GFCI problem when running high power
"John, N9JG" wrote in
et:
I am using an Orion to drive my Drake L-4B, and I operate mostly on 40
meters. My antenna is a 110 feet long dipole, center-fed with
open-wire feed line, and elevated about 30 feet with the support for
one end attached to the house chimney. My shack is in a 2nd floor
bedroom, and the circuit breaker panel is located in the basement at
the opposite end of the house. The house has a brick exterior, and one
end of the antenna is only a few feet from the shack.
When I operate high power on 40 meters, a GFCI equipped circuit
breaker, which is located in the house circuit breaker panel, moves to
the open position. None of my station equipment is attached to this
breaker; this particular breaker powers four outlets in the garage and
two outlets on the house exterior. None of these outlets are normally
in use. Is it possible (or even desirable) to install one or more
bypass capacitors inside the breaker panel, and immediately adjacent
to, the ground-fault circuit interrupter? If so, what type of
capacitor is recommended?
John, N9JG
I think GFCI refers to a breaker that operates on a small imbalance of
current on the active and neutral wires (or whatever you call them) of
the AC distribution. Typically, such things operate on quite small
current differential (30mA for standard devices in our part of the world)
and with fast operate times (~20mS). To perform this function they use
electronics to amplify the current difference from a current transformer,
and operate the breaker trip magnet. The electronics is usually powered
from the AC line. Do not overlook the potential for RF interference with
the electronics, although they should be designed for electromagnetic
compatibility, your switch may be susceptible to the levels that occur on
its AC line terminals.
Others have addressed whether the switch is responding to differential RF
currents. My guess is that it is less likely that the above, but that is
only a guess.
If that is the problem, remedial measures include replacing the switch
preferably with a different brand (though that might not fix the
problem), changing your station arrangements to reduce the RF on the AC
distribution (which could be coming from supply or load side of your
breaker), filtering on the power lines (again this may be effective if
located on the supply or load side, but you might be limited in what
measures you can employ easily on the supply side).
Owen
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