applied on top of

a semi-conducting tape. The conductor screen is applied under triple extrusion process over the conductor along

with the insulation and the insulation screen. The extruded semi-conducting compound is firmly bonded to the

insulation to exclude all air voids and can be easily hand stripped on site. The conductor screen is not necessary

for both PVC and EPR/HEPR insulated 1.8/3.6KV and 3.6/6KV cables.

Insulation:

Insulation is of polyvinyl chloride (PVC) intended for 1.8/3.6KV and 3.6/6KV cables, cross-linked polyethylene

compound (XLPE) or ethylene propylene rubber (EPR/ HEPR).

Table 1. Insulation Thickness Of XLPE Or EPR/HEPR Insulation

Nom. Cross
Section Area
  Insulation Thickness at Nom. Voltage
1.8/3kV
(Um=3.6)kV
3.6/6kV
(Um=7.2)kV
6/10KV
(Um=12KV)
8.7/15KV
(Um=17KV)
12/20KV
(Um=24KV)
18/30KV
(Um=36KV)
mm² mm mm mm mm mm mm
  XLPE/EPR XLPE EPR XLPE/EPR XLPE/EPR XLPE/EPR XLPE/EPR
  Unscr
eened
Scre
ened
10 2.0 2.5 3.0 2.5 - - - -
16 2.0 2.5 3.0 2.5 3.4 - - -
25 2.0 2.5 3.0 2.5 3.4 4.5 - -
35 2.0 2.5 3.0 2.5 3.4 4.5 5.5 -
50 – 185 2.0 2.5 3.0 2.5 3.4 4.5 5.5 8.0
240 2.0 2.6 3.0 2.6 3.4 4.5 5.5 8.0
300 2.0 2.8 3.0 2.8 3.4 4.5 5.5 8.0
400 2.0 3.0 3.0 3.0 3.4 4.5 5.5 8.0
500 - 1600 2.2-2.8 3.2 3.2 3.2 3.4 4.5 5.5 8.0

Insulaton Screen:

The insulation screen consists of an extruded layer of non metallic, semi-conducting compound extruded over

the insulation of each core. The extruded semi- conducting layer shall consist of bonded or cold strippable semi-

conducting compound capable of removal for jointing or terminating. As an option, a semi-conducting tape may

be applied over the individual cores or core assembly as a bedding for the metallic layer. The minimum thickness

is 0.3 mm and the maximum resistivity is 500 Ohm-m at 90°C. The screen is tightly fitted to the insulation to

exclude all air voids and can be easily hand stripped on site. The insulation screen is not necessary for both PVC

and EPR/HEPR insulated 1.8/3.6KV and 3.6/6KV cables. The screen may be covered by semi-conductive water

blocking swellable tape to ensure longitudinal watertightness.

Inner Covering & Fillers:

For cables with a collective metallic layer or cables with a metallic layer over each individual cores with additional

collective metallic layers, semi-conducting inner covering and fillers shall be applied over the laid up cores. The

inner covering and fillers are made of non hygroscopic material like polypropylene, except if the cable is to be

made longitudinally watertight. The inner covering is extruded in general but may be lapped if the interstices

between the cores are filled.

The approximate thickness of extruded inner coverings is given in Table 2:

Table 2. Approximate Thickness Of Extruded Inner Coverings

Ficititous Diameter Over Laid Up Cores

Approx. Thickress of Extruded Inner Covering

mm mm
>  <   
- 25 1.0
25 35 1.2
35 45 1.4
45 60 1.6
60 80 1.8
80 - 2.0

*The approximate thickness of lapped inner coverings shall be 0.4mm for fictitious diameters over the laid up

cores up to and including 40mm and 0.6mm for larger diameter.

Metallic Layer: The concentric copper screen wire is applied over the insulation, or over the insulation screen or over an inner covering. As an alternative, copper tape(s) with minimum thickness of 0.1mm can be applied with overlap. Total cross section of copper wire screen and copper tape screen layer are shown in Table 3a and 3b.


Table 3a. Total Cross Section and Max. DC Resistance of Copper Wire Screen

Nom. Cross Section Area of Conductor

Total Cross Section

 

Max. DC Resistance at 20℃

3.6/6KV (Um=7.2KV)

6/10KV (Um=12KV)

8.7/15KV (Um=17KV)

12/20KV (Um=24KV)

18/30KV (Um=36KV)

mm²

mm

mm

mm

mm

mm

Ω

10

10

-

-

-

-

1.075

16

16

16

-

-

-

1.075

25

16

16

16

16

-

1.075

35

16

16

16

16

-

1.075

50

16

16

16

16

16

1.075

70

16

16

16

16

16

1.075

95

16

16

16

16

16

1.075

120

16

16

16

16

16

1.075

150

25

25

25

25

25

0.688

185

25

25

25

25

25

0.688

240

25

25

25

25

25

0.688

300

25

25

25

25

25

0.688

400

35

35

35

35

35

0.491

500

35

35

35

35

35

0.491

630

35

35

35

35

35

0.491

Table 3b. Total Cross Section and Max. DC Resistance of Copper Tape Screen (0.1mm)

Nom. Cross Section Area of Conductor

Total Cross Section & Max. DC Resistance

3.6/6KV (Um=7.2KV)

6/10KV (Um=12KV)

8.7/15KV (Um=17KV)

12/20KV (Um=24KV)

18/30KV (Um=36KV)

 

Total Cross Section

Max. DC
Resistance at 20℃

Total Cross Section

Max. DC
Resistance at 20℃

Total Cross Section

Max. DC
Resistance at 20℃

Total Cross Section

Max. DC
Resistance at 20℃

Total Cross Section

Max. DC
Resistance at 20℃

mm²

mm

Ω

mm

Ω

mm

Ω

mm

Ω

mm

Ω

10

4.2

4.122

-

 

-

 

-

 

-

-

16

4.6

3.778

5.20

3.306

-

 

-

 

-

-

25

5.0

3.420

5.68

3.029

6.47

2.657

7.2

2.390

-

-

35

5.4

3.161

6.09

2.824

6.89

2.498

7.6

2.261

-

-

50

5.9

2.903

6.58

2.616

7.37

2.334

8.1

2.125

9.9

1.738

70

6.6

2.616

7.23

2.380

8.02

2.145

8.7

1.967

10.5

1.630

95

7.3

2.369

7.91

2.174

8.71

1.975

9.4

1.824

11.2

1.531

120

8.0

2.153

8.64

1.991

9.43

1.823

10.2

1.694

12.0

1.438

150

8.5

2.013

9.19

1.871

9.99

1.722

10.7

1.606

12.5

1.374

185

9.4

1.838

9.88

1.741

10.82

1.590

11.4

1.509

13.2

1.303

240

10.4

1.656

10.96

1.569

11.76

1.463

12.5

1.378

14.3

1.204

300

11.4

1.508

11.84

1.452

12.64

1.361

13.4

1.287

15.2

1.134

400

12.6

1.362

12.92

1.332

13.71

1.254

14.4

1.192

16.2

1.059

500

13.9

1.237

14.34

1.199

15.14

1.136

15.5

1.110

17.7

0.974

630

15.3

1.121

16.68

1.031

16.57

1.038

17.3

0.995

19.1

0.901

Separation Sheath (for armoured cable):

The separation sheath comprises a layer of extruded PVC, PE or  LSZH applied over the laid up cores under the

armour. PVC is normally of grade ST2 and PE of grade ST7. The nominal thickness is calculated by 0.02Du +

0.6mm where Du is the fictitious diameter under the sheath in mm. For cables without a lead sheath, the

nominal separation sheath thickness shall not be less than 1.2mm. For cables where the separation sheath is

applied over the lead sheath, the nominal separation sheath thickness shall not be less than 1.0mm.

Tabel 4. Separation Thickness

Cores Diameter Approx. Thickress of
Inner Sheath
mm mm
>  <   
35 45 1.4
45 60 1.6
60 80 1.8
80 - 2.0

Lapped Bedding (for armoured lead sheathed cable):

The lapped bedding applied to the lead sheath consists of either impregnated/synthetic compounded paper

tapes or a combination of two layers of these paper tapes followed by a few layers of compounded fabulous

materials. The thickness is around 1.5mm.

Armour (for armoured cable):

The armour is applied over the inner covering helically. It consists of either flat galvanized steel wire armour

(strip), round galvanized steel wire armour, and double steel tape armour.

Table 5. Round Armour Wire Diameter

Fictitious Diameter Under the Armour Armour Wire Diameter
mm mm
>  <   
- 10 1.25
10 15 1.25
15 25 1.6
25 35 2.0
35 60 2.5
60 - 3.15

Table 6. Armour Tape Thickness

Fictitious Diameter Under the Armour Galvanized Steel / Steel Aluminum / Aluminium Alloy
mm mm mm
>  <     
- 30 0.2 0.5
30 70 0.5 0.5
70 - 0.8 0.8

For flat wire armour and fictitious diameter under the armour greater than 15mm, the nominal thickness of the

flat steel wire diameter shall be 0.8mm.Cables with fictitious diameter under the armour up to and including

15mm, flat wire armour will not be used. The tape armour is applied helically in two layers so that the outer tape

is approximately central over the gap of the inner tape. If tape armour is used, the inner covering shall be

reinforced by taped bedding.

Over Sheath:

Overall sheath comprises a layer of extruded either thermoplastic compound (PVC ST3 type or PE ST7 type) or

elastomeric compound (polychlorprene CSP or chlorosulfonated PE). The nominal oversheath thickness is

calculated by 0.035D+1 where D is the fictitiuous diameter immediately under the oversheath in mm. For

unarmoured cables and cables with the oversheath not applied over the armour, metallic screen or concentric

conductor, the nominal oversheath thickness shall not be less than 1.4mm. And for cables with oversheath

applied over the armour, metallic screen or concentric conductor, the nominal oversheath thickness shall not be

less than 1.8mm.

PHYSICAL PROPERTIES:

Operating Temperature: up to 70°C (PVC insulation); up to 90°C (XLPE or EPR insulation)

Temperature Range: -5°C ( PVC sheath ); -20°C ( PE sheath )

Short Circuit Temperature( 5 seconds maximum duration ): 140-160 °C (PVC insulation);

250°C (XLPE or EPR insulation)

Bending Radius: 15 x OD
Table 7. Nominal /Operating /Testing Voltages

Rated Voltage Uo/U Operating Voltage (Um) Testing Voltage (rms)
1.8/3KV 3.6KV 6.5KV
3.6/6KV 7.2KV 12.5KV
6/10KV 12KV 21KV
8.7/15KV 17.5KV 30.5KV
12/20KV 24KV 42KV
18/30KV 36KV 63KV

*21/35KV and 26/35kV power frequency voltage test can be made under the following conditions: 2.5Uo x

30mins or 3.0Uo x 15mins. Numbers in brackets refer to the test values for 3.0Uo x 1.5mins.

Three Core 1.8/3KV (Um=3.6KV) Dimensional Data

 

 

Unarmoured Cables

Steel Round-Wire Armoured Cables

Nom. Cross- Section Area

Nom. Insulation Thickness

Nom. Sheath Thickness

Approx. Overall Diameter

Approx. Weight

Nom. Bedding Thickness

Armour Wire Size

Nom. Sheath Thickness

Approx. Overall Diameter

Approx. Weight

CU

AL

CU

AL

mm²

mm

mm

mm

kg/km

mm

mm

mm

mm

kg/km

10

2.0

1.8

23

650

460

1.2

1.6

1.8

28

1480

1290

16

2.0

1.8

24

840

540

1.2

1.6

1.9

29

1720

1410

25

2.0

1.8

26

1160

680

1.2

1.6

1.9

32

2130

1650

35

2.0

1.8

29

1490

820

1.2

2.0

2.1

36

2810

2140

50

2.0

1.9

32

1900

1000

1.2

2.0

2.2

39

3340

2450

70

2.0

2.0

36

2580

1290

1.2

2.0

2.3

42

4200

2910

95

2.0

2.2

40

3440

1640

1.3

2.5

2.4

47

5620

3820

120

2.0

2.3

43

4220

1950

1.3

2.5

2.5

51

6580

4310

150

2.0

2.4

46

5090

2290

1.4

2.5

2.7

54

7680

4870

185

2.0

2.5

50

6240

2730

1.5

2.5

2.8

58

9060

5560

240

2.0

2.7

56

8030

3430

1.6

2.5

3.0

64

11200

6600

300

2.0

2.8

60

9890

4100

1.6

2.5

3.1

69

13590

7500

400

2.0

3.1

68

12530

5150

1.8

3.15

3.4

78

17260

9880

500

2.2

3.3

75.7

16680

7510

1.8

3.15

3.5

84.3

21780

13025

630

2.4

3.5

84.9

21770

10040

1.8

3.15

3.8

94.6

27400

16050

 

Steel Flat Wire Armoured Cables

Double Steel Tape Armoured Cables

Nom. Cross- Section Area

 

Nom. Bedding Thickness

 

Armour Wire Size

 

Nom.Sheath Thickness

 

Approx. Overall Diameter

Approx. Weight

 

Nom. Bedding Thickness

No of Steel Tapes x Nom Tape Thickness

 

Nom. Sheath Thickness

 

Approx. Overall Diameter

Approx. Weight

 

CU

 

AL

 

CU

 

AL

mm²

mm

mm

mm

mm

kg/km

mm

mm

mm

mm

kg/km

10

1.2

0.8

1.8

24.5

1245

1065

1.2

2 x 0.2

1.8

23.6

925

750

16

1.2

0.8

1.8

27.1

1565

1280

1.2

2 x 0.2

1.8

26.2

1205

925

25

1.2

0.8

1.8

29.7

1975

1525

1.2

2 x 0.2

1.9

29.0

1590

1145

35

1.2

0.8

1.9

32.5

2420

1805

1.2

2 x 0.2

1.9

31.6

1985

1370

50

1.2

0.8

2.0

35

2860

2080

1.2

2 x 0.2

2.0

34.1

2400

1605

70

1.2

0.8

2.1

38.7

3685

2525

1.2

2 x 0.5

2.2

39.5

3570

2410

95

1.3

0.8

2.2

42.9

4695

3080

1.3

2 x 0.5

2.3

43.7

4570

2950

120

1.3

0.8

2.3

46.4

5650

3585

1.3

2 x 0.5

2.4

46.1

5510

3440

150

1.4

0.8

2.4

49.6

6630

4085

1.4

2 x 0.5

2.6

50.6

6500

3955

185

1.5

0.8

2.6

54.1

7990

4820

1.5

2 x 0.5

2.7

54.9

7825

4650

240

1.6

0.8

2.7

59.2

10060

5790

1.6

2 x 0.5

2.8

60.0

9825

5600

300

1.6

0.8

2.9

64.6

12230

6865

1.6

2 x0.5

3.0

65.4

12030

6660

400

1.8

0.8

3.1

71.0

15200

8280

1.8

2 x 0.5

3.2

71.8

14970

8055

500

1.8

0.8

3.3

79.5

19090

10255

1.8

2 x 0.8

3.5

80.5

18880

10035

630

1.8

0.8

3.6

89.8

24400

12920

1.8

2 x 0.8

3.8

92.3

25070

13620

Electrical Data

Nom. Cross- Section Area

D C Resistance CU / AL

A C Resistance CU / AL

Short Circuit Rating of Conductor CU / AL
1 sec

Capaci- tance

Charging Current

Reactance

Inductance

mm²

µΩ/m

µΩ/m

kA

pF/m

mA/m

µΩ/m

nH/m

10

1830/3080

2330/3920

1.4/0.9

160

0.25

101

390

16

1150/1910

1460/2420

2.2/1.4

180

0.27

98

370

25

727/1200

929/1538

3.6/2.3

220

0.29

95

350

35

524/868

668/1113

5.0/3.2

250

0.31

92

330

50

387/641

494/822

6.8/4.4

270

0.33

88

310

70

268/443

343/568

9.8/6.3

310

0.35

84

290

95

193/320

248/410

13.3/8.5

350

0.38

81

270

120

153/253

196/325

17.2/11.0

380

0.46

79

250

150

124/206

159/265

21.2/13.5

420

0.50

77

260

185

99/164

128/211

26.6/17.0

460

0.56

76

250

240

75/125

98/161

34.9/22.3

510

0.61

74

240

300

60/100

80/130

43.8/28.0

570

0.68

73

250

400

47/78

64/102

57.3/36.6

590

0.70

71

240

500

37/60

57/81

72.3/46.2

610

0.72

69

230

630

28/47

42/64

91.2/58.3

630

0.74

67

220

Three Core 3.8/6.6KV (Um=7.2KV)
Three Core 6/10KV (Um=12KV)
Three Core  8.7/15KV (Um=17.5KV)
Three Core 12/20KV (Um=24KV)
Three Core 18/30KV (Um=36KV)
Current Rating for Three Core 3.6/6KV(Um=7.2 )KV to 18/30KV(Um=36KV)

Current Rating Conditions:

Ground Temperature: 20°C

Ambient Temperature (air): 30°C

Depth of Soil: 0.8 m

Thermal Resistance of Soil: 1.5K•m/W