Gerald Brazil wrote:
> Thanks to all who responded to my "simple" question about 220v current. I
> think if I can distill it all down, the piece I didn't know about was that
> the two 110 legs of a 220 circuit are on different phases and that when
> connected to the same item this phase relationship provides the common which
> I thought was missing. I think I learned enough to pass the first section of
> an apprentices exam.
>
The way I explain it is to visualize a 110VAC circuit as a sine wave. The
average voltage (please let's not think about discussing what RMS means) is
110V,
measured to the middle. If you draw a second sine wave on top of that one, but
make this one go down when the first one goes up and up when it goes down
(backwards, or 180 degrees out of phase) you can see that it also has the same
average of 110V. If you look between the two you get 220V. And the middle is
the neutral line.
Three phase AC is the same thing, just three waveform 120 degrees out of phase.
The difference between each of the three windings is harder to visualize, but it
is way more than 110V and a bit less than 220V; it is 208V.
An aside: the inspector who asked someone to use a neutral instead of a ground
was wrong, unless there was also a metallic ground connect - either via conduit
or metal sheathed cables. It just isn't as safe that way.
>
> Those of us who play with British cars have a very rudimentary knowledge of
> anything electrical. For example, I believe that cars with Lucas systems
> operate on smoke.....if you keep the smoke inside the wires, they work. If
> the smoke leaks out, they don't.
The smoke theory of electronics is one of my favorites. Works for ICs the same
way.
And here is a link to the Lucas Electrics home page (apologies to those who've
seen it before. If you look very carefully you can just make out my 77 MG
Midget
and a Jensen Healey I once owned.
http://motorrad.cx/lucas.html
Mark Miller
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