The procedure to find out the separate losses from no-load test of an induction motor is as follows: The readings noted at normal voltage, and at rated frequency are considered to find out the fixed core losses.Ĭalculation from No-Load Test of Induction Motor Therefore, total power consumed = rotor iron loss + stator iron loss + copper loss in stator + friction and windage loss This can be neglected since the stator current is very small. A small amount of copper loss is also occurring in stator winding. Losses are occurring in iron core of the stator as well as the rotor which are called core losses. Since the motor is not loaded so input power absorbed by the motor is providing losses only. From this curve windage and friction losses are determined. The signs of readings are taken with various values of applied voltage and then curve is plotted against power and input voltage. To understand the concept properly, you should read also the power measurement in three phase circuits by two watt meter method. Total power drawn by the motor is the difference of the two wattmeter readings. of the motor is low less than 0.5, so one of the watt meters will give negative reading. Since the motor is running without load, p.f. On the mains side suitable instruments are connected between supply mains and motor terminals to measure power, line current and line voltage.įor power and power factor measurement, two single phase watt meters are used. The machine is started in the usual way and runs unloaded from normal voltage mains. The set up for no load test of induction motor is shown in the figure. This test tells us the magnitude of constant losses occurring in the motor.
The no load test of 3 phase induction motor is performed on induction motor when it is running without load.
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