Consider a DC series motordesigned to operate with VS = 200 V. Suppose the rotorresistance is 0.40 ohms. and the field coil resistance is0.10 ohms . An RPM measurement reveals that when the line currentis 35 A when the motor is spinning at n = 500 RPM. Assume that thebrush-commutator assembly has an RPM-independentvoltage drop of 2 volts and that the field flux is proportional toIrotor(i.e. Φ =α Irotor).
(i) Draw and label the equivalent circuit for these motor conditions
(ii) When the load is changed the line current decreases from 35 A to 20 A.Determine the new rotor RPM.