# 208 3ph running 240v single phase motors



## Almost Retired (Sep 14, 2021)

Phillipd said:


> We were at a potato farm today,they are serviced with 208 3ph and much of their equipment has 208-230v 1ph motors. Are the phases on 3 ph not 120 degrees out of phase and single phase 240 is 180 degrees. Wouid running them on 208 with only 2 phases not shorten the life of the motors and make them run rougher? Seems like a ars first idea to me?


if you meant to say bad idea ? I agree


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## wiz1997 (Mar 30, 2021)

Are there any VFD's controlling the motors?


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## Phillipd (Jan 7, 2020)

wiz1997 said:


> Are there any VFD's controlling the motors?


There’s vfd’s running the 3ph ones for speed control but they are running 2 phases 210v on the single phase


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## gpop (May 14, 2018)

Phillipd said:


> We were at a potato farm today,they are serviced with 208 3ph and much of their equipment has 208-230v 1ph motors. Are the phases on 3 ph not 120 degrees out of phase and single phase 240 is 180 degrees. Wouid running them on 208 with only 2 phases not shorten the life of the motors and make them run rougher? Seems like a ars first idea to me?



You are looking at how its made rather than how its used.

Yes 208 is 2 legs of a 3 phase Y 120 degrees out of sync. The motor does not see 2 phases it see's the voltage pressure between the 2 phases.

Im not sure who owns this image or if linking this way works but if it does the black line explains what the motor is seeing. The red and blue line are the 2 phases used to produce the black wave. 



https://uploads.tapatalk-cdn.com/20181104/d083976f19a663b6382be6626d368376.jpg


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## micromind (Aug 11, 2007)

I've connected over 100 115/230 and 115/208-230 single phase motors to 208 systems. 

The only issue I've ever had is the cheap chintzy 50,000,000 HP (runs on standard house current) air compressors have a hard time starting when its cold (like 20F). Otherwise no trouble at all.


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## Phillipd (Jan 7, 2020)

micromind said:


> I've connected over 100 115/230 and 115/208-230 single phase motors to 208 systems.
> 
> The only issue I've ever had is the cheap chintzy 50,000,000 HP (runs on standard house current) air compressors have a hard time starting when its cold (like 20F). Otherwise no trouble at all.


Haha thank you all, I’ll chalk it up to another day something learned!


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## 460 Delta (May 9, 2018)

micromind said:


> I've connected over 100 115/230 and 115/208-230 single phase motors to 208 systems.
> 
> The only issue I've ever had is the cheap chintzy 50,000,000 HP (runs on standard house current) air compressors have a hard time starting when its cold (like 20F). Otherwise no trouble at all.


Is that Metric HP, or Freedom HP?


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## micromind (Aug 11, 2007)

460 Delta said:


> Is that Metric HP, or Freedom HP?


Since metric hasn't got the intelligence to rate motors in HP, I guess it'd have to be Freedom.........

I just don't get it, IEC motors are rated in KW, not HP. KW is a measurement of electrical energy, not mechanical. Further, is it input power or output?

Since it's output KW, I guess it'd be easy to calculate efficiency. 

Idiots......


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## Forge Boyz (Nov 7, 2014)

micromind said:


> Since metric hasn't got the intelligence to rate motors in HP, I guess it'd have to be Freedom.........
> 
> I just don't get it, IEC motors are rated in KW, not HP. KW is a measurement of electrical energy, not mechanical. Further, is it input power or output?
> 
> ...


Oh but it is so much better. Especially if you call it SI instead of metric. Then you can really puff your chest out.

Sent from my SM-G970U using Tapatalk


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