On 7/10/2021 12:59 PM, Bob McGraw wrote:
Sure, power strips are inexpensive. But they really only protect
against one type of power surge. If the voltage spikes, the breaker
should trip. However, this isn’t always instantaneous. Delicate devices
can still be damaged, and many other types of surges will just pass
right through without tripping the surge protector. Not the best
solution. Despite being called a surge protector, this name doesn’t give
you the whole story. These don’t even come close to the protection
whole house surge protectors offer you.
The problem with MOV protectors is FAR greater than what is outlined
above. MOV "protectors" dump any spikes onto the equipment ground (green
wire), and the resulting IR drop raises the potential of the equipment
it is intended to protect. When that equipment is connected to other
equipment plugged into a different outlet, the DIFFERENCE in potential
between their their chassis can cause stuff to fry. The same thing can
happen when one or more pieces of the interconnected equipment has a
ground connection, but is not bonded to the other gear.
Properly bonding all equipment within a station minimizes the potential
differences between the gear, AND if an MOV protector is used, must be
bonded as well. N0AX and I finished working through this while finishing
the latest revision of his ARRL book on Grounding and Bonding, and it's
in both versions. I don't know if the new one is out yet.
At least 20 years ago, professional sound companies and designers of
large sound systems learned all this the hard way. Luckily, a new type
of protector had been invented -- a SERIES MODE protector that does not
dump the surge on the Green Wire, but instead stores it in the magnetic
field of a big inductor, then discharges it slowly after the surge
event. These protectors are much more expensive, but cost a lot less
than the gear they protect! When I was a consultant designing large
systems, I specified them for every project. And I have used them in my
home (for computers and home entertainment system), office (when I was
still working), and in the shack.
SurgeX is the company that developed products for pro audio. I use the
SA-20 (20A version of the SA15).
https://www.fullcompass.com/brand/sgx-surgex/
Years ago, I did some technical writing for them, producing this
tutorial "White Paper." I was specifying them for the systems I designed
LONG before writing it.
73, Jim K9YC
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