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[QUAVIET]

Question: A 12 wire 500HP refregeration motor which is labeled wye/delta and is really a wyewye/deltadelta motor, once seven seconds have passed and the electronics has determined that there is nothing wrong with the motor it adavnces to deltadelta with a phase reversal. Does the phase reversal boost or pull the delta delta between the two windings? It is a question of who is lagging or leading is it not? The question is purely academic but I was curious. It works now after you all, it has not worked in at least 3 years. This is a recap. Sometimes you only need a shoulder to cry on.

 

[aolalde]

Hi QUAVIET:

In reality to switch properly from Wye connection to delta connection the PHASE SEQUENCE should be the same. The magnetic field generated by the stator winding will rotate Clock wise or Counter clock wise depending on the voltage sequence applied. Due to the change of connection it appears that a phase reversal is done but the reason is to keep the same sequence.

The terminal markings depend on the region the motor was manufactured.
For USA the leads are marked 1 to 12 and the connection for two Wye – two Delta are:
WYE Delta
L1 – 1&7 L1 – 1,7,6&12
L2 – 2&8 L2 – 2,8,4&10
L3 – 3&9 L3 – 3,9,5&11
Neutral 4,5,6,10,11,12

Formerly in UK The leads were marked:
A4 equivalent to 1, B4 equiv to 2, C4 equiv to 3,
A3 equiv to 4, B3 equiv to 5, C3 equiv to 6
A2 equiv to 7, B2 equiv to 8, C2 equiv to 9
A1 equiv to 10, B1 equiv to 11, C1 equiv to 12

IEC motors use
U1 equiv to 1, V1 equiv to 2, W1 equiv to 3
U2 equiv to 4, V2 equiv to 5, W2 equiv to 6
U5 equiv to 7, V5 equiv to 8, W5 equiv to 9
U6 equiv to 10, V6 equiv to 11, W6 equiv to 12

These are only three examples but the connection is the same. ( U,V,W,X,Y,Z or Ua,Ub, Va,Vb etc,)