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
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|