MGVCL Exam Paper (30-07-2021 Shift 2)
In transformer, a Sweep Frequency Response Analysis (SFRA) test will help detect ____

Moisture in the windings
Age of the insulation
Aging by-products
Movement / damage to internal components

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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)
Interposing current-transformer (CT) is used in differential protection of a transformer to

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

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MGVCL Exam Paper (30-07-2021 Shift 2)
A coil having an inductance of 100 mH is magnetically coupled to another coil having an inductance of 900 mH. The coefficient of coupling between the coils is 0.45. Calculate the equivalent inductance if the two coils are connected in series opposing.

1270 mH
1135 mH
932 mH
730 mH

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