MGVCL Exam Paper (30-07-2021 Shift 1)
___ is the short time reduction in the rms voltage between 0.1 to 0.9 p.u for a duration of ___

Voltage sag, 0.5 cycle to 1 minute.
Voltage sag, greater than 1 minute
Voltage swell, greater than 1 minute
Voltage swell, 0.5 cycle to 1 minute.

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MGVCL Exam Paper (30-07-2021 Shift 1)
A single phase motor connected to 400 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.

99.5 μF
79.5 μF
89.5 μF
69.5 μF

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MGVCL Exam Paper (30-07-2021 Shift 1)
Insulation Power Factor testing on an oil-filled transformer is not helpful in determining ___

Condition of paper insulation (change in watts losses)
Whether the oil test indicates moisture
Movement of the windings (change in capacitance)
Turns ratio values

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MGVCL Exam Paper (30-07-2021 Shift 1)
The necessary equation to be solved during the load flow analysis using Fast-Decoupled methid is given below:
where B' and B'' are formed using the imaginary part of the bus admittance matrix Ybus, n is the total number of buses in the system, m is the number of voltage regulated buses. The size of matrix B' is
∆P/|Vi|= -B' ∆δ
∆Q/|Vi| = -B'' ∆|Vi|

(n-1) x (n-1)
(m-1) x (m-1)
(n-m-1) x (n-m-1)
(n-m) x (n-m)

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