Electric motor

 

                           Electric motors

Introduction-An electric motor is an electrical machine that convert electrical energy into mechanical energy those use in pump , fan and other equipment .

Type of motors-mostly two type motor use in electrical field .

·      A.C motors

·      D.C motors

Today we are discuss about a.c motors

                              A.C motors

 An a.c motor is the most commonly used in industrial application. Its is work on alternating current. Its using an electromagnetic induction phenomenon. The motor may be single phase or three phase. The three phase motor are mostly applied in the industry for bulk power conversion. For small power conversion the single phase a.c motor are used. In motor all part cover in main housing. In a front of motor a shaft is available those provide mechanical energy, in end  of motor fan is available for cooling propose because the induction motor can produce a lot of heat when in operation. So fan blown ambient air over the casing to cool down. If the induction motor becomes to hot the winding insulation melts , causing a short circuit and fire.fins increase surface area allowing more unwanted heat to be removed .motor shaft is  run with the help of bearing smoothly , that bearing install in the front shield and end shield of motor.

            In housing there are two main part .

·      Stator

·      Rotor

stator is static part of the motor it is installed in the motor casing. It is make with copper wire, copper wire wrapped and make a coil that is called stator winding. It is positioned around inner perimeter, this copper wire is cover with enameled. In a electric motor , the stator provide a rotating magnetic field .

          rotor is a rotating component of an electromagnetic system in the electric motor.

There are two type of rotor in a.c machine

    Squirrel cage rotor

    Wound type rotor or slip ring type rotor

 In a three phase induction motor every coil have two end point those connect with electrical terminal box at the top and output rotating shaft on the left ,when current flow through in wire, wire generates electromagnetic field . The magnetic field of the wire interacts with the magnetic causing movement. wire move upward or downward depending on direction of current and polarity of current then the rotor is start to run,

Its rotation is due to the interaction between the winding and the magnetic field which produces a torque around the rotor’s axis.

Advantages of a.c motors- three-phase induction motor is the most commonly used motor in industrial application because of the advantage listed below:

Simple design

Rugged construction

Reliable operation

Low initial cost

High efficiency

Easy operation and simple maintenance