# 3 phase motor wiring



## Karl_T (Apr 10, 2020)

My son has a #2 cinci tool and cutter grinder he got for hauling it off.

He knows it was running on 440 in the shop it came out of. Inspection of the 9 motor wire today shows all the lead numbers have faded to un readable. He says he can not find a readable name plate for how to wire it either. the motor connection box has sat full of oil for a VERY LONG time.

Is it fairly safe to assume the below wiring diagram is the correct one???

If so, he knows T1 T2 T3 cause they are the ones hooked to the in coming line

Is there an electrical test to ID T4 to T9. He knows a little bit cause there are three pairs of wires.


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## ErichKeane (Apr 10, 2020)

See here: https://electronics.stackexchange.com/questions/269189/identify-unmarked-leads-on-a-9-lead-motor

There are actually 2 types of wiring diagrams for a 3 phase motor, Delta or Y.  This is the wiring diagram that shows what it means: 
	

		
			
		

		
	




So unfortunately, there is no real good way to know based on just how it is wired.  However, I found these videos helpful for figuring it out: 









he starts both with how to identify, and helps you figure out which wire is which!


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## Karl_T (Apr 10, 2020)

I assume Y must be the over whelming majority of smaller motors. I've done dozens and never seen a low voltage wiring diagram like the low delta above.


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## ErichKeane (Apr 10, 2020)

Karl_T said:


> I assume Y must be the over whelming majority of smaller motors. I've done dozens and never seen a low voltage wiring diagram like the low delta above.


I think Y is more common, but I don't think it has anything to do with motor size.  That said, an ohm-meter and a few minutes make it easy enough to determine.  Basically, you group the wires based on continutity vs not.  A Y motor will have 3 pairs, plus 1 group of 3.  The delta motor will have 3 groups of 3.


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## Ulma Doctor (Apr 11, 2020)

most of the motors consumers will see are wired in the WYE configuration


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## Karl_T (Apr 11, 2020)

The kid wiped all the wires down with solvent last night. After they dried he could make out numbers on several wires with a bright light. problem solved.


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