Ac machines

Shaded-PoleSingle-Phase Motors

Shaded-pole motors

• are the original type of AC single-phase induction motor

• basically a small squirrel-cage motor in which the auxiliary winding is composed of a copper ring or bar surrounding a portion of each pole

• direction of rotation is from the unshaded side to the shaded (ring) side of the pole

Parts and Function• Shaded pole

• magnetic pole in an electric motor or solenoid with a shading coil that encircles a portion of the pole face

• Stator Winding• the stationary winding in an electric motor, either for rotary or linear

• End Bell• the cap at the end of the motor that houses the rotor bearing.

• Stator• is the stationary part of a rotary (electric) system or a Civil defense siren

• Shaft Bearing• is a mechanical component used to support an applied load, and

allow rotational or sliding motion between two or more parts• Rotor

• is the non-stationary part of a rotary electric motor, electric generator or alternator, which rotates because the wires and magnetic field of the motor are arranged so that a torques developed about the rotor's axis

Principle and Operation•“Starting Torque”

•the function of the shaded poles

•Out of phase magnetic field and shifting field

Speed/Load Characteristics• have low starting torque, low efficiency, medium high running current, low power characteristics, no capacitors, no starting switch and are low cost• found on small direct drive furnace blowers, window fans and other fan applications found in the residential community• motors should NOT be used to replace OTHER TYPES of single-phase motors, mostly due to the low torque and efficiency• output capability of a shaded pole motor will range from "sub-fractional HP" i.e. 1/30 HP to a maximum of 1/4 or 1/3 HP• speeds will be 2 pole (3000 RPM), 4 pole (1550 RPM) and 6 pole (1050 RPM)

Application•commonly found in applications that require light-duty fans such as small window air conditioners and exhaust fans used in rest rooms•also used in the paddlewheel-level sensor•mostly employed in small instruments, toys, small fans, electric clocks, hair dryers, ventilators, circulators etc.•best suited to low power household application because the motors have low starting torque and efficiency ratings

•compatible applications include hair dryers, humidifiers and timing devices•other applications include Microwave oven fan, cooling fan, can opener, nebulizer, oxygen concentrator, blower, mechanical and fan duty applications