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Lock rotor current & Short circuit current


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#1 sethar

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Posted 10 February 2004 - 07:45 AM

I want to know the defination of lock roter current & short circuit current ? Any body can explain me through practical example / through graph or curve?

#2 marke

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Posted 10 February 2004 - 06:06 PM

Hello sethar

The Locked Rotor current is the current that flows into an induction motor when full voltage is applied and the rotor is not turning. This is the current drawn when you Full voltage start an induction motor.
As a rule, induction motors draw close to Locked rotor current until they are almost at full speed. The current at 50% speed would typically be higher than 85% Locked Rotor Current.

Short circuit current is the current that would flow if the circuit to the motor or within the motor developed a short circuit. This current is limited by the falt current of the circuit and will be many times higher than the locked rotor current of the motor. (It should be at least 10 times the LRC of the motor in the case of a feeder short)

Best regards,




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