| in article gJ%9d.291$ snipped-for-privacy@nnrp1.ozemail.com.au, John G at | snipped-for-privacy@ozemail.com.au wrote on 10/9/04 5:52 PM: | |> American 2 phase is not really it is just one phase with the centre |> earthed and called the neutral | | You are describing the Edison three-wire system. Two phase as used here | really refers to a four phase system with neutral where only two phases 90 | degrees apart are used.
The 90 degree system could have been wired with 3, 4, or 5 wires, depending on configuration. Going along with the use of "Y" for a three phase WYE system, you could use "L" and "X" for these systems, with the center of the X perhaps connected or perhaps not. Or the load connection could be "L" or a full square on an "X" system.
The confusion is whether to call this 2 phase or 4 phase.
If you had a 3 wire system with a neutral and 2 hot phases at 120 degrees apart, would you call that 1 phase, 2 phase, or 3 phase?
What if they were 90 degrees apart instead?
What if they were 105 degrees apart?
What if they were vectors of unequal length, such as 2 at 120 volts at
180 degrees from each other, plus another at 207.846 volts 90 degrees different from the other 2?
If I have a 3 phase system with 2 phases at 120 volts (-90 degrees and
+90 degrees) and 207.846 volts at 0 degrees, and then I remove 1 phase, is that now a 2 phase system or a 1 phase system?
A 120/240 system could be considered as 2 phases at 180 degrees. But you can't derive other phase angles from it. However, a 170L/120 system can have other phase angles derived from it.
But if I were going to use a 90 degree system, I'd use 495X/350.