What is locked rotor current

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 amps that an electric motor draws for about half a second that are about 5X the normal amp draw of the motor are called locked rotor amps. The current through the motor is proportional to the torque produced by the motor.

The term Locked rotor current usually used in blocked rotor condition. It is the current drawn by the motor when the load applied is heavier such that the motor stops rotation. The starting current is the initial current flow into the motor which is usually very high and controlled by using starters.

Is Locked Rotor the starting current? Locked rotor current is basically the current drawn by the motor at its rated voltage when its rotor is kept stationary or in other words rotor is not spinning or rotating. So when we start a motor, its rotor is already at rest.

This means, starting current and locked rotor current should be same. What does locked rotor torque mean? This means, starting current and locked rotor current should be same. No, it is not so. See, motor can be started using one of the various starting methods. If the motor is started using Direct Online DOL method, then the voltage applied at its terminal will be rated voltage of motor. As the rotor is at rest during starting and voltage is rated voltage, the starting current will be equal to locked rotor current.

Ben Davis February 24, What is the locked rotor current? How many amps does a 3 ton air conditioner use? How do you calculate locked rotor amps? Should a motor run at FLA? What does FL Amps mean? What is the difference between full load amps and locked rotor amps? What is locked rotor amps used for? How do you lower lock rotor current? What causes locked rotor amps? Is locked rotor current the same as inrush current? Follow What is the difference between locked rotor current and starting current?

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