Does anyone run 208 volt 3 phase equip on 220 3 phase?

[PaulbusMax]

I am setting up a 36K BTU air conditioning unit i bought from GL a few years ago. I tested it with my MEP-003A and it works great. I'm now installing it in a 40 foot shipping container that I'm making into a small shop. I'm using a Phoenix Phase converter to produce the 3 phase. I've checked the output of the converter, and i have decent balance between the legs with a variance of maybe 2 volts. I'm reading 239 volts avg. The issue i'm having is the AC unit TM calls out 208 volts within 10 volts. Apparently my 239 volts is too much as the AC unit displays a fault light "over/under voltage". Question: Does anyone run their 3 phase 208 volt equipment off of commercial power? what issues, fixes are there to correct my issue?? Thank you.

 

[Triple Jim]

I used to run my vertical mill on 240 3 phase with a rotary converter, but the motor plate says 208-240 VAC. Any chance you could call the manufacturer and get a tech guy on the phone? You might get some information to help solve the problem. 239 is only 15% higher than 208, which normally isn't a problem for a lot of electrical equipment.

If that doesn't work, you might be able to pick up a buck-boost transformer cheaply.

 

[R Racing]

Sounds like a step down transformer would do the job. I run 3 CNC mills and 1 CNC Lathe all on phase converters in my shop. My Lathe had the same issue. So I bought a step down ( Buck / boost ) and haven't had any issues since.

 

[Triple Jim]

Just to clarify, a stepdown transformer is different from a buck-boost transformer. The stepdown supplies the full load power (voltage times current). A buck-boost, wired as a buck transformer, supplies only the load current times the buck voltage, not the full voltage. This means it can be much smaller and less expensive. In this case, you'd probably get something like a 32 volt buck-boost transformer, and that would get the 239 volts down to 207 volts.

 

[R Racing]

Then that would explain why my transformer is the size of a smart car LOL

 

[Guyfang]

If you think that the voltage difference is not toooooooooooooooooooooo great, and you got to admit the military tends to be over causes, then simply disconnect/jump the over/under relay.

Or, is it not possible to knob-dick with the volt regulator to lower the output? Might be cheaper.

 

[Triple Jim]

Excellent suggestion Guyfang, I don't know why I didn't think of that. Paul, you should be able to lower the generator output voltage by adjusting the voltage pot on the regulator board. Offhand I don't know how far down you can get it, but it will very likely get you low enough. That pot works together with the one on the generator panel to do the same thing... lower the regulator's setpoint.