We are looking for a solution to use a 3 phase network to supply a 1 phase load.

We are aware of the LeBlanc, Scott-T and Open-Delta arrangements. However they don't meet our requirements as the link below explains.


We are also aware that 12 leg 3 phase alternators can be reconfigured to 1 phase and ask why can't a similar concept be used in a transformer?

Basically we are looking for a transformer configuration (with no electronics) which will present a single phase load as balanced on a 3 phase network. The transformer may not be optimal in terms of efficiency or may need to be oversized.

Scott T

  • \$\begingroup\$ What is the 3 phase supply coming from? A generator or the grid? \$\endgroup\$ – Josh Jobin Dec 2 '15 at 12:00
  • \$\begingroup\$ If you have 3 phase from the grid, you should be able to simply take a single phase to drive your load. But if you are using a 3 phase generator you won't be able to get a balanced load \$\endgroup\$ – Josh Jobin Dec 2 '15 at 12:26
  • \$\begingroup\$ From that link, read the first bold sentence. \$\endgroup\$ – PlasmaHH Dec 2 '15 at 12:54
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    \$\begingroup\$ @chameleon95: If there was, you would not get an answer here, since we only can tell you what is known to man ... \$\endgroup\$ – PlasmaHH Dec 3 '15 at 13:07
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    \$\begingroup\$ The underlying challenge here is that a balanced three-phase load requires a continuous flow of energy, but a single-phase load inevitably results in a pulsating flow of energy. Therefore, the solution to your problem will require some kind of energy storage: inductors, capacitors, or the inertia of a rotating machine. Transformer connections alone can't do this. (But a transformer with a gapped core, which can store significant energy and is essentially an inductor, may be part of a solution.) \$\endgroup\$ – Fred Schleifer Dec 6 '15 at 7:18

Writing my comment as an Answer (though it is not) as I do not have enough reputation (in electrical forum) to comment.

Last year I tried this by connecting R + Y + (reversed)B phases (R+Y-B) in series on the secondary of 3Ph Transformer.

As R + Y gives a vector exactly opposite to B, by inverting B we get -B in Phase with R + B. I simulated this at 210V using 3X3Ph Transformers and lamp bank.

As expected, I got single phase supply (with appropriate scaling) but got disappointed to see Unbalanced Phase currents on primary side. Later rechecking model on paper showed me that my idea was wrong. Primary being 3 Phase it will always load B Phase (which was reversed) unbalanced. Hence discarded the idea.

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