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

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

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MGVCL Exam Paper (30-07-2021 Shift 2)
A 3-phase motor load has a p.f. of 0.397 lagging. The two wattmeter method used to measure power show the input as 30 kW. Find the reading on each wattmeter.

W1 = -5 kW and W2 = 35 kW
W1 = 10 kW and W2 = 20 kW
W1 = 5 kW and W2 = 25 kW
W1 = -10 kW and W2 = 40 kW

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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)?

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

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MGVCL Exam Paper (30-07-2021 Shift 2)
A three-phase 400 V, 6-pole, 50 Hz squirrel-cage induction motor is running at a slip of 5%. The speed of rotor with respect to stator magnetic field and speed of the stator magnetic field with respect to rotor magnetic field are

950 rpm, 1000 rpm
-50 rpm, 1000 rpm
950 rpm, zero
-50 rpm, zero

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