I'm trying to design a circuit to turn on and off an electrical 230V 1A 1-phase motor using a relay. I'd like to design it such that if the user inadvertedly short circuits the output, the relay is immediately opened.
My best idea so far is to use two relays. The first relay is in series with a 30 ohm resistor and with the load. The second relay is in parallell with the resistor.
If there is a short circuit when the first relay is turned on, this is sensed by a current sensor, and the relay is immediately turned off before the resistor overheats (a few ms). The current here will be <10A because of the resistor.
If there is no short circuit, the second relay, which is connected in parallell to the resistor, is switched on. This lets the full current through, and saves the resistor from overheating.
The whole thing is controlled by a microcontroller.
I think that if I only use one relay, and there is a short circuit, the inrush current may be in the 1000 of A, which I think a regular small relay cannot break.
Does this sound reasonable?
If not, how would you build a short-circuit disconnect function for a relay-based 230V motor controller?
It doesn't have to handle short circuits which occur during operation, only before startup.