Odd 3 phase bank connection

[rcdallas]

Make you a deal. I come to Ok, you feed me both food, beer and knowledge and I'll give you a Dallas Cowboy's hat since I know deep down inside you wish you where south of the Red River.

[wtdoor67]

Sooner go to Mexico.

[HIPotter]

Good info and picture, simple and strait forward answer, a good rerferance for all to see. Real life and it jumps off the screen right at ya, thanks for thread, now nobody **** it up by confusin anyone.

Would have been nice to know what the primary voltage was also, name plate info as far as primary, not that it really matters with this one, and before anybody brings up the 4 bushing secondary pots, please post pictures, and start a new thread and please explain what parallal and series mean and then post and discuss till ya can't type. Thanks

OK..makes sense now. Thanks for all the help.

And the primary is 7kv delta.

HP

[Tester]

This bank of transformer is scheduled for removal.

Primary is/was a Delta connection
Secondary service is 120/240 3 phase 4 wire

Both outside pots are 75kva, middle pot is 100kva

Here's the deal, left outside pot is 230/460, and other 2 pots are 110/230 per nameplate.

The way it's wired, I don't understand how it gives you that secondary voltage.

Any transformer guru's here?

Hopefully the attachment shows a clear enough picture

HP

This is how the secondary is hooked up and the voltages that you would have:
The transformer on the left is a 240/480 and the coils are paralleled to give you 240.
The other 2 transformers are 120/240 and their coils are in series.
Opps, I see I put 2 B-phases in the picture, forgot to change the primary letter when I copied the picture over. Should be A - B - C

[dogman]

Good information, Thanks

[rcdallas]

That's something wtdoor talked about awhile back in the past. Ability to use a 240/480 transformer in a 120/240 bank--just parallel the coils.

That diagram shows the wye grounded on the highside...maybe to close in, but I'd float once it's closed in - you'll burn a transformer up.

[Tester]

That's something wtdoor talked about awhile back in the past. Ability to use a 240/480 transformer in a 120/240 bank--just parallel the coils.

That diagram shows the wye grounded on the highside...maybe to close in, but I'd float once it's closed in - you'll burn a transformer up.

I agree that the primary should be floated after all the cutouts are closed.
I was trying to emphasize the secondary connections.

[topgroove]

I agree that the primary should be floated after all the cutouts are closed.
I was trying to emphasize the secondary connections.

Hey Tester welcome aboard bro! I'm glad you joined the forum. We all appreciate your knowedge around here!

This will probebly have a few people scratching their heads. That last bank schematic, if you leave the float grounded after its energized....... I could open one of those cutouts and the customer would never know the difference as long as their load was reasonable.