Assuming the motor has 9 leads. Test the nine leads for continuity to determine whether the motor is wye or delta connected. The star connected motor will have only one set of three leads with continuity between them, and three sets of two leads with continuity. The delta connected motor will have three sets of three leads with continuity between them
For “Star Connected Motor”, label the three leads with continuity, #7, #8, and #9.
Flash with a battery the #8 & #9 pair. Clip a DC voltmeter to each pair of leads with continuity between them, until you find a pair that produces minimum deflection when flashing. This pair of leads is #1 & #4.
Move the battery positive lead on the #7 lead and the negative lead to be used for flashing the #8 lead. When the voltmeter is so placed on the #1 & #4 pair that it measures a positive deflection on the "make" of the negative #8 lead, the voltmeter positive lead is the #1 motor lead, and the negative voltmeter is the #4 motor lead.
Move to #7 & #9 leads with the positive lead on the #9 motor lead, and the negative to flash the #7 lead. The positive voltmeter lead should match the #3 motor lead if it shows a positive kick and the negative lead should be on the #6 motor lead. Shift the battery to the #8 & #9 pair, with the positive battery lead on the #8 lead and the negative used for the flashing. An upscale kick will identify the #2 motor lead. The positive voltmeter lead will be found on the #2 lead, and the negative voltmeter lead will be the #5 lead.
For a Motor “Delta Connected”: Find the corner leads #1, #2, and #3. Using an ohmmeter, identify the leads that show the minimum resistance to the other two leads with continuity. The lead located halfway between the other two will thus be the corner lead of the delta. Repeat this for each group of leads, marking them #1, #2 and #3.
The other two leads of each group must be: #4 & #9 in the group of #1; #5 & #7 in the group of #2; #6 & #8 in the group of #3.
Next, use the inductive kick test method to identify the proper markings for the other two leads of each group. The flux produced by #3 & #6 and #3 & #8 combined, will be perpendicular to the axis of #1 & #4 and #2 & #7. Opening and closing a switch in this circuit will produce a kick in coils #1 & #9 and #2 & #5, but no kick in #1 & #4 and #2 & #7.
Therefore, if the battery is connected from #3 & #6 and #3 & #8, opening and closing the battery circuit, the voltmeter will identify leads #1, #4, and #9 and can be distinguished by noting the magnitude rather than the polarity. The voltmeter can then be connected to terminal #2 for determination of the leads #5 & #7. Leads #2 to #7 which will give little or no deflection, and leads #2 to #5 will give a substantial deflection.
The battery is then transferred to the corner of #1. Tie the battery between leads #1 & #4 & #9. Making and breaking the circuit will be perpendicular to #3 & #8 and #2 & #5, resulting in no deflection. However, there will be a deflection from leads #2 & #7 and #3 & #6.
Finally place the battery on the #2 & #5 and #2 & #7 leads which are perpendicular to #1 & #9 and #3 & #6 leads, therefore creating no deflection on them. Leads #1 & #4 and #3 & #8 will have a deflection.