# Gurus...will a 200 volt motor be ok at 230v?



## Barncat (Jun 21, 2020)

I need to up the size of my rotary phase converter for a new piece of equipment. I have seen some 3 phase 200 volt, 60hz motors for sale for fairly cheap compared to 230 volt rated. Does anyone know if a 200v motor can work and survive at the higher voltage. After the balancing caps are added, I think my voltage will be close to 242 volts. Will the 200 volt motor be ok as part of an RPC build, since there really won’t be a load on the motor?


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## Ulma Doctor (Jun 21, 2020)

generally speaking you can go 15% + or -
the 200v motor will be overexcited and run a little warmer, but i think you'll be ok for a RPC


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## Chipper5783 (Jun 21, 2020)

Yes, it will be fine.  It is even sort of odd that the motor would be listed as rated for 200V.  Strictly speaking, 200V would be a very odd 3 phase supply voltage(208, 220, 240V would all be much, much more common).  Perhaps it was simply labelled a generic "200V"?  My 3 phase system runs very close to 240V (now on a phase perfect) and I have motors variously from 208 to 240 and all seem to run fine.

I suspect a more significant issue would be the phase to phase voltage variation and power factor - getting VARS circulating (volt amps reactive).  I suggest you current clip each phase, stay within the current capacity (on each phase) and you won't have an issue.


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## Dabbler (Jun 21, 2020)

just a quick comment on 200V versus 208, etc.  Depending on how the supply is wired, the voltages could vary:  It is rather technical, and I'm not an expert, but a 200V motor is probably  a delta wired motor expected to be wired to a delta mode supply (instead of a Y mode).  The reality of the situation is that unless you intend to fully load the motor, or run it for very long run times you should be fine.

When you run a 208 motor on a 240V supply that delivers 230V RMS (240V is the nominal peak-to-peak voltage), it tends to run warmer than a perfectly matched motor.


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## Barncat (Jun 21, 2020)

I have read the 200 v rating is a Japanese spec. Although I don’t know if this is true.


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## rwm (Jun 21, 2020)

Dabbler said:


> just a quick comment on 200V versus 208, etc.  Depending on how the supply is wired, the voltages could vary:  It is rather technical, and I'm not an expert, but a 200V motor is probably  a delta wired motor expected to be wired to a delta mode supply (instead of a Y mode).  The reality of the situation is that unless you intend to fully load the motor, or run it for very long run times you should be fine.
> 
> When you run a 208 motor on a 240V supply that delivers 230V RMS (240V is the nominal peak-to-peak voltage), it tends to run warmer than a perfectly matched motor.


It is my understanding that for single phase power the indicated voltage is RMS, not peak. For three phase power is the peak voltage specified or is it again RMS? Just clarifying for future reference.
Robert


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## kb58 (Jun 21, 2020)

RMS in both cases. For those who are wondering, RMS essentially means "average ac voltage" (the equivalent energy of DC). Peak voltage will be 1.414 times higher.


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## CluelessNewB (Jun 21, 2020)

200V motors were common on machines used in schools with 208V 3 phase supply.  They work fine with many modern VFD's that allow you to program the motor voltage.


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## Ulma Doctor (Jun 21, 2020)

i have had to swap out old Baldor grinder motors that came from baldor with 200v nameplates, for use in the USA
they are running on 208 Wye supply and may do so for 20 years or so


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