[Towertalk] FOK

[Pete Goudreau]

Red wrote:

> Hi, Pete;

> Don't worry about the 100,000 amp strike. The average lightning 
stroke
> is 18,000 amp and lasts for something like a microsecond.

Yes, got that from the Polyphaser book.  It's interesting that 
regardless of the peak current, the slew rate is still around 10A/ns, 
or so.  Having designed power supplies that had to deal with slew 
rates like that in short circuit, it's not as intimidating as it 
seems, but it's still danged fast.  Nothing like designing snubbers 
for snubbers...

> The killer
> strikes, the 10% capable of lots of damage, have a continuing 
current
> of 100-200 amp between strokes that is not present in most strikes. 
I
> don't recall the maximum duration of those.

Wasn't aware of the continuous current between strikes but it makes 
sense.


> Look for "All About Lightning," Martin A. Uman, 1971; Dover
> Publications, Inc. For a more technical book, read "Lightning," 
Martin
> A. Uman, 1969, Dover Publications. These books should be available
> from a nearby library, perhaps on interlibrary loan.

They're still in print at Dover, got 'em on order.

Thanks very much,
Pete, AD5HD