Motors

Single-Phase Motors

Single phase motors are designed to operate from a single-phase supply and are manufactured in a large number of types to perform a wide variety of useful services in homes, offices, factories, workshops, vehicles, air crafts, power tools, etc.

Single-phase motors are usually classified based on their operating principle and method of starting, such as

(1) Induction motors (split-phase, capacitor, shaded-pole etc.)

(2) Repulsion motors (some times called inductive series motors)

(3) AC series motors

(4) Synchronous motors.

The single-phase induction motor is similar to a three-phase induction motor except that its stator is provided with a single phase winding and a special mechanism employed for starting purposes (It does not develop a rotating field but a pulsating field). It has a distributed stator winding and a squirrel cage rotor. Special mechanisms are employed for starting and there are different motor types based on starting method such as 

split phase (fans, blowers, centrifugal pumps, washing machines, small machine tools, duplicating machines, domestic refrigerators)

capacitor start (small power drives)

shaded-pole (small fans, toys, instruments, hair dryers, ventilators, circulators, electric clocks)

Repulsion type motor applications include machine tools, commercial refrigerators, compressors, pumps, hoists, floor-polishing and grinding devices, garage air-pumps, petrol pumps, mixing machines, lifts and hoists. 

The ac series motor is a modified ordinary dc series motor that can be connected to an ac supply. A similar one is the universal motor, which is a small version of ac series motor. This can work with both ac and dc and used in applications such as vacuum cleaners, food mixers, portable drills and domestic sewing machines. Single-phase synchronous motors are typically used in signaling devices, recording instruments and in many kinds of timers and house hold electric clocks.