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[Towertalk] grounding system

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Subject: [Towertalk] grounding system
From: (David Robbins)
Date: Mon, 29 Jul 2002 13:05:15 -0000
> > I suspect these numbers could represent worst case, but there are
> > many variables (orientation of wire, neight above ground, etc.) for
> > to believe that one voltage fits all.
> Absolutely Pete.
> If that were true, I'd be in deep "poo" here. 

And I would be out of a job!  Most of my job is writing software that
simulates lighting strokes to high voltage power lines.  We are still
doing basic research on things as basic as what happens when lightning
currents go into the ground because there have been so few full scale
controlled experiments.  Even with relatively simple geometries it is
very difficult to predict what lightning can do, and that is with direct
strokes.  Calculating the induced voltages from nearby strokes is even
worse.    In some of the experiments we have done with high current
pulses (up to about 40ka in a few microseconds) the biggest problems are
in keeping induced voltages on the remote signal leads to a minimum.
Fiber optics helps a lot to collect data, but keeping induced voltages
out of the short leads between sensors and fiber optic transmitters and
the fiber receivers and the digitizers often requires locking the
equipment inside metal boxes with battery power supplies to isolate them
from the world.

David Robbins K1TTT
AR-Cluster node: 145.69MHz or telnet://

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