Page 680 - Basic Electrical Engineering

rotor will rotate at a speed less than 1500 rpm, may be, say 1440 rpm. In such
a case slip S is

Changing the direction of rotation

It has been observed that if the sequence of the three-phase supply connected
to the three-phase stator windings is changed, the direction of the rotating

field produced will change, i.e., the field which was rotating in the clockwise
direction will now rotate in the anticlockwise direction. This has been shown
in Fig. 8.8. As shown in Fig. 8.8 (b), the connections to R- and Y-phase

supply to the stator windings have been interchanged but the connection to
phase B remains same as in Fig. 8.8 (a). The direction of rotation of the

rotating magnetic field will reverse, and hence the motor will rotate in the
opposite direction. Thus, to change the direction of rotation of a three-phase
induction motor we have to simply interchange the connections of supply of

any two phases.