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#1 mohamed


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Posted 27 August 2005 - 11:24 AM

We control air fan,speed between 800rpm & 3000rpm. the motor is variable speed motor.But there is low speed alarm is set at 1000rpm . Due to our operational requirement we need to operate this fan below the alarm level. I would like to know what will be the effect on the motor if we operate below 1000rpm. Is there any effect on the ABB frequency controller which is used for the speed control?

#2 marke


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Posted 27 August 2005 - 08:45 PM

Hello mohamed

Welcome to the forum.
The only major problem that I am aware of in operating at low speeds, is that the cooling on the motor is severely reduced due to the low speed of the motor cooling fan.

If the motor is over fluxed, you could over heat the motor at low speed with no shaft load. The answer is probably to try it and monitor the tmeperature rise of the motor. If this is not excessive, then you should be OK.

Some drives have a "economy" feature that reduces the flux at low speeds with pump and fan loads. This would help to reduce the heat dissipated in the motor.

Best regards,

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