transformer current capacity

[pegggu]

i was thinking of this the other day and wondering if someone could clarify for me.
say we have a 3 phase 1MVA, 347/600V transformer and wanted to know the max secondary current output.

i=p/v
i=1mva/600v/1.732
i=962.28A

now my question is, would be it 962.28A total capacity (divide by 3 for each phase, if balanced) or would it be 962.28A per phase total (2886A)?

thanks

 

[david luchini]

962A is the rated secondary current (not the "max" current.) It is per phase, don't divide by three.

 

[Besoeker]

i was thinking of this the other day and wondering if someone could clarify for me.
say we have a 3 phase 1MVA, 347/600V transformer and wanted to know the max secondary current output.

i=p/v
i=1mva/600v/1.732
i=962.28A

now my question is, would be it 962.28A total capacity (divide by 3 for each phase, if balanced) or would it be 962.28A per phase total (2886A)?

thanks

It's 962A line current for each of the lines. Doesn't matter whether you load it line to line or line to neutral 962A is the most you can pull from any line.

 

[mivey]

i was thinking of this the other day and wondering if someone could clarify for me.
say we have a 3 phase 1MVA, 347/600V transformer and wanted to know the max secondary current output.

i=p/v
i=1mva/600v/1.732
i=962.28A

now my question is, would be it 962.28A total capacity (divide by 3 for each phase, if balanced) or would it be 962.28A per phase total (2886A)?

thanks

Currents don't add across phases like that. For capacity calculations and summing you should stick to VA. Using amps for capacity calcs is a shorthand for a specific set of conditions and will get you in trouble. The 1 MVA is the sum of 0.333 MVA per phase thus you get the phase current from the phase MVA.

To increase the line current you would need to parallel transformers.