ghart
Aug 2, 2010, 01:52 PM
If I have 100 amps at 480 what will I have if I transfom it down to 208 three phase?
lobstertrap
Aug 8, 2010, 10:31 AM
You needs size 1/0 wire to haul 100 amps.
lobstertrap
Aug 8, 2010, 10:37 AM
you will have 230 amps because 480 volts X 100 amps = 48000 Watts, and divide that by the 208 = 230 amps. (amps X volts = Watts)
tkrussell
Aug 9, 2010, 05:58 AM
The following calculations are incorrect.
you will have 230 amps because 480 volts X 100 amps = 48000 Watts, and divide that by the 208 = 230 amps. (amps X volts = Watts)
When the system is three phase, you must use the constant of the square root of three, 1.73.
Therefore, total power of 100 Amps at 480 Volts 3 phase is:
480 volts x 1.73 x 100 amps = 83,040 Volt Amps.
A 100 Amp load at 480 volts 3 phase would need to be increased by 25%.
So the transformer will need to be at least a 103 KVA unit.
The next size transformer avaialbe is 112.5 Kva.
It can have an output of 312 amps at 120/208 Volts 3 phase.