Most AC motors are induction motors. Induction motors are favored due to their ruggedness and simplicity. In fact, of industrial motors are induction motors.
The natural question should arise at this point: how can the motor get started in the intended direction if it can run either way just as well?
The polyphase induction motor is the most commonly used industrial motor, finding application in many situations where speed regulation is not essential.

An induction motor can therefore be made without electrical connections to the rotor.

There are two general types of polyphase inductionmotors : the squirrel-cage type and the wound-rotor machine.

The three phase induction motor is the most widely used electrical motor. Almost of the mechanical power used by industries is provided by three phase induction motors because of its simple and rugged construction, low cost, good operating characteristics, absence of commutator and good speed regulation.














