A 230-V dc shunt motor has an armature-circuit resistance of 0.23. When operating from a 230-V supply

Question:

A 230-V dc shunt motor has an armature-circuit resistance of 0.23Ω. When operating from a 230-V supply and driving a constant-torque load, the motor is observed to be drawing an armature current of 60 A. An external resistance of 1.0Ω is now inserted in series with the armature while the shunt field current is unchanged. Neglecting the effects of rotational losses and armature reaction, calculate

a. The resultant armature current and

b. The fractional speed change of the motor.