Shaded-Pole Motor

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shaded-pole motor

[′shād·əd ¦pōl ′mōd·ər]
A single-phase induction motor having one or more auxiliary short-circuited windings acting on only a portion of the magnetic circuit; generally, the winding is a closed copper ring embedded in the face of a pole; the shaded pole provides the required rotating field for starting purposes.

Shaded-Pole Motor


a squirrel-cage induction motor in which a rotating magnetic field is created by the field winding (FW) and a short-circuited winding (SW) that encircles a part of each stator pole (Figure 1). The pulsating magnetic flux produced by FW induces currents in SW that, according to Lentz’s law, cause the pulsating magnetic flux through SW to be delayed compared with the other portion. This is the shading effect of SW. The rotor turns under the influence of the magnetic field that is created by the magnetic fluxes from the shaded and unshaded parts of the stator poles as a result of the displacement of the flux axes by angle θ and of the pulsation of the fluxes with the time lag.

Figure 1. Cross section of a shaded-pole motor: (FW) field winding, (SW) short-circuited winding, (θ) angle between the axes of the magnetic fluxes from the shaded and unshaded parts of the stator poles

Shaded-pole motors are used to drive tape recorders, record players, table fans, and other equipment for which a power of 20–300 watts is sufficient.


Vol’dek, A. I. Elektricheskie mashiny, 2nd ed. [Leningrad] 1974.
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