What is the primary effect on a 3-phase motor\'s operation when a locked-rotor c

Question

What is the primary effect on a 3-phase motor's operation when a locked-rotor condition exists? Excessive slip in the rotor Excessive counter-EMF due to increased inductive reactance in the field coils Excessive starting current in the commutator Excessive starting torque in the stator Which of the following types of rotors would not be found in a 3-phase induction motor? Permanent-magnet rotor Squirrel-cage rotor Wound rotor None of the above Which of the following is used to make a connection to a squirrel-cage rotor in an AC motor? Commutator Slip rings Stator windings None of the above Which of the following is the most necessary for proper operation of all AC induction motors? Rotating field Commutator Slip rings Interpoles (also known as commutating poles) Which of the following best describes the operation of a wound-rotor Induction motor which slip while connected to a 120VAC 60Hz source? There will be arcing/sparking at the slip rings The slip w

Explanation / Answer

a)When a locked rotor condition exists current will get increased in the commutator. The torque and the velocity of the rotor get reduced also.

b)The rotor of the three phase induction motor are further classified as

Squirrel cage rotor,

Slip ring rotor or wound rotor or phase wound rotor.

Mainly squirrel cage rotor is using

c)The squirrel cage motor is mostly started by star – delta stater and hence the stator of squirrel cage motor is delta connected. It is connected by stator windings

d) Each part is important in the motors. But the most important part is I think rotating field. Interpoles is designe in DC motors

e) There will be arcing at the slip rings when the voltage is increased.

e)

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