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Motor Current


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#1 honeywell

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Posted 24 February 2004 - 09:27 PM

I have a motor connected to a pump for low pressure hot water (62 dec c) on the data plate the motor says 400V 50Hz 1450 rpm 7.5Kw 0.82cos 15.20 amps delta connection. But when I connect my clamp on amp meter the current drawn is 18 amps why is this when the motor is rated at 15.20 amps is this rating not true power??

Thanks for any help


Paul Kav
Honeywell Controls

#2 marke

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Posted 25 February 2004 - 04:53 AM

Hi Paul

I would not continue to run the motor under those conditions. The motor is probably undersized for the pump.
The current on the nameplate, is the highest current that you should run the motor continuously. Operation at a higher current will result in increased heating and therefore a premature failure. You can reduce the load on the motor by reducing the flow of the hot water. This can be achieved by slighlty closing a valve on the outlet of the pump, or by fitting an orrifice plate on the output of the pump. (this will increase the pressure seen by the pump and reduce the flow, reducing the power drawn from the motor. If the pump is not a centrifugal design, then you may need to slow it down to reduce the loading.

Best regards,




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