I AM PROVIDING TRAINING FOR OUR PLANT ELECTRICIANS, AND I WANT TO CONFIRM A COUPLE BITS OF POWER THEORY PRIOR TO GOING LIVE.
EXAMPLE: 13,800V DELTA, 480-277V WYE, 2000KVA
TRANSFORMER.
X1 HAS 1000 AMPS
X2 HAS 1200 AMPS
X3 HAS 1400 AMPS
I HAVE ASKED THEM TO CALCULATE:
NEUTRAL CURRENT
ALL 3 DELTA LINE CURRENTS
ALL 3 DELTA PHASE CURRENTS
TO SOLVE FOR NEUTRAL CURRENT;
THE SQUARE ROOT OF...
1000 SQUARED + 1200 SQUARED + 1400 SQUARED
= 2098 AMPS
DELTA PHASE A CURRENT = 1000A/49.819 = 20AMPS
............B CURRENT = 1200A/49.819 = 24AMPS
............C CURRENT = 1400A/49.819 = 28AMPS
49.819 IS 13800/277.
DELTA A LINE CURRENT = 20 X 1.732 = 35AMP
......B LINE CURRENT = 24 X 1.732 = 42AMP
......C LINE CURRENT = 28 X 1.732 = 48AMP
I REALIZE THAT WITH THESE IMBALANCES, THERE WILL BE PHASE SHIFTS, BUT 120 DEGREE ANGLES WERE USED TO SIMPLIFY.
I HAVE A 50/50 CONFIDENCE LEVEL WITH MY CALCULATIONS.
