[geeks] D'OH!

[Greg A. Woods]

[ On Sunday, February 3, 2002 at 01:57:17 (-0500), Dave McGuire wrote: ]
> Subject: Re: [geeks] D'OH!
>
> On February 2, Greg A. Woods wrote:
> > FYI the single-phase three-wire 120/240VAC system used in North America
> > is sometimes called the "Edison System".
> 
>   If I remember history correctly, "Tesla Polyphase" would be more
> accurate.

If I'm not mistaken the reason North America commonly uses 110VAC
instead of 220VAC is because of public (and I suppose more importantly,
critical influence by the movers, shakers, and high-rollers of the day)
pressure instigated by Edison and his lawyers in their fight to preserve
their DC generating plant investments.  Edison's DC plants were designed
to generate 116.5 volts DC (which IIRC was engineered to be at a minimum
of 100 volts at the extremities of the system, a few city blocks at
most).  Use of a similar voltage in the "Westinghouse" AC system was
deemed to be beneficial (Edison lamps, for one, were immediately
compatible).  I can't find technical references to the voltages used by
Tesla and Westinighouse in the World's Fair though....

Edison also designed the three-wire distribution system with a positive
potential line, an equal but negative potential line, and a neutral line
(usually at ground potential).  This system was more efficient (in terms
of copper costs) than the original 2-wire feeder and mains systems used
by the first commercial Edison plant at Pearl St. in New York (which was
converted to use the three-wire system before the station was finally
shut down in 1895).

In the end I believe the three-wire single-phase 120/240VAC distribution
system used by (primarily North American) consumers is sometimes called
the "Edison System" because of these factors.

>  As others have pointed out, Edison was pushing DC while
> Nikola Tesla was pushing AC.  Tesla is very much the unsung hero of
> power distributino systems...Most of the best ideas were Tesla's while
> Edison got most of the credit.

Most of Tesla's ideas were appropriated by others, and many claim very
few of Tesla's many inventions were ever patented (he had only 110
patents in the USA).

However while Tesla's system is what we use today (completely unchanged
in its fundamental design and basic parameters since the patent was
issued in 1888), Edison really was the pioneer, and first successful
commercial exploiter of, eletric power distribution systems.

-- 
								Greg A. Woods

+1 416 218-0098;  <gwoods at acm.org>;  <g.a.woods at ieee.org>;  <woods at robohack.ca>
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