Correct Answer - Option 4 :
1410 rpm
Concept:
In a three-phase induction motor, synchronous speed is
\({N_s} = \frac{{120f}}{P}\)
Where Ns = Synchronous Speed in rpm
f = supply frequency in Hz
P = number of poles
Rotor speed, Nr = Ns (1 – s)
Calculation:
Given that,
Number of poles (P) = 4
Frequency (f) = 50 Hz
The synchronous speed of the induction motor is,
\({N_s} = \frac{{120 \times 50}}{4} = 1500\;rpm\)
Slip (s) = 6 % = 0.06
Full load speed, Nr = 1500(1 – 0.06) = 1410 rpm
