Re: Single vs Two Phase (was - Spark gap erosion resistance)

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Michael,

The reason for the "controversy" is that the true electrical engineering
definition says that the number of phases is related to the armature
construction of an alternator.  One winding gives single phase AC.  It
"does not matter if you take the center as ground", it is still single phase.  

Two windings give two phases at 90 degrees (pictures are more clear) and
three windings give three phase at 120 degrees apart.  It goes on for four,
and six for "odd" machines...  The 120 VAC in our houses is actually 1/2 of
a single phase (one side is neutral).  The 240 VAC for the oven and dryer
just uses the full phase.  Of course, this one phase to our houses is just
one leg of the original three phases from the "alternating plant" (in this
case, we won't give Edison the pleasure of referring to it is a generating
plant which is "supposed" to imply DC :-)))

If you were to really look hard, you would see that the common 120VAC in
homes actually has six variations around town that are 60 degrees apart.
This is done with the three phase transformers, pole transformers, and
grounding to split it all up.  However, it is not uncommon to refer to the
two 120VAC components to the house as phases even though it is not
technically correct.  That's what "I" did that got this mess started =:-O

If one figures all this out and adds in the delta and wye configurations,
you have "arrived"...  But for those that just see the wires and think they
are all "phases", "I" will "understand" and forgive them for not getting
into the messy details.  *:o)  We won't even touch the folks that refer to
the "neutral phase" and "ground phase" :o)))

If one takes the output of a three phase alternator and thinks off ALL the
ways to hook transformers and grounds together, you will see how complex it
can get.  EVERY one of those variations is in common use...  That's why we
have electricians and/or engineers to figure it all out for us.  ;-))  

This is what happens to something "simple" after engineers have 100 years
to work on it :o)))

Cheers,

	Terry
 

At 12:29 PM 1/9/2002 -0500, you wrote:
>Hi Phasers,
>
>I've not been following the nuances of this thread very well due to my lack 
>of EExpertise.  But I have a question that I have not seen answered yet: Are 
>there agreed-upon definitions of the terms single phase, two phase, three 
>phase, etc.?  If so, what are those definitions?  From my observations the 
>discussion so far has lacked agreement on term definitions.
>
>Regards,
>
>Michael Tandy
>