Quote from: wndsnb on March 12, 2022, 11:36:32 PM

You might want to look into voltage monitoring relays, like this: https://www.littelfuse.com/products/protection-relays-and-controls/protection-relays/voltage-monitoring-relays.aspx

They are used to shut off power when the voltage is out of range, either too high or too low.

The stuff you linked are controllers, they will need a contactor alongside in order to handle anything the size of a miner ( I am pretty sure you are aware of this, but OP might not know).

OP, APW3, and APW7 can operate at as low as 120v, however, the output power "wattage" will be reduced and the coils in the miners will be doing more work on 180v than on 220v to sustain the same hashrate, but I don't think anything serious will happen since the voltage is still within range, just make sure you keep them underclocked.

With that said, I would be more worried about what happens after the power outage, I used to live in a place where the voltage was low (this usually indicates a poor infrastructure) and when the power comes back the voltage will be too high or too low, the problem resides on the substation's side and it isn't something you can avoid, in that case, you will need some sort of protection like the one wndsnb mentioned.

Another option would be a voltage stabilizer, for an operation of your size, 5kw will be enough, you can probably find it for under $300 and it will keep the voltage at 220v, I think you should really consider this, check their prices locally and then decide if the price is worth it.