# Double Delta Parallel Feed Make-Up



## Wiresmith (Feb 9, 2013)

see picture.

Do you guys think it would be okay to hook a motor up with two isolated sets of delta windings(no internal connections, those leads are not parallel, the windings are and the leads have no connection(t1 to t1) internally)fed from a parallel feed
hooking it up like the picture shows without connecting all 6 wires of both T1's, T6's and both browns together at the motor, these would only be all tied together at the VFD.

do you think there would be problems down the road when one winding starts to breakdown more than the others and there starts to be an imbalance? the cable is not in conduit anywhere only cable tray. probably 200' run, shielded drive cable.

thanks


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## frenchelectrican (Mar 15, 2007)

I dont see any issue as you posted the connection diagram so you should be good to go as long the motor nameplate stated it is true double delta connection. 

I have done that quite few time but the question is how ya set up the OCPD ?


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## Wiresmith (Feb 9, 2013)

frenchelectrican said:


> I dont see any issue as you posted the connection diagram so you should be good to go as long the motor nameplate stated it is true double delta connection.
> 
> I have done that quite few time but the question is how ya set up the OCPD ?


no fuses if that's what your asking. its on a breaker with motor protection relay all before the VFD

this is the motor asked about in https://www.electriciantalk.com/f28/wye-delta-motor-drive-12-leads-only-labelled-1-6-a-266032/


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## frenchelectrican (Mar 15, 2007)

Wiresmith said:


> no fuses if that's what your asking. its on a breaker with motor protection relay all before the VFD
> 
> this is the motor asked about in https://www.electriciantalk.com/f28/wye-delta-motor-drive-12-leads-only-labelled-1-6-a-266032/


Ahh ok I get it now I follow up the link and yes I do recall the conversation on the fourm on the motor situation. 

That set up is perfectally fine with it. 

As you mention the connection with 6 conductors as you posted that can be done too so it work either way. 

I am pretty sure Jreaf or John will know this pretty well due it kinda their turf ditto with Mircominded I know he been farting around with some pretty big arse motors so I will see what he say as he chime in.


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## Wiresmith (Feb 9, 2013)

frenchelectrican said:


> Ahh ok I get it now I follow up the link and yes I do recall the conversation on the fourm on the motor situation.
> 
> That set up is perfectally fine with it.
> 
> ...


do you have any suggestion on how to connect all 6 of those wires? (2) 350, (4)1AWG. i know you can bolt them all together and make it work but i'm not coming up with a nice way. except extending motor leads to some busbars in a near junction box, which i would do if it was up to me, or get a better motor for the set-up


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## frenchelectrican (Mar 15, 2007)

Wiresmith said:


> do you have any suggestion on how to connect all 6 of those wires? (2) 350, (4)1AWG. i know you can bolt them all together and make it work but i'm not coming up with a nice way. except extending motor leads to some busbars in a near junction box, which i would do if it was up to me


Well I have few different ways to do it with the termation on the motor peckerhead location.

All it dpending on the tools you have on hand and size of peckerhead that will change a bit.

But typically with large connection I have at least 3 different ways you can get this done in correct way. 

A. Compression lugs plus bolt and cold shrink wrap tube 

B. Split bolts ( double splitbolts will do it ) if have room in peckerhead.

C. mini busbar connection only if oversized peckerhead box is there.

so that is one of few ways I can termatited them.


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## Wiresmith (Feb 9, 2013)

frenchelectrican said:


> Well I have few different ways to do it with the termation on the motor peckerhead location.
> 
> All it dpending on the tools you have on hand and size of peckerhead that will change a bit.
> 
> ...


i'm sorry but i have to ask, i know you answered this i just have to ask again, i cannot visualize it or i should say don't like what i see when i try to visualize it. (6) wires bolted together?(fairly big wires)


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## frenchelectrican (Mar 15, 2007)

Wiresmith said:


> i'm sorry but i have to ask, i know you answered this i just have to ask again, i cannot visualize it or i should say don't like what i see when i try to visualize it. (6) wires bolted together?(fairly big wires)


That fine I understand what you are saying on that.,

let me try find a photo with large conductor bolted together. 

but the issue is the size of peckerhead that what I am little conderstation or wondering on that. 

but being with 350 HP motor you should have pretty good sized peckerhead in there. 

so give me a little time to find it then I will post it.


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## micromind (Aug 11, 2007)

I've connected big motors this way many times. Even though the 2 sets of windings are sort of isolated in the motor terminal box, I feel it's better than trying to get a ton of big wires all spliced together in a fairly small enclosure. 

The following is sort of dumb but I do it anyway.......lol.

There are basically 2 'motors' combined in one frame. If the motor is 200HP, there are essentially 2 - 100HPs in the same frame. 

I will identify which sets of windings comprise one 'motor' and not connect all of one set to one of the incoming lines. In other words, I will connect T1 of 'motor' A to T6 of 'motor' B to one of the lines. Same way with the other 2 lines. 

The reason for this is if one splice burns up, the entire motor will single phase. An O/L will respond to an entire single phase situation faster than a half-single phase incident. Less chance of a burn-up this way. 

I don't know if it actually works or not because I've yet to have a splice like this fail. 

Someday though........lol.


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## Wiresmith (Feb 9, 2013)

micromind said:


> I've connected big motors this way many times. Even though the 2 sets of windings are sort of isolated in the motor terminal box, I feel it's better than trying to get a ton of big wires all spliced together in a fairly small enclosure.
> 
> The following is sort of dumb but I do it anyway.......lol.
> 
> ...


interesting, i was thinking to try to keep one parallel feed with one set of windings that way when one winding starts to degrade the currents on each leg in the cable would compensate with each other. say one cable has Brown running a little higher than the brown in the other cable, i was thinking it would be better so the magnetic fields would still cancel out, if you split them up i would think its similar to running all of your browns together, all yellows together, etc in parallel run(i'm not in conduit but it could effect the other cables in the tray). i know there would probably only ever be a small imbalance but that's what i was thinking might be a potential problem.

do you know how i would determine which set of windings go with which(without taking motor apart). mine are only two sets of t1-t6, no a and b or anything

thanks


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## micromind (Aug 11, 2007)

The way to determine which set is which is to look for continuity between one of the T1s and one of the T4s. Label that set as A. Do the same thing with T2 and T5 then T3 and T6.


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## Wiresmith (Feb 9, 2013)

micromind said:


> The way to determine which set is which is to look for continuity between one of the T1s and one of the T4s. Label that set as A. Do the same thing with T2 and T5 then T3 and T6.


I know that lol, i don't know how these type of motors are wound so i was wondering (it might not/probably doesn't matter) which t1/t4 winding goes with which t2/t5 and t3/t6, if i was going to not intermix them like you did.

reading back through your other post i now see how to do what your doing, i don't need to know what i was asking. i have to draw out that configuration your describing it looks weird in my head, but i love the idea i think it's brilliant and could save motors


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