Dry type transformer

[ptonsparky]

Providing adequate information at first post helps to limit playing '20 questions'.
Spit it out, we will sort it.

 

[ptonsparky]

Primary voltage is the low voltage side.

?

 

[infinity]

?

A question? This is a step up transformer.

 

[ptonsparky]

A question? This is a step up transformer.

Where did you come up with that information? I missed it.

 

[ptonsparky]

Where did you come up with that information? I missed it.

ooooo. NM.

Maybe posts 4 & 5.

 

[packersbay]

Can you post a photo of the transformer nameplate so we can look at the taps?

 

[packersbay]

Yes I can tomorrow when I show up back on-site.

 

[infinity]

ooooo. NM.

Maybe posts 4 & 5.

 

[packersbay]

In case you wondering how the math works.
With a ratio of 2.3
480/208=2.3
512/2.3= 222.6 primary voltage
If you want to do it the other way
208 to 480
208/480= .433
1/.433= 2.3

A pic of the tag will confirm your transformer set up. It will also give a list of taps which you can change to correct the output voltage if need be.
Look forward to what you find.

 

[packersbay]

 

[infinity]

View attachment 2563601

That nameplate shows a delta configuration on the high side with no neutral. Aren't the fixtures in question 277 volts?

 

[packersbay]

512v at indoor trans disconnect, thinking utility pad mount transformer needs to be tweaked down

 

[packersbay]

There’s is a neutral

 

[augie47]

Have you checked the voltage to ground (277) on all three phases....
From that nameplate you should not have a true neutral.

 

[ptonsparky]

There’s is a neutral

Where are you getting it?

 

[LarryFine]

The high-voltage side is delta/no neutral, and the low-voltage side is wye/with neutral.

If you're using this as a step-up transformer, your output will not have a neutral.

Thus, any line-to-ground voltages you're getting are meaningless and not usable.

 

[David Castor]

If this transformer is being used to step up 208/120 V to 480 V, there cannot be any 277 V loads on the 480 V delta winding because there is no neutral. If the 480 V "neutral" is connected to ground at the transformer, then this is a big mess.

 

[infinity]

If this transformer is being used to step up 208/120 V to 480 V, there cannot be any 277 V loads on the 480 V delta winding because there is no neutral. If the 480 V "neutral" is connected to ground at the transformer, then this is a big mess.

Also if it were corner grounded the voltage would be 480 to ground on two legs.

 

[ptonsparky]

I don't think anyone has said it yet but you need a transformer designed to step-up. Not reverse feed a stepdown.

Delta to Wye.

 

[infinity]

I'm thinking that if there is a 480Y/277 volt panel feeding the lighting the nameplate in post #30 is not the correct one.