Page 558 - Industrial Power Engineering and Applications Handbook

16/532 Industrial Power Engineering and Applications Handbook
Table A162 Comparative study of different insulating systems
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SI: Particulars PVC Paper XLPE insulated PE ?P rubber
no. 'nsulutrd PVC Jheuted
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1 Loss factor, tan 6 at 50 Hz and 20°( 0.07 Low, 0.003 Very low, 0,0005 Very low, <ow. 0.003
0.0005
2 Dielectric constant at 50 Hz and 20' 5.8 3.5 2.3 2.3 1.0
3 A.C. dielectric strength (kVlmm) 18 $0 40 30 10
4 Volume resistivity at 20°C (R-cm) 1012-10'5 10'5 10'7 1017 0'5
5 Specific gravity (g/cm3) Very heavy, Heavy, 1.1 Very light, 0.93 Very light, {cry heavy, 1.35
1.35-1.46 0.93
6 Thermal resistivity, "C (cm/W) 650 550 350 350 j00

7 Flexibility at 10°C Poor Poor Good Good 5xcellent
8 Abrasion resistance Good Poor Good Good 'oor
9 Deformation resistance at 150°C Poor Good Good Poor :xcellent
10 Fire resistance Excellent. Poor Poor Poor 'oor
Low smoke
and low
halogen
emission
under fire
conditions
11 Ageing resistance at
100°C Moderate Good Excellent Moderate Sood
120°C Poor Moderate Good Poor Moderate
150°C Poorer Poor Moderate Poorer Poor
12 Oil resistance at 70°C Good Poor Good Good Poor
13 Resistance to chemicals Good Moderate Excellent Good Moderate
14 Hydroscopic properties Non-hygro- Hygroscopic Non-hygrowipic Non-hygro- Hygroscopic
scopic scopic
15 Voltage range LT and HT 1.1 kV to 33 6.6 kV to 440 kV Below 6.6 k\ LT and HT up to
up to I1 kV kV (No LT and higher But not in us 11 kV
due to cost) due to cost
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16 Thermal rating
(i) For continuous operation "C 70 65 90 70 85-90
(ii) For short time overload "C 130 85 I30 90 120-130
(iii) For short-circuit Conditions 'C 160 I60 250 150 220-250
Utilizarion: Different rubber
(I j Higher operating tempera- compounds can
ture permits a greater operate at different
utilization of metal and temperatures.
allows a higher current Special compounds arc
rating compared to PVC available such as
and paper insulated silicon rubber that
cables. can provide yet higher
(2) A higher operating temperatures, say,
temperature will necessitat up to 150°C operating
checking of the surround- and 350°C during
ings at the point of short-circuits.
installation for any fire Uriliiution:
hazards or adverse therma As for XLPE cables
effects on the equipment,
devices, and components
installed in the vicinity.
When desired, the cable
may have to be derated to
operate at lower
temperaturcs
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17 Condition on fault Emits corrosive gases and Emits CO, and water. Does not melt. As for PVC
causes leakage of oil. Environment friendly
Not environment friendly
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18 Applicable standards IEC 60502-2 up to 33 kV 1EC-60502-1 BS 6708
1 and 2 IEC 60840 above 30 kV up to IS 9968 Part I Elastomer
150 kV SS-424 24 17 - insulated cables -
Swedish apecification- up to ll00V
12-420 kV Part I1 3.3-1 1 kV
(Conrd)