I guess what I was asking was whether the snubbing at the power entry
would allow MOVs to work for the branch circuit protection a
cost-effective share of the time. I have experienced problems with
Ethernet EMP pickup, but so far my cascaded MOVs have done the job, even
when I took a direct hit on my tower.
73, Pete N4ZR
The World Contest Station Database, at www.conteststations.com
The Reverse Beacon Network at http://reversebeacon.net, blog at
reversebeacon.blogspot.com,
spots at telnet.reversebeacon.net, port 7000 and
arcluster.reversebeacon.net, port 7000
On 9/17/2012 12:46 PM, Jim Brown wrote:
On 9/17/2012 3:20 AM, Pete Smith N4ZR wrote:
Our whole-house protector (from the power company) comes with good
insurance for things inside the house provided that you cascade a
point-of-use surge protector. They seem to assume that the latter
will be MOV-based. Is this a way to get around the IR/IZ drop
problem so that one doesn't have to spend $200-500 for even
consumer-grade Brick Wall products?
I'm not sure what you mean by "get around" the problem. What the
whole house solution does is snub a strike coming in on the power
line, but voltage and current can still be induced on wiring within
the building. The function of a branch circuit protector is to protect
against that.
MOVs are REAL CHEAP -- much less than a dollar. Most of what you pay
for MOV-based protectors is for packaging and marketing. Series-mode
protectors are expensive to build, for reasons that are obvious when
you see what's inside. There's a BIG inductor that stores the spike,
then discharges it slowly. It costs money to build something that will
reliably handle the energy of a strike, which IEEE studies say can be
as high as 6kV in a premises that is properly wired.
The big sound systems I designed used racks full of power amps, and
often a rack or two of low level signal processing. Often the bigger
power amps were only one or two to a circuit, so the cost of
protecting them could be a third the cost of the equipment. For that
reason, I did not specify protectors for the amps, but did for the
signal processing, where an entire 7 ft rack (or even two racks) could
be on the same circuit and cost a lot more than the two amps I could
put on a circuit.
So the short answer is that I don't know of a good lower cost solution.
73, Jim K9YC
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