# 12-lead three phase generator -> 6 phase/pole out

Lots of 3-phase generators are the 12-lead type. Form the hookup
diagrams I have seen, these are basically pairs of 120 volt windings
on each phase. Voltage regulation can then manage them between 100
and 140 volts. With that and several wiring configurations, most
every 3 phase setup can be obtained, either wye (3-star) or delta.
What I am wondering about is doing a different setup. Running the
voltage right at 120 per winding, I want to wire the two windings of
each phase in series to get 240 volts, and wire the center point in
to get an Edison style 240/120 volt system (120-0-120). And I want
to do this on each of the three phases connecting that center point
together between them. So there would be 7 wires plus a separate
ground coming out.
Would this be possible to do?
The vector diagram would be like this:
* *
\ /
\ /
*-----*-----*
/ \
/
\
* *
The idea is to get both 240 volts and 120 volts at full generator
capacity and WITHOUT using funny phasing like this:
*
/ \
/
\
* *-----*
which derates the capacity, anyway. Of course with the 7 wire system,
it would require 3 separate single phase breaker panels (and/or 2
separate three phase breaker panels).
> Lots of 3-phase generators are the 12-lead type. Form the hookup > diagrams I have seen, these are basically pairs of 120 volt windings > on each phase. Voltage regulation can then manage them between 100 > and 140 volts. With that and several wiring configurations, most > every 3 phase setup can be obtained, either wye (3-star) or delta. > > What I am wondering about is doing a different setup. Running the > voltage right at 120 per winding, I want to wire the two windings of > each phase in series to get 240 volts, and wire the center point in > to get an Edison style 240/120 volt system (120-0-120). And I want > to do this on each of the three phases connecting that center point > together between them. So there would be 7 wires plus a separate > ground coming out. > > Would this be possible to do? > > The vector diagram would be like this: > > * * > \ / > \ / > *-----*-----* > / \ > / \ > * * > > The idea is to get both 240 volts and 120 volts at full generator > capacity and WITHOUT using funny phasing like this: > > * > / \ > / \ > * *-----* > > which derates the capacity, anyway. Of course with the 7 wire system, > it would require 3 separate single phase breaker panels (and/or 2 > separate three phase breaker panels). > > -- > --------------------------------------------------------------------------
See page 6 of
Connect the stator leads in parallel double-delta arrangement for 120/240V 1ø 3-wire service. It will be better balanced about the neutral versus zigzag. Derate the genset output to two-thirds of nameplate power.
--s falke
| |> wrote in message |> > Lots of 3-phase generators are the 12-lead type. Form the hookup |> > diagrams I have seen, these are basically pairs of 120 volt windings |> > on each phase. Voltage regulation can then manage them between 100 |> > and 140 volts. With that and several wiring configurations, most |> > every 3 phase setup can be obtained, either wye (3-star) or delta. |> > |> > What I am wondering about is doing a different setup. Running the |> > voltage right at 120 per winding, I want to wire the two windings of |> > each phase in series to get 240 volts, and wire the center point in |> > to get an Edison style 240/120 volt system (120-0-120). And I want |> > to do this on each of the three phases connecting that center point |> > together between them. So there would be 7 wires plus a separate |> > ground coming out. | | | | See page 6 of
Connect | the stator leads in parallel double-delta arrangement for 120/240V 1? 3-wire | service. It will be better balanced about the neutral versus zigzag. Derate | the genset output to two-thirds of nameplate power.
You mean like this:
* * / \ / \ / \ / \ *-----*-----*
That's just another of the "funny phasing" I want to avoid.
1. I do not want to derate the genset output to 2/3. 2. I do want three separate 120/240 volt circuits. 3. I also want some three phase power obtained separately.
That's why I asked about issues involving wiring a 12-lead generator that way. I know I can get the 6-star configuration by running all three phases through three transformers with 120/240 volt secondaries and wiring all the neutrals in common. But if I can get that directly from the generator, I can avoid the transformers. Possible issues might include:
1. Excitation voltage regulation. 2. How to wire the generator circuit breaker.

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