A method and device for detecting ground fault with self-checking function

Abstract

The present invention discloses a ground fault detection device with a self-checking function, comprising: an induction coil, a neutral coil, a trip device, a manual test unit, a rectifier circuit unit, a power management unit, a ground fault detection unit, and a ground fault self-checking test unit. The ground fault detection unit receives the ground fault leakage current signal obtained by the induction coil and the neutral coil, and processes, amplifies, filters, transforms, and judges the effective leakage current signal, and controls the generation of a thyristor / tripper drive signal; the ground fault self-checking test unit detects the phase voltage signal, periodically generates a simulated ground fault leakage current signal, and detects whether the system leakage detection circuit and the trip circuit respond correctly to the simulated ground fault, and judges and outputs corresponding sound, light, and electrical alarm signals.

Description

Technical Field

[0001] The present invention relates to a self-checking ground fault detection method and device, and in particular to a self-checking ground fault detection circuit and a leakage detection protection method thereof. Background Art

[0002] Due to the rapid development of computers, semiconductors and electronic technologies and the continuous improvement of people's living standards, various electronic appliances and smart home appliances have been widely used in families. The safety awareness of ordinary people on electrical equipment has also been continuously enhanced. In order to ensure the safety of life and property, leakage protectors and electrical switch devices including leakage protectors are widely used in power supply system lines, so as to effectively detect leakage or electric shock accidents, cut off the power supply in time, and prevent the occurrence of electrical safety accidents.

[0003] However, the functions of leakage protectors or leakage detection circuit devices in the current prior art are too single. Most of them can only simply detect the AC leakage signal of the live wire or neutral wire to the ground, and cannot simultaneously have the function of detecting the A-type pulsating DC leakage signal of the live wire or neutral wire to the ground; or they can only detect the A-type leakage signal of the live wire to the ground, and cannot detect the A-type leakage signal of the neutral wire to the ground; at the same time, some so-called products capable of detecting the leakage of AC live wire and neutral wire to the ground are implemented with relatively backward technology and processes, with poor accuracy, poor consistency, weak anti-interference ability, and are very easy to cause misjudgment; furthermore, the aforementioned prior art The products do not include a self-test function. The traditional mode is used to manually test whether the product or device functions normally by periodically testing through the test button. However, in actual applications, few users will conduct manual tests regularly, which poses a great hidden danger. In addition, the test method will cut off the load power supply. Frequent testing will seriously affect normal production and life. When a live or neutral line leakage to the ground or electric shock accident occurs, it is very easy to cause damage to power supply facilities and load electrical equipment, and even cause fires and personal life accidents due to the inability to detect and cut off the load in a timely and accurate manner, which poses a great safety hazard. Furthermore, in the prior art, although it has the neutral / live line to ground detection and self-test functions, it does not have the precise delay setting function, etc., and cannot be applied to most higher-level power grid systems with graded leakage protection.

[0004] The patent with the patent publication number CN1818687A discloses an intelligent detection method and equipment for the end of life of a leakage protection device. The method adopts the MCU solution control to realize the detection and self-test (end of life detection) of the ground fault. The peripheral structure is complex. Since the MCU generally has certain defects in EMC and ESD, there will be problems in the selection of the MCU, such as poor electromagnetic compatibility, high cost, poor anti-interference characteristics and other shortcomings. At the same time, the patented solution uses the grid AC power to generate simulated ground faults for detection in each cycle, so it can only detect AC ground faults, which affects the normal ground fault detection and protection functions, and has great safety hazards.

[0005] The patent with the patent publication number CN102694364A discloses a ground fault circuit interrupter monitor and a ground fault simulation method. The patent description clearly states: a self-test monitor, which is configured to produce a simulated ground fault and detect a response to the simulated ground fault during a period starting from the first half of the first cycle of the AC power supply and extending to the second half of the first cycle of the AC power supply, wherein the first half of the first cycle of the AC power supply precedes the second half of the first cycle of the AC power supply. That is, the above description shows that in the implementation of its scheme, it is necessary to generate a simulated leakage signal for each AC cycle. Therefore, it can only detect AC leakage ground faults, and cannot detect type A ground faults. Similarly, the patent scheme cannot achieve a delay function. Summary of the invention

[0006] The purpose of the present invention is to solve the problem that the above-mentioned prior art and leakage protection devices do not have or do not simultaneously have the A-type pulsating DC detection function of the live wire and neutral wire to the ground with a self-checking function, and to provide a highly integrated, multi-functional, high-precision, high-reliability A-type leakage detection method and circuit device with a self-checking live wire and neutral wire to the ground.

[0007] The present invention discloses a ground fault detection device with a self-checking function, comprising: an induction coil coil1, a neutral coil coil2, a de-coupler device, a rectifier circuit unit, a power management unit, a ground fault detection unit, and a ground fault self-checking test unit;

[0008] The ground fault detection unit receives the ground fault leakage current signal obtained by the induction coil and the neutral coil, and outputs a control signal to drive the release device to cut off the load power supply when a ground fault occurs; the ground fault self-detection test unit detects the phase voltage at the output end of the release device, periodically generates a simulated ground fault leakage current signal and detects whether the ground fault detection unit and the release device respond correctly to the simulated ground fault.

[0009] In a preferred embodiment: the ground fault detection unit includes: a negative feedback amplifier and resistors R2, R3 and capacitor C2 connected thereto; the input end of the negative feedback amplifier is connected to the positive and negative input ends of the level shift circuit in the ground fault detection loop; the two ends of the capacitor C2 are respectively connected to the two ends of the secondary of the neutral coil coil2.

[0010] In a preferred embodiment: the ground fault detection unit obtains the ground fault leakage current signal through the secondary of the induction coil coil1, and converts it into a voltage difference signal through the resistor R4 connected to the secondary of the induction coil coil1, and the diodes D5 and D6 are reversely connected in parallel at both ends of R4 to limit the voltage amplitude.

[0011] In a preferred embodiment: the negative feedback amplifier circuit is used to amplify the voltage difference signal and output an oscillation frequency signal to charge and discharge the capacitor C2. The secondary of the neutral coil coil2 obtains the induced current and forms a positive feedback loop when a neutral line-to-ground fault occurs. When the fault current threshold condition is met, the output control signal drives the thyristor SCR1 to turn on and drives the release to cut off the load.

[0012] In a preferred embodiment: the ground fault detection unit further includes: a signal amplifier circuit, a rectifier circuit, a detection circuit, a delay circuit, a comparison judgment circuit, a logic control circuit, and an output driver;

[0013] The level shift circuit receives the induced current signal of the induction coil coil1, and converts it into a voltage difference signal through the resistor R4, and shifts the voltage difference signal to a level range superimposed with the internal bias reference voltage signal. The signal amplification circuit amplifies the differential voltage signal, and generates a single-ended output voltage signal through the rectifier circuit. After the signal is processed by the detection circuit, it is sent to the delay circuit, and then compared with the internal threshold reference value through the comparison judgment circuit, and then the logic control circuit outputs the control signal according to the comparison judgment result.

[0014] In a preferred embodiment: in the ground fault self-detection test unit, the phase detection circuit is used to be connected in series to the live wire Load Hot through the resistor R8, so as to detect the AC phase voltage value in real time.

[0015] In a preferred embodiment: in the ground fault self-detection test unit, the SCR loop detection circuit is used to detect the connectivity with the thyristor SCR1 anode and the release device through the resistor R7; the SCR loop detection circuit can also connect the thyristor anode through D8 to test the function of the thyristor SCR1.

[0016] In a preferred embodiment: in the ground fault self-detection test unit, the fault simulation output circuit is used to generate a simulated ground fault leakage current signal through resistors R9, R10 and transistor Q1; the fault simulation output circuit also generates a switching signal for switching between normal leakage detection / self-detection mode.

[0017] In a preferred embodiment: in the ground fault self-test unit, the alarm drive circuit is connected to an alarm device for outputting an alarm signal when the self-test fails, and the alarm device is one of an acoustic, optical, and electrical device.

[0018] In a preferred embodiment: in the power management unit, the voltage regulator is connected to the DC voltage output by the rectifier circuit through the resistor R1, and detects and stably generates the DC voltage outputted to the internal power supply system.

[0019] In a preferred embodiment: in the power management unit, the overvoltage protection circuit timely adjusts and stabilizes the output voltage value when an abnormally increased voltage is detected.

[0020] In a preferred embodiment: in the power management unit, the undervoltage lockout circuit cuts off the normal working state of the circuit when detecting that the voltage value is lower than the low voltage threshold.

[0021] In a preferred embodiment: in the power management unit, after the power is first powered on, when the voltage value is higher than the lower threshold, the power-on reset circuit generates a reset signal to enable the circuit system to work normally.

[0022] In a preferred embodiment: in the power management unit, the bandgap voltage reference circuit is used to generate a reference voltage; and the mirror current source circuit is used to generate a current source signal for each module.

[0023] In a preferred embodiment, the rectifier circuit unit rectifies the AC voltage into a DC voltage, and steps down the voltage through the resistor R1 and filters the voltage through the capacitor C1.

[0024] In a preferred embodiment: in the manual test unit, a resistor R11 is connected in series with a test button RESET, and both ends are respectively connected to the front end and the rear end of LoadHot and Load Neutral passing through the induction coil coil1 and the neutral coil coil2.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] The present invention provides a ground fault detection device system with a self-checking function. Under the premise of not disconnecting the load AC power supply and not affecting the normal A-type and AC-type leakage detection and protection work of the ground fault detection device and realizing the delay function, the system can periodically and automatically simulate ground faults online to detect and judge whether the leakage protection function of the ground fault detection device, the performance of key core components and the connectivity of the circuit are working normally, and can promptly send out sound, light, electricity and other alarm signals when an abnormality is detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a circuit schematic diagram of the ground fault detection device with self-checking function described in the present invention;

[0028] Figure 2 It is the ground fault detection below threshold current waveform diagram of the present invention;

[0029] Figure 3 It is the ground fault detection above threshold current waveform diagram of the present invention;

[0030] Figure 4 It is a normal waveform diagram of ground fault self-detection according to the present invention;

[0031] Figure 5 This is the abnormal waveform diagram of the ground fault self-detection described in the present invention. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships described in the drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] refer to Figure 1 This embodiment provides a ground fault detection device with a self-checking function, including: an induction coil coil1, a neutral coil coil2, a trip device 200, a manual test unit 100, a rectifier circuit unit, a power management unit 300, a ground fault detection unit 500, and a ground fault self-checking test unit 600.

[0036] The ground fault detection unit 500 receives the ground fault leakage current signal obtained by the induction coil coil1 and the neutral coil coil2, and processes, amplifies, filters, transforms, and judges the effective leakage current signal, and controls the generation of the thyristor / tripper drive signal; the ground fault self-detection test unit 600 detects the phase voltage signal, periodically generates a simulated ground fault leakage current signal, and detects whether the system leakage detection circuit and the trip circuit respond correctly to the simulated ground fault, and judges and outputs the corresponding sound, light, and electrical alarm signals.

[0037] The ground fault detection unit 500 includes: a negative feedback amplifier and resistors R2, R3 and capacitor C2 connected thereto; the differential input end of the negative feedback amplifier is connected to the positive and negative input ends of the level shift circuit in the ground fault detection loop; the two ends of C2 are respectively connected to the two ends of the secondary of the neutral coil coil2. The output end of the negative feedback amplifier is connected to R3 and R2, the other end of R2 is connected to C2 and one end of the secondary of the neutral coil coil2, and the other end of the secondary of the neutral coil coil2 is grounded together with the other end of C2. When the differential input end of the negative feedback amplifier receives a type A or AC type periodic ground fault leakage current signal, the negative feedback amplifier circuit amplifies the differential signal, and C2 and the secondary of the neutral coil coil2 will generate a periodic oscillation signal. If a center line to ground fault occurs at this time, the negative feedback circuit system, coil2, the neutral line and ciol1 will form a positive feedback loop. If the ground fault current exceeds the set threshold, the detection circuit will detect and trigger the thyristor SCR1 to turn on in time, driving the release 200 to disconnect the load power supply.

[0038] The ground fault detection unit 500 also includes: a level shift circuit, a signal amplifier circuit, a rectifier circuit, a detection circuit, a delay circuit, a comparison judgment circuit, a logic control circuit, an output driver, resistors R4, R5, and R6; capacitors C3, C4, C5, C6, C7, and C8; diodes D5, D6, and D7; and a thyristor SCR1.

[0039] In the ground fault detection unit 500, the induced fault current is obtained through the secondary of the induction coil coil1 and converted into a voltage difference through R4. The diode is reversely connected in parallel with both ends of R4 to limit the voltage amplitude. R5, R6 and C8 form a low-pass filter network to filter out high-frequency interference signals. C3, C4, C6 and C7 are ground filter capacitors, among which C7 can also be used as a delay setting capacitor.

[0040] In the ground fault detection unit 500, the negative feedback amplifier circuit is used to amplify the voltage difference obtained by the induction coil and output an oscillation frequency signal to charge and discharge C2. The secondary of the neutral coil obtains the induced current and forms a positive feedback loop when a neutral line-to-ground fault occurs. When the fault current threshold condition is met, the drive output device controls the drive thyristor SCR1 to turn on, and drives the release 200 to cut off the load.

[0041] In the ground fault detection unit 500, the level shift circuit receives the induction coil induced current signal, and after voltage conversion by R4, the small signal filtered by R5, R6 and C8, the differential voltage is shifted to the level range superimposed with the internal bias reference voltage signal, the signal amplifier circuit amplifies the differential voltage signal, and generates a single-ended output voltage signal through the rectifier circuit, and after the signal is processed by the detection circuit, it is sent to the delay circuit to effectively filter out the interference signal and generate a delay function, and then the voltage value of the judgment circuit is compared with the internal threshold reference value through the comparator comparison judgment circuit, and then the logic control circuit controls the output driver to work according to the comparison judgment result. When the converted voltage value is higher than the threshold voltage, the driver outputs a high level pulse to trigger the gate of the thyristor SCR1 to turn on.

[0042] The ground fault self-detection test unit 600 includes: an SCR loop detection circuit, a phase detection circuit, a logic control circuit, a timer circuit, an oscillator circuit, a leakage / self-detection mode switching circuit, a fault simulation output circuit, a frequency divider circuit, an alarm drive circuit, resistors R7, R8, R9, R10; a transistor Q1, a diode D8, and an LED.

[0043] In the ground fault self-test unit 600, the phase detection circuit is used to be connected in series to the live wire LoadHot through R8, and is used to detect the AC phase voltage value in real time. The R8 resistor is used to limit current and reduce voltage, and then the voltage is sent to the phase detection circuit, which determines the phase or AC signal cycle by detecting the voltage value, and provides a phase clock or reference signal to the internal circuit.

[0044] In the ground fault self-test unit 600, the SCR loop detection circuit is used to detect the connectivity with the thyristor SCR1 anode and the release device 200 through R7; the SCR loop detection circuit can also connect the thyristor anode through D8 to test the thyristor SCR1 function. When in the positive half cycle of the phase line voltage, the input end of the SCR loop detection circuit obtains a voltage signal after the voltage is reduced through D7 and R7, and the connectivity of the release device 200 and the thyristor SCR1 anode is detected in real time; when in the negative half cycle of the phase line voltage, D7 is cut off, the SCR loop detection circuit provides voltage to SCR1 through D8, the fault simulation output circuit generates a simulated leakage signal, the ground fault detection unit 500 detects the ground fault leakage signal, the output driver triggers SCR1 to turn on, the thyristor SCR1 anode voltage is reduced and detected by the SCR loop detection circuit, the detection is completed and the output voltage to the SCR1 anode is turned off. If the anode circuit of the release is abnormally disconnected or the simulated ground fault current signal cannot be detected and driven to trip the thyristor SCR1, the SCR circuit detection circuit will be tested multiple times in succession. If the detection still fails, it is judged as a self-test error and the alarm drive circuit is triggered to output an alarm signal.

[0045] In the ground fault self-detection test unit 600, the fault simulation output circuit is used to generate a simulated ground fault leakage current signal through resistors R9, R10 and transistor Q1; the fault simulation output circuit also generates a switching signal for switching the normal leakage detection / self-detection mode. R9 is connected to the output end of the fault simulation output circuit and the base of the transistor Q1, as the driving signal of the amplifier circuit, the emitter of Q1 is grounded, and the collector is connected in series with a step-down / current limiting resistor to the neutral end of LoadNetural. In the positive half cycle of the phase line, the collector end of Q1 is reversely cut off, and in the negative half cycle of the phase line, the collector of Q1 is reverse biased. When the fault simulation output circuit generates a driving signal, Q1 amplifies the driving current through the resistor and the collector to the ground, generating a simulated ground fault current signal that does not pass through the induction coil coil1 and the neutral coil coil2.

[0046] In the ground fault self-test unit 600, the alarm driving circuit is connected to the LED anode, and is used to drive the output of an alarm signal when the self-test fails, and can also drive other sound, light, and electrical devices.

[0047] The power management unit 400 includes a voltage stabilizer, an overvoltage protection circuit, an undervoltage lockout circuit, a power-on reset circuit, a bandgap voltage reference circuit, and a mirror current source circuit.

[0048] In the power management unit 400, the voltage regulator is connected to the DC voltage output by the rectifier circuit through the resistor R1, and detects and stably generates a DC voltage outputted to the internal power supply system.

[0049] In the power management unit 400, the overvoltage protection circuit timely adjusts and stabilizes the output voltage value when an abnormally increased voltage is detected. The overvoltage protection circuit is used to monitor the external input voltage value in real time, and when it is higher than the set threshold voltage, it provides a discharge channel or a protection alarm function;

[0050] In the power management unit 400, when the undervoltage lockout circuit detects that the voltage value is lower than the low voltage threshold, it promptly cuts off the normal working state of the circuit to prevent logic judgment errors or erroneous drive output.

[0051] In the power management unit 400 , after the power is first powered on, when the voltage value is higher than the lower threshold, the power-on reset circuit generates a reset signal to enable the circuit system to operate normally.

[0052] In the power management unit 400, the bandgap voltage reference circuit is used to generate a highly accurate and stable reference voltage; the mirror current source circuit is used to generate an accurate current source signal for each module.

[0053] The rectifier circuit unit 300 is composed of D1, D2, D3, and D4 to form a bridge rectifier circuit, which rectifies the AC voltage to a DC voltage, and then generates a stable DC voltage source through R1 step-down and C1 filtering for use by other circuits in the system.

[0054] In the manual test unit 100, a resistor R11 is connected in series with a test button RESET, and the two ends are respectively connected to the front end and the rear end of the Load Hot and Neutral Line passing through the induction coil and the neutral coil to generate an effective ground fault signal. The resistor R11 limits the current, and when the test button RESET is pressed, a manual simulated ground fault leakage is generated to detect whether the ground fault detection circuit is working properly.

[0055] As shown in Figure 2, in normal ground fault detection, a ground fault current is detected in the positive half cycle or negative half cycle of the phase voltage. If it is determined that the ground fault current value is lower than the set effective threshold, the output drive voltage is low, that is, no effective drive output signal is generated, and the thyristor will not be triggered to conduct and the release device will not trip to cut off the load power supply.

[0056] As shown in Figure 3, in normal ground fault detection, a ground fault current is detected in the positive half cycle or negative half cycle of the phase voltage. If it is determined that the ground fault current value is higher than the set effective threshold, the output drive voltage is high, that is, an effective drive output signal is generated, which can trigger the thyristor to conduct and the release device to trip and cut off the load power supply.

[0057] As shown in Figure 4, during the self-detection cycle, when the phase voltage enters the negative half cycle, the SCR detection port diode in the ground fault self-detection test unit 600 is reversely cut off, and the ground fault self-detection test unit 600 supplies power to the SCR1 thyristor anode terminal through the internal output, that is, at this time, the SCR detection port is a high-level output, and at the same time, the simulated ground fault leakage output is a valid high level, generating a simulated leakage signal, the ground fault detection unit 500 detects the effective simulated leakage signal and the output driver sends a signal, triggering the thyristor SCR1 to turn on, the SCR1 anode, that is, the SCR loop detection circuit port voltage drops and is detected by the internal circuit, proving that the simulated leakage is generated, the ground fault detection unit and the thyristor loop function normally, the simulated ground fault leakage output stops, the ground fault self-detection test unit 600 also shuts off the output to supply power to the SCR1 thyristor anode terminal through the internal, the alarm output port has no high level or pulse signal output, the cycle self-detection ends and waits for the next self-detection cycle to start.

[0058] As shown in Figure 5, during the self-detection cycle, when the phase voltage enters the negative half cycle, the SCR detection port diode in the ground fault self-detection test unit 600 is reversely cut off, and the ground fault self-detection test unit 600 supplies power to the SCR1 thyristor anode terminal through the internal output, that is, at this time, the SCR detection port is a high level output, and at the same time, the simulated ground fault leakage output is a valid high level, generating a simulated leakage signal. If the ground fault detection unit 500 cannot detect a valid simulated leakage signal, or the output driver does not send a signal in time, or the thyristor SCR1 cannot be triggered to turn on, that is, the SCR loop detection circuit port is not internally The circuit detects that within the negative half cycle of the self-test phase voltage, the voltage is triggered by the thyristor to drop after the simulated leakage signal is sent out. The simulated ground fault leakage output will output the simulated leakage signal for several consecutive negative half cycles of the phase voltage. The ground fault self-test test unit 600 also supplies power to the anode end of the SCR1 thyristor through internal output for several consecutive cycles. If the anode end voltage of the SCR1 thyristor is still not triggered and pulled down and is monitored internally, it proves that the simulated leakage generation circuit, the ground fault detection unit and the thyristor circuit are not functioning properly and the ground fault protection function cannot be realized. The alarm output port outputs a high level or generates a pulse signal output, and the periodic self-test ends.

[0059] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe the protection scope of the present invention.

Claims

1. A ground fault detection device with self-checking function, characterized in that include: Induction coil coil1, neutral coil coil2, de-coupler device, rectifier circuit unit, power management unit, ground fault detection unit, ground fault self-detection test unit; The ground fault detection unit receives the ground fault leakage current signal obtained by the induction coil and the neutral coil, and outputs a control signal to drive the release device to cut off the load power supply when a ground fault occurs; the ground fault self-test test unit detects the phase voltage at the output end of the release device, periodically generates a simulated ground fault leakage current signal and detects whether the ground fault detection unit and the release device respond correctly to the simulated ground fault; The ground fault detection unit includes: a negative feedback amplifier and resistors R2, R3 and capacitor C2 connected thereto; the input end of the negative feedback amplifier is connected to the positive and negative input ends of the level shift circuit in the ground fault detection loop; the two ends of the capacitor C2 are respectively connected to the two ends of the secondary of the neutral coil coil2; the ground fault detection unit obtains the ground fault leakage current signal through the secondary of the induction coil coil1, and converts it into a voltage difference signal through the resistor R4 connected to the secondary of the induction coil coil1, and the diodes D5 and D6 are reversely connected and connected in parallel to the two ends of R4 to limit the voltage amplitude; the negative feedback amplifier is used to amplify the voltage difference signal and output an oscillation frequency signal to charge and discharge the capacitor C2, the secondary of the neutral coil coil2 obtains the induced current and forms a positive feedback loop when a neutral line-to-ground fault occurs, and when the fault current threshold condition is met, the output control signal drives the thyristor SCR1 to turn on and drives the release to cut off the load; the ground fault detection unit also includes: a signal amplification circuit, a rectifier circuit, a detection circuit, a delay circuit, a comparison judgment circuit, a logic control circuit, and an output driver; The level shift circuit receives the induced current signal of the induction coil coil1, and converts it into a voltage difference signal through the resistor R4, and shifts the voltage difference signal to a level range superimposed with the internal bias reference voltage signal. The signal amplification circuit amplifies the differential voltage signal, and generates a single-ended output voltage signal through the rectifier circuit, and sends the signal to the delay circuit after the detection circuit processes the signal, and then compares it with the internal threshold reference value through the comparison judgment circuit, and then the logic control circuit outputs the control signal according to the comparison judgment result; in the ground fault self-detection test unit, the phase detection circuit is used to connect in series to the live wire Load through the resistor R8 Hot, used to detect the phase voltage value of AC power in real time; in the ground fault self-detection test unit, the SCR loop detection circuit is used to detect the connectivity with the thyristor SCR1 anode and the release device through the resistor R7; the SCR loop detection circuit can also connect the thyristor anode through the diode D8 to test the function of the thyristor SCR1; in the ground fault self-detection test unit, the fault simulation output circuit is used to generate a simulated ground fault leakage current signal through the resistors R9, R10 and the transistor Q1; the fault simulation output circuit also generates a switching signal for switching the normal leakage detection / self-detection mode; in the ground fault self-detection test unit, the alarm drive circuit is connected to the alarm device, which is used to output an alarm signal when the self-detection test fails, and the alarm device is one of an acoustic, optical, and electrical device.

2. The ground fault detection device with self-checking function according to claim 1, characterized in that: In the power management unit, the voltage regulator is connected to the DC voltage output by the rectifier circuit through the resistor R1, and detects and stably generates a DC voltage outputted to the internal power supply system.

3. The ground fault detection device with self-checking function according to claim 1, characterized in that: In the power management unit, the overvoltage protection circuit timely adjusts and stabilizes the output voltage value when an abnormally increased voltage is detected.

4. The ground fault detection device with self-checking function according to claim 1, characterized in that: In the power management unit, the undervoltage lockout circuit cuts off the normal working state of the circuit when detecting that the voltage value is lower than the low voltage threshold.

5. The ground fault detection device with self-checking function according to claim 1, characterized in that: In the power management unit, after the power is first powered on, when the voltage value of the power-on reset circuit is higher than the lower threshold, a reset signal is generated to enable the circuit system to work normally.

6. The ground fault detection device with self-checking function according to claim 1, characterized in that: In the power management unit, the bandgap voltage reference circuit is used to generate a reference voltage; and the mirror current source circuit is used to generate a current source signal of each module.

7. The ground fault detection device with self-checking function according to claim 1, characterized in that: The rectifying circuit unit rectifies the AC voltage into a DC voltage, and then reduces the voltage through the resistor R1 and filters through the capacitor C1.

8. The ground fault detection device with self-checking function according to claim 1, characterized in that: It also includes a manual test unit, in which a resistor R11 is connected in series with a test button RESET, and both ends are respectively connected to the front end and the rear end of Load Hot and Load Neutral passing through the induction coil coil1 and the neutral coil coil2.

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