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XLPE INSULATED
POWER CABLES
CABLE TYPE (Al-)XLPE/SWA
flat/PVC
6-35 kV
DESCRIPTION
Three-core XLPE/SWAF/PVC cable is being made in accordance with IEC 60502/98.
Copper or aluminium compacted stranded circular conductor, conductor screen of extruded
layer of semi-conducting XLPE, XLPE insulation, insulation screen of extruded layer of
semi conducting XLPE, semi-conducting bedding tape, metallic screen consisting of copper
wires applied helically with a counterspiral of copper tape. Three cores are being laid-up
together with suitable fillers, covered with PVC separation sheath, armoured with flat
galvanized steel wires and covered with PVC outersheath over in black colour.
Minimum
bending radius:
| |
cable during
instalation |
cable
placed in position adjacent to joints or terminations |
NON-ARMOURED |
15D |
12D |
ARMOURED |
12D |
10D |
D - outer cable diameter
Current carrying capacity has been calculated according to
IEC 287/82 (100 % load factor) and following conditions:
- Depth of laying 0.70 m, and for 20/35 kV cables 1.0 m.
- Soil thermal resistivity 1.0 K m/W.
- Ground temperature 20oC, ambient air temperature
30oC, maximum conductor operating temperature 90oC.
Type of laying :
- Sheaths bonded at both ends of an electrical section
RATING FACTORS
| |
Ambient
temperature oC |
15 |
20 |
25 |
30 |
35 |
40 |
| Factor |
Cable
in ground |
1.04 |
1.00 |
0.96 |
0.93 |
0.89 |
0.85 |
| Cable in air |
1.14 |
1.09 |
1.05 |
1.00 |
0.95 |
0.90 |
| |
Soil
thermal resistivity (Km/W) |
| Factor |
0.7 |
1.0 |
1.2 |
1.5 |
2.0 |
2.5 |
3.0 |
1.12 |
1.00 |
0.94 |
0.86 |
0.77 |
0.71 |
0.66 |
COMPARISON OF CHARACTERISTIC VALUES
OF INSULATING COMPAUNDS
| |
Type of
insulating compaunds |
UPET |
PET |
PVC |
| Maximum
continous conductor operating temperature oC |
90 |
70 |
65 |
| Maximum
conductor short-circuit temperature oC |
250 |
150 |
160 |
| Dielectric
power factor at 50Hz, 20oC |
4 x 10-4 |
2 x 10 -4 |
10-2 |
| Relative
permittivity at 50Hz, 20oC |
2.3 |
2.3 |
4-8 |
| Volume
resistivity at 20oC ohm.cm |
1017 |
1017 |
1014 |
| Thermal
resistivity K.m/W |
3.5 |
3.5 |
6.0 |
| Tensile
strenth, minimum N/cm2 |
200 |
150 |
250 |
| Elongation-at-break,
minimum % |
350 |
550 |
250 |
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