Click on the lower power supply and change the phase. If the Green and Orange sine waves in phase the Red sine wave will be double the voltage. If the Green and Orange sine waves are 180 degrees out of phase the Red sine wave is flat lined. If the Green and Orange sine waves are 120 degrees out of phase the Red sine wave is the same voltage with a 120 degree phase difference. 3 phase 120 degree phase shift is what's required for an open circuit delta. You can get all 3 phases the same from just 2 power supplies.
