Shaded pole motor

Figure 1.26(a) General arrangement of a shaded pole motor... 

Shaded-Pole Motor. A shaded-pole motor is a single-phase induction motor provided with an auxiliary short-circuited winding or windings displaced in magnetic position from the main winding. This makes the motor self-starting. 

Interparticle, delayed polarization, off-axis interactions. Here, in a fashion analogous to the action of the familiar shaded-pole motor, the action of the applied field combined with that of the phase-pole motor, the action of the applied field combined with that of the phase-delayed field arising from a nearby and actively polarizing particle produces a torque upon a given cell. This cell-cell interaction can be extensive and evoke massive rotational action of many... 

Shaded-Pole Motors. Instead of a start winding, shaded-pole motors have a continuous solid-copper loop around a small portion of each salient pole (Fig. 5.107). This shading coil causes the reaction necessary to start the motor, but produces rather low starting and accelerating torque. Because of their low starting torque, shaded-pole motors are best suited to hght-duty apphcations such as direct-drive fans and blowers. Efficiency and power factor are also lower than that of other single-phase motors. 

FIGURE 5.107 Schematic and speed vs. torque diagram—ac shaded-pole motor. 

Figure 1.26(b) Shaded pole 1-(t) motor [(Courtesy AUE (GE Motors)]... 

Repeated flicking of centrifuge tubes with the finger tip is, at times, quite painful. To avoid repeated discomfort, a simple flicking device can be constructed with a shaded pole a.c. phonograph motor (cost about 3.00). The motor is screwed onto a wooden board and a cork stopper, bored slightly off-center, is fitted to the motor shaft. When in operation,... 

Univmal motor. . . Two-valuc capacitor Ji-K-T Shaded pole R olsicm motor 3-[diase squirrel cage... 

A simple and reliable starting method, used by most modem fan motors and other low torque types is the "shaded pole" configuration. In Fig. 20.7, it can be seen that a small part of the metal or ferrite pole has a single turn of heavy copper wire around it. This acts like the short-circuited secondary coil of a transformer, as previously discussed on page 108. The inductance at that edge of the pole is decreased, similar to the effect of a small capacitor. The force vectors are quite complex. 

Some of the topics covered in the book might be difficult to find in other books, including the avoidance of measurement errors caused by excessively high or low input impedances, reading electrician s (as contrasted to electronic) symbols, understanding the shaded pole ac motor, getting 208 volts from delta or wye three-phase transformers, and optimizing a PK) furnace controller. 

Since there is only one winding and the poles are already shaded at one particular end, the direction of the rotating flux is fixed and so is the direction of rotation of the rotor. The direction of rotation cannot be altered as in the earlier cases. Since there is only one winding and no need of a speed-operated centrifugal switch, these motors require almost no operational maintenance. 

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