Page 711 - Basic Electrical Engineering

Example 8.3 A 3 hp, three-phase, four-pole, 400 V, 50 Hz induction motor
runs at 1440 rpm. What will be the frequency of the rotor-induced EMF?

Solution:

Synchronous speed,

Rotor speed, N = 1440 rpm
r

Slip,

Stator supply frequency, f = 50 Hz

Rotor induced EMF frequency, f = Sf
r
= 0.04 × 50

= 2 Hz

Example 8.4 The frequency of the rotor-induced EMF of 400 V, three-

phase, 50 Hz, six-pole induction motor is 2 Hz. Calculate the speed of the
motor.

Solution:

Rotor frequency, f = Sf
r
or, 2 = S × 50
or, S = 0.04

Again,