We use the single-phase power program more widely than 3 phase system for household purposes, commercial purposes and some extent in industrial uses. Because, the single-phase system is more economical than a three-phase system and the energy requirement in the majority of the homes, shops, offices are little, which can be easily met by a speed reducer single phase system.

The single phase AC motors are further classified as:

Solitary phase induction motors or asynchronous motors.

Single phase synchronous motors.

Commutator motors.

The squirrel cage rotor consists of aluminum, brass or copper bars. These aluminium or copper pubs are called rotor conductors and placed in the slots on the periphery of the rotor. The copper or light weight aluminum rings permanently short the rotor conductors known as the end rings.

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