Check out the wikipedia article on this at
http://en.wikipedia.org/wiki/Three-phase_electric_power . Lots of info
and some interesting animations.
You can build a neat DC power supply for your multi-kW station, if you
have 3 phase power. Low ripple, high power factor. Saves on filter caps...
73 Martin AA6E
Jim P wrote:
> Just an observation - and somebody correct me
> if I'm wrong ..
>>From what I have read and studied on power
> generation, power transmission and power
> distribution, the power companies extend out from
> the central (generating) station to the various sub-
> (step-down) stations all three phases of generated
> voltages from the generator (speaking of AC
> systems now! And I'm not addressing an inter-tied
> tructure as the present 'power grid' is built and
> operated either.).
> This would seem to be done for several reasons,
> not the least of which is, three phase power generation
> provides for a more equal 'torque-loading' (on
> account of the sinusoidal function involved when
> a wire is rotated in a circle and made to 'cut' through
> magnetic lines of force) of the generator's armature
> than a single phase would, and this also translates
> out into the user segment of the system when higher
> amounts of power (e.g industrial users and greater
> amounts of torque as say provided by three-phase
> motors) is required.
> It also seems that the power companies further
> extend three phase distribution lines out into the
> area to be served also for the purpose of being
> able to load-balance all three phases; single phase
> business and residential 'user' loads can easily
> be swung from a more heavily loaded phase,
> for instance, to a less loaded phase as an area
> develops or gets built-out. At some point, out
> towards the 'edge' of a service area single phase
> distribution lines begin to appear (we used to have
> an old REA line running along side one of our
> major secondary roads about 10 years back, but that
> 'line' has upgraded to all three phases now!)
> So, it is this generation/transmission/distribution of
> all three phases would appear to the be basis for
> the "divisable by three" rule.
> Caveat: All this is the result of observation and some
> self-paced study as I have never worked for, or worked
> in, the power generation or power transmission or
> power distribution industries.
> Jim P // WB5WPA //
> RFI mailing list
Martin Ewing, AA6E
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