I received the goods. If you insert 250V overvoltage protection, then when 250V is supplied, the relay turns off. According to the relay software, it turns on when the voltage drops to -15V (235V). In my apartment the voltage is 238-241V. It comes out after turning off the relay - I can no longer turn on the relay, even manually it does not turn on.
I can set the overvoltage to 260V and the relay will turn on when 245V drops, but the fact is that if the voltage rises above 250V to 260V, all my electronic equipment may burn out or fail. They should operate within 220-230V. Since the voltage in my house is 240V, they work at the limit.
the product is not effective because the software is not developed
Don't buy it. After the purchase, the seller stopped communicating.