# 460 motor running on 230



## NC Plc (Mar 24, 2014)

According to the information you supplied the motor is dual voltage.


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## Vintage Sounds (Oct 23, 2009)

If the motor was grossly oversized for the load it never reached a high enough current to overheat the windings. It should still be rewired for low voltage though.


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## frenchelectrican (Mar 15, 2007)

I agree with that..

It should be reconnect for correct voltage..

Look at the motor nameplate for connection diagram i know there is two most common connection ..


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## glen1971 (Oct 10, 2012)

bkrog said:


> Hello, i have a question about a fan motor. The motor info, 2.5 HP, 208-230/460v, 3 phase, amps 5.2/2.8. The motor was factory wired for 460v. Power supply is 230v. My question is, how was the motor running for 10 years like this? The amp draw was 1.7 and motor was running slow.


How the windings are connected is the secret... I think if it was wired for 230 and you were running at 460 the magic smoke may have been let out..


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## John Valdes (May 17, 2007)

A fan motor is a variable torque application and that is most likely why it continued to run at half voltage.
At half voltage, you will not get to base speed under load and as you can see, the motor is only drawing about half nameplate current.
I have seen this happen before, accept the customer had a the motor wired in a wye configuration when they should have connected it for delta.

When I worked in the motor shop, we regularly ran motors at lower voltages than nameplate. Of course this was only done for a short period of time.
But I have seen motors run "unloaded" at half or less voltage with no apparent motor damage.


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## JRaef (Mar 23, 2009)

John Valdes said:


> A fan motor is a variable torque application and that is most likely why it continued to run at half voltage.
> At half voltage, you will not get to base speed under load and as you can see, the motor is only drawing about half nameplate current.
> I have seen this happen before, accept the customer had a the motor wired in a wye configuration when they should have connected it for delta.
> 
> ...


Yep, that's the key issue. The lack of voltage drops the available peak torque from the motor at the SQUARE of the voltage change, so at 1/2 voltage, the peak torque was only 1/4 of what it was designed for. So with such a reduced torque output, it never gets the fan to full speed, meaning it never delivers full air flow for what it was designed for. But because it is a centrifugal load, the flow IS the load, so no full flow, no full load. If the OL protection was set up for the 240V amps, the current drawn by the motor was likely below that value, allowing the motor to run like that forever. 

Of course, that entire time the fan was not delivering anywhere NEAR what it was supposed to deliver in terms of air flow, but apparently nobody noticed or because it was like that from the beginning, they were unaware that more air COULD have been flowing.


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