Blocked Rotor Test On Induction MotorThis test is also called as Locked Rotor test or short circuit test.In the previous articles we had discussions on construction of induction motor,working of induction motor.We know induction motor is functionally similar to transformer.Like short circuit test on transformer blocked rotor test on induction motor is conducted.
Quick Point: Blocked rotor test on induction motor is to find out stator copper loss, rotor copper loss without friction and windage losses.
Procedure of Blocked Rotor Test of Induction Motor
1.First block the rotor of induction motor by pulley-belt mechanism.
2.Apply 10 to 15 % of rated voltage to stator of induction motor.(Because if we apply even more than 30% rated voltage rotor will be short circuited.)
3.Now, slowly increase the voltage in the stator winding so that current reaches to its rated value. At this point, note down the readings of the voltmeter, wattmeter and ammeter to know the values of voltage, power and current.
4.Now the applied voltage Vsc, the input power Wsc and a short circuit current Isc are measured.
As RL' = 0, the equivalent circuit is exactly similar to that of a transformer and hence the calculations are similar to that of short circuit test on a transformer.