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31.
THREE PHASE POWER UNBALANCE
Phase designation of leads for CCW rotation viewing shaft end.
To reverse rotation, interchange any two leads
Phase 1 or "A" – Black Motor Lead or T1
Phase 2 or "B" – Yellow Motor Lead or T2
Phase 3 or "C" – Red Motor Lead or T3
Notice: Phase 1, 2 and 3 may not be L1, L2 and L3.
T1 = 51 amps +
T2 = 46 amps +
T3 = 53 amps =
Total = 150 amps
150/3 = 50 amps
50-46 = 4 amps
4/50 = 0.08 or 8%
32.
TRANSFORMER SIZES
A full three phase supply is recommended for all three phase motors, consisting of three phase individual transformers
or one three phase transformer.
"Open" delta or wye connections using only two transformers can be used, but are more likely to cause problems from
current unbalance.
Transformer ratings should be no smaller than listed in the table for supply power to the motor alone.
4" Submersible Motors
Example:
T1 = 50 amps +
T2 = 49 amps +
T3 = 51 amps =
Total = 150 amps
150/3 = 50 amps
50-49 = 1 amps
1/50 = 0.02 or 2%
4MWP
T1 = 50 amps +
T2 = 48 amps +
T3 = 52 amps =
Total = 150 amps
150/3 = 50 amps
50-48 = 2 amps
2/50 = 0.04 or 4%
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