Polarity Checking Of 6 Lead 3Ph Induction Motor

1. Question: How to find out Motor Terminal?

Answer:

i) With a multimeter or continuity tester, you can segregate three sets of windings. Can't you?

ii) Now, assume one set of windings to be, say, winding "U" and also, designate its terminals as assumed "U1 & U2".

iii) Take a 9V Cell; Connect + ve of Battery to the assumed "U1" preferably thro a push-switch and - ve to the assumed "U2".

iv) Connect a zero centred galvanometer, to another set of winding, say winding "V" such that the assumed "V1" is connected to the + ve terminal of the galvanometer and the assumed "V2" to the - ve terminal of the meter.

v) Now, when the switch is pressed, the zero centred galvanometer would deflect in the positive direction, if the assumed "U1, U2, V1 & V2" are correct.

vi) Else, if the deflection is on the negative side in the galvanometer, change your assumptions for either one of the winding (That is may be the assumed U1 can be U2 and the assumed U2 is U1 . Or keep the assumptions for U winding as it is and reverse it for the V winding (that is assumed V1 is V2 and assumed V2 is V1).

vii) Repeat this test for applying voltage to other windings and confirm your terminal assumptions.

But, in many cases, in star-delta starters, it is not the motor internal winding connections, that would cause stalling, but the external connections. I have authored an article on this, but as it contains diagrams, I am unable to copy & paste here. If you can send me your mail ID thro this forum's mailbox, I shall send you the article.

Hi,

I will give you one more method.

First confirm U, V and W windings, by doing continuity test. Then follow the procedure given below.

1.Connect V and W windings in series.

2.Connect 110V/230V AC to U winding. In this case let us consider 230V is applied to U winding terminals.

3. Measure the voltage between V and W series circuit. If the meter reads about 460V, then opposite polarities are connected at the junction of V and W winding (V2 and W1 or V1 and W2)

4. If the meter reads about 0V. Then same polarities are connected at the juction of V and W winding (V1 and W1 or V2 and W2)

Repeat the same procedure to find U1 and U2 also.

But do it safely without touching any terminals during applied voltage.