AC Motors
AC MOTOR THEORY
For purpose of explanation, rotation of the magnetic field is developed in Figure 2 by "stopping"
the field at six selected positions, or instances. These instances are marked off at 60° intervals
on the sine waves representing the current flowing in the three phases, A, B, and C. For the
following discussion, when the current flow in a phase is positive, the magnetic field will develop
a north pole at the poles labeled A, B, and C. When the current flow in a phase is negative, the
magnetic field will develop a north pole at the poles labeled A’, B’, and C’.
Figure 2 Rotating Magnetic Field
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