A protective device comprising an electronic switch, a mechanical switch and a time logic circuit, wherein: a first output terminal of the time logic circuit is connected to the electronic switch; a second output terminal of the time logic circuit is connected to the mechanical switch; an input terminal of the time logic circuit is connected to an output terminal of a power supply; and the electronic switch is connected in series with the mechanical switch into a circuit under control, characterized in that the time logic circuit comprises a first drive circuit and a second drive circuit; the first drive circuit comprises a first resistor (R 1), a second resistor (R 2), a first capacitor (C 1), a first diode (D 1) and a flyback circuit, wherein: an end of the first resistor (R 1) is connected to the output terminal of the power supply, and the other end of the first resistor (R 1) is connected to an input terminal of the flyback circuit; an end of the first diode (D 1) is connected to the output terminal of the power supply, and the other end of the first diode (D 1) is connected to the input terminal of the flyback circuit; an end of the first capacitor (C 1) is connected to the input terminal of the flyback circuit, and the other end of the first capacitor (C 1) is grounded; and an end of the second resistor (R 2) is connected to the input terminal of the flyback circuit, and the other end of the second resistor (R 2) is grounded; the second drive circuit comprises a second capacitor (C 2) and a second diode (D 2), wherein: an end of the second diode (D 2) is connected to the output terminal of the power supply, and the other end of the second diode (D 2) is connected to the mechanical switch and an end of the second capacitor (C 2); and the end of the second capacitor (C 2) is connected to the second diode (D 2) and the mechanical switch, and the other end of the second capacitor (C 2) is grounded. a first output terminal of the time logic circuit is connected to the electronic switch; a second output terminal of the time logic circuit is connected to the mechanical switch; an input terminal of the time logic circuit is connected to an output terminal of a power supply; and the electronic switch is connected in series with the mechanical switch into a circuit under control, characterized in that the time logic circuit comprises a first drive circuit and a second drive circuit; the first drive circuit comprises a first resistor (R 1), a second resistor (R 2), a first capacitor (C 1), a first diode (D 1) and a flyback circuit, wherein: an end of the first resistor (R 1) is connected to the output terminal of the power supply, and the other end of the first resistor (R 1) is connected to an input terminal of the flyback circuit; an end of the first diode (D 1) is connected to the output terminal of the power supply, and the other end of the first diode (D 1) is connected to the input terminal of the flyback circuit; an end of the first capacitor (C 1) is connected to the input terminal of the flyback circuit, and the other end of the first capacitor (C 1) is grounded; and an end of the second resistor (R 2) is connected to the input terminal of the flyback circuit, and the other end of the second resistor (R 2) is grounded; an end of the first resistor (R 1) is connected to the output terminal of the power supply, and the other end of the first resistor (R 1) is connected to an input terminal of the flyback circuit; an end of the first diode (D 1) is connected to the output terminal of the power supply, and the other end of the first diode (D 1) is connected to the input terminal of the flyback circuit; an end of the first capacitor (C 1) is connected to the input terminal of the flyback circuit, and the other end of the first capacitor (C 1) is grounded; and an end of the second resistor (R 2) is connected to the input terminal of the flyback circuit, and the other end of the second resistor (R 2) is grounded; the second drive circuit comprises a second capacitor (C 2) and a second diode (D 2), wherein: an end of the second diode (D 2) is connected to the output terminal of the power supply, and the other end of the second diode (D 2) is connected to the mechanical switch and an end of the second capacitor (C 2); and the end of the second capacitor (C 2) is connected to the second diode (D 2) and the mechanical switch, and the other end of the second capacitor (C 2) is grounded. an end of the second diode (D 2) is connected to the output terminal of the power supply, and the other end of the second diode (D 2) is connected to the mechanical switch and an end of the second capacitor (C 2); and the end of the second capacitor (C 2) is connected to the second diode (D 2) and the mechanical switch, and the other end of the second capacitor (C 2) is grounded.