On Tue, 31 May 2005 19:39:47 +0300 (IDT), Peter wrote:

> On Tue, 31 May 2005, Chen Xiao Fan wrote:
> 
> > Oh yes. Gas arrestors are one of the best device for lighten
> > protection. The company I am working for have lots of
> > Over-voltage suppressor (lightning-protection barrier).
> >
> > Take a look at my company's web site.
> > http://www.pepperl-fuchs.com and search for P-LB and K-LB.
> > The discharge current is up to 10KA.
> 
> And the minimum firing voltage is 80V so you need something else after 
> the gas arrestors to stop the damage.

Yes, that's where you'd have something like a MOV - you need protection in depth for this sort of thing.  

The gas-discharge tubes do work - the Telcos have been using them for decades, at least.  I can remember 
hearing the ones in my telephone master socket give off a loud BZZZZT during a close-by thunderstorm - nothing 
got struck, it was just the induced voltage in the line.  A MOV on its own would be likely to be blown apart 
by the energy involved, whereas a gas discharge tube takes it in its stride.  

Of course we're not talking about direct lightning strikes here - in that case whatever you do in the 
electronic domain, you're still likely to end up with a box-full of carbon and deposited metal vapour!  :-)

Cheers,


Howard Winter
St.Albans, England


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