posted by JBD
"You can not have a phase angle difference on a single conductor. Yes the current flowing in the C-B winding will be at a different phase angle from the current in the C-A winding, but there is still only 1 current in the C phase conductor."
That is correct. All load on winding AC are in phase. They are not in phase with AB and BC.
"Go ahead and work out the math for the summation of these two winding currents at the C conductor and then tell me if it is substantially different from my method. I don't think it is worth the effort for sizing a conductor and overcurrent protective device."
If you add the phase load in AC to the single phase load you get 625 amps.
Just adding phase AC to AB you get 625 + 333
= 958 amps. Same for BC.
If load is contineous 958 x 1.25 = 1197.
Doing it with vectors you get
Ia = 835A
Ib = 577A
Ic = 890A
890 x 1.25 = 1112.
The higher the single phase load the greater the error.
[This message has been edited by Bob (edited 02-12-2006).]
