MGVCL Exam Paper (30-07-2021 Shift 2)
In a test by Murray loop for ground fault on 600 m of cable having a resistance of 1.5 Ω/km, the faulty cable is looped with a sound cable of the same length and area of cross section. If the ratio of the other two arms of the testing network at balance is 3 : 1, find the distance of the fault from the testing end of cables.

400 m
100 m
300 m
200 m

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MGVCL Exam Paper (30-07-2021 Shift 2)
In a short circuit test on circuit breaker, time to reach the peak re-striking voltage is 50 µs with the peak restriking voltage of 100 kV. Determine average RRRV (Rate of rise re-striking voltage)?

2 x 10⁶ kV/sec
1 x 10⁶ kV/sec
4 x 10⁶ kV/sec
3 x 10⁶ kV/sec

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MGVCL Exam Paper (30-07-2021 Shift 2)
Interposing current-transformer (CT) is used in differential protection of a transformer to

limit the main CT secondary current
match the standard ratio of CTs used on both sides of the transformer winding
minimize the effect of saturation of the main CTs
increase the sensitivity of the relay

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