JBD
Quote
"Specifically, when using only two "hot" wires of a wye, the currents in each conductor are not 120° out of phase with each other, however, the line to neutral currents are. You can not have a phase difference if you only have two wires (what goes out must come back)."
Specifically, in a wye system such as this the line current and the phase current are the same and they are out of phase by 120 degrees. If that were not true my caculations would not have produced the same answer as your formula. An by the way, the voltages are also 120 out of phase.
JBD
Quote
"When using only two "hot" wires of a single phase 3 wire system. the currents in each conductor are not 180° out of phase with each other, however the line to neutral currents are.
Neutral currents never subtract from each other, they always add (the trick is you may be adding a negative number)."
The voltage vector relationship depends on the way the secondary windings are wound in relationship to each other.
This is where the (+) and (-) polarity markings really become important. This notation is often used to reference the phasings of multiple AC voltage sources, so it is clear whether they are aiding ("boosting") each other or opposing ("bucking") each other.
To mathematically calculate voltage between "hot" wires, you must subtract voltages, because the polarity marks show them to be opposed to each other:
If we mark the two sources' common connection point (the neutral wire) with the same polarity mark (-), we must express their relative phase shifts as being 180o apart. Otherwise, we'd be denoting two voltage sources in direct opposition with each other, which would give 0 volts between the two "hot" conductors.
