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)
A THHN conductor will have 75°C termination on one end and a 60/75°C termination on the other, which ampacity column will be used?

60°C column
None of these
75°C column
90°C column

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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
18.75 MVA
12 MVA
15 MVA

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MGVCL Exam Paper (30-07-2021 Shift 1)
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, what will be the voltage across a 100 W lamp (L1)?

120V
240V
180V
160 V

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