Identifying Unmarked 9 Lead Motors: WYE Connection

unmarked leads blog

Let’s say the #1 and #4, which is in the same phase, are missing. Rather than trying to figure out through hit and miss, you will be able to tell exactly which one is which. In order to do this procedure, written by Augie Hand, you will need a 6 or a 12 volt battery an Analog Voltmeter, and tape to label leads.

First identify combinations. Check all 9 leads to look for pairs that have continuity. If you locate 3 pairs with continuity and one combination of 3, this is a WYE configuration. Label the combination of three 7, 8, and 9. This is the internal WYE connection.

Next, locate #1 and #4. Pay attention to which leads are positive and negative on the meter and the battery. To locate leads 1 & 4, flash 8 & 9. Leads 1 & 4 will show with little or no deflection and leads 3 & 6 and 2 & 5 will show strong deflection.

To identify 1 & 4 connect the + terminal of the battery to 7. The – battery terminal will be flashed to 8. Connect the voltmeter to 1 & 4. With an upscale deflection, the + lead of the voltmeter will be on 1 and the – lead of the voltmeter will be on 4. 1 & 4 can now be labeled.  Leads 3 & 6 can now be located. 3 & 6 will show little or no deflection. 2 & 5 will show strong deflection.

To identify 3 & 6: connect the voltmeter leads to 3 & 6 connect the – battery terminal to 7 and flash the terminal to 9. With an upscale reading, the + lead of the volmeter will be on 3 and the – voltmeter will be on 6. They can now be labeled.

Connect the voltmeter leads 2 & 5, connect the – battery terminal to 9. Flash 8 with the + battery terminal. With an upscale deflection, the voltmeter lead will be on 2 and the – volmeter lead will be on 5.

Once you’ve identified all 9 leads the motor can be safely energized, and you know the connections are correct. The Delta connected motor has a different procedure.

Watch a demonstration

To view our electric motors and other MRO equipment in stock, click here:

Electric Motor Outlet


Follow RepairZone on Linked In:

Please share our Content:

No comments yet.

Submit a Comment

We would love to hear your thoughts. Feel free to submit a comment and join the conversation!