MGVCL Exam Paper (30-07-2021 Shift 2)
Operating system is

a program that runs for short duration
a layer between the user and the hardware
a program that runs during log off
a program that runs during log off

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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

limit the main CT secondary current
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

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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

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

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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
decreases, increases
increases, increases
increases, remains constant

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MGVCL Exam Paper (30-07-2021 Shift 2)
A 50 Hz synchronous generator is connected to an infinite bus through a line. The p.u. reactances of generator and the line are j0.3 p.u. and j0.2 p.u. respectively. The generator no load voltage is 1.1 p.u. and that of infinite bus is 1.0 p.u. The inertia constant of the generator is 4 MW-sec/MVA. Determine the frequency of natural oscillations if the generator is loaded to 60% of its maximum power transfer capacity and small perturbation in power is given.

1.62 Hz
1.52 Hz
1.32 Hz
1.42 Hz

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