Blocked rotor test

A blocked rotor test is conducted on an induction motor. It is also known as short circuit test, locked rotor test or stalled torque test. From this test, short circuit current at normal voltage, power factor on short circuit, total leakage reactance, and starting torque of the motor can be found. The test is conducted at low voltage because if the applied voltage was normal voltage then the current through the stator windings would be high enough to overheat the windings and damage them. The blocked rotor torque test is not performed on wound-rotor motors because the starting torque can be varied as desired. However, a blocked rotor current test is conducted on squirrel cage rotor motors.