Hey, I'm really glad I read this post.  The subject line was the 
same one I gave it when I wrote to the list the other day, 
Moderating You Off the list.  So, I have been ignoring some of 
the posts with the same subject line since then.  I have also 
changed the subject line of this post to more accurately reflect 
the topic and what it's about.  Thank you for the most 
interesting information about the power grid.  I wonder what it 
will take to really make a "smart grid?" And then there's all the 
renewable stuff even people's solar panels, wind generators etc.  
What happens to the grid when you feed power into it from all 
these separate units? Jim WA6EKS

----- Original Message -----
From: Ron Miller <[log in to unmask]
To: [log in to unmask]
Date sent: Mon, 20 Aug 2012 19:16:38 -0400
Subject: Re: Moderating you off the list!

Martin,
That is very interesting.  I didn't have a clue about this.

Ron Miller
N6MSA
Dunedin, Fl.
USA
SKYPE: arjay1
-----Original Message-----
From: For blind ham radio operators 
[mailto:[log in to unmask]]
On Behalf Of Martin G.  McCormick
Sent: Monday, August 20, 2012 9:16 AM
To: [log in to unmask]
Subject: Re: Moderating you off the list!

	The power grid is pretty much what you describe but it is
surprisingly complex, also.

	As a student in the late seventies, I had a part-time job 
involving
the development of instructional materials for the training of 
power line
workers.  Somewhere along the way, we discussed what has to 
happen when you
connect an AC generator to the grid or more accurately, the 
grids.

	We have more than one large power network in North America 
which
includes the United States, Canada and Mexico.

	A very large grid runs all the way from Quebec and New York 
State
all the way across the nation to the Rocky Mountains and down to 
Texas.

	There is a Western grid from the Rockies to the West Coast 
and then
Texas has its own grid.

	This is based on what I learned in the seventies and it 
could be
that some of these grids have merged.  Here's the problem.  You 
know how, in
radio, you can tune a transmitter to the exact same frequency as 
another
transmitter and they are said to be at zero beat.  These 
generators are just
extremely low-frequency transmitters.  When you start one up, it 
may be a
cycle or two too fast or slow and its signals will beat with the 
rest of the
grid at some low frequency like two musical instruments that 
aren't quite in
tune.

	You may wonder how they connect AC generators in parallel.  
After
all, they do it all the time and here is where theory meets 
practice.

	The word heterodyne means to mix forces.  If two people are 
on a
tandem bicycle, they must both peddle at the same speed or 
nothing much good
happens.  Generators are like motors, so much so, that a motor 
can be a
generator under the right conditions and vice versa.  If you have 
two AC
generators running at the exact same speed, you can connect them 
together
and they will run as one.  The trick is making them run exactly 
the say
speed.

	What they have to do is connect an instrument to both 
generators
that can tell when both are close to being in phase.
When they are, it is safe to hook them together.

	When you do this, they keep each other in phase because if 
one tries
to lag a little, the energy from the other will force it back to 
speed.  It's
just like the tandem bike.

	If they have to take a generator off line, they disconnect 
it from
the grid, first and then they can safely stop it.

	Think about this.  In New York City, you could put a mark on 
the
armature of a generator at a power plant and do the same thing on 
a
generator in Oklahoma City and come back a week later and find 
both marks in
the same relationship to each other that they were when you made 
them
because all the generators in the Eastern grid must phase lock 
with each
other or terrible things will happen.  I'm talking about 
destroyed equipment
and lots of fire.

	I honestly do not know how one keeps the whole grid from 
drifting
slowly up or down in frequency, but I have heard that the 
long-term
frequency stability of the American power grids is superb.  I 
think they use
atomic standards to set the whole thing.

	That few months I worked in that job was really interesting 
and
amateur radio theory made it much more easy to understand this 
material.

Martin WB5AGZ


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