EBM 510 Tutorial Questions One

First tutorial sheet on direct current drives. Questions include a constant-frequency system controlling the speed of a direct current traction motor from a 250-volt supply with combined armature and field resistance of a quarter of an ohm, average current of twenty amperes and a chopper frequency of 176 hertz, where the pulse width must be found for an average back electromotive force of 100 volts; and a chopper-controlled separately excited motor on a 220-volt supply with armature resistance of 0.2 ohms and a motor constant of 0.08 per rpm driving a constant-torque load that requires twenty-five amperes of average armature current.