# Neutral on a Low Voltage Wye?



## swimmer (Mar 19, 2011)

Do 3-phase Wye motors have a neutral? If yes, then how is neutral connected when strapping for low voltage? Most connection drawings show T1-T7, T2-T8, T5-T6 as shown in the attached drawing. I expected the the centers to be connected by the neutral but it seems they are not.


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## chicken steve (Mar 22, 2011)

No noodle need apply there Swimmer ~CS~


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## hardworkingstiff (Jan 22, 2007)

You don't bring the neutral to a 3-phase motor. 

The drawing you show is of motor windings connected in a wye configuration.


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## frenchelectrican (Mar 15, 2007)

No not on 99.9% of three phase motor you do not bring neutral at all.

the three phase motor typcially connect in wye or delta connection depending on how it set up. 

The other reason why you don't bring neutral due some motor do connect in double wye connection ( parallel for low voltage connection and series in high voltage connection ) ditto with delta connections.,


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## glen1971 (Oct 10, 2012)

I worked with an engineer that designed all 3 phase motors as being fed with "4 wires + ground".. When I asked him about it, he said "it's a bargaining chip with the contractors to avoid extras".. I said "If an electrician pulled it that way, he shouldn't be doing the job since he doesn't know how to hook up a motor..".. Even had the principal engineer stumped for an application when I asked him about it...


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## micromind (Aug 11, 2007)

glen1971 said:


> I worked with an engineer that designed all 3 phase motors as being fed with "4 wires + ground".. When I asked him about it, he said "it's a bargaining chip with the contractors to avoid extras".. I said "If an electrician pulled it that way, he shouldn't be doing the job since he doesn't know how to hook up a motor..".. Even had the principal engineer stumped for an application when I asked him about it...


And these educated idiots are telling us what to do........

Some of the smartest people I've ever met are engineers. Most of the dumbest people I've ever met are engineers. 

But, as others have stated, the neutral is not connected to a 3Ø motor. If it were, there would be circulating currents present and the net result would be increased winding temperature. 

I have however, used a motor to derive a neutral from an ungrounded transformer for testing VFDs. 

The shop I was building the control panel in had 120/208Y and the VFDs were 480. So I reverse-connected a basic standard 480∆ - 120/208Y transformer but since the final destination was a 277/480Y, I didn't want to cut the MOVs out. 

I also didn't want to blow the MOVs up by using an ungrounded system so I connected a 15HP 12 lead motor series Y and used 10 - 11 - 12 as a solidly grounded neutral. 

It worked as planned, the VFDs tested ok and no blown MOVs.


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