Re: Lightning strikes monitor (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 05 Sep 2007 13:34:19 -0500
From: Bert Hickman <bert.hickman@xxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Lightning strikes monitor (fwd)

Hi Peter,

Sounds interesting! If you do plan to use a Rogowski coil to measure the 
lightning discharge currents, make sure to provide LOTS of clearance 
between the lightning conductor and the Rogowski toroid. The combination 
of very high di/dt (typically 5 - 16 kA/us) and unavoidable path 
inductance can cause very high transient voltages to be developed on 
even a robust, well-earthed conductor. Also, try to locate the Rogowski 
coil close to the point where the conductor is physically grounded to 
minimize voltage from inductive transients. You may also need to add 
electrostatic shielding on the coil itself. I'll forward you some 
additional information (off list) that you may find useful.

BTW, during some recent storms, three holes, about 6 feet apart, and 
each about 4" in diameter and 6" deep were created in a neighbors yard. 
These were from a sequence of three lightning bolts that occurred within 
a fraction of a second. Apparently the high wind during the storm was 
sufficient to blow plasma from the previous strike laterally between 
hits. Mud was blown onto nearby houses, and cable TV was killed on the 
block for several days.

Play VERY safely,

Bert

Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Sun, 2 Sep 2007 09:49:37 +0800
> From: Peter Terren <pterren@xxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Lightning strikes monitor
> 
> I am involved peripherally in a building that may be subject to lightning 
> strikes.  It is the Leaning Tower of Gingin in Western Australia and has had 
> the foundations laid. It is at the Gravity Discovery Center where I have 4 
> running displays (lifter, ferrofluid, maglev and can crusher).
> http://www.gdc.asn.au/futureprojects.php
> 
> I had in mind that if the lighning rod at the top was copper for part of the 
> segment, that a rogowski coil could nicely measure lighning strikes 
> current/time profile if attached to a datalogging computer.  I already have 
> experience with measuring 100kA discharges with my coinshrinker and lighning 
> is in this ballpark.
> http://tesladownunder.com/CanCrushing.htm#Measurement%20of%20high%20current%20pulses
> 
> The copper (or aluminium) rod needs to be done in construction (I am not 
> going to climb up there afterwards).  Any comments?
> 
> Peter
> 
> 
> 
> 
>> ---------- Forwarded message ----------
>> Date: Fri, 31 Aug 2007 23:40:28 -0700
>> From: Jim Mora <jmora@xxxxxxxxxxx>
>> To: 'Tesla list' <tesla@xxxxxxxxxx>
>> Subject: RE: Lightning strikes Sears Tower (fwd)
>>
>> Hello List,
>>
>> I have often wondered: what sort of grounding systems are used for these
>> bolts - particular Positive Lightning? Has anyone had experience with high
>> rise grounding systems? It's hard to imagine all the computers running in
>> Sear's Tower without a twitch after such events. The instantaneous 
>> magnetic
>> field must be enormous.
>>
>> Regards,
>> Jim Mora
>>
> 
> 
> 
>