Three Phase Motors

Three-phase motors (also annotated numerically as 3-phase motors)

are widely used in industry and have

become the workhorse of many mechanical

and electromechanical systems because of their relative

simplicity, proven reli

ability, and long

service life. Three-phase motors a

re one example of a type of induction

motor, also known as an asynchronous motor,

that operates using the principals of electromagnetic

induction. While there are also single-phase induction

motors available, those types of induction motors are

used less frequently in industrial applications but are

widely used in domestic applications such as in vacuum cleaners, refrigerator compr

essors, and air conditioners, owing to the use of single-phase

AC power in homes and offices. In this article, we will discuss

what a three-phase motor is and describe how it operates.

To access other resource

s ab

out motors, consult one of our other motor guides covering

article on the types of motors. A full list of related motor articles is found in the section on related articles.

How does a 3-Phase Motor Work?

Three-phase motors operate by the

principle of electromagnetic induction

which was discovered by the English

physicist Michael Faraday back in 1830. Faraday

noticed that when a conductor such as a coil or

loop of wire, is placed in a changing magnetic field,

there is an induced electromotive force or EMF that

is generated in the conductor. He also observed that

current flowing in a conductor such as wire will generate

a magnetic field and that the magnetic field will vary

as the current in the wire changes in either magnitude

or direction. This is expressed in mathematical form by

relating the curl of the electric field to the rate of change

in time of the magnetic flux: