transformer question

[steveng]

how do you determine the kva rating of a xfmr that has no name plate data?

can you take an ohm reading and determine the kva?

it is a480 to 240/120 single phase, i think it is a 7.5, but i am not sure,
i do know the pri and secondary load, it is 15 pri and 30 sec.

 

[bob]

Steve
I can't help with your question but 6 wins in a row must hurt.
Check this site. http://www.youtube.com/watch?v=2G3yIIJPGFM

War Eagle
Bob

 

[steveng]

hey bob

hey bob

ur right, but, after those flowers you sent, you could at least answer the question. :grin:

 

[rcwilson]

can you take an ohm reading and determine the kva?

QUOTE] Steve - Ohm reading cannot be translated to KVA.

Best guess would be to compare the physical dimensions with transformer catalog data, but that is not that accurate. The temperatrue rise ratings may be different- a lower temperature rise transformer will usually be larger than a high temeprature rise unit of the same KVA.

Your guess of 7.5 kva based on the CB sizing is proably as good (or bad) as any other method.

 

[DBack Elec]

how do you determine the kva rating of a xfmr that has no name plate data?

can you take an ohm reading and determine the kva?

it is a480 to 240/120 single phase, i think it is a 7.5, but i am not sure,
i do know the pri and secondary load, it is 15 pri and 30 sec.

Let me see if I have this right. You have 15 amps on 480 volt primary and 30 amps on 240 volts secondary. If that is right then according to my chart you have a 7.5 Kva transformer.