transformer calculations, and a big phantom load problem
transformer calculations, and a big phantom load problem
(OP)
First of all, a cluster of 3 200kva pole transformers gives me what kva capacity? Secondly, on a generator supplied system we are getting phantom loads of up to 300 amps. Basically, we generate 480V, step up to 13.8kv, step down to 4160, and then to 575 and 480 respectively. I'm suspecting a set of ancient step up transformers. Any thoughts?






RE: transformer calculations, and a big phantom load problem
On reading the second part of your post, my initial thought was "Rube Goldberg". If you can supply more specifics, it might help. Are you using more than one genset? Where/when do you see the 300A reading?
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
800% staring current will give a 600 amp surge.
Probably starting current.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
I have to second waross. Unless you post new information you, are chasing a problem that does not appear to exist. What you are describing does not constitute a problem.
Rafiq Bulsara
http://www.srengineersct.com
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
I am reminding myself that you are on site and I am not. There may be some subtle indications that are difficult to express but never the less, lead you to believe that the issue is not motor starting. You're there and I'm not and you may be right. How is the condition of your generator? If you have a failing AVR or an intermittent high resistance connection in your voltage control scheme it may be causing trouble. If the voltage is being driven high at the generator, any large device being driven into saturation may draw unexpectedly large currents for the duration of the event.
If you are using three single phase transformers rather than one three phase transformer, you may see indication of an impending failure one one transformer by high currents on one (wye) or two (delta) phases but not a balanced three phase fault current. If the transformers have been in service for years, what are the odds that all three would have the same short term fault at the same time for the same duration?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
Rafiq Bulsara
http://www.srengineersct.com
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
RE: transformer calculations, and a big phantom load problem
Bill
--------------------
"Why not the best?"
Jimmy Carter