I'm sure there are more than one kind of surge protector. The ones I am
familiar with cause more blown fuses, not less. That is intentional, and
it protects the equipment. The ones I am familiar with are MOVs. Metal
Oxide Varistors. These have breakdown voltages that should be selected
to about 2X to 3X the nominal AC mains voltage. They should shunt the AC
mains voltage after the fuses. When a higher than normal voltage spike
comes along, the MOV conducts, limiting the voltage, drawing a bunch of
current and blowing the fuse. Since the MOV breaks down before other
more expensive things in the equipment do, they cause more blown fuses,
not fewer. That is a good thing because the excessive current that blows
the fuse is going into the MOV, not into more expensive and more
difficult to change parts in your gear.
Of course, you could put the MOVs in a separate "Surge Protector" box
instead of in the equipment you are trying to protect. In this case the
external "Surge Protector" will blow it's own fuse or circuit breaker if
it has one. If it does not have a fuse or circuit breaker, it may still
be better than no surge protector at all. I think they are better with
fuses.
Most of my experience with MOVs has been in GE Mastr II repeater power
supplies on mountain tops. Without the MOVs various parts in the power
supply or the radio shelf would need replacing after lightning storms.
After MOVs were installed in all of the Mastr II power supplies, only
fuses and MOVs ever needed replacing after lightning storms. It was easy
to replace the fuses and MOVs, because we knew exactly where they were
located in the power supply. There was no troubleshooting required. Just
change them. The MOVs do not always need to be replaced, but when the
equipment is on a remote mountain top, providing public safety
communications, it is better to change them than to hope they weren't
damaged. A hand full of MOVs and fuses is much cheaper than the fuel to
drive back up the mountain. Change 'em all. Much more efficient than
having to figure out what was blown up in the radios as we had to do
before we started using the MOVs. Most lighting hits were to the AC
power grid and not to the antennas. Never had a direct hit on an
antenna. I'm sure the MOVs would not have been much help in that case.
Blown fuses are not such a bad thing. When a fuse has blown, it has done
its job, as intended (except in the case of poor quality defective
fuses) and has probably saved you a lot of trouble and money. Buy
quality fuses in quantities, not individually, and they will save you money.
DE N6KB
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