GATE EE 2014 Question Paper (01-Mar-2014) (Shift 2)

An 8 pole, 3 phase, 50 Hz induction motor is operating at speed of 700 rpm The frequency of the rotor current of the motor in Hz is _______

For a specified input voltage and frequency, if the equivalent radius of the core of a transformer is reduced by half, the factor by which the number of turns in the primary should change to maintain the same no load current is

A star connected 400 V, 50Hz, 4 pole synchronous machine gave the following open circuit and short circuit test results:

Open circuit test: $V_{OC}=400V$ (rms, line – to – line) at field current $I_f=2.3A$

Short circuit test: $I_{SC}=10A$ (rms, phase) at field current $I_f=1.5A$

The value of per phase synchronous impedance in Ω at rated voltage is ____________

The undesirable property of an electrical insulating material is

Three – phase to ground fault takes place at locations F₁ and F₂ in the system shown in the figure



If the fault takes place at location F₁, then the voltage and the current at bus A are V${}_{F1}$ and I${}_{F1}$ respectively. If the fault takes place at location F₂, then the voltage and the current at bus A are V${}_{F2}$ and I${}_{F2}$ respectively. The correct statement about voltages and currents during faults at F₁ and F₂ is