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%
decreases marginally
increases 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 short circuit current
Making current
Asymmetrical breaking current
Symmetrical breaking current

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MGVCL Exam Paper (30-07-2021 Shift 1)
___ is the short time reduction in the rms voltage between 0.1 to 0.9 p.u for a duration of ___

Voltage swell, 0.5 cycle to 1 minute.
Voltage sag, greater than 1 minute
Voltage sag, 0.5 cycle to 1 minute.
Voltage swell, greater than 1 minute

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