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How the safety check of missing ground is done in OpenEVSE
1 Comment
OpenEVSE Support
said
3 days ago
A small current is run through an opto-isolator from each hot to ground. This lights up the internal LED, a detector on the low voltage side tells the microprocessor that the current is flowing.
If the path to ground is broken anywhere between the station and the earth rod in your home, the LED will not illuminate and the microprocessor will prevent or stop charging.
The feature is required by UL to ensure there is always a path to ground so a short will trip GFCI. A broken ground plus a short to the chassis would cause the whole station and vehicle to be at line level.
amaan
The third point claims that a missing ground is detected and then the AC relays are switched open to de-energize the system. Am I right in thinking that this feature exists because there can be a case where the protective earth conductor is broken and thus on the event of earth fault the EV can be raised to the touch voltage?
If so, how exactly is this safety checking enabled in the OpenEVSE? Is it in the hardware or simply in software?