ECN Forum Forums Technical Discussion Electrical Theory and Applications Transformer Banks

I am doing a line diagram for the machine shop in earlier threads, and on their only print they have, it shows the sub station and the (2) 4160 services. The first one is cut and dry, it shows a 600Kva 460V dry transformer in the back, but it is really a 600Kva 440V...Not the problem..

The problem lies with the 208V side. There are 3 "pot" transformers making up the service, not 1 big transformer like the 440V side.
The print states, (3) Pot 100kva..
The service has parallel 500MCM pulled in to the MDP.

Is it safe to assume that this really is a 300KVA 208V service? They are additive aren't they?


So this would ponder the thought that a 45Kva 3 ph transformer is really (3) 15Kva cores?

Dnk...

[This message has been edited by Dnkldorf (edited 03-18-2006).]

Yes, they are additive. Three 100 Kva transformers hooked together in a bank would constitute a 300 Kva bank.

And yes, a 3 phase transformer is essentially 3 in 1. The core is common to all three.

Think of the core as a digital LCD figure "8" like you would see on an alarm clock except that it is on its side. Each of the three vertical legs would have a winding on it, but it is still essentially a single core since all three are bridged top and bottom.

There is another core design called "shell" which is similar to the above, except that it is taken a step further and the core comes around the outside two phases, so each phase is completely surrounded by a steel core. This is usually used in the larger units.

[This message has been edited by WFO (edited 03-18-2006).]

They are additive, but on a line diagram, I would note them as separate, or being a bank, as you stated in your post " (3) Pot 100kva".

Thanks Fellas...


Dnk..