On Thu, 9 Aug 2018 18:09:17 -0500, Mark Lloyd
wrote:

On 08/09/2018 04:32 PM, trader_4 wrote:

[snip]

Fretwell's new interesting position is that phases disappear if they
are 180. And that also somehow also kills off other phases, because he says
if I take a 3 phase system and move the 120 phase to 180, POOF, it
becomes a single phase system.

If you think you see an oddity like that (phase disappearing at 180),
there's something wrong.

I'm beginning to understand about 2 phases making a 3-phase delta
system, but there's still something wrong with that "disappearing
phase(es)".

It is not odd but if you do have 3 windings and one comes off the
center tap of the single phase winding (Traders rotated to 180)
you actually do see 2 phase. That is the Scott T connection I have
talked about but it required 3 windings in a wye, not 2 end to end.
You also get that illusion on a scope if you look at a center tapped
delta.
https://upload.wikimedia.org/wikipedia/commons/thumb/4/43/High_leg_delta_transformer.svg/330px-High_leg_delta_transformer.svg.png
You will swear you are looking at 2 phase with a 90 degree
displacement but your 3 phase motors are happily humming along.
It is pretty much impossible to scope that pretty 3 phase signal you
see in the book even if you "float" the scope..