SES Sizing and Step Down XFMR

[ElectricalEngineer!]

Greetings All,
What size service entrance at 277/480V
3 Phase will I need to feed (15) 200AMP Panels 120/240V?

Planning for 75kVA step down transformer, would that be sufficient?

Would 100 AMP circuit breaker be sufficient?

 

[infinity]

So you're using a separate step down transformer for each panel? The secondaries are 3 phase, 4 wire, Delta?

 

[petersonra]

Greetings All,
What size service entrance at 277/480V
3 Phase will I need to feed (15) 200AMP Panels 120/240V?

Planning for 75kVA step down transformer, would that be sufficient?

Would 100 AMP circuit breaker be sufficient?

You need a load calculation first.

 

[infinity]

You need a load calculation first.

I believe that the 100 amp question is for the primary to the 75 kva transformer.

 

[petersonra]

I believe that the 100 amp question is for the primary to the 75 kva transformer.

Could be. Still need load calculations. The op does not even say if the transformers are single or three phase.

 

[infinity]

The op does not even say if the transformers are single or three phase.

Yes, I asked the same question. Let's see what he says.

 

[ElectricalEngineer!]

So you're using a separate step-down transformer for each panel?
I would like to know the step-down transformer size for both options (one xfmr for each panel), and (one xfmr for all 15 panels)

The secondaries are 3 phase, 4 wire, Delta?
Yes

 

[electrofelon]

So you're using a separate step-down transformer for each panel?
I would like to know the step-down transformer size for both options (one xfmr for each panel), and (one xfmr for all 15 panels)

The secondaries are 3 phase, 4 wire, Delta?
Yes

How could we possibly say without knowing what the loads are? IF you want to know the KVA to supply a panel or panels that are loaded to their full rating, I assume that being an electrical engineer you know how to calculate that.

 

[infinity]

It sounds like he's interested in using the full load rating of 200 amps and calculate for either 1 or 15 transformers.