Page 676 - Basic Electrical Engineering

represented by a dot. Accordingly, all the current directions have been shown
and the resultant field drawn. It is observed that for half cycle of current flow,
i.e., in time t to t , the magnetic-field axis has rotated by 180°. For one
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complete cycle of current flow, the resultant magnetic field produced will

rotate by 360° i.e., one revolution. As current continues to flow through the
three windings, the magnetic-field axis will go on rotating at a speed given by

If frequency is high, N will be high and if number of poles, P is high, N will
s
s
be low.

Figure 8.5 (a) Three-phase supply; (b) two-pole, three-phase stator winding has been drawn three
times to show the field produced at time t , t , and t , respectively
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