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  HomeProuductsMedium Voltage Cables

Three Core Cables to BS 6622/BS 7835

APPLICATIONS

The three core cables are designed for distribution of electrical power with nominal voltage Uo/U ranging from 3.6/6.6KV to 19/33KV 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.

STANDARD

  • BS 6622
  • BS 7835 (LSZH Version)

CONSTRUCTION

BS6622/BS7835 Three Core Cables Three Core Cables to BS6622/BS7835 - Medium Voltage Cable
Conductor Plain annealed copper or aluminium complying with IEC 60228/BS 6360. Copper conductors shall be stranded (class 2) and aluminium conductors shall be either solid or stranded (class 2).
Conductor Screen Extruded layer of semi-conducting cross-linkable compound is applied over the conductor and shall cover the surface completely. The minimum thickness is 0.3mm and the maximum resistivity shall not exceed 500 Ohm-m at 90°C.
Insulation Insulation is of cross-linked polyethylene compound XLPE (GP8) conforming to BS 7655-1.3 or EPR (GP7), conforming to BS 7655-1.2.

Table 1. Insulation Thickness

Nom. Cross Section Area Insulation Thickness at Nominal Voltage
3.8/6.6KV (Um=7.2KV) 6.35/11KV (Um=12KV) 8.7/15KV (Um=17.5KV) 12.7/22KV (Um=24KV) 19/33KV (Um=36KV)
mm^2 mm mm mm mm mm
70 – 185 2.5 3.4 4.5 5.5 8.0
240 2.6 3.4 4.5 5.5 8.0
300 2.8 3.4 4.5 5.5 8.0
400 3.0 3.4 4.5 5.5 8.0
Above 500 3.2 3.4 4.5 5.5 8.0

 

Insulaton Screen Extruded layer of semi-conducting cross-linkable compound is applied 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.
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 is made of non hygroscopic material, except if the cable is to be made longitudinally watertight. The inner covering shall be extruded or lapped.

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 0.6mm.

 

Metallic Layer The metallic layer shall be applied over each core or applied as a collective screen. The metallic screen shall consist of either copper tapes or a concentric layer of copper wires or a combination of tapes and wires. The metallic layer provides an earth fault current path, capable of withstanding fault current to earth of 1000A for one second at maximum temperature 160°C. Copper wires are applied over the conducting water blocking layer with a minimum diameter of 0.5mm. 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

Nominal Cross-
Section of Cables		 Total Cross Section Max. DC Resistance of Copper Wire Screen at 20℃
3.8/6.6KV (Um=7.2KV) 6.35/11KV (Um=12KV) 8.7/15KV (Um=17.5KV) 12.7/22KV (Um=24KV) 19/33KV (Um=36KV)
mm² mm² Ω
70 16 16 16 16 16 1.19
95 16 16 16 16 16 1.19
120 16 16 16 16 16 1.19
150 25 25 25 25 25 0.759
185 25 25 25 25 25 0.759
240 25 25 25 25 25 0.759
300 25 25 25 25 25 0.759
400 35 35 35 35 35 0.271
500 35 35 35 35 35 0.271
630 35 35 35 35 35 0.271

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

Nominal Cross- Section of Cables Total Cross Section & Max DC Resistance
　 　 　 　 　
Cross Section Resistance at 20℃ Cross Section Resistance at 20℃ Cross Section Resistance at 20℃ Section Resistance at 20℃ Cross Section Resistance at 20℃
mm² mm² Ω mm² Ω mm² Ω mm² Ω mm² Ω
70 6.6 2.616 7.23 2.380 8.02 2.145 8.7 1.967 10.5 1.075
95 7.3 2.369 7.91 2.174 8.71 1.975 9.4 1.824 11.2 1.075
120 8.0 2.153 8.64 1.991 9.43 1.823 10.2 1.694 12.0 1.075
150 8.5 2.013 9.19 1.871 9.99 1.722 10.7 1.606 12.5 0.688
185 9.4 1.838 9.88 1.741 10.82 1.590 11.4 1.509 13.2 0.688
240 10.4 1.656 10.96 1.569 11.76 1.463 12.5 1.378 14.3 0.688
300 11.4 1.508 11.84 1.452 12.64 1.361 13.4 1.287 15.2 0.688
400 12.6 1.362 12.92 1.332 13.71 1.254 14.4 1.192 16.2 0.491
500 13.9 1.237 14.34 1.199 15.14 1.136 15.5 1.110 17.7 0.491
630 15.3 1.121 16.68 1.031 16.57 1.038 17.3 0.995 19.1 0.491

 

Separation Sheath (for armoured cable) The separation sheath comprises a layer of extruded PVC, PE or LSZH. The nominal thickness is calculated by 0.02Du + 0.6mm where Du is the fictitious diameter under the sheath in mm. The nominal separation sheath thickness shall not be less than 1.2mm.
Armour (for armoured cable) The armour consists of galvanized steel wire applied over the inner covering with diameter specified as in Table 4.

Table 4. Armour Wire Diameter

Fictitiious Diameter under the Armour Armour Wire Diameter
mm mm
> <  
- 25 1.6
25 35 2.0
35 60 2.5
60 - 3.15

 

Over Sheath Overall sheath comprises a layer of extruded either PVC type 9 conforming to BS 7665-4.2 or MDPE type TS2 conforming to BS 7655-10.1; LSZH can be offered as an option. The over sheath is normally black in colour. When a DC voltage test is to be performed on the over sheath, a semi-conducting layer such as graphite coating shall be applied over the surface of the extruded over sheath. The nominal over sheath thickness is calculated by 0.035D+1 where D is the diameter immediately under the over sheath in mm. For cables with the over sheath not applied over the armour, the nominal over sheath thickness shall not be less than 1.4mm. And for cables with over sheath applied over the armour, the nominal over sheath thickness shall not be less than 1.8mm.

PHYSICAL PROPERTIES

Operating Temperature up to 90°C
Temperature Range -5°C ( PVC or LSZH sheath ); -20°C ( PE sheath )
Short Circuit Temperature 250°C (short circuit duration up to 5 seconds)
Bending Radius 12 x OD

Table 5. Nominal /Operating /Test Voltages

Rated Voltage Uo/U Operating Voltage (Um) Testing Voltage (rms)
3.8/6.6KV 7.2KV 15KV
6.35/11KV 12KV 25.5KV
8.7/15KV 17.5KV 35KV
12.7/22KV 24KV 51KV
19/33KV 36KV 76KV

Three Core 3.8/6.6KV (Um=7.2KV)

Dimensional Data
Nom. Cross- Section
Area		 Nom. Insulation Thickness Copper  Wire Screen Area Copper Tape Screen Area Nom.Bedding Thickness Nom. Armour Wire Diameter Nom.Sheath Thickness Approx. Overall Diameter Approx. Weight
CU AL
mm² mm mm² mm² mm mm mm mm kg/km
70 2.5 16 6.6 1.3 2.5 2.6 55.0 6570 5240
95 2.5 16 7.3 1.4 2.5 2.7 58.9 7760 5890
120 2.5 16 8.0 1.5 2.5 2.8 62.1 8810 6510
150 2.5 25 8.5 1.5 2.5 2.9 65.8 10110 7310
185 2.5 25 9.4 1.6 2.5 3.0 69.5 11520 7960
240 2.6 25 10.4 1.7 2.5 3.2 75.9 13920 9140
300 2.8 25 11.4 1.8 3.15 3.5 83.1 17400 11620
400 3.0 35 12.6 2.0 3.15 3.7 93.0 21900 13980
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 Screen 1 sec 　 Current Ratings
Reac- tance Induc- tance Ground Duct Air
Copper Wire Copper Tape CU AL CU AL CU AL
mm² µΩ/m µΩ/m kA pF/m mA/m kA µΩ/m nH/m A A A
70 268/443 343/568 9.8/6.3 383 0.46 1.96 0.96 97 310 255 195 215 165 270 210
95 193/320 248/410 13.3/8.5 432 0.52 1.96 1.06 92 290 300 230 255 200 330 250
120 153/253 196/325 17.2/11.0 474 0.57 1.96 1.17 89 280 340 265 290 225 375 295
150 124/206 159/265 21.2/13.5 511 0.61 3.06 1.25 87 280 380 295 330 255 430 330
185 99.1/164 128/211 26.6/17.0 562 0.67 3.06 1.37 86 270 430 335 370 290 490 385
240 75.4/125 98/161 34.9/22.3 602 0.72 3.06 1.52 83 260 490 380 425 335 570 450
300 60.1/100 80/130 43.8/28.0 622 0.75 3.06 1.67 82 260 540 435 470 375 650 510
400 47.0/77.8 64/102 57.3/36.6 648 0.78 4.29 1.84 80 250 590 480 520 420 700 570

Three Core 6.35/11KV (Um=12KV)

Dimensional Data
Nom. Cross- Section Area Nom. Insulation Thickness Copper Wire Screen Area Copper Tape Screen Area Nom.Bedding Thickness Nom. Armour Wire Diameter Nom.Sheath Thickness Approx. Overall Diameter Approx. Weight
CU AL
mm² mm mm² mm² mm mm mm mm kg/km
70 3.4 16 7.23 1.4 2.5 2.7 59.2 7200 5870
95 3.4 16 7.91 1.5 2.5 2.8 63.2 8420 6550
120 3.4 16 8.64 1.6 2.5 3.0 67.0 9580 7190
150 3.4 25 9.19 1.6 2.5 3.1 70.3 10830 8030
185 3.4 25 9.88 1.7 2.5 3.2 73.9 12290 8720
240 3.4 25 10.96 1.8 3.15 3.4 81.2 15620 10790
300 3.4 25 11.84 1.9 3.15 3.6 86.1 18030 12240
400 3.4 35 12.92 2.0 3.15 3.8 95.0 22350 14350
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 Screen 1 sec 　 Current Ratings
Reac- tance Induc- tance Ground Duct Air
Copper Wire Copper Tape CU AL CU AL CU AL
mm² µΩ/m µΩ/m kA pF/m mA/m kA µΩ/m nH/m A A A
70 268/443 343/568 9.8/6.3 298 0.60 1.96 1.05 103 330 255 195 215 165 270 210
95 193/320 248/410 13.3/8.5 334 0.67 1.96 1.16 99 310 300 230 255 200 330 250
120 153/253 196/325 17.2/11.0 365 0.73 1.96 1.26 96 310 340 265 290 225 375 295
150 124/206 159/265 21.2/13.5 392 0.78 3.06 1.34 93 300 380 295 330 255 430 330
185 99.1/164 128/211 26.6/17.0 430 0.86 3.06 1.44 90 290 430 335 370 290 490 385
240 75.4/125 98/161 34.9/22.3 476 0.95 3.06 1.60 87 280 490 380 425 335 570 450
300 60.1/100 80/130 43.8/28.0 524 1.05 3.06 1.73 85 270 540 435 470 375 650 510
400 47.0/77.8 64/102 57.3/36.6 580 1.16 4.29 1.89 81 260 590 480 520 420 700 570

Three Core 8.7/15KV (Um=17.5KV)

Dimensional Data
Nom. Cross- Section
Area		 Nom. Insulation Thickness Copper
Wire Screen Area		 Copper
Tape Screen Area		 Nom. Bedding Thickness Nom. Armour Wire Diameter Nom. Sheath Thickness Approx. Overall Diameter Approx. Weight
CU AL
mm² mm mm² mm² mm mm mm mm kg/km
70 4.5 16 8.02 1.5 2.5 2.9 64.6 8030 6700
95 4.5 16 8.71 1.6 2.5 3.0 68.2 9160 7330
120 4.5 16 9.43 1.7 2.5 3.1 71.7 10340 8030
150 4.5 25 9.99 1.7 2.5 3.2 75.4 11730 8930
185 4.5 25 10.82 1.8 3.15 3.4 80.6 14170 10570
240 4.5 25 11.76 1.9 3.15 3.6 86.6 16670 11810
300 4.5 25 12.64 2.0 3.15 3.7 91.3 19140 13340
400 4.5 35 13.71 2.1 3.15 4.0 100.0 23360 15410
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		 Capacitance Charging
Current　		 Short Circuit Rating
of Screen
1 sec		 Reac- tance Induc- tance Current Ratings
Copper Wire Copper Tape Ground Duct Air
CU AL CU AL CU AL
mm² µΩ/m µΩ/m kA pF/m mA/m kA µΩ/m nH/m A A A
70 268/443 343/568 9.8/6.3 240 0.65 1.96 1.17 110 350 255 195 215 165 270 210
95 193/320 248/410 13.3/8.5 267 0.73 1.96 1.27 105 330 300 230 255 200 330 250
120 153/253 196//325 17.2/11.0 291 0.79 1.96 1.38 102 320 340 265 290 225 375 295
150 124/206 159/265 21.2/13.5 312 0.85 3.06 1.46 98 310 380 300 330 255 430 330
185 99.1/164 128/211 26.6/17.0 340 0.93 3.06 1.58 95 300 430 335 370 290 490 385
240 75.4/125 98/161 34.9/22.3 375 1.02 3.06 1.72 91 290 490 380 425 335 570 450
300 60.1/100 80/130 43.8/28.0 411 1.12 3.06 1.85 89 280 540 435 470 375 650 510
400 47.0/77.8 64/102 57.3/36.6 454 1.24 4.29 2.00 84 270 590 480 520 420 700 570

Three Core 12.7/22KV (Um=24KV)

Dimensional Data
Nom. Cross- Section
Area		 Nom. Insulation Thickness Copper
Wire Screen Area		 Copper Tape Screen Area Nom.Bedding Thickness Nom. Armour Wire Diameter Nom. Sheath Thickness Approx. Overall Diameter Approx. Weight
CU AL
mm² mm mm² mm² mm mm mm mm kg/km
70 5.5 16 8.7 1.6 2.5 3.0 69.0 8710 7370
95 5.5 16 9.4 1.7 2.5 3.2 73.1 10000 8130
120 5.5 16 10.2 1.7 3.15 3.3 77.7 12040 9730
150 5.5 25 10.7 1.8 3.15 3.4 81.7 13550 10750
185 5.5 25 11.4 1.9 3.15 3.6 85.5 15150 11610
240 5.5 25 12.5 2.0 3.15 3.7 91.3 17710 12840
300 5.5 25 13.4 2.0 3.15 3.9 96.0 20170 14360
400 5.5 35 14.4 2.2 3.15 4.1 104.8 24520 16480
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 Screen
1 sec		 Reac- tance Induc- tance Current Ratings
Ground Duct Air
Copper
Wire		 Copper
Tape		 CU AL CU AL CU AL
mm² µΩ/m µΩ/m kA pF/m mA/m kA µΩ/m nH/m A A A
70 268/443 343/568 9.8/6.3 207 0.83 1.96 1.28 115 370 255 195 225 170 275 215
95 193/320 248/410 13.3/8.5 229 0.92 1.96 1.38 110 350 295 230 260 205 330 260
120 153/253 196/325 17.2/11.0 249 1.00 1.96 1.48 106 340 335 260 300 235 380 300
150 124/206 159/265 21.2/13.5 266 1.06 3.06 1.56 103 330 375 290 335 265 430 335
185 99.1/164 128/211 26.6/17.0 289 1.16 3.06 1.66 100 320 420 330 380 300 490 390
240 75.4/125 98/161 34.9/22.3 318 1.27 3.06 1.82 95 300 480 380 430 345 570 460
300 60.1/100 80/130 43.8/28.0 348 1.39 3.06 1.95 93 300 530 425 480 385 650 520
400 47.0/77.8 64/102 57.3/36.6 383 1.53 4.29 2.11 87 280 590 480 520 420 700 570

Three Core 19/33KV (Um=36KV)

Dimensional Data
Nom. Cross- Section Area Nom. Insulation Thickness Copper Wire Screen Area Copper Tape Screen Area Nom.Bedding Thickness Nom.
Armour Wire Diameter		 Nom. Sheath Thickness Approx. Overall Diameter Approx. Weight
CU AL
mm² mm mm² mm² mm mm mm mm kg/km
70 8.0 16 10.5 1.8 3.15 3.5 82.5 11840 10440
95 8.0 16 11.2 1.9 3.15 3.6 86.4 13200 11350
120 8.0 16 12.0 2.0 3.15 3.7 89.9 14520 12190
150 8.0 25 12.5 2.0 3.15 3.8 93.6 16070 13280
185 8.0 25 13.2 2.1 3.15 3.9 97.3 17710 14090
240 8.0 25 14.3 2.2 3.15 4.1 103.2 20370 15460
300 8.0 25 15.2 2.3 3.15 4.3 108.2 22980 17210
400 8.0 35 16.2 2.4 3.15 4.5 116.8 27480 19450
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 Screen
1 sec		 Reac- tance Induc- tance Current Ratings
Ground Duct Air
Copper
Wire		 Copper
Tape		 CU AL CU AL CU AL
mm² µΩ/m µΩ/m kA pF/m mA/m kA µΩ/m nH/m A A A
70 268/443 343/568 9.8/6.3 159 0.95 1.96 1.54 127 400 255 195 225 170 275 215
95 193/320 248/410 13.3/8.5 175 1.05 1.96 1.64 121 390 295 230 260 205 330 260
120 153/253 196/325 17.2/11.0 189 1.13 1.96 1.75 117 370 335 260 300 235 380 300
150 124/206 159/265 21.2/13.5 201 1.21 3.06 1.83 113 360 375 290 335 265 430 335
185 99.1/164 128/211 26.6/17.0 217 1.30 3.06 1.93 109 350 420 330 380 300 490 390
240 75.4/125 98/161 34.9/22.3 237 1.42 3.06 2.09 104 330 480 380 430 345 570 460
300 60.1/100 80/130 43.8/28.0 258 1.55 3.06 2.21 101 320 530 425 480 385 650 520
400 47.0/77.8 64/102 57.3/36.6 282 1.69 4.29 2.37 96 290 590 480 520 420 700 570