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

Single Core Cables to IEC 60502

Application

The single core cables are designed for distribution of electrical power with nominal voltage Uo/U ranging from 1.8/3KV to 18/30KV 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 firmly bonded to the insulation to exclude all air voids. The conductor screen is not necessary for both PVC and EPR/HEPR insulated 1.8/3KV and 3.6/6KV cables.

Insulation: Insulation is of polyvinyl chloride (PVC) intended for 1.8/3KV 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 Nominal Voltage
1.8/3KV
(Um=3.6KV)
3.6/6KV
(Um=7.2KV)
6/10KV
(Um=12KV)
8.7/15KV
(Um=17.5KV)
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
  Unscreened Screened
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

*Insulation Thickness of PVC is 3.4mm (1- 1600mm sq) for 3.6/6KV cables.

Insulaton Screen:

The insulation screen consists of an extruded layer of non metallic, semi- conducting compound extruded over the insulation. 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 extruded semi-conducting layer 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 1.8/3KV and 3.6/6KV cables. The screen may be covered by semi-conductive water blocking swellable tape to ensure longitudinal watertightness.

Metallic Layer:

The metallic layer may be applied over the individual cores or the core assembly collectively.
The following types of metallic layers are provided:
1) Metallic Screen
2) Concentric Conductor
3) Metallic Sheath
4) Metallic armour
The metallic screen shall consist of either copper tapes or a concentric layer of copper wires or a combination of tapes and wires to provide an earth fault current path. The concentric conductor is applied directly either over the insulation, or over the insulation screen or over an inner covering. The metallic sheath consists of lead or lead alloy applied as a tightly fitting seamless tube. The metallic armour consists of either flat wire armour, round wire armour, and double tape armour.

Table 2. Minimum Total Cross Section Of Metallic Screen

Nom. Cross-Section
Area of Cable
Min. Cross-Section of Metallic Screen DC Resistance of the Copper Wire Screen
mm² mm² mm
up to 120 16 1.06
150-300 25 0.72
400-630 35 0.51
800-1000 50 0.35

Separation Sheath (for armoured cable):

The separation sheath comprises a layer of extruded PVC, PE or LSZH, applied under the armour .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.

Lapped Bedding (for armoured lead sheathed cable):

The lapped bedding 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 consists of round aluminium wire armour applied helically over an extruded separation sheath.
Table 3. Round Armour Wire Diameter

Fictitious Diameter Under the Armour Armour Wire Diameter
mm mm
>  <   
- 10 0.8
10 15 1.25
15 25 1.6
25 35 2.0
35 60 2.5
60 - 3.15

Over Sheath:

Overall sheath comprises a layer of extruded thermoplastic compound (PVC, PE or LSZH can be offered as an option.) 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: 20 x OD

Table 4. 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.

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

Nom.
Cross-
Section
Area
  Unarmoured Cables Steel Wire Armoured Cables
Nom.
Insulation
Thickness
Copper
Tape Thickness
Copper Wire Screen
Area*
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 mm² mm mm kg/km mm mm mm mm kg/km
10 2.0 0.1 16 1.8 13 240 180 1.2 1.6 1.8 18 460 400
16 2.0 0.1 16 1.8 13 300 200 1.2 1.6 1.8 19 530 430
25 2.0 0.1 16 1.8 15 410 250 1.2 1.6 1.8 20 650 500
35 2.0 0.1 16 1.8 16 510 300 1.2 1.6 1.8 21 780 560
50 2.0 0.1 16 1.8 17 640 350 1.2 1.6 1.8 22 930 640
70 2.0 0.1 16 1.8 19 850 440 1.2 1.6 1.8 24 1170 750
95 2.0 0.1 16 1.8 20 1130 540 1.2 1.6 1.8 26 1460 870
120 2.0 0.1 16 1.8 22 1370 630 1.2 1.6 1.8 27 1730 990
150 2.0 0.1 25 1.8 23 1650 730 1.2 1.6 1.8 29 2030 1110
185 2.0 0.1 25 1.8 25 2010 860 1.2 1.6 1.9 30 2430 1280
240 2.0 0.1 25 1.8 27 2570 1050 1.2 1.6 2.0 33 3040 1530
300 2.0 0.1 25 1.8 29 3160 1250 1.2 2.0 2.1 36 3760 1860
400 2.0 0.1 35 1.9 33 3980 1560 1.2 2.0 2.2 39 4660 2230
500 2.2 0.1 35 2.1 35.5 4910 1905 1.3 2.5 2.5 43 5930 2930
630 2.4 0.1 35 2.2 39.7 6340 2420 1.4 2.5 2.6 49 7370 3430
800 2.6 0.1 50 2.3 44.5 7890 2980 1.4 2.5 2.7 52 9070 4230
1000 2.8 0.1 50 2.5 49.4 9890 3700 1.5 2.5 2.9 56 11100 4950

*Optional wire screen can be provided in combination of copper tapes. Nominal screen area, as stated in the table, can be supplied as standard.

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 Short
Circuit Rating of Copper
Wire
Screen
1 sec
Short Circuit Rating of Copper Tape Screen
1 sec
Reactance Inductance Impedance
Trefoil Flat
Spaced
Trefoil Flat
Spaced
Trefoil Flat Spaced
cu AL cu AL
mm² µΩ/m µΩm kA pF/m mA/m kA kA µΩ/m nH/m µΩ/ m µΩ/ m
10 1830/3080 2330/3920 1.4/0.9 182 0.27 4.8 8.2 151 201 384 558 2332 3846 2332 3840
16 1150/1910 1460/2420 2.2/1.4 201 0.29 4.8 8.2 140 193 362 546 1462 2411 1478 2420
25 727/1200 927/1538 3.6/2.3 222 0.32 4.8 8.2 131 185 345 535 936 1544 952 1554
35 524/868 668/1113 5.0/3.2 251 0.35 4.8 8.2 122 178 327 524 679 1121 695 1131
50 387/641 494/822 6.8/4.4 281 0.39 4.8 8.2 116 172 313 514 511 834 527 844
70 268/443 343/568 9.8/6.3 341 0.45 4.8 8.2 110 165 300 495 364 583 386 597
95 193/320 248/410 13.3/8.5 397 0.50 4.8 8.2 104 160 287 485 272 427 300 446
120 153/253 196/325 17.2/11.0 430 0.55 4.8 8.2 104 159 283 480 225 345 257 367
150 124/206 159/266 21.2/13.5 464 0.59 4.8 8.2 100 156 280 475 193 287 229 313
185 99.1/164 128/211 26.6/17.0 513 0.65 4.8 8.2 98 154 274 465 165 237 206 267
240 75.4/125 98/161 34.9/22.3 573 0.70 4.8 8.2 94 150 267 459 140 191 185 226
300 60.1/100 80/130 43.8/28.0 652 0.72 4.8 8.2 91 147 260 455 128 163 174 203
400 47.0/77.8 64/102 57.3/36.6 727 0.75 4.8 8.2 90 147 253 445 113 141 164 184
500 36.6/60.5 51/81 72.3/46.2 754 0.79 4.8 8.2 89 145 248 435 105 124 158 171
630 28.3/46.9 42/64 91.2/58.3 786 0.87 4.8 8.2 86 143 245 425 97 110 151 160
800 22.1/36.7 35/55 114.4/75.0 846 0.91 4.8 8.2 85 142 243 415 92 101 147 153
1000 17.6/29.1 30/46 143.0/94.0 916 0.99 4.8 8.2 83 141 239 405 88 95 144 148

Single Core 3.6/6KV (Um=7.2KV)
Single Core 6/10KV (Um=12KV)
Single Core 8.7/15KV (Um=17.5KV)
Single Core 12/20KV (Um=24KV)  
Single Core 18/30KV (Um=36KV)
Single Core 21/35KV (Um=42KV)
Current Rating for Single Core 1.8/3KV(Um=3.6KV ) to 26/35KV(Um=42KV)

Current Rating Conditions:

Ground Temperature: 20°C
Ambient Temperature (air): 30°C
Depth of Soil:
0.8m
Thermal Resistance of Soil: 1.5K•m/W