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Re: [RFI] Power Lines

To: rfi@contesting.com
Subject: Re: [RFI] Power Lines
From: Martin Ewing - AA6E <aa6e@ewing.homedns.org>
Date: Sun, 23 Dec 2007 17:54:14 -0500
List-post: <mailto:rfi@contesting.com>
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 //
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Martin Ewing, AA6E

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