Exam Question

(a) Sketch a graph of starting current and torque against speed of rotation for a single cage motor (6)

(b) A 230V motor, which normally develops 10kW at 1000 rev/min with an efficiency of 85 percent, is to be used as a generator. The armature resistance is 0.15 ohm and the shunt feild resistance is 220 ohm. If it is driven at 1080 rev/min and the field current is adjusted to 1.1A, by means of the shunt regulator, what output in kW could be expected as a generator, if The armature copper loss was kept down to that when running as a motor (10)