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I know that if you have two transformers connected in parallel that are of slightly different turns ratios, then there will be a circulating flow of VARs.

I also know that if you have two transformers that are mutually phase-shifted, you will have a circulating flow of watts.

My question is: what is a circulating flow of watts? To my knowledge, having more VARs implies more current implies more losses. But, having a circulating flow of watts seems like the exact same thing to me.

So what is a circulating flow of watts?

Thanks!

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    \$\begingroup\$ I think you need to draw a picture of what you mean to minimize ambiguity. \$\endgroup\$
    – Andy aka
    Dec 10, 2018 at 10:25
  • \$\begingroup\$ Hi Andy, I don't really know how to do that. But perhaps I can explain it a little bit better. Imagine we have a three-phase grid and, connected to the grid, are two transformers in parallel. One of the transformers is a normal transformer of turns ratio N; the other is a phase-shifting (a small phase-shift, for example) transformer also with turns ratio N. If ideal, identical transformers are placed in parallel, they will share the current equally; a different turns ratio causes VARs to circulate; a different phase causes Watts to circulate. What does "circulating Watts" mean? \$\endgroup\$
    – Lerbi
    Dec 14, 2018 at 4:15
  • \$\begingroup\$ I don't know what a small phase shifting transformer is and I don't follow your words. Draw a circuit and name the components. \$\endgroup\$
    – Andy aka
    Dec 14, 2018 at 8:24
  • \$\begingroup\$ Well, if you don't know what a phase-shifting transformer is, I'm not sure you can help me. Thanks anyway! \$\endgroup\$
    – Lerbi
    Dec 14, 2018 at 18:05
  • \$\begingroup\$ A star delta transformer only shifts 30 degrees and 30 degrees aint small by any means. But you know best how to attract someone to answer your question. \$\endgroup\$
    – Andy aka
    Dec 14, 2018 at 18:16

1 Answer 1

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"Power flow divides inversely with the relative impedances on a common base" RUS Design guide for substations - section 5.2.7 - Parallel Operation of Transformers

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