460 primary, 208 secondary

[machinetechnology]

All,

I have a tranformer that is labeled 480vac primary 208 vac secondary.

My facility has 208vac service and I have a 480vac machine with a computer that runs on 230vac 1ph.

Is there any issues with reversing the primary and secondary connections?

If not, would there be any concerns with the 230vac supply?

Any info would be appreciated.

 

[mpparent]

There shouldn't be any problems w/ reversing the primary/secondary. Typically, equipment can run with a +/- 10% voltage tolerance, so I don't think in your application this is an issue.

Mike

 

[ccjersey]

The machine must have had a transformer to get to the 230V for the computer or maybe it tolerated the 277? Anyway you might have to have a neutral on the 480V side to get 277V for the computer supply or get a transformer for 480 to 240 if you don't have a neutral.

 

[davidbeach]

Odds on, the transformer is a delta on the 480V side and a wye on the 208V side. The transformer won't give a whit one way or the other about which side the power flow from and to, but feeding the 480V side from the 208V side will cause problems grounding the 480V side. You will have one of three conditions: ungrounded; corner grounded; or a separate grounding transformer will be needed. If the the machine has a neutral connection, neither of the first choices will work. The third choice will probably be nearly as expensive as buying a 208 delta - 480Y/277V transformer.

Ungrounded and corner grounded systems both have numerous disadvantages.