MGVCL Exam Paper (30-07-2021 Shift 2)
In a synchronous motor with field under excited, the power factor will be

lagging
unity
leading
zero

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MGVCL Exam Paper (30-07-2021 Shift 2)
A generating station having 'n' section busbars each rated at Q kVA with ×% reactance is connected on the tie-bars systems through busbar reactances of b%. Determine the short circuit kVA if a 3-phase fault takes place on one section.

Q[(1/x) + (n+1)/(bn+x)]
Q[(1/x) + (n-1)/(bn+x)]
Q[(1/x) + (n+1)/(bn-x)]
Q[(1/x) - (n+1)/(bn-x)]

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MGVCL Exam Paper (30-07-2021 Shift 2)
A 50 Hz synchronous generator is connected to an infinite bus through a line. The p.u. reactances of generator and the line are j0.3 p.u. and j0.2 p.u. respectively. The generator no load voltage is 1.1 p.u. and that of infinite bus is 1.0 p.u. The inertia constant of the generator is 4 MW-sec/MVA. Determine the frequency of natural oscillations if the generator is loaded to 60% of its maximum power transfer capacity and small perturbation in power is given.

1.32 Hz
1.62 Hz
1.42 Hz
1.52 Hz

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MGVCL Exam Paper (30-07-2021 Shift 2)
Interposing current-transformer (CT) is used in differential protection of a transformer to

increase the sensitivity of the relay
match the standard ratio of CTs used on both sides of the transformer winding
minimize the effect of saturation of the main CTs
limit the main CT secondary current

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