MGVCL Exam Paper (30-07-2021 Shift 1)
A transformer designed for operation at 60 Hz supply is working at 50 Hz supply system without changing its voltage and current ratings. Compared to the full load efficiency at 60 Hz, the full load transformer efficiency at 50 Hz.

decreases marginally
remains unaltered
increases marginally
increases by 30%

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MGVCL Exam Paper (30-07-2021 Shift 1)
Consider the following two statements and choose the correct answer.
Statement 1: The V-curves of a synchronous motor show relationship between armature current and supply voltage.
Statement 2: The plot of power factor against the field current of synchronous motor is known as inverted V curves.

Both Statement 1 and Statement 2 are TRUE
Statement 1 is TRUE and Statement 2 is FALSE
Statement 1 is FALSE and Statement 2 is TRUE
Both Statement 1 and Statement 2 are FALSE

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MGVCL Exam Paper (30-07-2021 Shift 1)
Voltage dips cannot be caused by which of the following:

Local and Remote faults
Capacitive Switching
Inductive Loading
Switching on of Large Loads

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MGVCL Exam Paper (30-07-2021 Shift 1)
The expression for voltage regulation of a short transmission line for lagging power factor is given by: ___, where, 'I' is the line current, 'V_r' is the receiving end voltage, 'R' is the line resistance and 'X' is the line reactance.

(IR cosφ_r + IX sinφ_r)/V_r
(IX cosφ_r + IR sinφ_r)/V_r
(IX cosφ_r - IR sinφ_r)/V_r
(IR cosφ_r - IX sinφ_r)/V_r

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