Electrical Engineering Objective Questions { Induction Motors }

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232. Which of the following statements regarding repulsion-start induction motor is incorrect?

A. It requires more maintenance of comutator and other mechanical devices

B. It makes quite a bit of noise on starting

C. In fractional horse power motors, it has replaced the capacitor motors

D. It is not easily reversed

233. A.C. series motor as compared to D.C. series motor has

A. smaller brush width

B. less number of field turns more number of armature turns

C. all of the above

D. none of the above

234. Locked rotor current of a shaded pole motor is

A. equal to full load current

B. less than fullload current

C. slightly more than full load current

D. several times the full load current

235. Speed control of a universal motor achieved by

A. varying field flux with tapped field windings

C. extermely sensitive to

D. all of the above methods

236. Hysteresis motor is particularly useful for high-quality record players and tape-recorders because

A. it revolves synchronously

B. it is not subject to any magnetic or mechanical vibrations

C. it can be easily manufactured in extremely small sizes of upto 1 W output

D. it develops hysteresis torque which is extremely steady both in amplitude and phase

237. Which of the following statements regarding hysteresis motor is incorrect?

A. It is fluctuations in supply voltage

B. Its high starting torque is due to its high rotor hysteresis loss

C. It is extremely quite in operation

D. It accelerates from rest to full-speed almost instantaneously

238. Which of the following statements regarding single-phase induction motor is correct?

A. It requires only one winding

B. It can rotate in one direction only

C. It is self-starting

D. It is not self-starting

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