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Motor Start

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#1 SAJ


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Posted 17 September 2011 - 12:30 PM

Normally for any induction motors i know the starting current will be high & through starters we decrease it.But i want to know what will be the starting speed if the motor starts ?

#2 marke


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Posted 17 September 2011 - 08:45 PM

Hello SAJ

Welcome to the forum.

Yes, the start current with an induction motor is very high. If the motor is Direct On Line, or Full Voltage started, the start current will be in the order of 6x - 9x the rated current of the motor.
This is a function of the motor design and terminal voltage, not the driven load.

The motor will accelerate to full speed (determined by the number of ples and the line frequency of the supply) in a period of time that is a function of the start torque generated by the motor and the total inertia of the motor and driven load.
This could be as short as one second for a pump or as long as 40 seconds for a crusher.

Best regards,

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