MGVCL Exam Paper (30-07-2021 Shift 2)
The expression for voltage regulation of a short transmission line for leading power factor is given by: ____, where, 'I' is the line current, 'V_r' is the receiving end voltage, 'R' is the line resitance and 'X' is the line reactance.

(IRcosφ_r + IXsinφ_r)/V_r
(IXcosφ_r + IRsinφ_r)/V_r
(IRcosφ_r - IXsinφ_r)/V_r
(IXcosφ_r - IRsinφ_r)/V_r

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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)
In a test by Murray loop for ground fault on 600 m of cable having a resistance of 1.5 Ω/km, the faulty cable is looped with a sound cable of the same length and area of cross section. If the ratio of the other two arms of the testing network at balance is 3 : 1, find the distance of the fault from the testing end of cables.

300 m
400 m
100 m
200 m

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MGVCL Exam Paper (30-07-2021 Shift 2)
The voltage applied to a transformer primary is increased keeping V/f constant. With this, the core loss ____ and the magnetizing current (Im) ____

remains constant, decreases
increases, remains constant
increases, increases
decreases, increases

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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

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
increase the sensitivity of the relay

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