Grounding fault detection method and apparatus having self-checking function

Abstract

Disclosed in the present invention is a grounding fault detection apparatus having a self-checking function. The grounding fault detection apparatus comprises: an induction coil, a neutral coil, a trip unit, a manual test unit, a rectifier circuit unit, a power supply management unit, a grounding fault detection unit and a grounding fault self-checking test unit. The grounding fault detection unit receives grounding fault leakage current signals acquired by means of the induction coil and the neutral coil, then processes, amplifies, filters, converts, performs determination, etc. on effective leakage current signals, and performs control to generate silicon-controlled rectifier / trip unit driving signals; the grounding fault self-checking test unit detects a phase voltage signal, periodically generates a simulated grounding fault leakage current signal, detects whether the response of a system electric leakage detection loop and a tripping loop to a simulated grounding fault is correct, and performs determination and can output corresponding acoustic, optical and electrical alarm signals.

Description

A method and device for detecting ground faults with self-testing function Technical Field

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

[0002] Thanks to the rapid development of computers, semiconductors, and electronic technologies, as well as the continuous improvement of people's living standards, various electronic appliances and smart home appliances have become widely used in households. The public's safety awareness of electrical equipment has also been continuously enhanced. To ensure the safety of life and property, leakage protectors (RCDs) and electrical switchgear, including RCDs, are widely used in power supply system circuits. They can effectively detect leakage or electric shock incidents, promptly cut off the power supply, and prevent electrical safety accidents.

[0003] However, the functions of the leakage protector or leakage detection circuit device in the current existing technology are too simple. 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 that can detect the leakage of AC live wire and neutral wire to the ground are implemented with relatively backward technology and process, with poor accuracy, poor consistency, weak anti-interference ability, and are very easy to cause misjudgment; furthermore, the above-mentioned existing technology The product does not include a self-test function. The traditional method of manually testing the product or device regularly by pressing a test button is used to test whether the function is normal. However, in actual applications, few users will conduct regular manual tests, which poses a great risk. 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, the inability to detect and cut off the load in a timely and accurate manner can easily cause damage to power supply facilities and load electrical equipment, and even cause fires and personal life accidents, posing a great safety hazard. Furthermore, although the existing technology has neutral / live line to ground detection and self-test functions, it does not have a precise delay setting function, etc., which cannot be applied to most higher-level power grid systems with graded leakage protection.

[0004] Patent publication number CN1818687A discloses an intelligent detection method and equipment for the end of life of a leakage protection device. The method uses an MCU solution to control the detection and self-testing of ground faults (end of life detection). The peripheral structure is complex, and since MCUs generally have certain defects in EMC and ESD, there are problems in the selection of MCUs, such as poor electromagnetic compatibility, high cost, and poor anti-interference characteristics. At the same time, the patented solution uses the AC power of the grid to generate a simulated ground fault for detection in each cycle, so it can only detect AC ground faults, which affects the normal ground fault detection and protection functions, and poses a huge safety hazard.

[0005] Patent publication number CN102694364A discloses a ground fault circuit interrupter monitor and ground fault simulation method. The patent description clearly states: "A self-test monitor is configured to generate a simulated ground fault and detect a response to the simulated ground fault during a period beginning in the first half of a first cycle of an AC power source and extending to the second half of the first cycle of the AC power source, wherein the first half of the first cycle of the AC power source precedes the second half of the first cycle of the AC power source." This description indicates that implementation of this solution requires generating a simulated leakage signal for each AC cycle. Therefore, it can only detect AC leakage ground faults, not Type A ground faults. Similarly, the patented solution cannot implement a time delay function.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to solve the problem that the above-mentioned existing technology 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-test function, and to provide a highly integrated, multi-functional, high-precision, high-reliability A-type leakage detection method and circuit device with self-testing live wire and neutral wire to the ground.

[0008] The present invention discloses a ground fault detection device with a self-checking function, comprising: an induction coil coil 1, a neutral coil coil 2, a tripping device, a rectifier circuit unit, a power management unit, a ground fault detection unit, and a ground fault self-checking test unit;

[0009] 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 power supply to the load 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.

[0010] In a preferred embodiment, the ground fault detection unit includes: a negative feedback amplifier and its connected resistors R2, R3 and capacitor C2; 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; and the two ends of capacitor C2 are respectively connected to the two ends of the secondary of neutral coil coil2.

[0011] 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. The diodes D5 and D6 are connected in parallel at both ends of R4 in reverse order to limit the voltage amplitude.

[0012] 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-to-ground fault occurs. When the fault current threshold condition is met, the output control signal drives the thyristor SCR1 to turn on, driving the release to cut off the load.

[0013] In a preferred embodiment: the ground fault detection unit further includes: a level shift circuit, a signal amplifier circuit, a rectifier circuit, a detection circuit, a delay circuit, a comparison and judgment circuit, a logic control circuit, and an output driver;

[0014] The level shift circuit receives the induced current signal from the induction coil coil1 and converts it into a voltage difference signal through resistor R4. The voltage difference signal is shifted 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. Then, it is compared with the internal threshold reference value through the comparison and judgment circuit, and the logic control circuit outputs a control signal based on the comparison and judgment result.

[0015] In a preferred embodiment: in the ground fault self-detection test unit, the phase detection circuit is connected in series to the live wire Load Hot through the resistor R8, and is used to detect the AC phase voltage value in real time.

[0016] In a preferred embodiment, in the ground fault self-test unit, the SCR loop detection circuit is used to detect connectivity with the thyristor SCR1 anode and the trip device through the resistor R7; the SCR loop detection circuit can also be connected to the thyristor anode through D8 to test the function of the thyristor SCR1.

[0017] 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.

[0018] 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.

[0019] 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 a DC voltage output to the internal power supply system.

[0020] 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.

[0021] 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.

[0022] In a preferred embodiment: 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, the power-on reset circuit generates a reset signal to enable the circuit system to operate normally.

[0023] 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.

[0024] In a preferred embodiment, the rectifier circuit unit rectifies the AC voltage into a DC voltage, and then reduces the voltage through the resistor R1 and filters the DC voltage through the capacitor C1.

[0025] In a preferred embodiment, in the manual test unit, a resistor R11 is connected in series with the test button RESET, and its two 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.

[0026] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0027] 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 periodically and automatically simulates 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 issue sound, light, electricity and other alarm signals when an abnormality is detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] FIG1 is a circuit diagram of a ground fault detection device with a self-checking function according to the present invention;

[0029] FIG2 is a waveform diagram of a current below a threshold value for ground fault detection according to the present invention;

[0030] FIG3 is a waveform diagram of a current exceeding a threshold value for detecting a ground fault according to the present invention;

[0031] FIG4 is a normal waveform diagram of the ground fault self-detection according to the present invention;

[0032] FIG5 is a waveform diagram of abnormal ground fault self-detection according to the present invention. DETAILED DESCRIPTION

[0033] 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships depicted in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "set / 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.

[0036] 1 , this embodiment provides a ground fault detection device with a self-test function, including: an induction coil coil 1, a neutral coil coil 2, 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-test test unit 600.

[0037] 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, thereby controlling the generation of the thyristor / tripper drive signal; the ground fault self-test 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 can judge and output corresponding sound, light, and electrical alarm signals.

[0038] The ground fault detection unit 500 includes a negative feedback amplifier and its connected resistors R2 and R3 and capacitor C2. The differential inputs of the negative feedback amplifier are connected to the positive and negative inputs of the level shift circuit in the ground fault detection loop. The two ends of C2 are connected to the two ends of the secondary of neutral coil 2, respectively. The output of the negative feedback amplifier is connected to R3 and R2, and the other end of R2 is connected to C2 and one end of the secondary of neutral coil 2. The other end of the secondary of neutral coil 2 is connected to the same ground as the other end of C2. When the differential inputs of the negative feedback amplifier receive a type A or AC periodic ground fault leakage current signal, the negative feedback amplifier circuit amplifies the differential signal, and C2 and the secondary of neutral coil 2 generate a periodic oscillation signal. If a neutral line-to-ground fault occurs, the negative feedback circuit system, coil 2, the neutral line, and C111 form a positive feedback loop. If the ground fault current exceeds a set threshold, the detection circuit detects it and promptly triggers the thyristor SCR1 to conduct, driving the trip unit 200 to disconnect the load power supply.

[0039] The ground fault detection unit 500 further includes: a level shift circuit, a signal amplifier circuit, a rectifier circuit, a detection circuit, a delay circuit, a comparison and 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.

[0040] 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. A diode is connected in parallel with both ends of R4 in reverse order 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 serve as a delay setting capacitor.

[0041] In the ground fault detection unit 500, a 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-to-ground fault occurs. When the fault current threshold condition is met, the drive output device controls the thyristor SCR1 to turn on, driving the release 200 to cut off the load.

[0042] In the ground fault detection unit 500, a level shift circuit receives the induced current signal from the induction coil and, after voltage conversion by R4 and filtering by R5, R6, and C8, shifts the differential voltage to a level range superimposed with an internal bias reference voltage signal. A signal amplifier circuit amplifies the differential voltage signal and generates a single-ended output voltage signal through a rectifier circuit. After signal processing by a detection circuit, the signal is fed into a delay circuit, effectively filtering out interference signals and generating a delay function. A comparator then compares the voltage value of the judgment circuit with an internal threshold reference value. The logic control circuit then controls the operation of the output driver based on the comparison result. When the converted voltage value exceeds the threshold voltage, the driver outputs a high-level pulse, triggering the gate of the thyristor (SCR1) to turn on.

[0043] The ground fault self-test 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-test mode switching circuit, a fault simulation output circuit, a frequency divider circuit, an alarm drive circuit, resistors R7, R8, R9, and R10; a transistor Q1, a diode D8, and an LED.

[0044] In the ground fault self-test unit 600, the phase detection circuit is connected in series to the hot line (Load Hot) via resistor R8 to detect the AC phase voltage in real time. Resistor R8 limits current and reduces voltage, which is then fed to the phase detection circuit. The detected voltage determines the phase or AC signal cycle, providing a phase clock or reference signal for the internal circuits.

[0045] In the ground fault self-test unit 600, the SCR circuit detection circuit is used to detect connectivity with the anode of the thyristor (SCR) 1 and the trip unit 200 via R7. The SCR circuit detection circuit can also connect to the anode of the thyristor (SCR) 1 via D8 to test the function of the thyristor 1. During the positive half-cycle of the phase line voltage, the SCR circuit detection circuit input receives a voltage signal after being stepped down by D7 and R7, thereby detecting connectivity between the trip unit 200 and the anode of the thyristor 1 in real time. During the negative half-cycle of the phase line voltage, D7 is cut off, and the SCR circuit detection circuit supplies voltage to SCR1 via D8. The fault simulation output circuit generates a simulated leakage signal, and the ground fault detection unit 500 detects the ground fault leakage signal. The output driver triggers SCR1 to conduct, causing the anode voltage of the thyristor 1 to decrease and be detected by the SCR circuit detection circuit. Upon completion of the detection, the output voltage to the anode of SCR1 is shut off. If the anode circuit of the trip unit is abnormally disconnected or fails to detect and drive the thyristor SCR1 to trip after issuing a simulated ground fault current signal, the SCR circuit detection circuit will test it multiple times in succession. If the detection still fails, it will be determined as a self-test error and the alarm drive circuit will be triggered to output an alarm signal.

[0046] In the ground fault self-test unit 600, the fault simulation output circuit is used to generate a simulated ground fault leakage current signal through resistors R9 and R10 and transistor Q1. The fault simulation output circuit also generates a switching signal for switching between normal leakage detection and self-test modes. R9 is connected to the output terminal of the fault simulation output circuit and the base of transistor Q1, serving as the drive signal for the amplifier circuit. Q1's emitter is grounded, and its collector is connected in series with a step-down / current-limiting resistor to the neutral terminal of the load network. During the positive half-cycle of the phase line, Q1's collector is reverse-biased and cutoff. During the negative half-cycle of the phase line, Q1's collector is reverse-biased. When the fault simulation output circuit generates a drive signal, Q1 amplifies the drive current through the resistor and collector to ground, generating a simulated ground fault current signal that does not pass through the induction coil 1 and the neutral coil 2.

[0047] 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. It can also drive other sound, light, and electrical devices.

[0048] The power management unit 400 includes a voltage regulator, an overvoltage protection circuit, an undervoltage lockout circuit, a power-on reset circuit, a bandgap voltage reference circuit, and a mirror current source circuit.

[0049] In the power management unit 400 , the voltage regulator is connected to the DC voltage output by the rectifier circuit via the resistor R1 , and detects and stably generates a DC voltage output to the internal power supply system.

[0050] In the power management unit 400, the overvoltage protection circuit promptly adjusts and stabilizes the output voltage value when it detects an abnormally high voltage. The overvoltage protection circuit is used to monitor the external input voltage value in real time and provide a discharge channel or protection alarm function when it exceeds the set threshold voltage;

[0051] 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.

[0052] In the power management unit 400 , after the power is first powered on, the power-on reset circuit generates a reset signal when the voltage value is higher than the lower threshold value to enable the circuit system to operate normally.

[0053] In the power management unit 400 , the bandgap voltage reference circuit is used to generate a highly accurate and stable reference voltage; and the mirror current source circuit is used to generate an accurate current source signal for each module.

[0054] 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 to provide it to other circuits in the system.

[0055] In the manual test unit 100, a resistor R11 is connected in series with a test button RESET. Its two ends are connected to the front and rear ends of the Load Hot and Neutral Lines, respectively, which pass through the induction coil and neutral coil, to generate an effective ground fault signal. Resistor R11 limits the current, and pressing the test button RESET generates a manual simulated ground fault leakage, which is used to verify the proper functioning of the ground fault detection circuit.

[0056] 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.

[0057] 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 triggers the thyristor to conduct and the release device to trip and cut off the load power supply.

[0058] As shown in Figure 4, during the self-test cycle, when the phase voltage enters the negative half-cycle, the diode at the SCR detection port in the ground fault self-test test unit 600 is reversely cut off, and the ground fault self-test test unit 600 supplies power to the anode end of the SCR1 thyristor through the internal output. That is, at this time, the SCR detection port is a high-level output. At the same time, the simulated ground fault leakage output is valid high-level, generating a simulated leakage signal. The ground fault detection unit 500 detects the valid simulated leakage signal and sends a signal from the output driver, triggering the thyristor SCR1 to turn on. The voltage at the anode of SCR1, that is, the SCR loop detection circuit port, drops and is detected by the internal circuit, proving that the simulated leakage has occurred and the ground fault detection unit and the thyristor loop are functioning normally. The simulated ground fault leakage output stops, and the ground fault self-test test unit 600 also shuts off the output power to the anode end of the SCR1 thyristor. There is no high-level or pulse signal output from the alarm output port, and the periodic self-test ends and waits for the next self-test cycle to start.

[0059] 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 anode end of the SCR1 thyristor through the internal output. That is, at this time, the SCR detection port is a high-level output. 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 and drops after the simulated leakage signal is issued. 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 internally monitored, it proves that the simulated leakage generation circuit, the ground fault detection unit and the thyristor circuit are malfunctioning 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.

[0060] The above is only a preferred specific embodiment of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with this 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 scope of protection of the present invention. Industrial Applicability

[0061] The present invention provides a ground fault detection system with a self-checking function. Without disconnecting the AC power supply to the load and affecting the ground fault detection system's normal Type A and Type AC leakage detection and protection functions, or implementing its delay function, the system periodically and automatically simulates ground faults online to detect and determine whether the ground fault detection system's leakage protection function, the performance of key core components, and the connectivity of its circuits are functioning properly. Furthermore, the system can promptly issue audible, visual, and electrical alarm signals if an abnormality is detected. This system has excellent industrial applicability.

Claims

1. A ground fault detection device with a self-checking function, characterized in that Including: Induction coil coil1, neutral coil coil2, tripping 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 signals obtained by the induction coil and the neutral coil, and outputs a control signal to drive the tripping 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 tripping device, periodically generates an analog ground fault leakage current signal, and detects whether the ground fault detection unit and the tripping device respond correctly to the analog ground fault.

2. The ground fault detection device with self-checking function according to claim 1, characterized in that The ground fault detection unit includes: a negative feedback amplifier and the connected resistors R2, R3 and capacitor C2; 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 circuit; both ends of the capacitor C2 are respectively connected to the two ends of the secondary of the neutral coil coil2.

3. The ground fault detection device with self-checking function according to claim 2, wherein, 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. The diodes D5 and D6 are connected in reverse parallel across the two ends of R4 to limit the voltage amplitude.

4. The ground fault detection device with self-checking function according to claim 3, wherein, 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 an induced current and forms a positive feedback loop when a neutral-to-ground fault occurs. When the fault current threshold condition is met, a control signal is output to drive the thyristor SCR1 to conduct and drive the tripping device to cut off the load.

5. The ground fault detection device with self-checking function according to claim 2, characterized in that, The ground fault detection unit further includes: a level shift circuit, a signal amplification circuit, a rectifier circuit, a detection circuit, a delay circuit, a comparison and judgment circuit, a logic control circuit, an output driver; The level shift circuit receives the induced current signal of the induction coil coil1, converts it into a voltage difference signal through the resistor R4, shifts the voltage difference signal to the level range superimposed with the internal bias reference voltage signal. The signal amplification circuit amplifies the differential voltage signal, generates a single-ended output voltage signal through the rectifier circuit, processes the signal through the detection circuit and then sends it into the delay circuit, then compares it with the internal threshold reference value through the comparison and judgment circuit, and then the logic control circuit outputs a control signal according to the comparison and judgment result.

6. The ground fault detection device with self-checking function according to claim 1, characterized in that, 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 to detect the AC phase voltage value in real time.

7. The ground fault detection device with self-checking function according to claim 1, characterized in that In the ground fault self-detection test unit, the SCR loop detection circuit is used to detect the connectivity with the anode of the thyristor SCR1 and the tripping device through the resistor R7; the SCR loop detection circuit can also test the function of the thyristor SCR1 by connecting D8 to the anode of the thyristor.

8. The ground fault detection device with self-checking function according to claim 1, characterized in that In the ground fault self-detection test unit, the fault simulation output circuit is used to generate an analog ground fault leakage current signal through the resistors R9, R10 and the triode Q1; the fault simulation output circuit also generates a signal for switching between normal leakage detection / self-detection modes.

9. The ground fault detection device with self-checking function according to claim 1, characterized in that, In the grounding fault self-detection test unit, the alarm drive circuit is connected to the alarm device and is used to output an alarm signal when the self-detection test fails. The alarm device is one of the sound, light, and electrical devices.

10. 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 stabilizes the DC voltage output for the internal power supply system.

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

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

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

14. 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; the mirror current source circuit is used to generate current source signals for each module.

15. The ground fault detection device with self-checking function according to claim 1, characterized in that, The rectifier circuit unit rectifies the AC voltage to a DC voltage, and steps down the voltage through the resistor R1 and filters it through the capacitor C1.

16. The ground fault detection device with self-checking function as described in claim 1, characterized in that, In the manual test unit, the resistor R11 is connected in series with the test button RESET, and the two ends are respectively connected to the front end and the rear end of Load Hot and Load Neutral that pass through the induction coil coil1 and the neutral coil coil2.

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