[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Single vs Two Phase



Original poster: "Ray von Postel by way of Terry Fritz <twftesla-at-qwest-dot-net>" <vonpostel-at-prodigy-dot-net>

Tesla list wrote:

> Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<davep-at-quik-dot-com>
>
> Tesla list wrote:
>
> > Original poster: "Wall Richard Wayne by way of Terry Fritz
> > <twftesla-at-qwest-dot-net>" <rwall-at-ix-dot-netcom-dot-com>
>
> big snip
>
>         In that case, how is 220VAC available?
>         If one be '+' 110 and one be '-' 110, then the sum be zero.
>
>         best
>         dwp

dwp:

Try this way of thinking:
Take two  1.5 volt dry cells and connect them in series.  If you measure
from one end
of the string to the other you will read 3 volts.  If you read from the center
connection to either end you will read 1.5 volts.  The only catch is that
you have to
change the polarity of the leads on your d.c... meter.

Look at a single phase 220 a.c. circuit the same way.  The center
connection or ground
on
the a.c. circuit is the same as the point where the 2 dry cells were connected
together.  If you measure from the center point to either end of the 220
a.c. supply
line your meter will read 110 volts, but because we are using an a.c. meter
we don't
know if the voltage is negative or positive with respect to the center
connection.
Actually, the polarity is constantly changing by an equal amount at the HOT
ENDS.  When
one goes +110 volts the other is going -110 volts with respect to the center
connection.  What we read when we measure across the two outside hot leads
is the
DIFFERENCE in volts between the two leads.  In this case the DIFFERENCE  is
always 220
volts.  Here we are only talking about voltage i.e. potential DIFFERENCE.

Or graphically:......
Take a piece of paper and draw a line on it.
Call one end of the line -1 and the other end +1
Call the exact center point 0 (zero) (or ground.)
>From 0 to +1 is one unit in length (volt)
>From 0 to - 1 is one unit in length ( volt)
>From -1 to + 1 is two units in length. (2 volts), or,   the DIFFERENCE in
length
(volts) is 2 units in length.
    If you rotate  the paper around the 0 point the DIFFERENCE in length
(volts) will
remain the same.

Tesla:
I think, subject to a fault memory, that while Tesla did not invent  poly phase
alternating current, he did invent a method of using it and the advantages
of it as a
means of power
transmission and generation.  Seems to me his invention of the two phase
electric motor
was what brought it from a lab. curiosity to practical engineering.  If I
am wrong,
please, some one, correct me.  I wouldn't think of saying anything else but
thank you.

Hope this helps

Ray