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

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MGVCL Exam Paper (30-07-2021 Shift 2)
In a 3-phase, 4-wire, 400/230 V system, a lamp (L1) of 100 W is connected to one phase and neutral and a lamp (L2) of 150 W is connected to the second pahse and neutral. If the neutral wire is disconnected accidently, then

both 100 W lamp (L1) and 150 W lamp (L2) becomes dim
100 W lamp (L1) becomes brighter and 150 W lamp (L2) becomes dim
100 W lamp (L1) becomes dim and 150 W lamp (L2) becomes brighter
both 100 W lamp (L1) and 150 W lamp (L2) becomes brighter

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MGVCL Exam Paper (30-07-2021 Shift 2)
The magnitude of the generator earth-fault current is limited by

inserting the stabilizing resistance in series with the relay
inserting suitable resistance in neutral grounding circuit
using higher rating CTs
controlling field exciter

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MGVCL Exam Paper (30-07-2021 Shift 2)
A 50 Hz synchronous generator is connected to an infinite bus through a line. The p.u. reactances of generator and the line are j0.3 p.u. and j0.2 p.u. respectively. The generator no load voltage is 1.1 p.u. and that of infinite bus is 1.0 p.u. The inertia constant of the generator is 4 MW-sec/MVA. Determine the frequency of natural oscillations if the generator is loaded to 60% of its maximum power transfer capacity and small perturbation in power is given.

1.32 Hz
1.52 Hz
1.42 Hz
1.62 Hz

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