Passive alarm circuit matched with electric leakage monitoring of acquisition terminal meter box

The invention discloses a passive alarm circuit matched with an acquisition terminal meter box for electric leakage monitoring. According to the passive alarm circuit, the passive alarm circuit comprises an interface protection circuit, a resistance-capacitance voltage reduction circuit and a voltage monitoring and alarm output circuit, wherein the interface protection circuit can suppress common/differential mode interference of an input port and protect a post-stage circuit, and the circuit topology is simple and practical; the resistance-capacitance step-down circuit adopts the modes of resistance-capacitance step-down, half-wave rectification and voltage stabilization of a voltage-regulator tube to convert alternating current voltage between the metal shell of the meter box and the PE protection ground into stable direct current during electric leakage, the circuit structure is simple, the leaked alternating current is used for providing a power supply, and independent power supply is not needed; the volt