Re: Lightning strikes monitor (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Fri, 7 Sep 2007 08:34:13 +0800
From: Peter Terren <pterren@xxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Lightning strikes monitor (fwd)

I need to do some reading on this and thanks for the references and groups. 
The di/dt of perhaps 10kA/us is similar to my cap bank which gets to 100kA 
plus in 10us.
One needs to know where the voltage across the single lighning rod will go 
and also the RF and electrostatic shielding.  This would all be a lot 
simpler at ground level where there are 4 main legs. These are all steel of 
course and I don't know how steel will affect things. Presumable enough 
current will saturate the iron but I am not sure that 25kA per leg would do 
that.

Neverthe less it might be one of those once in 10 years events and I am not 
sure I am patient enough.

Peter

> ---------- 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
>>>
>>
>>
>>
>>
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