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

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

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MGVCL Exam Paper (30-07-2021 Shift 2)
A three-phase 400 V, 6-pole, 50 Hz squirrel-cage induction motor is running at a slip of 5%. The speed of rotor with respect to stator magnetic field and speed of the stator magnetic field with respect to rotor magnetic field are

-50 rpm, zero
950 rpm, 1000 rpm
950 rpm, zero
-50 rpm, 1000 rpm

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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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