I would like to use a uC + relay with 230V output to control a 230V input/400V three phase output contactor.
The contactor is connected to a 3kW water heater/3 elements).
At the moment, the setup is not controlled by a uC+relay but rather a 230V timer, so I'm using two
230V bi-metal temperature sensors and an automatic circuit breaker/fuse in series in the 230V circuit for safety.
When I replace the timer with a uC+relay, what is the best fail-safe mechanism and "automatic fuse" to use
and how can I keep the uC alive in case of worst case failure (e.g. both bi-metal sensors are shorted)
and sense the failure ?