List of top Electrical Machines Questions asked in GATE EE

A 20 MVA, 11.2 kV, 4-pole, 50 Hz alternator has an inertia constant of 15 MJ/MVA. If the input and output powers of the alternator are 15 MW and 10 MW, respectively, the angular acceleration in mechanical degree/s\(^2\) is _________. (round off to nearest integer)
A 280 V, separately excited DC motor with armature resistance of 1 \(\Omega\) and constant field excitation drives a load. The load torque is proportional to the speed. The motor draws a current of 30 A when running at a speed of 1000 rpm. Neglect frictional losses in the motor. The speed, in rpm, at which the motor will run, if an additional resistance of value 10 \(\Omega\) is connected in series with the armature, is ________. (round off to nearest integer)
The frequencies of the stator and rotor currents flowing in a three-phase 8-pole induction motor are 40 Hz and 1 Hz respectively. The motor speed, in rpm, is ________. (round off to nearest integer)
The type of single-phase induction motor, expected to have the maximum power factor during steady state running condition, is

The correct combination that relates the constructional feature, machine type and mitigation is \(\underline{\hspace{2cm}}\). 

An 8-pole, 50 Hz, three-phase, slip-ring induction motor has an effective rotor resistance of 0.08 \(\Omega\) per phase. Its speed at maximum torque is 650 RPM. The additional resistance per phase that must be inserted in the rotor to achieve maximum torque at start is \(\underline{\hspace{3cm}}\) \(\Omega\). (Round off to 2 decimal places.) Neglect magnetizing current and stator leakage impedance. Consider equivalent circuit parameters referred to stator.
A DC shunt generator running at 300 RPM delivers 100 kW at 200 V. When belt breaks, it becomes a motor taking 10 kW from 200 V supply. Armature resistance = 0.025 \(\Omega\), field resistance = 50 \(\Omega\), brush drop = 2 V. Neglect armature reaction. Speed of motor is \(\underline{\hspace{2cm}}\) RPM. (Round off to 2 decimals.)
In a single-phase transformer, total iron loss is 2500 W at 440 V, 50 Hz. At 220 V, 25 Hz, the iron loss is 850 W. Find hysteresis and eddy current losses at nominal voltage and frequency.
An alternator with internal voltage and reactances is delivering 0.866 p.u real power. Find (δ₁ − δ₂). (Round to 2 decimals).
A 500 V, 50 Hz, 3-phase induction motor receives 40 kW input. Stator losses = 1 kW, friction and windage losses = 2.025 kW. Efficiency = \(\underline{\hspace{2cm}}\) %.