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Hello .. Rich here .. I can help you with this what is the amperage of the panel you are feeding with this transformer ?
For the 200 amp service you would need 2/0 copper or 4/0 aluminum .. out of the transformer
the primary of this transformer will draw about double the current 450 amps .. that would take 400 kcmil and a 450 amp breaker
Just re-read your question the load on the 440 3p side of the transformer will not exceed 90A...
Each phase? Doesnt seem to add up...what is the math?
208V 3p in
440V 74 KVA load at 89 amps - rating on the equipment
75 KVA transformer
Hi, I'm Norm.The primary (208 V.) current for the 75 kVA transformer is, coincidentally, 208 Amps. A breaker for that side must be at least 1.25 times that value, or 260 Amps. The next standard overcurrent device is 300 Amps, so use that with 300 kcmil copper wire with THHN insulation, no more than 3 current-carrying conductors in conduit. The secondary (480 V.) current is 90 Amps, so you can use #4 copper with THHN insulation, also no more than three current-carrying conductors in conduit. I use 480 Volts rather than 440 Volts as that is the standard utility voltage today, even though your load may have a 440-Volt nameplate.