You need an hysteresis based comparator - one that changes state (OFF) when voltage falls below 180 V and then changes state again (ON) when the voltage rises above 191 V. I believe you can use a simple op-amp comparator with hysteresis - only you need to scale the input voltage by a factor of 100 (180 V becomes 1.8 V and 191 V becomes 1.91V) to remain within the op-amp's specs.
I am a little concerned that you profess to have little knowledge on the subject, and are working with lethal voltages, I would strongly suggest that you enlist direct help from someone who is used to working with such voltages, and that your work is looked over before commissioning to ensure it is safe, cheers, Richard
I do have knowledge about ac line, I have a running POD with 5 minutes delay and that cuts off at 180 volt, I just can't get to activate it at exact 191 volt. my circuits activates at 185 volt, I've tried changing my zener diode but I still cannot get the desired 191 volt activation.
