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

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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:

25 kVAR
50 kVAR
100 kVAR
75 kVAR

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MGVCL Exam Paper (30-07-2021 Shift 2)
A single phase motor connected to 415 V, 50 Hz supply takes 30 A at a power factor of 0.7 lagging. Calculate the capacitance required in parallel with the motor to raise the power factor to 0.9 lagging.

66.32 µF
76.32 µF
86.32 µF
96.32 µF

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MGVCL Exam Paper (30-07-2021 Shift 2)
A power factor less than unity results in which of the following disadvantages?
(i) Large kVA rating of equipment
(ii)Poor voltage regulation
(iii) Greater conductor size

(i), (ii) and (iii)
(ii) and (iii) only
(i) and (ii) only
(i) and (iii) only

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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) ____

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

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