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A 3φ, 50 Hz, 132 kV transmission line consists of conduct or of 1.17 cm diameter and spaced equilaterely at a distance of 3m. The line conductors have smooth surface with value for m = 0.96. The barometric pressure is 72 cm of Hg and temperature of 20°C. The corona loss in foul weather condition will be
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- 3.12 kW/km/phase
- 4.84 kW/km/phase
- 8.70 kW/km/phase
- none of these
Correct Option: A
Diameter =1.17 cm; r = 0.585 cm; d = 3 m
| ∴ | = |  |  | = 512.8 | ||
| r | 0.585 |
| or √ | = √ | | | = 0.044 | ||
| d | 512.8 |
| δ = | = | = 0.96 | ||
| 273 + t | 293 |
| V = | = 76.21 kV/phase | |
| √3 |
∴ Vd = 21.1 × 0.96 × 0.96 × 0.585 ln (512.8)
= 70.98 kV (line to neutral)
Corona loss under foul weather condition will be when the disruptive voltage is taken as
Vd = 0.8 × fair weather value
= 0.8 × 70.98 = 56.78
| PC = 241 × 10–5 | | | × √ | (V - Vd) | ||
| 6 | d |
| = 241 × 10–5 × | | | × √ | (76.21 - 56.78) | ||
| 0.96 | 512.8 |
= 3.12 k W/k m/phase
