The porcupine device was designed to reduce general static build
up...especially on dry windy days. If I recall correctly it was primarily
for repeater systems but I could be wrong. I know it has been mentioned
numerous times over the years on the repeater-builder group.
73,
Jon
KD5SFA
On Sat, Aug 8, 2015 at 2:45 PM, Stan Labinsky Jr. <K2STN@frontier.com>
wrote:
> 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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>>
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>
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