MGVCL Exam Paper (30-07-2021 Shift 2)
A three-phase, 12 kV, 50 Hz and 300 kW load is operating at 0.8 pf lag. If the pf is to be improved to unity, using star connected capacitor, the per phase value of the reactive VAR required is:

100 kVAR
25 kVAR
50 kVAR
75 kVAR

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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)
The miniature circuit breaker (MCB) with Class D trip characteristics trips instantaneously when the current flowing through it reaches ____ the rated current.

between 2 to 3 times
between 3 to 5 times
between 5 to 10 times
between 10 to 20 times

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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
limit the main CT secondary current
match the standard ratio of CTs used on both sides of the transformer winding

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