# Voltage Questions



## william1978 (Sep 21, 2008)

Are you a electrician?


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## djn602 (Aug 12, 2009)

I am a low level maintenance person with the company.


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## mattsilkwood (Sep 21, 2008)

It's "an electrician".
:jester:


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## djn602 (Aug 12, 2009)

removed


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## william1978 (Sep 21, 2008)

mattsilkwood said:


> It's "an electrician".
> :jester:


 Ok, I won't forget the n next time.:thumbsup:


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## mattsilkwood (Sep 21, 2008)

william1978 said:


> Ok, I won't forget the n next time.:thumbsup:


 :thumbsup:


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## zgozvrm (Jun 17, 2009)

Usually, when the voltage rating of a motor is designated with a slash (such as "240/480V"), it means that the motor can be re-wired (star or delta) to run on one voltage or the other. If the voltage rating is instead shown with a dash (such as "208-240V"), it means that the motor can run with voltages within that range.

What I suspect you have is motors with nameplate voltage ratings like "208-230/460V" which means that the motor will run in the range of 208-230V when wired for low voltage (delta) or at 460V when wired for high voltage (wye). The +/- 10% factor still applies, meaning that (for low voltage), the motor should be able to run in the range of 187V (208 minus 10%) to 253V (230 plus 10%).

If your motors are actually rated as 208/230V (on the nameplate), with no 460V rating, then it is strictly one voltage or the other. In this case, the motor runs on 208V when wired low volts, and 230V when wired high. You should be able to determine which voltage it's running on by looking at the wiring diagram on the nameplate and comparing to the actual wiring.

If NONE of your motors (or other equipment) is running on 230V, then switching from 240 delta to 208 wye should be okay. This is probably not the case though, since 240V (or 230V) tends to be more common than 208V (especially with motors). Also, if any of your motors are actually rated for 240V (rather than 230V), then the -10% rating only allows for 216V and 208V would not be sufficient, whereas 230V motors would allow for voltages as low as 207V. This is so close to the 10% tolerance, that I wouldn't advise doing it.

In our plant, we run delta panels for motors and other equipment, and wye panels for lighting and controls. That way, we get the voltage we want where we want it.


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