List of top Electrical Machines Questions on DC Motor asked in GATE EE

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)
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.)