# 460 v single phase motor



## Zog (Apr 15, 2009)

Whaty were the meg readings and DAR?


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## John Valdes (May 17, 2007)

European motor? IEC? 460 volt single phase?


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## mightyjoe (Sep 20, 2010)

The megger was good. We had several motors tested in our shop and found the same readings.


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## j johnson (Jul 20, 2009)

That sounds like a 3 phase motor not a 1 phase


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## retiredsparktech (Mar 8, 2011)

mightyjoe said:


> Recently I was asked a question by one of our service techs regarding ohming out a 460v single phase motor. Readings were taken with both Simpson 260 and a Fluke 87. The ohm readings were S-C 16,R-C 16,S-R 17. Typicallly you would expect S-R to equal S-C + R-C. I am suspecting the common lead has a winding in series with it. Does anyone have any more info for me? How would you trouble shoot this type of motor?


What is the application of this motor? The only single phase 460V motors I've seen are condensor fan motors for larger type air conditioners. Is there a capacitor used with this motor?


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## Vintage Sounds (Oct 23, 2009)

retiredsparktech said:


> What is the application of this motor? The only single phase 460V motors I've seen are condensor fan motors for larger type air conditioners. Is there a capacitor used with this motor?


Just curious, why would they bother with a single phase motor if the machine is 3 phase anyway? Because a 2 pole contactor is cheaper than 3 pole?


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## retiredsparktech (Mar 8, 2011)

Vintage Sounds said:


> Just curious, why would they bother with a single phase motor if the machine is 3 phase anyway? Because a 2 pole contactor is cheaper than 3 pole?


That's one of the many mysteries working on this equipment. Probably because of rotation issues. Any reciprocating compressors are not phase sensitive.


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## MDShunk (Jan 7, 2007)

Those readings make me think those were more like each of the three phases, rather than start, run, and common. Are you sure this is a 460V, single phase motor? 

Think about this.... is it possible that, on the controls end, it's fed with single phase, but they're using caps for some phase shift to manufacture a third phase to feed a three phase motor, thus assuring that the rotation is always correct?

Is it also possible that this is a 3-phase motor, fed with single phase, and has some caps and a potential relay to get it running on "3-phase", then they drop out and it runs as single phase at 66% of nameplate capacity?


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## retiredsparktech (Mar 8, 2011)

The OP still didn't specify what these motors are used in.


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## mightyjoe (Sep 20, 2010)

MDShunk said:


> Those readings make me think those were more like each of the three phases, rather than start, run, and common. Are you sure this is a 460V, single phase motor?
> 
> Think about this.... is it possible that, on the controls end, it's fed with single phase, but they're using caps for some phase shift to manufacture a third phase to feed a three phase motor, thus assuring that the rotation is always correct?
> 
> ...


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