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.

remains unaltered
increases marginally
decreases 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.

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

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MGVCL Exam Paper (30-07-2021 Shift 1)
The current flowing to a balanced delta connected load through line 'a' is 15 A when the conductor of line 'b' is open. With the current in line 'a' as reference, compute the symmetrical components of the line currents. Assume the phase sequence of 'abc'.

Ia₀ = 0 AIa₁ = (-7.5 - j13) AIa₂ = (-7.5 - j4.33) A
Ia₀ = 0 AIa₁ = (7.5 - j13) AIa₂ = (7.5 + j13) A
Ia₀ = 0 AIa₁ = (7.5 + j4.33) AIa₂ = (-7.5 - j4.33) A
Ia₀ = 0 AIa₁ = (7.5 + j4.33) AIa₂ = (7.5 - j 4.33) A

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