Polyphase Induction Motors MCQ - Electrician (Set-1) with Answers

Polyphase Induction Motors MCQ - Electrician (Set-1) with Answers

21) If a 3-phase motor runs with two phases only, it is called single phasing. It will ultimately :

Answer is:

Burn out

22) On switching 'ON' the starter, the magnetic contractor vibrates heavily. The possible cause is :

Answer is:

low voltage and dirt between the contacts

23) A squirrel cage motor of above 3 H.P. should not be started by a D.O.L starter because :

Answer is:

the motor takes 5 to 7 times of its full load current which will spoil the starter

24) Thermal overload relays are _____ than magnetic overload relays.

Answer is:

slower

25) Which of the following reduces vibration, chattering, noise, wear and heat in the armature of a starter ?

Answer is:

Shading coil

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