Stati-Cats Protect, Serve
by Mark Persons
Radio World Article
December 22, 1999
Lightning happens almost anywhere. The
difference between one location and another is the frequency of lightning
strikes per year. Florida gets the
highest number. I, and most of my
clients, are in Minnesota. We are a
long ways from Florida. However,
that doesn't exempt this area from lightning damage.
At least twice each summer, I am called to repair lightning damage. Each time, financial damage to a facility starts at $500.00
and goes up from there. One
of our clients suffered $18,000.00 damage from a single lightning strike this
summer. That station would have
spent four days off the air if there had not been a backup transmitter
Most lightning damage occurs at facilities where there is no lightning
protection. You are mistaken if you
think a lightning rod at the top of a tower is lightning protection. The rod usually provides a convenient place for lightning to
strike and protects the tower beacon light next to it.
In the case of the station with $18,000.00 damage, there was a lightning
rod at the top of the tower. The
station had major damage to an exciter, high voltage rectifier stacks, low
voltage rectifier stacks, remote control, and audio processing equipment.
You probably know that lightning strikes are the result of a high voltage
buildup between two places. There
is cloud to cloud lightning that doesn't do any more than annoy us. Then there is cloud to ground lighting. Lightning can actually strike from a cloud down to the ground
or from the ground up to a cloud depending on the polarity of the electric
charge at those two locations.
What can Cortana Static Cats do to prevent the problem or reduce the severity of a lightning strike? Static Cat technology is not magic, but is based on physics. Static Cats have hundreds of sharp points, which bleed off static charges. That bleeding action is a flow of electrons, like through a resistor, to reduce the potential or voltage between cloud and ground. The result is that the number of lightning strikes is reduced and the severity of the lighting hits is less. Some problem prone stations have reported their lightning problems have been virtually eliminated using Static Cats.
If sharp points are all that is required, why can't I build my own? Because tower maintenance is expensive, the best answer is to
purchase a commercially produced product with a long expected life.
Cortana uses stainless steel rods that have been sharpened to a fine
point. Those rods are mounted in
aluminum bars with a high strength adhesive.
They are not something I can imagine the average person making.
Even with stainless steel points, a static cat may not last forever.
High discharge rates actually heat the points making them dull at the
ends after years of faithful service. Static
Cats should be inspected annually and repaired or replaced as necessary.
If you need to spend some money repairing a Static Cat, you know it has
been working hard for you.
With a Cortana Static Cat, you get professional advice on how many
stainless steel points would be right for your situation.
That advice is worth as much as the product itself.
I recommend Cortana Static Cats for all installations.
There are even some small inexpensive ones for STL towers.
As far as I am concerned, they are cheap at twice the price.
Cortana is now out of
business...replaced by Nott Ltd.
of Mark Persons:
ham W0MH, is certified by the
Society of Broadcast Engineers as a Professional Broadcast Engineer with more
than 30 years experience. He has written numerous articles for Radio World over
the years. His Web site is www.mwpersons.com
Questions? Email Mark Persons: firstname.lastname@example.org
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