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%
remains unaltered
decreases marginally
increases marginally

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MGVCL Exam Paper (30-07-2021 Shift 1)
Determine maximum permissible load which a 15 MVA, ONAN cooled transformer to IS : 2026 can take for 6 hr, if the initial load on it was 12 MVA. The weighted ambient temperature is 20˚C. Assume the permissible load kVA as a fraction of rated kVA is 1.25.

9.6 MVA
15 MVA
18.75 MVA
12 MVA

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MGVCL Exam Paper (30-07-2021 Shift 1)
Stability of power system can be improved by
1. Reducing voltage of transmission
2. Using parallel transmission lines
3. Using series compensators
Which of the above statements are correct?

1 and 2 only
2 and 3 only
1 and 3 only
All 1, 2 and 3

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MGVCL Exam Paper (30-07-2021 Shift 1)
Which type of connection is employed for current transformers for the protection of delta- star connected 3-phase transformer?

delta-delta
star-delta
star-star
delta-star

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