Three-phase Power Systems
Chapter 10 - Polyphase AC Circuits

The only way for the voltage to be 207.85 at -30 degrees is if the voltage source at 120 degree was also at an opposite polarity or having an additional 180 phase shift putting it's actual phase shift at -60 degrees.

If that is the case then what would the actual phase shift for the third voltage source at 240 degrees be? How can this be 3-phase if the sources are not actually 120 out of phase?
Chapter 10 - Polyphase AC Circuits

The only way for the voltage to be 207.85 at -30 degrees is if the voltage source at 120 degree was also at an opposite polarity or having an additional 180 phase shift putting it's actual phase shift at -60 degrees.

If that is the case then what would the actual phase shift for the third voltage source at 240 degrees be? How can this be 3-phase if the sources are not actually 120 out of phase?