Transformer connections

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The only neutral is in the main switch gear they only ran the three phase conductors to the main machine. The machine that the transformer is for seem to be working the way i wired the transfromer but im not sure it right.
 
You do not have a separately derived system, therefore you cannot wire it like one.

Pull a neutral conductor from your main equipment or replace your auto-transformer with an isolation style.
 
That the machine is working does not mean that the installation is correct. It may work just fine, or it may work with reduced reliability, or it may work with reduced safety.

The transformer _will_ create a neutral. The line-neutral voltage will be poorly regulated, and the neutral to ground voltage will be all over the place.

If you actually intend to use the neutral it is supposed to be connected to the supply neutral.

If the line-neutral load is very small and used only for control, with the bulk of the system using 3 phase line-line power, it is quite likely that the system will work.

If you don't really need line-neutral power then this transformer is just fine.

-Jon
 
This machine uses a small amount of line to neutral but some of the small motors are var drive single phase which uses the neutral . ill have to get a 15 kva 480 delta to 400 wye transformer
 
Might be cheaper to replace the var drive for the small motors with something connected line-line. If you can change everything over to not using the neutral then I don't see a problem with using this transformer
 
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