A 500V, DC shunt motor has armature and field resistance of 2.5Ω and 500Ω respectively.
When the motor run unloaded, the line current is 3A and the speed is 1200rpm. Calculate
torque Developed at full load armature current of 50A, the motor speed if the load is
constant-torque type when 3Ω resistance is added to the armature circuit and the motor
speed if the field is reduced by 15%.