[TowerTalk] Lightning Protection

[Jim Lux]

On 7/6/13 6:22 AM, James Wolf wrote:

>
> Through my occupation, I talk frequently to the Transector Rep.   He tells
> me that over time  (< 5 years) MOV's lose their effectiveness.  I've not
> heard this before.  If this is true, need to get on that.
>

MOVs are notorious for this.  Each time they clamp a transient, they die 
a little bit.  It's a real problem for MOVs used in line voltage 
applications, when too low of a voltage is selected (e.g. 130Vrms for 
120V use) and the normal transients that one sees gradually kills the 
MOV.  Eventually, the device fails: either open (providing no 
protection) or shorted (blowing fuses or causing fires).

Gas or vacuum gap is what you really want in an environment likely to 
see many transients (and I think antennas fit in that bucket).

Standler's book on transient suppression (and the website) are a good 
resource.  $20 well spent. http://www.amazon.com/dp/0486425525