Step-down Transformer

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Ohio
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Contractor
When determining the Power after a 480V 3p Transformer, utilizing the A=VA/(1.732*V) formula. is the outcome the amount per leg/phase?

so for instance, 60A 480V-208/120 Transformer would provide about 83 A. Is this per leg/phase?
 

retirede

Senior Member
Location
Illinois
The answer to your question is “yes”, but I can’t make sense of your example. If 60A is the primary current, that would correspond to a 50KVA transformer and the resulting secondary current would be about 139A.

And if you already know the primary current, you can simply ratio it by the voltage ratio: 60 x (480/208) = 138.5.

Ignoring losses…..
 

d0nut

Senior Member
Location
Omaha, NE
A transformer doesn't change the power of an electrical system. It is the same on the primary and secondary side of the transformer. A transformer changes the voltage and current of the system (one goes up as the other goes down, based on the turns ratio).

Also ignoring losses.
 

Hv&Lv

Senior Member
Location
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Occupation
Engineer/Technician
If you could show how you got those numbers…
As mentioned above, kVA is kVA, no matter if It’s coming or going…
that 1.732 comes into play also in a delta with respects to line currents vs phase currents
you can have 60 amps of phase currents but that will equal 104 amps of line current.
 
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