On a lightning focused Yahoo group, populated by professionals... the PhD
types, there is a war raging over the porcupine guys.
The folks who came up with them also sell them and forced their acceptance
into the IEEE specs as being OK... no, preferred.
However there are reports that they are not worth the expense and effort to
install them, people hurt, property destroyed, mostly outside the U.S.
Franklin had it right, a tall sharp point to enable the strike to make it to
ground without frying everything else around is the way to go.
Stan
-----Original Message-----
From: Patrick Greenlee
Sent: Saturday, August 08, 2015 12:19 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Static Discharge Porcupines?
My quick literature search showed the US Navy and others tested the ESD
(Electrostatic Dissipation devices AKA porcupines) and found them to not
reduce the frequency or number of lightning strikes on their test
structures.
Seems counter-intuitive to me but I can't argue with their results as I
have no experimental results to the contrary. From what I read the
porcupines can't handle the currents required to prevent the charge
building up and having a strike.
I'm sure folks in the business of selling protective devices put the
best face on their product as possible but...
In my early years I was taught that lightning rods were to prevent a
strike by draining off the charge preventing a build up sufficient to
make for a strike and to be well grounded with low resistance-low
inductance paths to ground in case they took a strike. Oh well,
empiricism trumps theory and or wishful thinking.
Patrick NJ5G
On 8/7/2015 10:12 PM, Jim Lux wrote:
On 8/7/15 7:39 PM, Tony wrote:
All:
I came across this video from Nott Ltd that describes how their static
discharge arrays or "Porcupines" help disapate static electricity to
prevent lightning strikes.
https://www.youtube.com/watch?v=JYILAHIx2lk
I understand they are used in several industries including
communications towers and was wondering if anyone has experience with
them. Installation is easy enough, but I wonder how this work work with
crank-ups?
Totally ineffective.
You're not going to "dissipate" the charge in a thunderstorm.
http://lists.contesting.com/_towertalk/2004-07/msg00971.html has a
discussion. Run back and forth in the thread for more discussion.
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