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What is the overall diameter of a single core cable when its working on a three phase 264 kV system? The maximum permissible stress in the dieletric is not to exceed 20 kV/mm is ________ mm
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- 21.4 mm
- 214 mm
- 2.14 mm
- .214 mm
Correct Option: A
| Effective value (rms) of the phase voltage = | = 152.4 kV. | |
| √3 |
| Peak value of phase voltage = | × √2 = 215.5 kV. | |
| √3 |
For economical size of the cable, optimum ratio of sheath and core radii is given by R/r = e
| gmax = | = | = | |||
| rIn(R/r) | r × 1 | r |
| or 20 = | ||
| r |
| r = | = 10.7 mm | |
| 20 |
Economical core diameter
= 10.7 × 2 = 21.4 mm
