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voltage defference


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#1 venkas

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Posted 05 April 2006 - 08:48 AM

i have several motors rated 3phase 460v, 60hz,100hp but the operating voltage on the syetm where they are going to operate will be 440v,60HZ. now the argument is that the same motors operating at the lower volatge than the rated volatge will be more expensive in fuel consumption...is this correct?...what happens if the system voltage go to the range of 400v....460v rated motors operating at 400v what will be economical impact???/any one help me???

#2 marke

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Posted 05 April 2006 - 09:14 AM

Hello venkas

Welcome to the forum.

Operating 460 volt motors on 440 volts will result in a higher current for the rated shaft torque. The power into the motor will increase by a small amount due to the increase in copper loss in the stator. There will also be a small reduction in iron loss due to the reduction in flux, but the copper loss increase would be higher than the iorn loss decrease.
The increase in current will be in the order of 5%, so the increase in copper loss will be 1.05 x 1.05 = 1.1025 or a 10% increase in copper loss. The opper loss on a 100HP motor is pretty small, could be in the order of 5% of the motor rating, so the copper loss may increase to somewhere in the order of 5.5% of the motor rating.
This change in energy usage is very small.

Best regards,




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