I've been trying to locate info on a technique that was used (at least in the US) for detecting ground faults in mining equipment.
the basic concept was to inject a signal into the power and look for it in the ground. If it was detected there, you had a fault. The signal may have been 800Hz.
Is anything like this still used?
I just looked at the datasheets on these, and they seem to be "regular" GFC detectors that null out current and any difference is assumed to be leaking to ground, and not the mystery systems that adds a signal to the power itself.
Yes, that is how most GFC's work because a ground and is supplied with the line that can be used to off set the balance...
Any thing else, most likely is custom made..
If you want to modulate the line with 800 hz, you can do that with an inline xformer at the generation end and some simple band pass detection circuit on the equipment end..
Having something engineered for the mining industry comes with a large liability. You may find it tough searching for engineers stepping up to the plate.
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