DANGER WILL ROBINSON!
those two examples are both BAD!
first the SurgeX one appears to show that when the MOV arresters divert current
to the ground/neutral they feed that to one component, but not to the unshown
other devices. This one doesn't show the flow of current back out to the
common ground point after it has been diverted onto the ground & neutral. nor
does it show the connection of all the other devices on the power system....
and it seems to label pin-1 as a 'back door' to damage the equipment.
In the Brick Wall page, they show again only a single device with stuff hanging
off of it and are assuming that their device clamps the line voltage, stores
the surge, and slowly diverts it to the neutral. This may be good for surges
caused by power line transients, but is hardly adequate to describe lightning
transients that would easily flashover such a device. the Brick wall device
doesn't even show that it has to be connected to the safety ground also, nor
cover what happens if the surge is on the safety ground (common in lightning
events) rather than the incoming power line.
the most important function of a whole house or similar large arrester serving
a building is to equalize the voltage between all the conductors so that all
the equipment connected to it is as the same potential. this prevents the
equipment from becoming the path between the surge and where the surge isn't.
The importance of these is that they protect the equipment even if the surge is
on the ground! This is the common case when lightning misses the power line
and hits the tower or hits the ground itself, the current through the ground
system raises the ground voltage, the arrester at the service entrance/single
point ground actually routes current FROM the ground TO the power conductors to
raise their voltage so that any equipment on the other side all goes up at the
same time.
Jan 3, 2011 11:05:23 AM, w9ac@arrl.net wrote:
Pete,
Surge diversion to the ground conductor can raise the ground potential
unequally between equipment. If the rise and fall of the ground potential
is equal across interconnected equipment on a branch circuit, there's little
issue. During a surge event, small amounts of resistance can create large
amounts of potential difference between grounded equipment.
By storing the surge energy and slowly dissipating it onto the neutral (a
conductor actually meant for carrying current), the surge event does not
create a potential difference between grounded equipment:
http://www.surgex.com/library/22001.html
http://www.brickwall.com/how-it-works.html
>From the descriptions in the above links, you can see why the ONLY place for
"all three modes" of MOV protection is at the service entrance.
Paul, W9AC
----- Original Message -----
From: "Pete Smith"
To:
Sent: Monday, January 03, 2011 10:13 AM
Subject: Re: [TowerTalk] Fwd: WHOLE HOUSE SURGE SUPRESSORS
> Why is this, Paul?
>
> 73, Pete N4ZR
>
> The World Contest Station Database, updated daily at
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at
> reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000
>
>
>
> On 1/3/2011 10:01 AM, Paul Christensen wrote:
>>> The gold standard is to have both... whole house to protect heavy
>>> equipment
>>> like AC compressors, etc. then end-point protectors for LCD TVs,
>>> refrigerator CPUs, PCs, Ham Radios, etc.
>> But only if the secondary suppressors are single mode (fault current path
>> to
>> neutral), rather than devices that offer the popular "all three modes" of
>> protection. If secondary protection is desired after installing a
>> whole-house protector, it should only be single mode (e.g., SurgeX,
>> Brickwall, ZeroSurge). Except for the whole-house surge protector,
>> "three
>> modes of protection" devices have no place in a home.
>>
>> Paul, W9AC
>>
>> _______________________________________________
>>
>>
>>
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>>
>>
> _______________________________________________
>
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