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Nominal Area Of Conductor mm2 |
Rating Factor |
Upto & Including 185 |
1.07 |
240 |
1.10 |
300 |
1.08 |
400 |
1.04 |
500 |
1.00 |
630 |
1.00 |
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| 3. Rating Factor for variation in underground temperature for cables laid direct in ground & laid in duct. |
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| Ground Temperature 0C |
15 |
20 |
25 |
30 |
35 |
40 |
45 |
| Rating Temperature |
1.17 |
1.17 |
1.17 |
1.17 |
1.17 |
1.17 |
1.17 |
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| 4. Rating Factor for variation in underground temperature for cables laid direct in ground & laid in duct. |
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| Ground Temperature 0C |
15 |
20 |
25 |
30 |
35 |
40 |
45 |
| Rating Temperature |
1.33 |
1.25 |
1.16 |
1.09 |
1.0 |
0.90 |
0.83 |
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Short Circuit Rating Of Alluminium Conductor Cable :
Techno Flex cables manufacturing method based on quality assurance plan & use of high standard raw material, therefore it withstand high Magnitude of short circuit rating. It is calculated as under: |
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where Ish --> short circuit ratings in r.m.s. amp.
t --> duration of short circuit in seconds
A --> Area of conductor in sq.mm |
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Tabulated The Constant For Different Duration Of Short Circuits : |
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Duration of Short Circuit in sec. |
1 Cycle = 0.02 sec |
2 Cycle
= 0.04 sec |
5 Cycle
= 0.1 sec |
10 Cycle
= 0.2 sec |
25 Cycle
= 0.5 sec |
50 Cycle
= 1.0 sec |
2
sec |
3
sec |
4
sec |
5
sec |
Short Circuit constant Per unit area |
536 |
378 |
239 |
169 |
107 |
75.7 |
53.0 |
43.6 |
37.8 |
34 |
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Example: Short Circuit rating of 70 sq.mm area of conductor with short duration 0.5 sec = 70 x 107 = 7490A |
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Recommendation For Installation: |
Cables are the most important asset of any organization. Any damage to it will result in break down of the complete plant & machinery, hence proper attention should be paid while handling and laying them. So for its silent features which should be kept in view during installation as under:- |
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1. Before laying the installation ofthe cable, It should be checked by meggar as a preliminary check against any probable fault. |
2. The drum should be always rolled in the direction of the arrow or opposite to the outside cable end. |
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3. Avoid the possibility cable twist which will brutally damage the cable because cable have itself twisting force. |
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4. Properly check the sequence of cores & no crossing of cores while connecting, also decide the direction in which the cable is to be pulled. |
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5. Possible bending radius should be 12 times the overall diameter of the cable to be maintained. But at any case it should not be less than 8 times. |
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6. In low temperature area the bending should not be very small radius because PVC compound become stiff & brittle and it shall get crack. |
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7. All joints terminations armour wires & external metallic bonding should be connected to the earth, wherever possible armour at one end of the cable should be connected to main earth system at the supplying end by employing metallic connectors.
Precautions should be taken to eliminate the chemical & by metallic corrosion ofthe earth connector. |
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8. The design of the box & composition of the filling compound should provide an effective sealing against entry of moisture to conductor & annour connector. |
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9. If hot pouring protective compounds are used, the temperature of the compound while pouring should not exceed
150°C. |
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10. Where the cables are crossing the roads, the same should be laid in concrete ducts & avoid the sharp edges of concrete ducts in other hand cable may be damaged. |
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11. We strongly recommend the user that after installation, 2KV DC voltage test should be carried out, through the each core before earthing. |
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For More Details » |
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