Looking for advice on a buck boost transformer....

[fastjer]

TL;DR

hooking up a 45kva general transformer to buck to 208v

I have a 45kva GE transformer in the pics and here. Its set up for 480 to 208, i need to wire it for 250v to 208v. Could someone please point me to the correct diagrams for this general type of transformer?

Thank you

 

[berkeman]

Summary:: hooking up a 45kva general transformer to buck to 208v

I have a 45kva GE transformer in the pics and here. Its set up for 480 to 208, i need to wire it for 250v to 208v. Could someone please point me to the correct diagrams for this general type of transformer?

Thank you

Welcome to PF.

It looks like your images are no longer available. Can you use "Attach files" (lower left of window) or provide updated links?

Also, what is the application? What is your background?

Finally, it looks like from your post that you want to do an AC conversion to lower the working voltage of the system, but from your thread title, it sounds like you want to do a DC conversion? Please clarify. Thanks.

 

[fastjer]

 

[fastjer]

So, I have tile kilns that run on 208v, but 248v comes into my business. To replace the elements for 208 is pretty pricy. I purchased this transformer pretty cheap, it works, but just need to figure out how to buck the voltage a little and still pull about 45 amps through. This one is set up for 480, so when I hook it up the the 3 phase at my building i get 56v to neutral, or about 112 across two of the output terminals.
Background: 15 years in hvac, degree in ee (a LONG time ago), been wiring small circuits and diagnosing general stuff for a long time

 

[berkeman]

So, I have tile kilns that run on 208v, but 248v comes into my business. To replace the elements for 208 is pretty pricy. I purchased this transformer pretty cheap, it works, but just need to figure out how to buck the voltage a little and still pull about 45 amps through. This one is set up for 480, so when I hook it up the the 3 phase at my building i get 56v to neutral, or about 112 across two of the output terminals.
Background: 15 years in hvac, degree in ee (a LONG time ago), been wiring small circuits and diagnosing general stuff for a long time

Have you pulled a permit for this electrical work yet? What are your local building codes regarding this upgrade work? Are you familiar with the NEC?

 

[Baluncore]

Maybe you could consider rewiring it as 3 phases of autotransformer.
https://en.wikipedia.org/wiki/Autotransformer

 

[fastjer]

Have you pulled a permit for this electrical work yet? What are your local building codes regarding this upgrade work? Are you familiar with the NEC?

hello berkeman, we are just seeing if it works. If so, i'll pull the permit, not a big deal.

 

[fastjer]

Maybe you could consider rewiring it as 3 phases of autotransformer.
https://en.wikipedia.org/wiki/Autotransformer

Yes, that's what the goal is

 

[berkeman]

hello berkeman, we are just seeing if it works. If so, i'll pull the permit, not a big deal.

Great, thanks.

So, I have tile kilns that run on 208v, but 248v comes into my business. To replace the elements for 208 is pretty pricy. I purchased this transformer pretty cheap, it works, but just need to figure out how to buck the voltage a little and still pull about 45 amps through. This one is set up for 480, so when I hook it up the the 3 phase at my building i get 56v to neutral, or about 112 across two of the output terminals.
Background: 15 years in hvac, degree in ee (a LONG time ago), been wiring small circuits and diagnosing general stuff for a long time

So can you say which NEC regulations apply to the new installation? What do you need to install in your business to support this new electrical feed? Also, have you talked with your business insurance agent about this electrical change to your business?