Socket circuit for leakage and overvoltage alarm

Circuit working principle: 220 V AC mains power is stepped down by C1 and rectified by VD1 and VD2
, and then supplies power to the control circuit . R1 is the bleeder resistor of C1. A varistor RV is connected across the input end of the mains. It has two functions: one is to protect electrical appliances and control circuits
when 380 V AC is introduced due to incorrect wiring and phase error ; the other is to suppress and absorb low-voltage grid channeling. Incoming instantaneous surge voltage (such as lightning interference, etc.).