Grounded Delta Phase Angles?

[Cfris]

Hi, I'm an EE student and was wondering if I can get some clarity on a couple topics. I have been researching the Grounded Delta configuration, also known as the "high leg" configuration. And while I understand how the voltages are calculated I cannot find anything on how to determine the phase angles from phase to phase and each phase to neutral? does this grounding change the angles for each phase?

 

[jumper]

Welcome to the forum.

People will be along shortly to answer your question.

 

[jaggedben]

I'm going to go out on a limb here and say that which node is grounded never changes the phase angles.

Wikipedia has a decent graph of the voltage cycle.
(It doesn't show all three 240V angles, only one.)
https://en.wikipedia.org/wiki/High-leg_delta#/media/File:CenterTappedTransformer_Voltages.svg

Evidently the high leg is 180degress from the others with respect to neutral/ground. Someone else will have to explain the math for you though, I'm not an EE.

 

[smoothops10]

This may be helpful
https://www.youtube.com/watch?v=V7_ulixULiw

 

[GoldDigger]

I'm going to go out on a limb here and say that which node is grounded never changes the phase angles.

Wikipedia has a decent graph of the voltage cycle.
(It doesn't show all three 240V angles, only one.)
https://en.wikipedia.org/wiki/High-leg_delta#/media/File:CenterTappedTransformer_Voltages.svg

Evidently the high leg is 180degress from the others with respect to neutral/ground. Someone else will have to explain the math for you though, I'm not an EE.

Just look at the drawing with windings and imagine that each coil is replaced by a phasor at the same angle and position.
The right angle at the bottom as well as the 120 degree phase to phase angles become simple geometry. Same for voltages (= phasor length)

 

[winnie]

Measurements of voltage and phase always require a reference point.

Phase terminal to phase terminal the phase angles stay the same. In other words if you make the waveform from terminal A to B your zero degree reference, then you B to C and C to A phase angles will stay the same no matter what the grounding.

But if you use _ground_ as your reference for voltage, and say terminal A to ground as your phase angle reference, and look at your terminal B to ground and terminal C to ground phase angles, these will change with different grounding.

Which is just a complicated way of saying that all of your relative terminal to terminal phase angles remain constant, but if you use different terminals as your phase reference then the phase angles will appear to change.

-Jon