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A three phase, 50 Hz transmission line consists of three equal conductors of radii r placed in a horizontal plane with a spacing of 6 m between middle and each outer conductor. If radius of each conductor is 12.5 mm, then indutance per phase per km of the transposed line will be _________ mH/km
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- 1.33 mH /k m.
- 2.33 mH /k m.
- 13.3 mH /k m.
- 13.3 mH /k m.
Correct Option: A
| L = 2 × 10-7In |  |  | |
| r' |
Here Dm = (D × D × D)1/3 = 1.26
⇒ D = 1.26 × 6 = 7.56 m
r' = 0.7788 × r = 0.7788 × 12.5 × 10–3
= 9.735 × 10–3 m
| ∴ L = 2 × 10–7 ln | | | |
| 9.735 × 10-3 |
= 13.31 × 10–7 H/m
= 1.33 × 10–3 × 10–3H/m
= 1.33 mH /k m.
