- #1
sandy.bridge
- 798
- 1
Hello all,
I'm having a bit of a difficult time following a specific conversation that I had with one of my professors. Occasionally, we would be given a 3-phase load (balanced or unbalanced), with merely the wires shown (the formation of the sources was not revealed. See the image below.
I asked what formation do we assume the sources are in, and he said that it doesn't matter. However, I was analyzing a few questions assuming wye connection, followed by delta connection, and I was getting different results; meaning that it did appear to matter.
As an example, say we are given a line voltage of 208V for a) in the image.
If we assume wye orientation of the sources, then in phasor form we would have,
[tex](U_{23}, U_{31}, U_{12}) = (208e^{j30}, 208e^{-j90}, 208e^{j150})[/tex]
All of these are leading their respective phase voltages in wye.
If we assume everything remains the same but we merely change the sources to delta configuration we get the following:
[tex](U_{23}, U_{31}, U_{12}) = (208e^{j0}, 208e^{-j120}, 208e^{j120})[/tex]
This is due to the fact that the phase voltages are the same as the line voltages in this orientation.
Furthermore, there is an actual conversion from one to the other. However, I am just not seeing how you can assume the original orientation and get the same results. Any idea where I am going wrong, or what?
Thanks!
I'm having a bit of a difficult time following a specific conversation that I had with one of my professors. Occasionally, we would be given a 3-phase load (balanced or unbalanced), with merely the wires shown (the formation of the sources was not revealed. See the image below.
I asked what formation do we assume the sources are in, and he said that it doesn't matter. However, I was analyzing a few questions assuming wye connection, followed by delta connection, and I was getting different results; meaning that it did appear to matter.
As an example, say we are given a line voltage of 208V for a) in the image.
If we assume wye orientation of the sources, then in phasor form we would have,
[tex](U_{23}, U_{31}, U_{12}) = (208e^{j30}, 208e^{-j90}, 208e^{j150})[/tex]
All of these are leading their respective phase voltages in wye.
If we assume everything remains the same but we merely change the sources to delta configuration we get the following:
[tex](U_{23}, U_{31}, U_{12}) = (208e^{j0}, 208e^{-j120}, 208e^{j120})[/tex]
This is due to the fact that the phase voltages are the same as the line voltages in this orientation.
Furthermore, there is an actual conversion from one to the other. However, I am just not seeing how you can assume the original orientation and get the same results. Any idea where I am going wrong, or what?
Thanks!