MGVCL Exam Paper (30-07-2021 Shift 1)
A transformer designed for operation at 60 Hz supply is working at 50 Hz supply system without changing its voltage and current ratings. Compared to the full load efficiency at 60 Hz, the full load transformer efficiency at 50 Hz.

remains unaltered
decreases marginally
increases marginally
increases by 30%

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MGVCL Exam Paper (30-07-2021 Shift 1)
An RC series circuit with R = 150 Ω and C = 2 μF is excited by a DC source of 15 V by closing the switch at t = 0 with an initially uncharged capacitor. The initial and final voltages across the capacitor respectively are

10 V, 15 V
0 V, 15 V
15 V, 10 V
0 V, 10 V

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MGVCL Exam Paper (30-07-2021 Shift 1)
Case 1: The PV connected to the DC bus was injecting 20 kW of power constituting of 1 kW of loss
Case 2: The same PV is connected to the AC bus constituting to 1.5 kW loss. Find out the change in efficiency from Case 1 to Case 2?

2.5% decrease
5% decrease
2.5% increase
5% increase

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