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When having Y-Δ or Δ-Y 3 phase circuits, it is more convenient to transform the source configuration into the load configuration to make the circuit easier.

When going from a Δ source with line-line voltage of 400V to a Y source with phase voltage of 400/sqrt(3), we need to subtract -30 degrees from the initial phase of the Δ source, correct?

schematic

simulate this circuit – Schematic created using CircuitLab

Volpina
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  • [Very much related answer](https://electronics.stackexchange.com/questions/191232/why-does-a-delta-wye-transformer-make-30-degrees-phase-shift/191243#191243). – Andy aka Nov 18 '22 at 14:11
  • @Andyaka So the Δ source is ahead of the Y source by 30 degrees? – Volpina Nov 18 '22 at 14:15
  • If you mean when transforming a delta source to a wye source via a transformer then yes. – Andy aka Nov 18 '22 at 14:20
  • im talking about 3 phase source transformation – Volpina Nov 18 '22 at 14:22
  • You need to probably draw what you mean. However, if you want to compare a straight delta supply with a transformed-to-Y supply you would advance the phase of the delta supply by 30 degrees to keep the transformed Y output in phase with the original delta supply. – Andy aka Nov 18 '22 at 14:49
  • So if we want to compare a Δ supply with a initial phase of 0 degrees then when we transform it to a Y supply we need to subtract 30 degrees. – Volpina Nov 18 '22 at 15:18
  • Loads on the secondary of the transformers don't care about the phase relation between primary and secondary. – Peter Bennett Nov 18 '22 at 15:38

2 Answers2

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Line voltage leads phase voltage by 30° as per this diagram (taken from here): -

enter image description here

\$V_{AB}\$ is the line voltage and, \$V_A\$ is its related phase voltage. So, if you wanted a version of \$V_A\$ that is in phase with \$V_{AB}\$, you need to advance it by 30° in time or, subtract 30° from it.

Andy aka
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I tried simulating it on the multisim live circuit simulator and these are the results:

It is clearly shown that when transforming sources we must take into consideration the phase shift between Δ and Y source(the voltage of the resistor with the Δ voltage source is ahead of the voltage of the resistor with the Y source by 30 degrees).

Volpina
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