Wednesday, April 1, 2009

Power flow in an Induction motor

The exact equivalent circuit model of an Induction motor is


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-


How the efficiency of induction motor is measured?

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

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.

Figure 2.1 – Typical Power flow of standard motors

More pdf

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