transformer

[mast1234]

480v primary 3-phase
230v secondary 3-phase
? amps primary
200 amps secondary or
400 amps secondary
?kva for both
Thanks for your time

 

[roger]

Your question doesn't make any sense the way you are asking it.

Roger

 

[Besoeker]

480v primary 3-phase
230v secondary 3-phase
? amps primary
200 amps secondary or
400 amps secondary
?kva for both
Thanks for your time

You need to provide actual kVA rating to work out the currents.

 

[ggunn]

You need to provide actual kVA rating to work out the currents.

Don't the secondary currents and voltage determine the kVA for the two cases?

 

[mast1234]

that's my question what kva would i need and how many primary amps would it draw?

 

[Besoeker]

Don't the secondary currents and voltage determine the kVA for the two cases?

Yes, they could but we don't have appear to have a definitive value for that. Is it 200A or 400A?

 

[charlie b]

that's my question what kva would i need and how many primary amps would it draw?

Your question still does not make sense. Tell us what you do know, and what you are trying to figure out. For example, if you are telling us that you have a secondary load of 200 amps with a 3-phase voltage of 230V, then to get the KVA you multiply those two numbers, and then multiply the result by the square root of 3 (approximately 1.732), and finally divide by 1000. That gives you a final answer of 79.7 KVA. Is that what you are asking? If you are also asking the same question, but starting with a secondary load of 400 amps, then I will let you do the math.

Once you know the KVA (and by the way it will be the same on the primary as on the secondary), you get the primary current in the opposite way from what I describe above. Start with 79.7 KVA, multiply by 1000, divide by the primary voltage of 480, and divide again by 1.732. I get an answer of 95 amps. You can do the math for the 400 amp secondary version.

 

[mast1234]

Yes, they could but we don't have appear to have a definitive value for that. Is it 200A or 400A?

I'm looking for both

 

[LMAO]

480v primary 3-phase
230v secondary 3-phase
? amps primary
200 amps secondary or
400 amps secondary
?kva for both
Thanks for your time

when drawing 200A at secondary:
primary current = 95.83A
Rating = 79.7kVA

when drawing 400A at secondary:
primary current = 191A
Rating = 159.4kVA

 

[Smart $]

Aside from what's been covered so far, your nominal secondary voltage will be 240V... not 230V... and your kVA will be based on this 240V nominal rating, i.e. 200/400A @ 240V ~ 83/166kVA. Primary rated current will be exactly half the secondary rated current.

 

[mast1234]

that's what i needed

 

[Besoeker]

I'm looking for both

So two different transformers?