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Phase Sequence

Author: E.E. Kimberly

In Fig. 9-1 (a), the emf in conductor 1 is at its maximum value. After 120 degrees more of rotation, the emf in conductor 3 will be maximum in the same sense. After an additional 120 degrees the emf in conductor 2 will be maximum in like sense.

The emf's in these conductors are said to have a phase sequence of 1, 3, 2. If the direction of rotation were reversed, the phase sequence would be 1, 2, 3. The phase sequence of a three-phase power source is important in the application of three-phase induction and synchronous motors described in Chapters 18 and 19 because the direction of rotation of such motors is determined by the phase sequence of the applied voltages.

Last Update: 2010-10-05