Donald H Locker wrote:
>
> Hmmmm. I'll try some ASCII art.
>
> C
> / \
> / \
> / \
> / \
> / \
> / \
> / \
> / \
> A--------n--------B
>
> Phases A and B are the 120 legs, n is neutral, C is the third phase.
This is for the 3 phase delivered to a normal
distribution system and can be 220 440 or higher.
>
>
> PFM! (pure magic)
> Donald.
>
Love the Ascii art. But one thing is missing here. In
normal house wiring the leg feeding the pole or vault
mounted transformer is only on of these phases. In other
words, the power coming into your house is the A_C, A_B
or C_B leg fed through a center-tapped step-down
transformer.
A ----------------------------
B ---------------------------- 3 Phase from
generatior and substation
C ----------------------------
G ____________________________ Ground
When the utility runs a pole or line into a typical
subdivision they only run in one of those high power,
high voltage lines from the main trunk.
Transformer
windings
Leg A to Ground is fed into transformer
A_(((((((((((((((((((((((_G Hi voltage side
---------------------
---------------------
L1_)))))))))))||)))))))))))))_L2
|
N
Transformer supplies 2 lines 1800 out of phase but equal
in voltage and power.
The other odd stuff comes into play when a 3 phase panel
is tapped for single or 2 phase loads.
That is why the question that sparked this whole thread
is so curious; How come you've got 208 but no 3 phase?
Probablly an old distribution system. I've seen 208 all
by itsef, with no 3 phase nearby, but not in a long
time.
--
Matt Mahoney
Vancouver WA
E-Mail is munggled.
I am at home if you wish to reply.
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