# Electrical Engineering Objective Questions { Induction Motors }

358. A 3-phase induction motor requires a stater

359.  For a rotor-fed 3-phase induction motor, the absolute speed of the rotating magnetic field in space is

360.  A 3-phase induction motor has a full-load slip of 3 per cent at normal voltage. Which one of the following will be the value of the slip of the motor if it develops the same torque theoretically while operating at 110 per cent of its normal voltage?

361.  A 6-pole, 3-phase, 60 Hz induction motor runs at 1000 rpm developing maximum torque. Rotor resistance per phase is 1.2 ohms. Neglecting stator impedance, then for developing maximum torque, the external resistance to be connected in series with each rotor phase will be

362. . The capacitor-start single-phase induction motors develop much larger starting torque in comparison with the "split-phase" motors, because the use of capacitors in the auxiliary winding

363. The rotor of a three-phase induction machine is replaced by a rotor with a commutator type winding having no external connection between the brushes. The stator is supplied from a balanced three-phase source and the rotor is driven at twice the synchronous speed in the direction opposite to the stator mmf. The frequency of the emf induced between consecutive brushes will be (f is the supply frequency)

364.  Which one of the following relations between starting torque 'Ts' and maximum torque 'Truax' is correct? ('a' is the ratio of rotor resistance to standstill rotor reactance)Ts

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