Date: Thu, 30 Dec 2004 18:32:46 +0000
From: "J. Allen" <vy1ja@northwestel.net>
To: rsgb_lf_group@blacksheep.org
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Subject: LF: Power Line Rotation, & Auroral effects de VY1JA
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Good afternoon, Bryan, and All.

The problem with being one of they or them "what speaks", is that in doing 
so the mouth is opened, increasing the chances of foot-in-mouth disease.

In answer to your question, I will attempt to explain the power line 
rotation as I have seen all across North America and yet line rotation is 
not something which I was able to locate via Google.  It would have been 
nice to simply put a link on the LF reflector to a site which explains this 
better than I.  The description is a little over-simplified, but here 
goes....

The power lines are very real transmission lines as we in radio come to know 
them, both at 50/60 Hz and at the other frequencies, such as PLC which they 
carry.  The line which passes by the front of my home goes part of the way 
north toward Dawson, and then runs east to Faro, about a 250 mile length. 
The line develops voltage peaks and nulls to the different frequencies 
placed on it just like an RF feeder can from rig to antenna.  Large reactors 
are required to cancel the effects of line length. If one set of lines is 
always on the outside of the transmission line or is always nearer the earth 
below the line, it causes effects such as increased capacitance to ground 
and imballance of the line currents and voltages in long lines.  A line 
which is always in the center is impacted by fields from two wires, but the 
outside lines of a flat transmission line are impacted by the fields from 
mainly the one adjacent to it.  For these and other reasons, it is necessary 
to rotate the lines.

Power line rotation takes a number of structures to accomplish.  How the 
lines are rotated depends on the normal line configuration.  For this 
discussion the grounding/grounded conductor is ignored.

Here are three of the more common configurations:

1.  All lines on a single line parallel to the earth.
XYZ

2.  Lines in a triangle with two in line vertically.
X
      Y
Z

3.  A single line at the top with two lines on a crossarm below.

     X
 Y      Z

In Yukon, the 138,000 Volt three-phase lines are arranged in a flat line 
parallel with the earth, and then in triangles with one line elevated, using 
both 1 and 2 configurations above, so starting with the flat line 
configuration 1 above:

XYZ

The left line is elevated at the first structure of the rotation, and we are 
now in configuration 2 above;

X
      Z
Y

At the next structure is a reverse of configuration 2, the lower two lines 
shift left while the top line stays high and shifts right.

      X
Y
      Z

At the final structure, the elevated right line drops to the same level as 
the other two lines and we are back to configuration 1.

YZX


This is one rotation for a flat configuration of lines, and after a 
relatively short distance at power line frequencies, the rotation is done 
again in the same direction.  At each structure of rotation, the lines are 
commonly labeled ABC, XYZ, 123, or color coded Yellow, Red, and Blue.  One 
can look at those structures where the markings are located to see that the 
placement of the conductors has changed from time to time...but always 
maintaining the phase rotation sequence.  XYZ, then YZX then ZXY.

As you travel along the highway on your next trip, with someone else at the 
wheel, watch the high-tension lines for transitions similar to the one 
described here.  Now that you know what to look for, transitions should be 
easy to spot, regardless of the line configuration.

I hope this was clear enough....

And I agree... "they" in one country may not take any notice of  the work of 
those in another country, especially considering current politics.  Being an 
optimist here has its advantage... As Darby O'Gill said, "The only person 
who is happy altogether is the villige itiot.", and in my optomistic 
ignorance I do try to be happy.. :o)

It is interesting to watch http://sec.noaa.gov/pmap/pmapN.html and the 
propagation changing together these days.  The shape of the Auroral halo is 
a bit flattened on the map  in such a way that the NA east coast to EU west 
coast path is not impeded by the Auroral cloud.  Parts of Alaska are out 
from under the halo and are able to communicate with major areas of the 
world, while we in Yukon, only a few hundred miles away, are blocked from 
even communicating with sections of NA south of us.

I hope that things turn around soon, so that I can send you captures of your 
signals into Yukon.


J.
VY1JA
CP20kw