130810-1121 EDT
In the post numbered 36 your statement was:
I believe the phenomenon leading to false-tripping of the GFI-fitted CB is related to Ferroresonance.
Why you selected the word "Ferroresonance" seemed strange. What was important about ferroresonance vs just resonance? I don't see why resonance has anything to do with the problem unless the device, GFCI, has a tuned circuit and it happens to be tuned to the frequency of the resonance in this "Ferroresonant" thing.
The rate of rise of capacitor voltage and the peak capacitor voltage diminish as the resonant frequency is lowered by increasing the capacitance in parallel with a fixed inductance, and keeping the initial inductor energy the same.
In the real world a transformer primary with unloaded secondary will have a self resonant frequency determined by the inductance of the primary and the equivalent shunt capacitance from the winding. A small, 175 kVA, transformer that I tested has a self resonance at about 40 kHz at a low excitation level, less than a volt. This could be considerably different at a higher level.
#14 Romex has a capacitance of about 16 pfd per foot. Thus, 100 ft of this Romex would provide about 1600 pfd in shunt with the transformer primary, if the switch controlling power to the transformer was at the input to the Romex line, then the frequency will be lower with this added cable capacitance. This is what I suspect is one of the LC circuits to which you were referring.
What do I mean by source? The origin of the driving energy. In an RL series circuit with a switch and battery the source is the battery until the switch is opened. After opening the switch the source is the inductor.
There is much that we do not know about ritelec's circuit. Is the low voltage supply simply a transformer at the input, or something else? I don't believe that has been clearly defined.
There seems to be some contridictory information as the circuit changed. Initially I believe there was no contactor, and wall switches controlled the low voltage power supplies. It appears from the first post that the low voltage supplies are only transformers, and I will assume that means just a magnetic transformer and nothing else. However, there are persons in other posts that have referred to devices that use electronics as part of the supply to lower the output voltage as transformers.
Initially we had mechanical switches, wiring, transformers, low voltage lamp loads, and sometimes false GFCI tripping. At this point false tripping appeared to occur when switching off something. The exact combinations are not clear. However, adding a test shunt lamp near one of the transformers seemed to eliminate the problem, at least for the circuit associated with the test lamp. Thus, the conclusion seemed to be that inductive kick was the problem source, and the lamp absorbed some of this discharge energy.
This statement does not fit the other occurances,
One time I went to reset the breaker and it tripped as I reset the breaker with lights off.
and needs separate consideration.
Another statement that seems to be uncorrelated is
Currently... I hooked everything back up the way it was and the way it "should be"??.
The 3 ways control a lighting contactor in a control panel so at that location I spliced in the 60w bulb.
All is working fine and the way it is supposed to... lol.. the only issue is everytime the owner turns on his pool lights, a light turns on at the other side of the yard... :- )
Now a contactor is present. The strange part is this other light on the other side of the yard.
In post #26 manually cycling the contactor causes no tripping of the GFCI breaker that supplies the contacts of the contactor, and in turn the transformers. Also from this post the control circuit for the contactor coil is derived from a different circuit than the problem GFCI. When this control circuit is used, then the GFCI trips on energization of the contactor.
All this information does not correlate. Possibly the implication is some other cause than inductive kick from the transformers.
How is that remote yard light controlled? If it is simply a manual toggle switch, or some X10 equivalent? If it is a simple toggle switch, then there is a screwup some place in the wiring. If it is X10 or an equivalent, then the problem is the fundamental design of these devices. X10 is not and can not be an overall reliable system as designed. Not hard to jam or cause false operation.
Truely more new information is needed from ritelec. This other yard light seems like the starting point. It should be uncorrelated with the pool lights.
If manual operation of the contactor truely never causes a false trip of the GFCI, and the GFCI actually feeds the contacts on the contactor, then the transformers are not the source of false tripping.
Then we are down to the control circuit for the contactor, or its coil. But since this is on a different circuit than the GFCI why is transient noise into the input side of the GFCI causing it to trip.
Why has tripping shifted to the turn on time of the contactor, rather than turn off? Is this control circuit using the same neutral from the GFCI breaker, but getting power from a different circuit? This would certainly trip the GFCI at turn on of the contactor.
Possibly a single toggle switch on its own new wire to control the the solenoid would be a useful test. Might derive it from the GFCI circuit at the contactor as a different test.
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