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Join Date: Jul 2009
Location: Goshen, Oregon
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How to Determine Phase Relationships for Unmarked Motor Leads

12/08/2009 1:21 PM

We have a 480V 12 lead motor with no wiring information. I can find the windings ok with my ohm meter but I'm not sure how to wire the windings for the right phase relationships. Does anyone have any advice?

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Active Contributor

Join Date: Dec 2009
Posts: 12
#1

Re: How to Determine Phase Relationships for Unmarked Motor Leads

12/08/2009 9:26 PM

Do you have the info off the name plate? Make, H.P., F.L.A., frame size? If you could get me more info i might be able to help

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#2

Re: How to Determine Phase Relationships for Unmarked Motor Leads

12/08/2009 9:52 PM

Usually motors have the lead numbers tagged or printed right onto the individual wires. If there is no wire number markings you may have to have a motor repair shop open it up and retrace each wire to its proper winding and then renumber them again.

Its possible to do a manual trace with a lower voltage AC source if you buzz each winding and then find its matching winding and relative phasing polarity relationship.

Normally motors that are 12 lead are dual or multi voltage types that have each pair of windings for each phase together in the core so if you find one set that has a very close voltage match to the source thats most likely the right one.

Then move to another set and do the same until you have three sets that have matching voltages when powered up.

If the 1,4 and the 7,10 are placed in the right series connection you should get nearly double your input voltage from lead 1 to lead 10 as whats being applied to the 1,4 winding, 4 and 7 are the center tap.

Phase one should be 1,4 and 7,10. Phase two should be 2,5 and 8,11. Phase three should be 3,6 and 9,12

Unfortunatly this can be very slow and time consuming even if you know what your doing. And may not prove to be 100% correct the first time either.

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#3

Re: How to Determine Phase Relationships for Unmarked Motor Leads

12/09/2009 3:41 AM

Yep. Get the motor manufacturer involved ASAP.

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#4

Re: How to Determine Phase Relationships for Unmarked Motor Leads

12/09/2009 6:48 AM
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#5

Re: How to Determine Phase Relationships for Unmarked Motor Leads

12/09/2009 6:48 AM
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