PDA

View Full Version : How many amps at 208 volt to supply a transformer to create 480 volt 150 amp


neilmcentee
Feb 16, 2011, 03:58 PM
Power requirements using a 112.5 kva transformer

jcaron2
Feb 16, 2011, 05:07 PM
The total volt-amps are the same on the primary and secondary. If the secondary is at 480V, 150A, that's a total of 72 kVA.

Therefore, if the primary is at a voltage of 208V, the current must be 72,000/208 or about 350 Amps.

tkrussell
Feb 17, 2011, 03:47 AM
I will assume this is 3 phase, in which case the calculation is for example;

480 Volts x 150 Amps x 1.73 = 124,560 VA

jcaron2
Feb 17, 2011, 05:57 AM
Good point.