From: gtaylor@tnetconsulting.net   
      
   On 10/3/19 9:03 PM, gfretwell@aol.com wrote:   
   > This could go on forever but generally single phase is one sine wave,   
   > typically originating from two ungrounded conductors.   
      
   In retrospect, I realize that this didn't actually give the answer I was   
   looking for.  Or at least I didn't understand it to be that.   
      
   As you say, the phase typically originates from two ungrounded   
   conductors.  Thus the single conductor / leg / wire is /not/ the phase.   
      
   The phase is across two ungrounded conductors; AB / BC / CA or black red   
   / red blue / blue red.  (Assuming 3 wire ∆.)  Or the phase is across one   
   ungrounded conductor and a grounded conductor; AN / BN / CN or black   
   white / red white / blue white.  (Assuming 4 wire Y.)  The point being   
   that the single wire, A / B / C is /not/ the phase without another   
   conductor to form the circuit.  Correct?   
      
   > The fist fight starts when you start arguing about whether you call   
   > those 2 ungrounded conductors two phases   
      
   I can see how if you look at the two lines from the opposite ends of the   
   transformer on an oscilloscope they will be 180° out of phase with each   
   other, thus two different phases.   
      
   However, through constructive interference with each other, they are   
   effectively one single phase with twice the voltage when referencing   
   each other, vs referencing neutral.   
      
   Also, after reading about 2ɸ, and learning that the phases are 90° out   
   of phase with each other, I completely agree that the two legs are   
   decidedly /not/ 2ɸ.   
      
   > and that gets more complicated for some people when you ground the   
   > center tap of the transformer but it is still only one phase.   
      
   I'm not sure what grounding the center tap changes.  Unless it serves as   
   evidence for some that the two legs aren't the same phase.  ¯\_(ツ)_/¯   
      
   > A lot of strange language has come up around how you explain this to   
   > homeowners ("split Phase", really a type of motor winding. Two phases   
   > 180 out ... but isn't 180 degrees a straight line? The list goes on)   
   > It is single phase, get over it.   
      
   I agree that /functionally/ and /effectively/ it's 1ɸ.   
      
   > The other common implementation is 3 phase where you have 3 separate   
   > phases displaced by 120 degrees. That one usually gets by with little   
   > confusion unless you ground one corner of a delta.   
      
   I'm aware of the corner grounded ∆, but my brain doesn't want to go   
   there tonight.   
      
   > There is also 2 phase but it is pretty rare and most people have   
   > never seen it. This is typically a 5 wire service and looks like a   
   > cross or plus sign with the phases being displaced by 90 degrees.   
      
   I did some light reading on 2ɸ and agree that it's rare.  Though I can   
   see why it might be advantageous for starting motors.   
      
   I also did some light reading on split-phase motors and see how that   
   uses a single phase, through alternate winding arrangements, to simulate   
   two phases to start motors.  Not large motors at that.  Something about   
   1kW being the cut off point.  Not high starting torque motors either.   
      
   > A 3 wire implementation would be 3 wire looking like an ell. That is   
   > still a 90 degree displacement tho.   
      
   I sort of understand that.  But I think I'm going to acknowledge it and   
   move on as I'm unlikely to ever encounter it myself.   
      
   > In the electronic world I suppose there are things with more phases   
   > but that is not anything utilities usually do.   
      
   Agreed.   
      
      
      
   --   
   Grant. . . .   
   unix || die   
      
   --- SoupGate-Win32 v1.05   
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