This graph shows a single line to ground fault occurring on line A of a 3 phase system.
Va is red, Vc blue.
At first I thought Va had went to ground. But its actually in behind Vc. It's almost as if Va has halved and taken on the characteristics of Vc.
This is going to sound like a stupid question, for someone at my level. But clearly those lines aren't completely isolated from each other. Right?
I spend most of my time with math. I'm slightly in the dark when it comes to the real thing.
Has the voltage halved across the two lines or something?
That might result in, half the magnitude and the same phase angle, which corresponds to the results I seem to be getting

 

For some reason Va and Vc have become the same voltage, in anti-phase to Vb (at a lower voltage).

Mathematically this could be achieved by subtracting Va from Vc, to give the new waveforms of Va & Vc.

 

Thanks Hymie - Oh yeh I see that now. Both Vc and Va have taken on a new phase angle.
I had thought Va had taken on Vc's phase angle or vice-versa, but now I see they are both different and at anti phase to Vb.

I could define it as this
Vca = Vc - Va