The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the

The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the ratio of supply voltage to supply frequency (V/f ) constant. At rated frequency of 50 Hz and rated voltage of 400 V its speed is 1440 rpm. Find the speed at 30 Hz, if the load torque is constant 

(A) 882 rpm (B) 864 rpm (C) 840 rpm (D) 828 rpm
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Answer :

The speed of a 4-pole induction motor is controlled by varying the supply frequency while maintaining the ratio of supply voltage to supply frequency (V/f ) constant. At rated frequency of 50 Hz and rated voltage of 400 V its speed is 1440 rpm. Find the speed at 30 Hz, if the load torque is constant 

(A) 882 rpm (B) 864 rpm (C) 840 rpm (D) 828 rpm

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