Equivalent Circuit Of Induction Motor.
The induction motor works based on the working of the
transformer. That is why it is also called a rotating transformer. When we
provide electromagnetic power to the stator of an induction motor, a voltage is
induced in the rotor as a result of electromagnetic induction.
{tocify} $title={Table of Contents}
In the induction
motor, the stator is the primary side of the transformer and the rotor is the
secondary side of the transformer. So the equivalent circuit of the induction
motor is a lot like a transformer.
The induction motor always runs at a slower speed than the
synchronous speed. And the relative difference between synchronous speed and
rotor speed is called slip of induction motor. It is expressed by S.
S=(Ns-N)/Ns
Here is the synchronous speed of the NS
induction motor.
Ns=120f/P
P = number of poles of induction motor.
f = frequency of supply voltage
What is the equivalent circuit?
The circuit by which all the parameters and losses of the
machine can be expressed is called an equivalent circuit. Machine losses are
usually expressed with the help of inductors or resistors. You can read this
article to know about the loss of the induction motor.
All parts of the motor and their power losses are illustrated
by the equivalent circuit. Below is an equivalent circuit of induction motor (considering
1 phase).
Here,
R1 = stator is the resistance of its coil
X1 = stator Inductionance of its coil.
RC = core loss.
XM = Coil Magnetizing Reactance.
R2 / S = power of the rotor. The output power and the copper
loss of the motor is connected.
If we draw the equivalent circuit by pointing to the stator,
it will be as follows:
Here,
R2 ’= indicating the stator is the resistance of the rotor to
its coil.
X2 '= Indicance of the rotor's coil indicating the stator.
R2 (1 - S) / S = Output power. This register indicates the
power of the motor which is converted into mechanical power.