Altering equipment voltage?

[Jayyy]

Question; I have a 208v delta to 230/400 Y xformer supplying a machine. Only one VFD motor in the machine is 400/3p/3w (.9kva). The rest of the components are 1ph.230 w/neutral;(one leg to neutral). I want to remove all of the components off of the supply transformer and just supply the VFD with a smaller xformer, and then supply the machine with 120/208Y. Does a component that is 230v -(one leg to neutral) have the ability to be supplied with 208v/1p (2 legs) if they are rated at 208/230?
I have never even thought about this before until working on European equipment. The intent is to maximize the efficiency of the xformer as it is using a 25kva xformer for 5.5kva equipment. The 6kva xformer will be cheaper and cooler. Also it consumes a large footprint currently.
Any help would be appreciated.

 

[Jraef]

Too many "what if's" to provide a comprehensive answer. If the 230V circuits require a grounded neutral, that is going to be a problem. if they feed things such as motors or transformers, the frequency difference will add another dimension of complexity. If they are supplying power supplies, you would need to investigate the input voltage range (and frequency) of each one. If the 230V loads are heaters, they will put out less heat at the lower voltage, which may mean either the desired temperature can't be reached, or it will take longer to get there. If they feed incandescent lights, you will get less light, etc etc etc...

 

[Jayyy]

Good point with the heater ( a major item with this machine), we'll have to look at that a little closer. The frequencies are 50/60 hz rated, I think that would be fine. The confusing part is using a single leg w/neutral as 230 volts and replacing it with 2 legs of 208. We would have to rewire the neutral bar etc., and set it up as another circuit with ocp, but that ok. The plc and computer have their own dc converters in them. Fan motors and relays should be good, Wouldn't you think?

 

[LarryFine]

Jayy, welcome to the forum! :smile: Random thoughts (as if I had any other kind :wink:

To start with, you'd have to make sure every component, controller, OCPD, and supply wiring are or can be wired line-to-line. Make sure nothing is regrounded anywhere.

To supply all of the 1ph loads from a single supply, you'd have to make sure nothing depends on, or can be damaged by, a voltage difference between any two lines.

You could use a B/B transformer to convert the 208v to 230v (I'm using 230 instead of 240 because the OP did), but you're still stuck with the neutral-becoming-hot issues.

You could also try supplying 230v 1ph through a transformer, and bond one end of the secondary, creating your own 230v 1ph system. Grounding as necessary, of course.

 

[Jraef]

. Make sure nothing is regrounded anywhere.

To supply all of the 1ph loads from a single supply, you'd have to make sure nothing depends on, or can be damaged by, a voltage difference between any two lines.

You could use a B/B transformer to convert the 208v to 230v (I'm using 230 instead of 240 because the OP did), but you're still stuck with the neutral-becoming-hot issues.

You could also try supplying 230v 1ph through a transformer, and bond one end of the secondary, creating your own 230v 1ph system. Grounding as necessary, of course.

All excellent points. Checking for re-grounding is something that has bitten me (more than once I'm embarrassed to say) on EU machinery I've had to rework for US operation.