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Re: [TenTec] Slightly OT: Sunspots for propagation? Who needs 'em?

To: tentec@contesting.com
Subject: Re: [TenTec] Slightly OT: Sunspots for propagation? Who needs 'em?
From: Jim Brown <k9yc@audiosystemsgroup.com>
Reply-to: k9yc@arrl.net, Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 27 Aug 2016 11:32:15 -0700
List-post: <tentec@contesting.com">mailto:tentec@contesting.com>
I'm not sure what you mean by "intelligent power management system." But think about the fundamentals of how this might be done. You've got to reshape the total load current in each phase to make it sinusoidal without increasing the total current drawn! Things like this may be possible, but something like this is not cheap. The EU has regulations about this that apply to large systems, and it costs a lot to comply.

73, Jim K9YC


On Sat,8/27/2016 10:58 AM, Gary J FollettDukes HiFi wrote:
And you don’t think that intelligent power management systems available today 
could correct for this?

Gary



On Aug 27, 2016, at 12:30 PM, Jim Brown <k9yc@audiosystemsgroup.com> wrote:

3-phase power is not the universal blessing that you believe it to be. The overwhelming bulk of the power 
delivered to today's homes is to electronic loads, which draw highly distorted current, resulting in very 
high harmonic content. That, in turn, results in high neutral currents that consist of "triplen" 
harmonics of the fundamental rate (50 or 60 Hz). Triplen harmonics are those whose order is a multiple of 3, 
and they add in the neutral rather than cancel, even with loads that are perfectly balanced. Those harmonics 
also add in the "green wire," producing the characteristic "ground buzz" (180 Hz, 360 Hz, 
540 Hz, 720 Hz, . . . ), as opposed to hum (50/60 Hz).

Neutral currents in 3-phase systems can easily exceed the current in a phase conductor. 
Neutral current is what started the very real "Towering Inferno" and burning 
insulation running up cable risers carried the flames.

73, Jim K9YC

On Sat,8/27/2016 1:37 AM, Gary J FollettDukes HiFi wrote:
Only politics, and the relentless battle that power companies wage every day to 
avoid capital investment in new power delivery apparatus.

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