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.

increases by 30%
increases marginally
decreases marginally
remains unaltered

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MGVCL Exam Paper (30-07-2021 Shift 1)
___ is the rms value of the total current comprising the AC and DC components of the current in the circuit breaker pole at the instant of contact separation.

Symmetrical breaking current
Making current
Asymmetrical breaking current
Symmetrical short circuit current

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MGVCL Exam Paper (30-07-2021 Shift 1)
A single phase motor connected to 400 V, 50 Hz supply takes 30 A at a power factor of 0.7 lagging. Calculate the capacitance required in parallel with the motor to raise the power factor to 0.9 lagging.

99.5 μF
79.5 μF
89.5 μF
69.5 μF

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MGVCL Exam Paper (30-07-2021 Shift 1)
Determine the ohmic value of the current limiting reactor per phase external to a 30 MVA, 11 kV, 50 Hz, three phase synchronous generator which can limit the current on short circuit of 5 times the full load current. The reactance of the synchronous generator is 0.05 pu.

0.605 Ω
0.405 Ω
0.305 Ω
0.805 Ω

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MGVCL Exam Paper (30-07-2021 Shift 1)
Consider the following two statements and choose the correct answer.
Statement 1: The V-curves of a synchronous motor show relationship between armature current and supply voltage.
Statement 2: The plot of power factor against the field current of synchronous motor is known as inverted V curves.

Both Statement 1 and Statement 2 are FALSE
Statement 1 is TRUE and Statement 2 is FALSE
Both Statement 1 and Statement 2 are TRUE
Statement 1 is FALSE and Statement 2 is TRUE

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