We use the single-phase power program more widely than three phase system for domestic purposes, commercial purposes plus some extent in commercial uses. Because, the single-phase system is more economical than a three-phase program and the energy requirement in most of the homes, shops, offices are little, which can be very easily met by an individual phase system.

The single phase AC motors are further classified as:

Solitary phase speed reducer induction motors or asynchronous motors.

Single phase synchronous motors.

Commutator motors.

The squirrel cage rotor includes aluminum, brass or copper bars. These aluminum or copper bars are known as rotor conductors and placed in the slot machines on the periphery of the rotor. The copper or aluminum rings permanently short the rotor conductors known as the end rings.

To provide mechanical power, these rotor conductors are braced to the finish ring and hence form a complete closed circuit resembling a cage and therefore got its name since squirrel cage induction motor. As end rings completely short the bars, the rotor electrical resistance is very small and it is not possible to add external resistance as the pubs get permanently shorted. The absence of slip ring and brushes make the building of single phase induction motor very easy and robust.