MGVCL Exam Paper (30-07-2021 Shift 2)
In a 3-phase, 4-wire, 400/230 V system, a lamp (L1) of 100 W is connected to one phase and neutral and a lamp (L2) of 150 W is connected to the second pahse and neutral. If the neutral wire is disconnected accidently, then

both 100 W lamp (L1) and 150 W lamp (L2) becomes dim
100 W lamp (L1) becomes brighter and 150 W lamp (L2) becomes dim
100 W lamp (L1) becomes dim and 150 W lamp (L2) becomes brighter
both 100 W lamp (L1) and 150 W lamp (L2) becomes brighter

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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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