Confused

[Richterfan]

Ok so I am having a brain fart here I think. Can anyone tell me what size trans I need because when I figure it out by what they list it doesn’t add up.
I have a new 30kva trans 480v pri 36.1a / 208v sec 83.3a. I have 208v 3ph and have to step up to 480v and was going to reverse feed this trans but the 20kva trans that they recommended doesn’t seem large enough.

 

[texie]

Using a standard xformer in reverse is a terrible idea for a number of reasons. Best to get a proper 208 delta X 480Y unit. Didn't check the sizing.

 

[Richterfan]

Using a standard xformer in reverse is a terrible idea for a number of reasons. Best to get a proper 208 delta X 480Y unit. Didn't check the sizing.

I had asked the square d supplier and he had said this trans can be done this way. It’s what they had recommended I use but not sure what to use with the document I listed.

 

[roger]

Letting a supplier engineer for you is not the best idea.

Roger

 

[Richterfan]

Letting a supplier engineer for you is not the best idea.

Roger

I agree but I told them what I needed according to the document I attached and they said these can be wired both ways. He is not engineering this but I asked and this is what he said will work.
Do you have the answer? I posted on here for my dilemma of what’s listed on the paperwork but seems I am getting responses to something different.

 

[augie47]

The numbers you show are the correct currents for the 30kva.
From what I see in the picture it seems they are calling for a 50kca which would provide 60 amps (75 usinga 125% allowable factor)

 

[Richterfan]

The numbers you show are the correct currents for the 30kva.
From what I see in the picture it seems they are calling for a 50kca which would provide 60 amps (75 usinga 125% allowable factor)

Thanks Augie, what do you make of the specs that says 220/480 requires a step up transformer (20kva) recommended. This is the part that is throwing me off.

 

[augie47]

can not read to document spictured well enough to have an opinion

 

[Richterfan]

 

[Jraef]

You're right, that is weirdly contradictive. If it needs 60A and 50kVA, you are not going to get that from a 20kVA tranny. You are not going to get 60A at 480 from a 30kVA tranny either for that matter. It's definitely worth a phone call to Amada.

Side note: "220/480"? not 240/480 or 220/440? Maybe this was written by someone in marketing who has no clue...

 

[JoeStillman]

Maybe they are assuming you will use an auto-transformer.