? open delta, three phase?

[BHD]

this is probably more of a engineering questing,

but does 240, open delta, three phase produce a true three phase signature,

or are all thee sine waves present if one would put it on a oscilloscope, if there were no motors running, (the motors would generate a third, phase, as a rotary phase converter does), or are there just two at 120 degrees apart and 120 degrees with a missing one on the third 120 degrees?

I know it is not "two" phase, but is it true three phase,

[wbrooks]

I believe you would. The beauty of a delta xformer system is that when you loose a phase coil (open delta) the other two in the system take up the slack as long as you size the Xformer correctly. When you loose a phase coil the capacity of the remaining 2 is 57.7% of the full 3.
In the following diagram you will note that the 10KW load across the open delta sees the sum of the 0 phase and the 120 phase. If you put pen to paper and draw the sine waves you will note that the sum of the 0 and 120 phases creates a 240 phase
http://www.nexicom.net/~wbrooks/opendelta.jpg