We use the single-phase power program more widely than three phase system for household purposes, commercial purposes and some extent in commercial uses. Because, the single-phase system is less expensive than a three-phase program and the energy requirement in the majority of the houses, shops, offices are small, which can be easily met by a single phase system.
The single phase AC motors are further classified as:
Single phase induction motors or asynchronous motors.
Solitary phase synchronous motors.
The speed reducer squirrel cage rotor contains aluminum, brass or copper bars. These light weight aluminum or copper bars are called rotor conductors and placed in the slot machine games on the periphery of the rotor. The copper or aluminium rings permanently short the rotor conductors called the end rings.
To provide mechanical strength, these rotor conductors are braced to the end ring and therefore form a complete closed circuit resembling a cage and therefore got its name because squirrel cage induction motor. As end rings permanently short the bars, the rotor electrical level of 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 structure of single phase induction motor very simple and robust.