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Below is a per-phase representation of a small power system from Power Systems Analysis (Grainger and Stevenson, p206).

I'm trying to imagine the three-phase version of this circuit diagram. Let's take the connection between bus 1 and bus 2 as an example. Presumably, we would draw three line segments between bus 1 and bus 2. Would we also need to draw three buses at 1 and three buses at 2?

I've heard that any given bus will have associated with it just one voltage. I'm confused about how to reconcile this hearsay with the notion that, in a three-phase system, three lines with different voltages would be connected to the same bus (unless there are actually three buses?)

enter image description here

artist_and_not_EE_by_training
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1 Answers1

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They are three separate lines (busses), one for each phase.

  • In a Delta system, there are just these three lines (X, Y, Z)
  • In a Y system, there's also a fourth line, for the neutral (N)

In practice, there's one more line: earth (E)

More info: https://www.belden.com/blogs/3-phase-power-wye-it-matters

Y, delta

Davide Andrea
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