Kva

[27hillcrest]

Hi All,

I am having a complete brain fart! When a customer says I have

60amp A phase
71amp B phase
58amp C phase

Does the total KVA = E*I*1.73/1000

Is "I" all the 3 phase currents added together or do just use the highest phase current in this case B phase for the calculation?

TIA

 

[dbuckley]

You're calcing it as three single phase loads, so the easiest way is to add the currents and multiply by the single phase voltage.

Your calc is definitely wrong used the way you suggest, but you could make it right by using the average of the three currents in that formula!

Assuming 120/208, heres the sums firstly, adding single phase currents and using single phase voltage:

(60 + 71 + 58) = 189A. 189 x 120 / 1000 = 22.68KVA

Or, averaging (60 + 71 + 58) gives 63A, so 63 * 208 * 1.73 / 1000 = 22.67KVA