A leakage detection circuit

Abstract

The utility model relates to the field of electric leakage detection circuit, especially electric leakage detection circuit, residual current transformer (L1) for detecting electric leakage current in the detection circuit, its pin 3 (RCD-B) outputs high level when detecting electric leakage, peripheral circuit includes resistance (R2), resistance (R3), resistance (R4), resistance (R6), triode (Q2), wherein the pin 3 (RCD-B) of residual current transformer (L1) is connected through resistance (R2) and the base of triode (Q2), the emitter of triode (Q2) is grounded, and the collector is connected to signal line DI-RCD-A+B, one end of resistance (R6) is connected with the base of triode (Q2), and the other end is grounded, one end of resistance (R4) is connected with 3.3V power supply, and the other end is connected with the collector of triode (Q2), software detection module. Overall circuit improves detection sensitivity, accelerates response speed, and increases self-checking function, thereby more effectively guaranteeing personal and property safety.

Description

Technical Field

[0001] This utility model relates to the field of leakage current detection circuits, and more particularly to a leakage current detection circuit. Background Technology

[0002] In the field of electrical safety, leakage current detection circuits are key devices for preventing electric shock accidents and electrical fires. However, existing leakage current detection circuits still have some significant drawbacks in practical applications, limiting their detection effectiveness and reliability.

[0003] First, insufficient detection sensitivity is one of the main problems faced by existing leakage current detection circuits. Traditional leakage protection circuits typically only activate when the leakage current reaches 30mA, failing to detect smaller leakage currents. This means that in the early stages of leakage, before the current value reaches the threshold, the circuit cannot issue an alarm or cut off the power supply in time, thus leaving a safety hazard.

[0004] Secondly, slow response speed is also a drawback of existing technology. When a leakage occurs, the circuit needs a certain amount of time to detect and confirm the leakage signal before triggering the protection action. This delay may cause the leakage current to persist, increasing the risk of electric shock and electrical fires.

[0005] Furthermore, the lack of self-testing functionality is another shortcoming of existing leakage current detection circuits. After prolonged use, components in the circuit may fail due to aging, damage, or poor contact. However, current technology typically cannot automatically detect the circuit's operating status, nor can it promptly issue alarms or take remedial measures when a fault occurs, thus affecting the circuit's reliability and stability. Utility Model Content

[0006] To address the aforementioned problems, this utility model provides an improved leakage current detection circuit, which aims to enhance detection sensitivity, accelerate response speed, and add self-testing functionality, thereby more effectively protecting personal and property safety.

[0007] To achieve the above objectives, the technical solution adopted by this utility model is: a leakage current detection circuit, including: a residual current transformer L1, used to detect leakage current in the circuit, and its pin 3 (RCD-B) outputs a high level when leakage current is detected;

[0008] The peripheral circuit includes resistors R2, R3, R4, R6, and transistor Q2;

[0009] Pin 3 (RCD-B) of the residual current transformer L1 is connected to the base of transistor Q2 through resistor R2. The emitter of transistor Q2 is grounded, and the collector is connected to the signal line DI-RCD-A+B.

[0010] One end of resistor R3 is the signal input terminal (RCD-A), and the other end of resistor R3 is connected to the base of transistor Q2; one end of resistor R6 is connected to the base of transistor Q2, and the other end is grounded; one end of resistor R4 is connected to a 3.3V power supply, and the other end is connected to the collector of transistor Q2.

[0011] The software detection module is connected to the signal line DI-RCD-A+B and is used to monitor the level status of the signal line DI-RCD-A+B in real time.

[0012] Furthermore, a self-test circuit is also included, comprising: resistors R1, R5, and R7, and MOSFET Q1; one end of resistor R1 is connected to a 5V power supply, and the other end is connected to pin 4 (CHK PIN) of the residual current transformer L1; one end of resistor R5 is connected to the software detection module, and the other end is grounded through resistor R7; one end of resistor R7 is connected to the base of MOSFET Q1, and the other end is grounded; the self-test circuit controls the conduction and cutoff of MOSFET Q1 through the output signal DO-LI-CAL of the software detection module, thereby controlling the level state of pin 4 (CHK PIN) of the residual current transformer L1.

[0013] Furthermore, the self-test circuit also includes a capacitor C1, one end of which is grounded and the other end is connected to pin 3 (RCD-B) of the residual current transformer L1.

[0014] Furthermore, the peripheral circuit components also include a capacitor (C2), one end of which is grounded and the other end is connected to the collector of the MOSFET (Q1).

[0015] The beneficial effects of this utility model are as follows:

[0016] The residual current transformer L1 used in this invention has high sensitivity and can detect leakage current as low as 6mA. Compared with traditional leakage protection circuits (which usually operate at 30mA), it significantly improves the detection sensitivity.

[0017] Improving detection sensitivity means being able to detect leakage signals in their early stages, thereby more effectively preventing electric shock accidents and electrical fires and protecting personal and property safety.

[0018] Speed ​​up response:

[0019] The circuit structure designed in this utility model is simple and efficient. From the occurrence of leakage to detection and identification, and then to the triggering of protection action, the entire process has a fast response speed, which can minimize the harm caused by leakage.

[0020] Faster response times ensure that power is quickly cut off or an alarm is triggered when a leakage occurs, preventing the leakage accident from escalating and improving the safety performance of the circuit.

[0021] Add self-test function:

[0022] This utility model integrates a self-test circuit, which can perform a self-test after the circuit is started to verify whether the residual current transformer L1 and its peripheral circuits are functioning normally.

[0023] The addition of a self-test function improves the reliability and stability of the circuit, ensuring that the leakage current detection circuit is in good working order before each use. Simultaneously, the self-test circuit can promptly issue an alarm or disconnect the power supply in case of a circuit fault, preventing leakage current detection failure due to circuit malfunction. Attached Figure Description

[0024] Figure 1 This is a specific circuit structure diagram of a leakage current detection circuit. Detailed Implementation

[0025] Please see Figure 1 As shown, this utility model relates to a leakage current detection circuit, including a residual current transformer L1 for detecting leakage current in the circuit. Its pin 3 (RCD-B) outputs a high level when leakage is detected. The peripheral circuit includes resistors R2, R3, R4, and R6, and a transistor Q2. Pin 3 (RCD-B) of the residual current transformer L1 is connected to the base of transistor Q2 through resistor R2. The emitter of transistor Q2 is grounded, and its collector is connected to the signal line DI-RCD-A+B. One end of resistor R3 is the signal input terminal (RCD-A), and the other end is connected to the base of transistor Q2. One end of resistor R6 is connected to the base of transistor Q2, and the other end is grounded. One end of resistor R4 is connected to a 3.3V power supply, and the other end is connected to the collector of transistor Q2. A software detection module is connected to the signal line DI-RCD-A+B for real-time monitoring of the signal line's level.

[0026] The core of this leakage current detection circuit lies in using a residual current transformer L1 to accurately sense the leakage current in the circuit, and converting the leakage signal into a level change that can be recognized by the software detection module through external circuitry. The residual current transformer L1 is the core component for leakage current detection. Under normal operating conditions, the current vector sum in the circuit is zero, and there is no induced current in the secondary winding of L1; its pin 3 (RCD-B) outputs a low level. When leakage occurs in the circuit, the current vector sum is no longer zero, an induced current is generated in the secondary winding of L1, and pin 3 (RCD-B) outputs a high-level signal.

[0027] The high-level signal output from pin 3 (RCD-B) of L1 drives the base of transistor Q2 after passing through the current-limiting resistor R2, turning Q2 on. Once Q2 is on, its collector and emitter act as a closed switch, pulling the signal line DI-RCD-A+B connected to the collector of Q2 down to near ground (low level). Resistor R6 acts as a pull-down resistor, ensuring that the base of Q2 remains stably low when there is no leakage current, preventing Q2 from being mis-turned on. Resistors R3 and R4 act as current-limiting resistors, respectively protecting transistor Q2 and stabilizing the collector level of Q2. The software detection module continuously monitors the level of the signal line DI-RCD-A+B. During normal circuit operation, the DI-RCD-A+B signal line is pulled up to a high level of 3.3V. If leakage current occurs, Q2 turns on, and the DI-RCD-A+B signal line is pulled low. Once the software detection module detects this level change, it immediately determines it as a leakage fault and triggers corresponding protection measures, such as disconnecting the circuit output and promptly informing the user of the leakage fault information through screen display or sound alarm, thereby effectively protecting personal and property safety.

[0028] Furthermore, the signal input terminal (RCD-A) is connected to the base of transistor Q2 through resistor R3. When an appropriate level signal is input to RCD-A, the signal can drive transistor Q2, causing it to enter either the on or off state. Specifically, when a high-level signal is input to RCD-A, the signal, after being current-limited by resistor R3, can drive the base of transistor Q2, turning Q2 on; conversely, when a low-level signal is input to RCD-A, Q2 remains off.

[0029] The signal input terminal (RCD-A) can be connected to a common leakage current detection device to detect AC leakage current of 30mA, referred to as A-leakage. The RCD-A terminal is designed for connecting to an external leakage current detection device or signal source. In practical applications, the RCD-A terminal can be connected to a common leakage current detection device capable of detecting AC leakage current of 30mA. When the device detects a leakage current reaching or exceeding 30mA, it will generate a corresponding level signal (such as a high level) at the RCD-A terminal. This signal drives transistor Q2 through resistor R3, thereby triggering subsequent protection actions. This connection method allows this leakage current detection circuit to be compatible with and utilize existing leakage current detection devices, achieving effective detection of AC leakage current of 30mA (referred to as A-leakage).

[0030] Compared with existing technologies, the leakage current detection circuit of this invention has the following significant advantages: This leakage current detection circuit can detect much smaller leakage currents. Compared with traditional leakage current protection circuits that typically only activate when the leakage current reaches 30mA, this circuit can accurately detect leakage current as low as 6mA and trigger protection action, significantly improving the sensitivity of leakage current detection and thus more effectively protecting personal safety.

[0031] The circuit design is simple and efficient. From the occurrence of leakage to detection and identification, and then to the triggering of protection action, the response speed is fast, which can minimize the damage caused by leakage and prevent the expansion of leakage accidents.

[0032] The circuit consists of only a small number of commonly used components such as resistors and transistors, making it simple in structure and easy to implement and maintain. This simple circuit structure also translates to higher reliability, reducing the probability of circuit failure and ensuring the stable operation of the leakage current detection function.

[0033] The circuit design includes a self-test function, which automatically performs a self-test upon each power-on or periodically to verify the proper functioning of the residual current transformer L1 and its peripheral circuitry. Only after the self-test passes does the circuit enter normal operating mode, thus ensuring the reliability of the leakage current detection function and avoiding missed or false detections caused by circuit malfunctions.

[0034] The software detection module can not only realize leakage detection and protection functions, but also record leakage events, count the number of leakages, analyze the causes of leakage, and even communicate with the host computer to realize remote monitoring and management, which greatly improves the functionality and intelligence of the leakage detection circuit.

[0035] Furthermore, a self-test circuit is also included, comprising: resistors (R1), (R5), and (R7), and a MOSFET (Q1); one end of resistor (R1) is connected to a 5V power supply, and the other end is connected to pin 4 (CHKPIN) of the residual current transformer (L1); one end of resistor (R5) is connected to the software detection module, and the other end is grounded through resistor (R7); one end of resistor (R7) is connected to the base of the MOSFET (Q1), and the other end is grounded; the self-test circuit controls the conduction and cutoff of the MOSFET (Q1) through the output signal DO-LI-CAL of the software detection module, thereby controlling the level state of pin 4 (CHKPIN) of the residual current transformer (L1) to achieve the self-test function.

[0036] To ensure the reliability and stability of the leakage current detection circuit, this invention also integrates a self-test circuit. The self-test circuit controls the conduction and cutoff of the MOSFET Q1 through the output signal DO-LI-CAL from the software detection module. When DO-LI-CAL outputs a high level, MOSFET Q1 conducts, pulling pin 4 (CHK PIN) of the residual current transformer L1 low; when DO-LI-CAL outputs a low level, MOSFET Q1 is cut off, and pin 4 (CHK PIN) of the residual current transformer L1 is pulled high through resistor R1. By controlling the level state of pin 4 (CHK PIN), the normal operating state of the leakage current detection circuit can be simulated, thereby verifying whether the residual current transformer L1 and its peripheral circuits function correctly.

[0037] The circuit design includes a self-test function, which periodically verifies the functionality of the residual current transformer L1 and its peripheral circuitry. Only after passing the self-test does the circuit enter normal operating mode, ensuring the reliability of the leakage current detection function and preventing missed or false detections due to circuit malfunctions. The self-test circuit can promptly issue an alarm or disconnect the power supply when a circuit fault occurs, thus protecting personal and property safety. Regular self-tests ensure that the leakage current protection function remains effective, improving the overall safety of the circuit.

[0038] Furthermore, the self-test circuit also includes a capacitor C1, one end of which is grounded, and the other end is connected to pin 3 (RCD-B) of the residual current transformer L1. Capacitor C1 serves as a filter and voltage regulator, ensuring a stable voltage level at pin 3 (RCD-B) during the self-test, thus guaranteeing the reliability of the self-test process. The addition of capacitor C1 further improves the stability and reliability of the self-test circuit, ensuring the accuracy of the self-test process.

[0039] Furthermore, the peripheral circuit components also include capacitor C2, one end of which is grounded and the other end is connected to the collector of Q1. Capacitor C2 primarily functions as a filter and voltage regulator. In electronic circuits, capacitors are often used as filter elements to remove AC noise or high-frequency interference, retaining the required DC or low-frequency signals. Connecting capacitor C2 to the collector of Q1 smooths voltage fluctuations at that point, reducing circuit performance degradation caused by power instability or signal interference. Simultaneously, capacitor C2 helps maintain a stable collector voltage level for Q1, ensuring the stability and reliability of the self-test circuit. Through its filtering effect, C2 reduces noise and interference in the circuit, improving the stability and reliability of the leakage current detection circuit, thereby enhancing the accuracy and reliability of the detection.

[0040] The overall circuit works as follows: After the circuit is started, it first performs a self-test. The self-test circuit controls the conduction and cutoff of the MOSFET Q1 through the output signal DO-LI-CAL of the software detection module, thereby controlling the level state of pin 4 (CHK PIN) of the residual current transformer L1.

[0041] When DO-LI-CAL outputs a high level, MOSFET Q1 is turned on, pulling pin 4 of L1 low; when DO-LI-CAL outputs a low level, MOSFET Q1 is turned off, and pin 4 of L1 is pulled high through resistor R1. By controlling the level state of pin 4, the self-test circuit simulates the normal working state of the leakage current detection circuit, verifying whether the residual current transformer L1 and its peripheral circuits are functioning correctly. The specific judgment method is:

[0042] (a) When pin 4CHK PIN is set to a high level (3.3~5V), Vout rises from a low level to a high level;

[0043] (b) When pin 4CHK PIN is set to low level (<0.2V), Vout drops to low level (0V). Only after completing items (a) and (b) above can it be determined that the leakage current sensor has normal function and the self-test process ends.

[0044] Therefore, we connect R1 to pin 4 through a 5V power supply, first giving it a high level. After that, we give DO-LI-CAL a high level through the MCU, driving Q1 to pull pin 4 low, so as to complete a self-test process.

[0045] Additionally, capacitor C1 is connected to pin 3 (RCD-B) of L1, serving as a filter and voltage regulator to ensure that the level of pin 3 (RCD-B) remains stable during the self-test, thereby guaranteeing the reliability of the self-test process.

[0046] After a successful self-test, the circuit enters the normal leakage current detection mode. The residual current transformer L1, as the core detection element, monitors the current vector sum in the circuit in real time. Under normal operating conditions, the current vector sum is zero, there is no induced current in the secondary winding of L1, and pin 3 (RCD-B) outputs a low level. When leakage occurs, the current vector sum is no longer zero, an induced current is generated in the secondary winding of L1, and pin 3 (RCD-B) outputs a high-level signal. This high-level signal drives transistor Q2 to conduct through the current-limiting resistor R2, pulling the signal line DI-RCD-A+B connected to the collector of Q2 low. The software detection module continuously monitors the level of the DI-RCD-A+B signal line. Once a low level is detected, it immediately determines a leakage fault and triggers protection measures, such as disconnecting the circuit output and issuing an alarm. Furthermore, capacitor C2 in the external circuit, connected to the collector of Q1, also serves as a filter and voltage regulator, helping to maintain the stability of the Q1 collector level and ensuring the stability and reliability of the self-test circuit.

[0047] This invention's leakage current detection circuit offers significant advantages: High-sensitivity leakage current detection: The circuit can detect leakage currents as low as 6mA, significantly improving detection sensitivity compared to traditional leakage protection circuits (which typically operate at 30mA), thus more effectively protecting personal safety. Fast response and timely protection: The circuit design is simple and efficient. From leakage occurrence to detection and identification, and then to triggering protection action, the response speed is fast, minimizing the harm caused by leakage and preventing the escalation of leakage accidents. High reliability and stability: The circuit structure is simple, with few components and clear connections, reducing the probability of failure. Simultaneously, the self-testing circuit performs a self-check before each startup to ensure normal circuit function, further improving the circuit's reliability and stability. Powerful functional expandability: The software detection module not only implements leakage current detection and protection functions but can also record leakage events, count leakage occurrences, analyze leakage causes, and even communicate with a host computer for remote monitoring and management, greatly enhancing the circuit's functionality and intelligence. The leakage current detection circuit of this invention provides strong protection for circuit safety with its high sensitivity, fast response, high reliability and powerful functional expandability, and has broad application prospects.

[0048] The above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of the present utility model. Various modifications and improvements made to the technical solutions of the present utility model by those skilled in the art without departing from the spirit of the present utility model should fall within the protection scope defined by the claims of the present utility model.

Claims

1. A leakage current detection circuit, characterized in that, include: The residual current transformer (L1) is used to detect leakage current in the circuit. Its pin 3 (RCD-B) outputs a high level when leakage is detected. The peripheral circuit includes resistors (R2), (R3), (R4), (R6), and transistor (Q2); Pin 3 (RCD-B) of the residual current transformer (L1) is connected to the base of the transistor (Q2) through resistor (R2). The emitter of the transistor (Q2) is grounded, and the collector is connected to the signal line DI-RCD-A+B. One end of resistor (R3) is the signal input terminal (RCD-A), and the other end of resistor (R3) is connected to the base of the transistor (Q2). One end of resistor (R6) is connected to the base of the transistor (Q2), and the other end is grounded. One end of resistor (R4) is connected to a 3.3V power supply, and the other end is connected to the collector of the transistor (Q2). The software detection module is connected to the signal line DI-RCD-A+B and is used to monitor the level status of the signal line DI-RCD-A+B in real time.

2. The leakage current detection circuit according to claim 1, characterized in that, It also includes a self-test circuit, which comprises: resistor (R1), resistor (R5), resistor (R7), and MOSFET (Q1); one end of resistor (R1) is connected to a 5V power supply, and the other end is connected to pin 4 (CHK PIN) of the residual current transformer (L1); one end of resistor (R5) is connected to the software detection module, and the other end is grounded through resistor (R7); one end of resistor (R7) is connected to the base of MOSFET (Q1), and the other end is grounded; the self-test circuit controls the conduction and cutoff of MOSFET (Q1) through the output signal DO-LI-CAL of the software detection module, thereby controlling the level state of pin 4 (CHK PIN) of the residual current transformer (L1).

3. The leakage current detection circuit according to claim 2, characterized in that, The self-test circuit also includes a capacitor (C1), one end of which is grounded and the other end is connected to pin 3 (RCD-B) of the residual current transformer (L1).

4. The leakage current detection circuit according to claim 2, characterized in that, The peripheral circuit components also include a capacitor (C2), one end of which is grounded and the other end is connected to the collector of the MOSFET (Q1).

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