On Tue, 18 Aug 2009 08:13:23 -0700, Michael Tope wrote:
>BTW, I am not familiar with series suppressors
Series-mode suppressors have been developed that are quite
effective on power line branch circuits. They work by storing the
strike voltage in a very large inductor, then discharging it
slowly once the strike event has past. The principal virtues of
series-mode suppressors are that 1) they don't force the strike
current onto the ground conductor, which raises the voltage of the
ground relative to other grounds, and causes destructive failure
of interconnected equipment; 2) they are not sacrificial -- that
is, they do not have a limited life, so they can take the largest
strike that can occur on a branch circuit (per IEEE data) without
damage.
SurgeX is the mfr of series mode surge suppressors that are widely
used in the pro audio/video world to protect expensive equipment.
I have been doing consulting work for them since 2004 (technical
writing, teaching at industry conventions, customer technical
support). For at least five years before that, I was specifying
their products for every installation and buying them to use in my
own home and office.
It is impractical to build protectors using their technology for
circuits rated at more than about 30A, and their methods are
applicable only to power circuits. I recommend whole house shunt
mode protection at the service entrance and series-mode products
on branch circuits.
For more about series mode suppressors see www.surgex.com and my
own tutorial on power and grounding for audio and video systems at
http://audiosystemsgroup.com/publish
BTW -- the SurgeX products are based on a patent licensed
initially to three companies, each of which was granted rights to
promote the product in a particular market. SurgeX bought rights
to the the pro audio/video market, and has been very well
respected in that world. One of the other licensees used the name
Brick Wall. I don't recall the name of the third company.
Now -- the REALLY critical issue with shunt-mode protectors is
where the "cold" lead goes. If it goes to the wrong place, it will
blow up equipment, just like MOV suppressors on power circuits do.
The key is to give them a "zero length" path to the star ground.
That's why "whole house" suppressors at the service entrance are a
good idea and MOVs on branch circuits are a recipe for disaster.
73,
Jim Brown K9YC
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