An 8 pole wound rotor induction motor operating on 60 Hz supply is driven at 1800 r.p.m. by a prime mover in

An 8 pole wound rotor induction motor operating on 60 Hz supply is driven at 1800 r.p.m. by a prime mover in the opposite direction of revolving magnetic field. The frequency of the rotor current is (a) 30 Hz (b) 60 Hz (c) 120 Hz (d) 180 Hz 
by

1 Answer

Answer :

30 Hz

As the frequency of the rotor is given by 
F= N*P/120
so from the above equation the frequency of the rotor current can be easily calculated 
i.e. 1800×8/120=30
Hence the required value of rotor frequency is 30 Hz
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