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A 1 km of a three phase metal sheathed belted cable gave a measured capacitance of 0.7 µF bet ween one conduct or and the other two conductors bunched together with the earth sheath and 1.5 µF measured between the three bunched conductors and the sheath. What is the charging current, when the cable is connected at 11 kV, 50 Hz supply?
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- 0.80 A/phase
- 1.40 A/phase
- 1.59 A/phase
- 1.695 A/phase
Correct Option: C
2Cc + Cs = 0.7
⇒ 3Cs = 1.5
⇒ Cs = 0.5
Now, 2 Cc + 0.5 = 0.7
| ⇒ Cc = | = 0.1 F | |
| 2 |
| CL = | C0 | |
| 2 |
| = | (3Cc + Cs) | |
| 2 |
| = | (3 × 0.1 + 0.5) = 0.4 F | |
| 2 |
Charging current =Vp ω C0
| Diversity factor = | × 2π × ƒ × 2CL | |
| √3 |
| = | × 2π × 50 × 2 × 0.4 × 10-6 | |
| √3 |
= 1.59 Ampere/phase
