[TowerTalk] Static, Lightening, and protection
kb9cry at comcast.net
kb9cry at comcast.net
Wed Mar 24 20:04:51 EST 2004
You know what guys, I think this thread is really going nowhere. One could postulate that if you're setting up a charge bleed path from the cloud to the earth via your tower then wouldn't the lightning strike want to follow that path since you've already started the process?
Then again one could argue that considering the infinitly massive charge sink that you're trying to reduce will just as quickly be replenished will charge from the surrounding cloud mass? Kinda like when the kids leave the door open in the summer, you air conditioner will indeed try to cool the whole world but you couldn't measure it.
All these theories sound great; reminds me of back in college days where we would all sit around, after tossing back a few, and solve all of the world's problem in one afternoon! And many times, we did indeed solve all of the world's problems!
Also, sounds a lot like when a group of Commissioners draft a NPRM and state quite a few times that "We believe that BPL will not cause interference to licensed services." And they offer no scientific evidence to back up their belief. Oops, sri about that, I just got myself started.
Employ good grounding practices, don't rely on luck, and remember that Mother Nature will find a way, so be prepared. Phil KB9CRY
> I have one MAJOR disagreement with this argument of Davids- One is NOT
> trying to attract lightning to the tower- one is trying to provide an easy
> path to bleed down the charge (opposite in sign to the charge in the cloud)
> in the region around the tower. This should be steady and always available.
> If the charge is reduced and the charge gradient is less, the easiest path
> for the leaders is somewhere else. A high charge gradient is the equivalent
> of a high pressure which needs relief. a strike provides that.
> At 11:46 PM 3/23/2004 +0000, you wrote:
> > >
> > > The "rules" seem to be like this:
> > > If you want to create "umbrella lightning repellent" protection
> > > the tower should be as high as possible. Roughly it will protect
> > > hemisphere with
> > > radius of the tower.
> >The more common 'rule' is that a tower will protect a circle roughly
> >equal to its height by attracting lightning to itself from the area.
> >Larger or smaller distances are claimed by some authors. The effect is
> >dependent on total height and the peak stroke current among other
> >variables. Low current strokes are known to 'sneak' in the sides and
> >actually hit the sides of buildings and towers instead of the top. This
> >is because the streamers from the ground structures are shorter and the
> >attraction of the opposite charges on the structure pulls the leader
> >closer as it comes down. High current strokes are less affected by the
> >structures and the streamers are much longer going up to meet the
> >David Robbins K1TTT
> >e-mail: mailto:k1ttt at arrl.net
> >web: http://www.k1ttt.net
> >AR-Cluster node: 145.69MHz or telnet://dxc.k1ttt.net
> >See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> >Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
> >any questions and ask for Sherman, W2FLA.
> >TowerTalk mailing list
> >TowerTalk at contesting.com
> Bill Aycock - W4BSG
> Woodville, Alabama
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
> Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
> and ask for Sherman, W2FLA.
> TowerTalk mailing list
> TowerTalk at contesting.com
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