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.

1.42 Hz
1.62 Hz
1.32 Hz
1.52 Hz

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MGVCL Exam Paper (30-07-2021 Shift 2)
The line currents in amperes in phases a, b and c respectively are 500 +j150, 100 – j600 and – 300 + j600 referred to the same reference vector with phase sequence of abc. Find the symmetrical component of currents.

Ia₀ = (100+j50) AIa₁ = (546.41+ j165.47) AIa₂ = (546.41-j165.47) A
Ia₀ = (100+j50) AIa₁ = (546.41+j165.47) AIa₂ = (-146.41-j65.47) A
Ia₀ = (100+j50) AIa₁ = (146.41+ j65.47) AIa₂ = (546.41-j165.47) A
Ia₀ = (100+j50) AIa₁ = (200+ j107.75) AIa₂ = (200-j107.75) A

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

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MGVCL Exam Paper (30-07-2021 Shift 2)
In transformer, a Sweep Frequency Response Analysis (SFRA) test will help detect ____

Moisture in the windings
Movement / damage to internal components
Age of the insulation
Aging by-products

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