Leakage protection circuit with over-temperature protection and power line damage protection functions
By incorporating temperature detection and power cord damage detection circuits into the plug, combined with power supply and tripping output circuits, precise over-temperature protection and power cord damage protection are achieved, solving the problems of poor plug contact and power cord damage, ensuring safety and low energy consumption.
Patent Information
- Application Number
- CN202511272095.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-08
- Publication Date
- 2026-01-30
AI Technical Summary
Poor contact in existing plugs can lead to overheating and fire risks; overheat protection in plugs is not precise enough; and damaged power cords pose a risk of electric shock.
The system employs controlled switches on both the live and neutral wires, combined with temperature detection circuits, power cord damage detection circuits, and leakage signal detection circuits. Over-temperature protection and power cord damage protection are achieved through power supply and tripping output circuits. Temperature and leakage signals are detected using thermistors and residual current transformers, and a solenoid is independently driven to disconnect the power connection.
It achieves precise plug over-temperature protection and power cord damage protection, avoiding the risk of plug overheating and fire and power cord electric shock. It has independent functions and low current consumption.
Smart Images
Figure CN121440490A_ABST
Abstract
Description
[TECHNICAL FIELD]
[0001] The present application relates to a leakage protection circuit with over-temperature protection and power line breakage protection functions. [BACKGROUND]
[0002] In use, the existing plug often has the phenomenon that the plug blade and the socket sleeve are not tightly engaged, and the contact between the two is poor. When the current is too large, serious heating, melting, and even fire may occur. In the existing leakage protection plug with plug blade over-temperature protection, the integrated temperature of the zero line blade and the live line blade is detected by a temperature control switch for control. Such protection temperature is not accurate enough. On the other hand, in the existing leakage protection plug with power line protection, the power line is covered with a shielding layer of the zero line and the live line. The shielding layer of the zero line and the live line is connected to the zero line and the live line through a resistor, so that the shielding layer is electrified. Once the power line is broken, there is a risk of electric shock. [SUMMARY]
[0003] The present application overcomes the shortcomings of the prior art and provides a leakage protection circuit with over-temperature protection and power line breakage protection functions.
[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:
[0005] A leakage protection circuit with over-temperature protection and power line breakage protection functions, characterized in that: it comprises a live line current-carrying line and a zero line current-carrying line connected with a live line and a zero line of a commercial power supply respectively, a controlled switch for controlling the on-off of power on the live line current-carrying line and the zero line current-carrying line, a power supply and tripping output circuit connected with the live line current-carrying line and the zero line current-carrying line for supplying power and controlling the on-off of the controlled switch, a temperature detection circuit connected with the power supply and tripping output circuit for detecting the temperature of the input end of the live line current-carrying line and the zero line current-carrying line and outputting a tripping signal to the power supply and tripping output circuit when the temperature is too high, and a reference power supply circuit for taking power from the power supply and tripping output circuit to supply power to the temperature detection circuit and provide a reference voltage, a shielding line is sleeved on the live line current-carrying line and the zero line current-carrying line respectively, a series connection wire is connected between the two shielding lines, and a power line breakage detection circuit is connected with the live line current-carrying line, the zero line current-carrying line and the series connection wire for detecting a leakage signal of the shielding line and outputting a tripping signal to the power supply and tripping output circuit when the leakage signal is detected.
[0006] The leakage protection circuit with over-temperature protection and power line breakage protection functions as described above, characterized in that: the power supply and tripping output circuit is connected with a leakage signal detection circuit for detecting a leakage signal of the live line current-carrying line and the zero line current-carrying line and outputting a tripping signal to the power supply and tripping output circuit when the leakage signal is detected.
[0007] The over-temperature protection and power line breakage protection function leakage protection circuit has the characteristics that the temperature detection circuit includes a thermistor RT, one end of the thermistor RT is connected with the reference power supply circuit and the pin 4 of the operational amplifier U5 respectively, the other end of the thermistor RT is connected with the pin 1 of the operational amplifier U5 and one end of the resistor R12 respectively, the other end of the resistor R12 is grounded, the pin 5 of the operational amplifier U5 is grounded, and the pin 3 of the operational amplifier U5 is connected with the power supply and tripping output circuit.
[0008] The over-temperature protection and power line breakage protection function leakage protection circuit has the characteristics that the over-temperature protection value of the temperature detection circuit is set by the parameters of the thermistor RT and the resistor R12.
[0009] The over-temperature protection and power line breakage protection function leakage protection circuit has the characteristics that the reference power supply circuit includes a resistor R10, one end of the resistor R10 is connected with the power supply and tripping output circuit, the other end of the resistor R10 is connected with the temperature detection circuit, the capacitor C11, the negative electrode end of the thyristor U4 and one end of the resistor R11A respectively, one end of the capacitor C11 is grounded, the positive electrode end of the thyristor U4 is grounded, the control end of the thyristor U4 is connected with the other end of the resistor R11A, one end of the resistor R11B and the power supply and tripping output circuit respectively, the other end of the resistor R11B is grounded.
[0010] The over-temperature protection and power line breakage protection function leakage protection circuit has the characteristics that the power supply and tripping output circuit includes a rectifier DB1, the pin 1 of the rectifier DB1 is connected with the live current-carrying line, the pin 3 of the rectifier DB1 is connected with the zero current-carrying line, the pin 4 of the rectifier DB1 is grounded, the pin 3 of the rectifier DB1 is connected with one end of the resistor R2 and one end of the solenoid L1 respectively, the other end of the resistor R2 is connected with the pin 1 of the control and over-voltage protection chip U2, the drain electrode end of the MOS tube Q1 respectively, the control end of the MOS tube Q1 is connected with the pin 2 of the control and over-voltage protection chip U2, the source electrode end of the MOS tube Q1 is connected with the pin 3 of the control and over-voltage protection chip U2, the reference power supply circuit and one end of the resistor R3 respectively, the pin 4 of the control and over-voltage protection chip U2 is grounded, the other end of the resistor R3 is connected with the positive electrode end of the lamp LED and the power line breakage detection circuit respectively, the negative electrode end of the lamp LED is connected with the leakage signal detection circuit, the other end of the solenoid L1 is connected with the positive electrode end of the silicon controlled rectifier SCR, the negative electrode end of the silicon controlled rectifier SCR is grounded, the control end of the silicon controlled rectifier SCR is connected with one end of the capacitor C1, the leakage signal detection circuit and the output end of the double diode Q2 respectively, the other end of the capacitor C1 is grounded, one input end of the double diode Q2 is connected with the temperature detection circuit and the power line breakage detection circuit.
[0011] The leakage protection circuit with over-temperature protection and power line breakage protection function has the features that the power line breakage detection circuit comprises diode D1 and diode D2, the negative terminal of diode D1 is connected with the live line, the negative terminal of diode D2 is connected with the zero line, the positive terminal of diode D1 is connected with the positive terminal of diode D2 and one end of resistor R6 respectively, the other end of resistor R6 is connected with pin 1 of photoelectric coupler U3, one end of resistor R7 and one end of capacitor C9 respectively, the other end of resistor R7 is connected with the series connection of the line, the other end of capacitor C9 and the negative terminal of stabilizing diode ZD1 respectively, the positive terminal of stabilizing diode ZD1 is connected with pin 2 of photoelectric coupler U3 through resistor R8, pin 3 of photoelectric coupler U3 is connected with the power supply and tripping output circuit, pin 4 of photoelectric coupler U3 is connected with one end of capacitor C10 and the power supply and tripping output circuit through resistor R9 respectively, and the other end of capacitor C10 is grounded.
[0012] The leakage protection circuit with over-temperature protection and power line breakage protection function has the features that the leakage signal detection circuit comprises residual current transformer ZCT sleeved on the live line and the zero line, one output end of residual current transformer ZCT is connected with one end of capacitor C4, one end of resistor R4 and one end of resistor R5A respectively, the other output end of residual current transformer ZCT is connected with the other end of capacitor C4, the other end of resistor R4 and one end of resistor R5B respectively, the other end of resistor R5A is connected with one end of capacitor C8, pin 2 of leakage detection chip U1 and one end of capacitor C6 respectively, the other end of capacitor C6 is grounded, the other end of resistor R5B is connected with the other end of capacitor C8, pin 1 of leakage detection chip U1 and one end of capacitor C7 respectively, the other end of capacitor C7 is grounded, pin 3 of leakage detection chip U1 is grounded, pin 5 of leakage detection chip U1 is grounded through capacitor C5, pin 6 of leakage detection chip U1 is grounded through capacitor C3, pin 7 of leakage detection chip U1 is connected with the power supply and tripping output circuit, pin 8 of leakage detection chip U1 is connected with the negative terminal of electrolytic capacitor C2, the negative terminal of stabilizing diode ZD2 and the power supply and tripping output circuit respectively, the positive terminal of electrolytic capacitor C2 is grounded, and the positive terminal of stabilizing diode ZD2 is grounded.
[0013] The leakage protection circuit with over-temperature protection and power line breakage protection function has the features that one test end of residual current transformer ZCT is connected with one end of test switch SW, the other end of test switch SW is connected with the zero line, the other test end of residual current transformer ZCT is connected with one end of resistor R1, and the other end of resistor R1 is connected with the live line.
[0014] The leakage protection circuit with over-temperature protection and power line breakage protection function has the features that the input end of the zero line is connected with the input end of the live line through pressure-sensitive resistor MOV.
[0015] The beneficial effects of this invention are:
[0016] This invention includes a temperature detection circuit for detecting the plug temperature at the input terminals of the live and neutral wires and outputting a trip signal to the power supply and trip output circuit when the temperature is too high; and a power cord damage detection circuit for detecting leakage current in the shielded wire and outputting a trip signal to the power supply and trip output circuit upon detection of leakage current. This achieves over-temperature protection and power cord damage protection functions for the leakage current protection circuit. Simultaneously, the over-temperature protection value in the plug temperature detection circuit can be adjusted by modifying the parameters of resistors RT and R12 as needed. The reference power supply circuit provides a reference voltage for the temperature detection circuit and also powers the operational amplifier chip U5 in the temperature detection circuit, resulting in low current consumption. Furthermore, the leakage current detection function, plug temperature detection function, and power cord damage detection function all use the same drive solenoid L1, and their functions are independent of each other. [Image Description]
[0017] Figure 1 This is a schematic diagram of the invention;
[0018] Figure 2 This is the circuit diagram of the present invention. [Detailed Implementation]
[0019] The technical solutions in the embodiments of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.
[0020] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. Furthermore, descriptions involving "preferred," "second-best," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "preferred" or "second-best" may explicitly or implicitly include at least one of those features.
[0021] like Figures 1-2As shown, a leakage current protection circuit with over-temperature protection and power cord damage protection functions includes a live wire and a neutral wire connected to the mains live wire and neutral wire respectively. A controlled switch 1 is installed on the live wire and neutral wire to control the on / off state of the circuit. A power supply and trip output circuit 2 is connected to the live wire and neutral wire to supply power and control the on / off state of the controlled switch 1. The power supply and trip output circuit 2 is connected to a circuit for detecting the temperature of the input terminals of the live wire and neutral wire and outputting a power supply and trip output when the temperature exceeds the limit. The circuit 2 includes a temperature detection circuit 3 that outputs a trip signal, and a reference power supply circuit 4 that draws power from the power supply and trip output circuit 2 to supply power to the temperature detection circuit 3 and provide a reference voltage. Shielded wires 5 are respectively wrapped on the live wire and the neutral wire. A series wire 6 is connected between the two shielded wires 5. A power line damage detection circuit 7 is connected to the live wire, the neutral wire, and the series wire 6 to detect the leakage signal of the shielded wire 5 and output a trip signal to the power supply and trip output circuit 2 after detecting the leakage signal. After power-on, the power supply and trip output circuit 2 draws power from the live wire and neutral wire and supplies power to the reference power supply circuit 4. The reference power supply circuit 4 supplies power to the temperature detection circuit 3 and provides a reference voltage. When the temperature detection circuit 3 detects that the plug temperature is too high, it outputs a trip signal to the power supply and trip output circuit 2, causing the power supply and trip output circuit 2 to control the controlled switch 1 to disconnect the power connection. After power-on, the power cord damage detection circuit 7 detects in real time whether there is a leakage signal on the shield wire 5. When the power cord is damaged, a leakage signal is generated on the shield wire 5. When the power cord damage detection circuit 7 detects the leakage signal on the shield wire 5, it outputs a trip signal to the power supply and trip output circuit 2, causing the power supply and trip output circuit 2 to control the controlled switch 1 to disconnect the power connection, thus realizing the over-temperature protection and power cord damage protection functions of the leakage protection circuit.
[0022] like Figure 1 As shown, the power supply and trip output circuit 2 is connected to a leakage signal detection circuit 8, which detects leakage signals on the live wire and neutral wire and outputs a trip signal to the power supply and trip output circuit 2 upon detection of a leakage signal. When the leakage current protector is in operation after power-on, the leakage signal detection circuit 8 detects leakage signals on the live wire and neutral wire. Upon detection of a leakage signal, it outputs a trip signal to the power supply and trip output circuit 2, causing the power supply and trip output circuit 2 to control the controlled switch 1 to disconnect the power connection, thus achieving the leakage protection function.
[0023] like Figure 2 As shown, when the input terminals of the live wire and neutral wire are powered on, the AC power supply is rectified by the rectifier DB1 in the power supply and trip output circuit 2 and enters the step-down voltage regulation circuit composed of resistor R2, control and overvoltage protection chip U2, and MOSFET Q1, and outputs DC voltage VDD at the output terminal of pin 3 of control and overvoltage protection chip U2.
[0024] Leakage protection function of fire line and zero line: the DC voltage VDD in the power supply and tripping output circuit 2 supplies power to the leakage detection chip U1 in the leakage signal detection circuit 8 through the resistance R3 and the lamp LED, at this time the lamp LED serves as both a power supply path and an indication of the power-on of the whole machine, and the Zener diode ZD2 and the capacitor C2 perform voltage stabilizing and filtering on the power supply voltage of the leakage detection chip U1.
[0025] When the residual current transformer ZCT in the leakage signal detection circuit 8 detects a leakage signal, it is output to the pins 1 and 2 of the leakage detection chip U1, after internal comparison and judgment, the leakage detection chip U1 outputs a high-level pulse at pin 7, so that the thyristor SCR in the power supply and tripping output circuit 2 is turned on, the solenoid L1 is energized, and the controlled switch 1 is turned off, preparing for the next manual reset switch.
[0026] Plug over-temperature protection function: the DC voltage VDD in the power supply and tripping output circuit 2 supplies power to the thyristor U4 in the reference power supply circuit 4 through the resistance R10, the thyristor U4 provides two voltage paths, one of which outputs a stable voltage to the pin 2 of the inverting input terminal of the operational amplifier U5 in the temperature detection circuit 3, which is a constant reference voltage; the other outputs a voltage VCC to supply power to the operational amplifier U5, the thermistor RT and the resistance R12, the thermistor RT and the resistance R12 form a voltage dividing circuit, the output voltage is VR12=VCC*(R12 / (RT+R12)), and is output to the pin 1 of the non-inverting input terminal of the operational amplifier U5. When the temperature decreases, the resistance of the NTC thermistor RT increases, the voltage VR12 decreases, when the voltage is less than the set value, the voltage VR12 at the pin 1 of the non-inverting input terminal of the operational amplifier U5 is less than the constant reference voltage at the pin 2 of the inverting input terminal, the operational amplifier U5 outputs a low level, the diode connected to the operational amplifier U5 in the double diode Q2 is cut off, the thyristor SCR in the power supply and tripping output circuit 2 is cut off, the solenoid L1 is not energized, and the controlled switch 1 remains in the on state; when the temperature increases, the resistance of the NTC thermistor RT decreases, the voltage VR12 increases, when the voltage is greater than the set value, the voltage VR12 at the pin 1 of the non-inverting input terminal of the operational amplifier U5 is greater than the constant reference voltage at the pin 2 of the inverting input terminal, the operational amplifier U5 outputs a high level, the diode connected to the operational amplifier U5 in the double diode Q2 is turned on, the thyristor SCR in the power supply and tripping output circuit 2 is turned on, the solenoid L1 is energized, and the controlled switch 1 is turned off, preparing for the next manual reset switch.
[0027] Power cord damage protection function: When the shielding wire 5 ages or is damaged, and it comes into contact with the live wire and neutral wire, current flows through the Zener diode ZD1, resistor R8, pin 2 of the input terminal of the optocoupler U3 diode in the power cord damage detection circuit 7. Resistor R7, capacitor C9, resistor R6, diode D1, and diode D2 form a detection circuit. When the detected current reaches the set value, pins 3 and 4 of the output terminal of the optocoupler U3 are triggered to conduct, thereby turning on the diode connected to the optocoupler U3 in the dual diode Q2, turning on the SCR in the power supply and trip output circuit 2, energizing the solenoid L1, and turning off the controlled switch 1, preparing for the next manual reset switch. When the shielding layer 5 is not in contact with the live wire and neutral wire, since there is no current at the input terminal of the optocoupler U3, the output terminal of the optocoupler U3 is cut off, causing the diode connected to the optocoupler U3 in the dual diode Q2 to be cut off. At this time, it does not affect the operation of other circuits.
[0028] In this case, the over-temperature protection value in the temperature detection circuit 3 for detecting the plug temperature can be achieved by modifying the parameters RT and R12 as needed. The reference power supply circuit 4 provides a reference voltage for the plug temperature detection circuit and also powers the operational amplifier U5, with relatively low current consumption. Meanwhile, the leakage current detection function, plug temperature detection function, and shielded wire damage detection function in this case all use the same circuit driving solenoid L1, and their functions are independent of each other.
[0029] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct or indirect applications in other related technical fields, are included within the patent protection scope of the present invention.
Claims
1. A leakage current protection circuit with over-temperature protection and power cord damage protection functions, characterized in that: The application relates to a power supply and tripping output circuit (2) connected with a power supply and tripping output circuit (2) for supplying power and controlling the on-off of the controlled switch (1), a temperature detection circuit (3) for detecting the temperature of the input end of the live wire and the zero wire and outputting a tripping signal to the power supply and tripping output circuit (2) when the temperature is too high, and a reference power supply circuit (4) for supplying power to the temperature detection circuit (3) and providing a reference voltage after taking power from the power supply and tripping output circuit (2), the live wire and the zero wire are respectively sleeved with shielding wires (5), the two shielding wires (5) are connected with a series wire (6), and the live wire, the zero wire and the series wire (6) are connected with a power line damage detection circuit (7) for detecting a leakage signal of the shielding wire (5) and outputting a tripping signal to the power supply and tripping output circuit (2) when the leakage signal is detected.
2. The ground fault circuit of claim 1, wherein: The power supply and tripping output circuit (2) is connected with a leakage signal detection circuit (8) for detecting a leakage signal of the live wire and the zero wire and outputting a tripping signal to the power supply and tripping output circuit (2) when the leakage signal is detected.
3. A leakage current protection circuit with over-temperature protection and power line damage protection functions according to claim 1, characterized in that: The temperature detection circuit (3) comprises a thermistor RT, one end of the thermistor RT is connected with the reference power supply circuit (4) and the pin 4 of an operational amplifier U5 respectively, the other end of the thermistor RT is connected with the pin 1 of the operational amplifier U5 and one end of a resistor R12 respectively, the other end of the resistor R12 is grounded, the pin 5 of the operational amplifier U5 is grounded, and the pin 3 of the operational amplifier U5 is connected with the power supply and tripping output circuit (2).
4. The ground fault circuit of claim 3, wherein: The over-temperature protection value of the temperature detection circuit (3) is set by the parameters of the thermistor RT and the resistor R12.
5. The ground fault circuit of claim 1, wherein: The reference power supply circuit (4) comprises a resistor R10, one end of the resistor R10 is connected with the power supply and tripping output circuit (2), the other end of the resistor R10 is connected with one end of a resistor R11A, the negative electrode end of a thyristor U4, the temperature detection circuit (3) and one end of a capacitor C11 respectively, the other end of the capacitor C11 is grounded, the control end of the thyristor U4 is connected with the other end of the resistor R11A, one end of a resistor R11B and the power supply and tripping output circuit (2) respectively, the other end of the resistor R11B is grounded, and the positive electrode end of the thyristor U4 is grounded.
6. The ground fault circuit of claim 2, wherein: The power supply and tripping output circuit (2) comprises a rectifier DB1, the pin 1 of the rectifier DB1 is connected with the live line, the pin 3 of the rectifier DB1 is connected with the zero line, the pin 4 of the rectifier DB1 is grounded, the pin 3 of the rectifier DB1 is connected with one end of the resistor R2 and one end of the solenoid L1 respectively, the other end of the resistor R2 is connected with the pin 1 of the control and overvoltage protection chip U2 and the drain end of the MOS tube Q1 respectively, the control end of the MOS tube Q1 is connected with the pin 2 of the control and overvoltage protection chip U2, the source end of the MOS tube Q1 is connected with the pin 3 of the control and overvoltage protection chip U2, the reference power supply circuit (4) and one end of the resistor R3 respectively, the pin 4 of the control and overvoltage protection chip U2 is grounded, the other end of the resistor R3 is connected with the positive end of the lamp LED and the power line breakage detection circuit (7) respectively, the negative end of the lamp LED is connected with the electric leakage signal detection circuit (8), the other end of the solenoid L1 is connected with the positive end of the thyristor SCR, the negative end of the thyristor SCR is grounded, the control end of the thyristor SCR is connected with one end of the capacitor C1, the electric leakage signal detection circuit (8) and the output end of the double diode Q2 respectively, the other end of the capacitor C1 is grounded, one input end of the double diode Q2 is connected with the temperature detection circuit (3) and the power line breakage detection circuit (7).
7. The ground fault circuit of claim 1, wherein: The power line breakage detection circuit (7) comprises the diode D1 and the diode D2, the negative end of the diode D1 is connected with the live line, the negative end of the diode D2 is connected with the zero line, the positive end of the diode D1 is connected with the positive end of the diode D2 and one end of the resistor R6 respectively, the other end of the resistor R6 is connected with the pin 1 of the photoelectric coupler U3, one end of the resistor R7 and one end of the capacitor C9 respectively, the other end of the resistor R7 is connected with the series electric line (6), the other end of the capacitor C9, the negative end of the voltage stabilizing diode ZD1 respectively, the positive end of the voltage stabilizing diode ZD1 is connected with the pin 2 of the photoelectric coupler U3 through the resistor R8, the pin 3 of the photoelectric coupler U3 is connected with the power supply and tripping output circuit (2), the pin 4 of the photoelectric coupler U3 is connected with one end of the capacitor C10 and the power supply and tripping output circuit (2) through the resistor R9 respectively, the other end of the capacitor C10 is grounded.
8. The ground fault circuit of claim 2, wherein: The leakage signal detection circuit (8) comprises a residual current transformer ZCT sleeved on the live wire and the zero wire, one output end of the residual current transformer ZCT is connected with one end of a capacitor C4, one end of a resistor R4 and one end of a resistor R5A respectively, the other output end of the residual current transformer ZCT is connected with the other end of the capacitor C4, the other end of the resistor R4 and one end of a resistor R5B respectively, the other end of the resistor R5A is connected with one end of a capacitor C8, a pin 2 of a leakage detection chip U1 and one end of a capacitor C6 respectively, the other end of the capacitor C6 is grounded, the other end of the resistor R5B is connected with the other end of the capacitor C8, a pin 1 of the leakage detection chip U1 and one end of a capacitor C7 respectively, the other end of the capacitor C7 is grounded, a pin 3 of the leakage detection chip U1 is grounded, a pin 5 of the leakage detection chip U1 is grounded through a capacitor C5, a pin 6 of the leakage detection chip U1 is grounded through a capacitor C3, a pin 7 of the leakage detection chip U1 is connected with the power supply and tripping output circuit (2), a pin 8 of the leakage detection chip U1 is connected with a negative electrode of an electrolytic capacitor C2, a negative electrode of a voltage stabilizing diode ZD2 and the power supply and tripping output circuit (2) respectively, a positive electrode of the electrolytic capacitor C2 is grounded, and a positive electrode of the voltage stabilizing diode ZD2 is grounded.
9. The ground fault circuit interrupter with over-temperature protection and power line breakage protection according to claim 8, characterized in that: One test end of the residual current transformer ZCT is connected with one end of a test switch SW, the other end of the test switch SW is connected with the zero wire, the other test end of the residual current transformer ZCT is connected with one end of a resistor R1, and the other end of the resistor R1 is connected with the live wire.
10. The ground fault circuit of claim 1, wherein: A pressure sensitive resistor MOV is connected between the input end of the zero wire and the input end of the live wire.