Page 300 - Electronic Mechanic - TP - Volume - 2

ELECTRONICS MECHANIC - CITS

Now connect A2 with B1 so that the two windings are in series

Now apply 230V A.C between A1 and A2 and measure the voltage across A1 and B2.
If we notice the measured voltage is less than the applied voltage then our assumption is correct. Otherwise
interchange the terminals A1 and A2 and repeat the process so that we can find the terminals A1, A2, B1 and B2

Now take the third winding mark it as C1, C2 (this is the assumption) and take second winding B1B2 (already
known) connect B2 with C1 so that the two windings are in series as shown in Fig

Now apply 230V A.C between B1 and B2 and measure the voltage across B1 and C2
If we notice that the measured voltage is less than the applied voltage then our assumption is correct. Otherwise
interchange the terminals C1 and C2 and repeat the process so that we can find the terminals B1, B2, C1 and C2.

Once we can identify all the terminals they are connected for Star or Delta fashion, for star connection join
A2B2C2 or A1B1C1, for delta connection connect A2B1, B2C1 and A1C2.
Finding Polarity of Induction motor-Method (by D.C)

Procedure to identify terminals A1, A2 and B1, B2
1 Randomly choose one of phase winding terminals say A1 and A2
2 Connect the positive terminal of the battery to A1 and the negative terminal to A2 through switch
3 The meter is connected across one of the other two phase windings say B phase randomly
4 At the instant of closing the switch, observe the deflection of the meter pointer
5 If there is a positive or clockwise deflection, then the terminal connected to the positive of meter is B2 and
connected the negative terminal is B1
6 If the deflection is in the opposite direction, then the polarities are B1 and B2 respectively
Procedure to identify other terminals C1, C2

1 Select the first winding with terminals say A1 and A2
2 Connect the positive terminal of the battery to A1 and the negative terminal to A2 through switch
3 The meter is connected across the third phase winding
4 At the instant of closing the switch, observe the deflection of the meter pointer

5 If there is a positive or clockwise deflection, then the terminal connected to the positive of meter is C2 and
connected the negative terminal is C1
6 If the deflection is in the opposite direction, then the polarities are C1 and C2 respectively

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CITS : E & H - Electronics Mechanic - Exercise 205