Which are the must conditions to be fulfilled for the operation of an Electric Motor?

An electric motor is an electro-mechanical energy conversion device i.e converts electrical energy into mechanical energy. The motors are generally classified as:

D.C motors.
A.C motors.

Operating principle

It works on the principle of lorent'z force law i.e "Whenever a current carrying conductor placed inside a magnetic field experiences a force".

Conditions for the operation of an electric motor

For any type of motor, the two conditions are must to be satisfied. They are as follows:

There must be the interaction of two magnetic fields.
Both the magnetic field must be stationary with respect to each other i.e relative speed between two fields must be zero.
The number of stator poles and rotor poles must be same.

What happens if this conditions are not satisfied?

The operation of an electric motor depends on the presence of electromagnetic torque. The expression for electromagnetic torque is given by

Where

Now, if 1st condition is not satisfied i.e one of the above two fluxes is zero, then "Tem" torque will be zero.
Similarly, if both fields are not stationary with respect to each other then electromagnetic torque produced will be pulsating in nature i.e at one instant of time the stator poles will attract the rotor and at other instant it will repel the rotor. So, eventually the rotor will experience jerks and will not rotate.

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