Electric Motor AC- A Look at Induction Motors

AC motors and DC motors differ in their power source. As the name implies, AC motors run on alternating current and DC motors run on direct current. Horsepower is the unit used for measuring the power of AC motors and rotations per minute or RPM is used for measuring speed. Of all the types of AC motors, fractional horse-power motors are the most commonly seen type.

An induction motor, also known as an asynchronous motor, is a type of electric motor AC where the electric current in the rotor is created from the electromagnetic induction produced by the stator winding’s magnetic field. This electrical current is needed to produce the torque. This kind of electric motor AC needs no excitation, either separate or self. Nor does it need any mechanical commutation for the energy conveyed from the stator to the rotor. The rotor of an induction motor are of two types: wound type or squirrel cage type.

Of the AC motors and DC motors available, three-phase squirrel-cage induction motors are very reliable, economical and rugged and find many uses in industrial drives. On the other hand, single-phase induction motors are used in household appliances. Even though these induction motors are used mainly in fixed-speed services, they are also being used in variable-speed services, with variable frequency drives.

When AC power supply is provided to an AC electric motor, whether induction or synchronous, a magnetic field is produced. The speeds of the rotor and stator are the same in a synchronous motor but they are different in an induction motor. Among AC motors, it is the huge motors which range to thousands of horse power that are used in factories. The smaller ones are used for uses appropriate to their power level. All kinds of such motors can be bought at Teco Electric Co. Ltd.