The

**exact equivalent circuit model**of an**Induction motor**iswhere

R1 is the stator resistance per phase

X1 is the stator reactance per phase

R2' is the equivalent rotor resistance referred to stator per phase

X2' is the equivalent rotor reactance referred to stator per phase

Rc is the resistance representing core losses

Xm is the magnetizing reactance per phase

V1 is the per phasesupply voltage to the stator

s is the slip of the motor

**Power flow in an Induction motor**

From the circuit, we see that the total power input to the rotor Pg is

The power flow diagram is-

The power flow diagram is-

**Source**

http://powerlearn.ece.vt.edu/modules/PE2/index.html

**How the efficiency of induction motor is measured?**

**Abstract**

The efficiency is of paramount importance nowadays due

to increasing electrical energy demand, increasing awareness of

environmental problems as greenhouse effects and increasing

fossil fuel prices.

This paper tries to show the different results between the

standards for efficiency evaluation and the necessity of

harmonization worldwide. Then, it is going to be explained the

different standards for measurement of efficiency, and the main

differences between the standards (IEEE 112, IEC 60034-2 and

JEC-37).

To complete this study, it is going to be described the steps

in order to estimate efficiency on the jobsite and expressed the

different efficiency labels motors.