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Home The Polyphase Induction Motor Speed of an Induction Motor  
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Speed of an Induction MotorAuthor: E.E. Kimberly It has just been shown that in twothirds of one cycle the magnetic field rotated through twothirds of one revolution. With a frequency of 60 cycles, the field would rotate 60 times per second and 3600 times per minute. In one cycle the field moves through 360 electrical degrees. Since there are 360 electrical degrees for every two poles around the winding, a fourpole motor contains 720 electrical degrees; so two cycles are required for every revolution of the field. Hence, a fourpole motor runs only onehalf as fast as a twopole motor. A few common synchronous speeds for 60cycle motors are given in the following table.
Rotating fields for motors with two, four, and six poles are shown in Fig. 188.


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