208 3 phase to 230v 3 phase

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HipHopHead

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NJ
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Electrical contractor
I have 208 - 3 phase and was wondering if anyone had ideas on the most cost efficient way to boost to 230v for a vfd controller. Circuit draws approximately 25 amps.

thanks for any input
 
The only potential concern I can think of is if the motor will be operated on bypass and it is unusually voltage sensitive.

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I have a contractor telling me that he needs 230v And 208 is no good.It’s water to an open school on the line. I actually have 215 phase to phase. Is he full of it?
 
oldsparky52 said:
Could be. Did he say why he could not get by with 208?
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He didn’t. I didn’t have that kind of time so I’m faced with a) roll the dice, I know there’s a good chance 208 is fine, although I may have to upsize the wire to be safe. And if it doesn’t work I’m an ass and there is no water. Or B) find a cost efficient way to get to 230-240 and not think about it again🤷🏼‍♀️.
 
HipHopHead said:
He didn’t. I didn’t have that kind of time so I’m faced with a) roll the dice, I know there’s a good chance 208 is fine, although I may have to upsize the wire to be safe. And if it doesn’t work I’m an ass and there is no water. Or B) find a cost efficient way to get to 230-240 and not think about it again🤷🏼‍♀️.
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If you don't need the neutral, a couple of buck boost transformers will probably be the least expensive way to get what you need assuming this is just one load you are talking about.

ETA: If you are feeding a VFD, others will tell you if there are problems with using BB transformers on 2 legs (might be).

But if this is a time crunch, not sure what will work. I would sure check out the VFD and nail down the why 208 won't work.

Make the person demanding 230 sign off on what you do (if you can).
 
That’s only 6% low on a motor designed to run 10% low..
If the VD isn’t too bad I’d say your about in the sweet spot
 
Unless the motor will actually run at full load, full speed for significant amounts of time the motor will be at less than full volts/full frequency - probably a majority of the time and 208 instead of 240 input volts to the drive would be fairly insignificant I would think.
 
oldsparky52 said:
If you don't need the neutral, a couple of buck boost transformers will probably be the least expensive way to get what you need assuming this is just one load you are talking about.
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It is. Would this essentially be a transformer per phase? I don’t believe I need a neutral.
 
All amazing stuff guys thanks! I’m looking at some 3 phase acme Transformers. Leaning towards just giving him what he asked for and washing my hands.
 
HipHopHead said:
It is. Would this essentially be a transformer per phase? I don’t believe I need a neutral.
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You can do it with 2 or 3 transformers. If you do it with 3 then all the line voltages will be the same in reference to ground (higher than 120). If you do it with 2 transformers then the 2 legs boosted will be higher to ground than the non boosted leg (which would still be 120V to ground).
 
25A at 230V, probably a 10HP pump. 90% of motors in that size range made for 230V are actually going to be rated 208-230V because 208V 3 phase is far more common. If this is a pump on a VFD, all it will mean is that the torque at full speed might be slightly reduced, but if you are running on a VFD, that means you DON’T run it at full speed all the time, so why does it matter?
 
Your assumption is correct. That is exactly what it is a 10hp pump. I’ve requested spec sheets from the contractor to review before going forward. Thanks again for all the help you guys give. This forum is an amazing resource.

ryan
 
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