Residual current monitoring protection circuit of intelligent miniature circuit breaker

Abstract

The invention discloses a residual current monitoring and protecting circuit of an intelligent miniature circuit breaker. The monitoring and protecting circuit comprises a residual current transformer (CT1), a residual current protecting circuit, an isolating circuit and a residual current monitoring circuit, the input end of the residual current protection circuit is connected to a residual current transformer (CT1); the residual current monitoring circuit is connected with the residual current transformer (CT1) through the isolation circuit. The invention provides an optimized circuit for solving the problems that an existing intelligent miniature circuit breaker adopts two groups of residual current transformers to realize residual current monitoring and protection, so that the internal space occupation of a product is large, the installation difficulty is increased, and the cost is increased. According to the optimization circuit, the number of residual current transformers is reduced, and the product design redundancy is reduced. Product material cost and production labor cost are effectively reduced, product size is reduced, field installation is more convenient, and a better circuit solution is provided for development of intelligent miniature circuit breakers.

Description

Technical Field

[0001] The present invention relates to the technical fields of circuit measurement and protection, and particularly relates to a residual current monitoring and protection circuit for an intelligent miniature circuit breaker. Background Art

[0002] A circuit breaker is an essential protection component in a power distribution system, and a residual current protection circuit breaker is used for indirect electric shock protection of people. When the residual current is abnormal, a traditional residual current protection circuit breaker will actively protect and trip. Compared with the traditional circuit breaker, an intelligent miniature circuit breaker also has the function of real-time residual current monitoring on the basis of the residual current protection function. Users can give early warnings according to the residual current value in the circuit and conduct hidden danger investigation, rather than only providing passive protection when people are electrocuted. Most manufacturers in the current market implement the residual current monitoring and protection of intelligent miniature circuit breakers through two sets of residual current transformers. The first set of residual current transformers is used for the protection tripping function, and the second set of residual current transformers is used for monitoring the real-time value of the residual current. Although this method simply adds a second set of residual current transformers to the original technology to achieve the residual current monitoring function of the intelligent circuit breaker, the disadvantage of this solution is that adding a set of residual current transformers will greatly increase the internal space occupancy rate of the product, making the product have to be enlarged, increasing the installation difficulty of the product and raising the product cost. Summary of the Invention

[0003] The present invention aims to provide an optimized circuit for an intelligent miniature circuit breaker to solve various problems caused by using two sets of residual current transformers in the prior art, and while realizing the residual current monitoring and protection functions, reduce the product cost, reduce the volume and improve the installation convenience.

[0004] To achieve the above object, the present invention designs a residual current monitoring and protection circuit for an intelligent miniature circuit breaker. The monitoring and protection circuit includes a residual current transformer, a residual current protection circuit, an isolation circuit and a residual current monitoring circuit; the input end of the residual current protection circuit is connected to the residual current transformer; the residual current monitoring circuit is connected to the residual current transformer through the isolation circuit, and its output is connected to the circuit breaker MCU detection unit; The output end of the residual current transformer is sampled through a series-connected sixth resistor and thirty-sixth resistor and used as the input signal of the residual current protection circuit; The residual current transformer is used to convert the leakage current signal into an electrical signal, providing a sampling signal for the residual current protection circuit and the residual current monitoring circuit; the residual current transformer is the signal acquisition source of the entire monitoring and protection circuit, and its operation is based on the principle of electromagnetic induction; under normal circumstances, the current in the circuit is in a balanced state, the vector sum of the primary side currents of the residual current transformer is zero, and no induced current is output on the secondary side; once a leakage occurs in the circuit, a residual current will be generated, and this residual current will generate an alternating magnetic field on the primary side of the residual current transformer, and then induce a corresponding electrical signal on the secondary side; The residual current protection circuit has a signal processing chip as the core, and the input signal is connected to the input end of the signal processing chip after being sampled by a resistor and filtered by a capacitor; The isolation circuit includes an isolation operational amplifier chip and its peripheral circuit, and the input signal of the isolation circuit includes the signal sampled by the 6th resistor at the output ends (ZCT1 and ZCT2) of the current transformers; this signal is connected to the input ends (VINP and VINN) of the isolation operational amplifier chip after being filtered by a resistor-capacitor circuit; The residual current monitoring circuit includes a signal amplification module and a filtering and protection module, the input signal is connected to the output ends (VP and VN) of the isolation operational amplifier chip, and enters the residual current monitoring circuit through a current-limiting resistor and is transmitted to the metering chip in the breaker MCU detection unit for residual current sampling and metering.

[0005] The residual current protection circuit further includes a sampling and filtering module and an overvoltage protection module; the two ends of the input signal of the sampling and filtering module are respectively connected to the two input ends of the signal processing chip through the 4th resistor and the 7th resistor, and at the same time, the front end of signal sampling is filtered by a resistor-capacitor circuit composed of the 4th resistor, the 5th capacitor, the 7th resistor, and the 6th capacitor, the 7th resistor and the 5th capacitor are interconnected with one input end of the signal processing chip, and at the same time, one input end of the signal processing chip is connected to the 9th capacitor grounded; the overvoltage protection module includes the 6th bidirectional voltage regulator tube, and the 6th bidirectional voltage regulator tube is connected in parallel with the 6th capacitor.

[0006] The residual current protection circuit has a signal processing chip as the core, mainly responsible for detecting the leakage signal and triggering a protection action when the residual current is abnormal; the filtering module filters the input signal to remove noise interference and improve the signal quality. When an excessive voltage appears, the bidirectional voltage regulator tube of the overvoltage protection module conducts, bypassing the excessive voltage to prevent it from damaging the signal processing chip; the signal processing chip analyzes and judges the filtered signal received, and according to the preset residual current threshold, when it detects that the residual current reflected by the signal exceeds the threshold, it outputs a corresponding signal to trigger a protection action.

[0007] The two ends of the input signal of the isolation circuit are respectively transmitted to the isolation operational amplifier chip via a resistor-capacitor filter network composed of a 17th resistor, a 19th resistor, a 61st capacitor, a 73rd capacitor, and an 87th capacitor. Among them, the 17th resistor and the 19th resistor are respectively connected to two input pins of the isolation operational amplifier chip. A 73rd capacitor is also connected in parallel between the two input pins of the isolation operational amplifier chip. Both ends of the 73rd capacitor are grounded through the 61st capacitor and the 87th capacitor respectively.

[0008] The capacitor is used to filter out the interference of common-mode and differential-mode noise signals in the circuit to ensure the accuracy of the signal. The isolation circuit takes the isolation operational amplifier chip as the core. Its main function is to avoid the interference signal of the ground potential difference generated by the non-common ground of the residual current protection circuit and the residual current monitoring circuit, ensure the accuracy of signal transmission, and at the same time perform differential amplification on the signal from the residual current transformer to improve the anti-interference ability and transmission quality of the signal.

[0009] In the residual current monitoring circuit, the two ends of the input signal of the signal amplification module are respectively connected to the positive input terminal and the negative input terminal of the operational amplifier chip through a 23rd resistor and a 29th resistor. The negative input terminal of the operational amplifier chip is connected to its output terminal through a feedback resistor, the 27th resistor. And the output terminal is connected to one input terminal of the filter protection module through a low-pass filter circuit composed of a 25th resistor and an 89th capacitor. The positive input terminal of the operational amplifier chip is connected to the output reference of the metering chip in the breaker MCU detection unit through a 22nd resistor. The filter protection module includes two lines, and the two lines are respectively connected to the metering chip in the breaker monitoring circuit through two resistor-capacitor circuits composed of a 63rd resistor and a 51st capacitor, and a 78th resistor and a 53rd capacitor. A 3rd bidirectional voltage regulator tube is connected to the front ends of the two resistor-capacitor circuits of the filter protection module, and the 3rd bidirectional voltage regulator tube is located in the middle of the two resistor-capacitor circuits.

[0010] The residual current monitoring circuit is mainly used to receive the differentially amplified signal, filter and amplify the received signal to make the electrical signal meet the sampling requirements of the analog-to-digital converter, so as to realize the accurate detection of the residual current. Through the cooperation of resistors in the signal amplification module, the operational amplifier chip can automatically adjust the gain according to the magnitude of the residual current signal to ensure that the output signal is within the sampling range of the analog-to-digital converter. The filter protection module is composed of a 3rd bidirectional voltage regulator tube, a 63rd resistor, a 51st capacitor, a 78th resistor and a 53rd capacitor, and is used to filter out common-mode and differential-mode noise signals and perform overvoltage protection on the signal.

[0011] The gain of the signal amplification module is determined by the 22nd resistor and the 27th resistor. The filter circuit in the filter protection module has an attenuation effect on high-frequency signals, and the cut-off frequency is determined by the parameters of the resistor and the capacitor, which can effectively filter out high-frequency interference signals and make the output signal smoother and more stable.

[0012] The output end of the residual current protection circuit is connected to the input end of the circuit breaker tripping device.

[0013] When there is an abnormal residual current in the residual current protection circuit, the residual current protection circuit outputs a control signal to the circuit breaker tripping device, driving the circuit breaker tripping device to quickly cut off the circuit, thereby ensuring personal safety and normal operation of the equipment.

[0014] The circuit breaker MCU detection unit outputs and connects to the circuit breaker tripping device, driving the tripping device to act according to the set tripping current, and generally this current is less than the action current of the protection circuit when needed.

[0015] The residual current monitoring circuit provides an accurate residual current signal for the circuit breaker MCU detection unit. After receiving the sampling signal, the circuit breaker MCU detection unit compares it with the internally set residual current threshold to support the circuit breaker MCU detection unit to realize real-time monitoring of the residual current in the circuit; at the same time, the MCU can also perform data analysis, storage and transmission on the sampling signal for users to perform real-time monitoring and fault troubleshooting.

[0016] The residual current monitoring circuit also includes two series resistors connected across the input signal: the 109th resistor and the 110th resistor, and the middle of the two series resistors is grounded.

[0017] The 109th resistor and the 110th resistor are used for subsequent circuit debugging, function expansion or connecting to the circuit to adjust circuit parameters when other resistors fail, and the 109th resistor and the 110th resistor are connected in parallel at the back end of the bidirectional voltage regulator tube.

[0018] During circuit debugging, the 109th resistor and the 110th resistor can select resistors with appropriate resistance values to be connected according to actual needs, and adjust parameters such as the size and gain of the signal by changing the resistance value of the circuit. During function expansion, the resistance value of the resistor to be connected can be determined according to the requirements of the new function for circuit parameters. When other resistors fail, select a spare resistor with a resistance value close to that of the faulty resistor to be connected to ensure the normal operation of the circuit.

[0019] The advantages and beneficial effects of the present invention are as follows: 1. Cost reduction: By using a single residual current transformer to replace two sets of transformers, the hardware cost is reduced. At the same time, due to the reduction of the installation of one residual current transformer, the development cost and production labor cost are further reduced.

[0020] 2. Volume reduction: Reducing one set of residual current transformers effectively reduces the internal space occupancy rate of the product by 10%, reduces the volume of the product, and makes it more convenient for installation and layout.

[0021] 3. Improve installation convenience: After the product volume is reduced, it is more flexible during the actual installation process, reducing the installation difficulty and improving the installation efficiency. Brief Description of the Drawings

[0022] Figure 1 is the circuit principle block diagram of the present invention; Figure 2 is the schematic diagram of the residual current protection circuit; Figure 3 is the schematic diagram of the isolation circuit; Figure 4 is the schematic diagram of the residual current monitoring circuit; Detailed Embodiments

[0023] The following combines the drawings and embodiments to further describe the detailed embodiments of the present invention. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0024] Embodiment 1: An intelligent miniature circuit breaker residual current monitoring and protection circuit, as Figure 1 , Figure 2 , Figure 3 , Figure 4 shown, the monitoring and protection circuit includes a residual current transformer CT1, a residual current protection circuit, an isolation circuit, and a residual current monitoring circuit; the input end of the residual current protection circuit is connected to the residual current transformer CT1; the residual current monitoring circuit is connected to the residual current transformer CT1 through the isolation circuit, and its output is connected to the circuit breaker MCU detection unit; As Figure 2 shown, the output end of the residual current transformer CT1 is sampled by the series-connected sixth resistor R6 and thirty-sixth resistor R36 and used as the input signal of the residual current protection circuit; The residual current transformer CT1 is used to convert the leakage current signal into an electrical signal and at the same time provide a sampling signal for the residual current protection circuit and the residual current monitoring circuit; the residual current transformer CT1 is the signal acquisition source of the entire monitoring and protection circuit, and its operation is based on the principle of electromagnetic induction; under normal circumstances, the current in the circuit is in a balanced state, the vector sum of the primary side currents of the residual current transformer is zero, and no induced current is output on the secondary side; once a leakage occurs in the circuit, a residual current will be generated, and this residual current will generate an alternating magnetic field on the primary side of the residual current transformer, and then induce a corresponding electrical signal on the secondary side; Preferably, the secondary side of the residual current transformer CT1 is connected to the residual current protection circuit through the sequentially connected 6th resistor R6 and 36th resistor R36; when an electrical signal is induced, the signal is converted into a voltage signal through the 6th resistor R6 and 36th resistor R36. A part of the voltage signal is directly transmitted to the residual current protection circuit to provide a sampling signal for detecting the leakage signal; another part obtains the signal from both ends of the 6th resistor R6 and is transmitted to the isolation circuit as the sampling signal source of the residual current monitoring circuit, thereby realizing the preliminary acquisition and distribution of the leakage current signal; The residual current protection circuit takes the signal processing chip U7 as the core. In this embodiment, the signal processing chip U7 adopts a chip of model M54123, and the input signal is connected to the input end of the signal processing chip after being sampled by a resistor and filtered by a capacitor; There is a differential amplifier in the M54123 chip, and its function is to perform differential amplification processing on the input signal. In leakage detection, it can amplify the weak residual current signal detected by the zero-sequence current transformer so that the subsequent circuit can more accurately process and judge whether leakage occurs; As Figure 3 shown, the isolation circuit includes an isolation operational amplifier chip U15 and its peripheral circuit. The input signal of the isolation circuit includes the signal sampled by the 6th resistor R6 at the output ends (ZCT1 and ZCT2) of the current transformers; this signal is connected to the input ends (VINP and VINN) of the isolation operational amplifier chip after being filtered by a resistor-capacitor; In this embodiment, the isolation operational amplifier chip U15 adopts a chip of model NSI1300D25-DSWVR. The NSI1300D25-DSWVR chip is a high-performance isolation amplifier. The NSI1300D25-DSWVR chip effectively electrically isolates the input signal and the output signal, so that there is no direct electrical connection between the input and the output, but the signal is transmitted through a capacitor. This can achieve electrical isolation of up to thousands of volts and can protect sensitive circuits from interference and damage.

[0025] As Figure 4 shown, the residual current monitoring circuit includes a signal amplification module and a filtering protection module. The input signal is connected to the output ends (VP and VN) of the isolation operational amplifier chip, and enters the residual current monitoring circuit through a current-limiting resistor and is transmitted to the metering chip of the circuit breaker MCU detection unit for residual current sampling and metering.

[0026] Embodiment 2: The difference from Embodiment 1 is that this embodiment focuses on showing the connection relationship and working principle between the components in the circuit; As Figure 2As shown, the residual current protection circuit further includes a sampling and filtering module and an overvoltage protection module; both ends of the input signal of the sampling and filtering module (ZCT1 and ZCT2) are respectively connected to two input ends (IN and VR) of the signal processing chip U7 through the 4th resistor R4 and the 7th resistor R7 connected in series in the circuit. At the same time, the front end of signal sampling is filtered by a resistor-capacitor circuit composed of the 4th resistor R4, the 5th capacitor C5, the 7th resistor R7, and the 6th capacitor C6. The 7th resistor R7, the 5th capacitor C5 are interconnected with an input end VR of the signal processing chip U15. At the same time, an input end VR of the signal processing chip U7 is connected to the 9th capacitor C9 grounded; the overvoltage protection module includes the 6th bidirectional voltage regulator tube, and the 6th bidirectional voltage regulator tube D6 is connected in parallel with the 6th capacitor C6.

[0027] In this embodiment, the residual current protection circuit takes the signal processing chip U7 as the core, which is mainly responsible for detecting leakage signals and triggering protection actions when the residual current is abnormal; the filtering module filters the input signal to remove clutter interference and improve the signal quality; when an excessive voltage appears, the overvoltage protection module conducts to bypass the excessive voltage and prevent it from damaging the signal processing chip; the signal processing chip analyzes and judges the filtered signal received. According to the preset residual current threshold, when it detects that the residual current reflected by the signal exceeds the threshold, it outputs a corresponding signal to trigger the protection action.

[0028] Both ends of the input signal of the isolation circuit (VINP and VINN) are respectively transmitted to the isolation operational amplifier chip U15 through a resistor-capacitor filtering network composed of the 17th resistor R17, the 19th resistor R19, the 61st capacitor C61, the 73rd capacitor C73, and the 87th capacitor C87. Among them, the 17th resistor R17 and the 19th resistor R19 are respectively connected to two input pins (VINP and VINN) of the isolation operational amplifier chip U15. The 73rd capacitor C73 is also connected in parallel between the two input pins (VINP and VINN) of the isolation operational amplifier chip. Both ends of the 73rd capacitor C73 are grounded through the 61st capacitor C61 and the 87th capacitor C87 respectively.

[0029] The capacitor is used to filter out the interference of common-mode and differential-mode noise signals in the circuit and ensure the accuracy of the signal; In this embodiment, the isolation circuit takes the isolation operational amplifier chip U15 as the core. Its main function is to avoid the interference signal of the ground potential difference generated by the non-common ground of the residual current protection circuit and the residual current monitoring circuit, ensure the accuracy of signal transmission, and at the same time perform differential amplification on the signal from the residual current transformer to improve the anti-interference ability and transmission quality of the signal; Such as Figure 4As shown, in the residual current monitoring circuit, both ends of the input signal (VP and VN) of the signal amplification module are respectively connected to the positive input terminal IN+ and the negative input terminal IN- of the operational amplifier chip IC3 through the 23rd resistor R23 and the 29th resistor R29. The negative input terminal IN- of the operational amplifier chip IC3 is connected to its output terminal OUT through the feedback resistor, the 27th resistor R27. And the output terminal OUT is connected to one input terminal ADCLS of the filter protection module through a low-pass filter circuit composed of the 25th resistor R25 and the 89th capacitor C89. The positive input terminal IN+ of the operational amplifier chip IC3 is connected to the output reference of the metering chip in the breaker MCU detection unit through the 22nd resistor R22. The filter protection module includes two lines, and the two lines are respectively connected to the metering chip in the breaker monitoring circuit through two resistor-capacitor circuits composed of the 63rd resistor R63 and the 51st capacitor C51, and the 78th resistor R78 and the 53rd capacitor C53. A third bidirectional voltage regulator VD3 is connected to the front ends of the two resistor-capacitor circuits of the filter protection module, and the third bidirectional voltage regulator VD3 is located in the middle of the two resistor-capacitor circuits.

[0030] In this embodiment, the operational amplifier chip IC3 uses a chip of model MS8605. MS8605 is a single-channel rail-to-rail input-output single-supply operational amplifier. It uses a rail-to-rail input structure and can process input signals close to the power rails. The characteristics of low offset voltage and low input bias current ensure the accuracy of signal processing. It realizes a high open-loop gain through internal multi-stage amplification to amplify the input signal. The wide bandwidth characteristic ensures the effective amplification of signals with different frequencies. The rail-to-rail output structure makes the output voltage close to the power rails to adapt to different loads. In this embodiment, the residual current monitoring circuit is mainly used to receive the differentially amplified signal, filter and amplify the received signal to make the electrical signal meet the sampling requirements of the analog-to-digital converter, so as to realize the accurate detection of the residual current. Through the cooperation of resistors in the signal amplification module, the operational amplifier chip IC3 can automatically adjust the gain according to the magnitude of the residual current signal to ensure that the output signal is within the sampling range of the analog-to-digital converter. The filter protection module is composed of the third bidirectional voltage regulator VD3, the 63rd resistor R63, the 51st capacitor C51, the 78th resistor R78 and the 53rd capacitor C53, and is used to filter out common-mode and differential-mode noise signals and perform overvoltage protection on the signal.

[0031] The gain of the signal amplification module is determined by the 22nd resistor R22 and the 27th resistor R27. The filter circuit in the filter protection module has an attenuation effect on high-frequency signals, and the cut-off frequency is determined by the parameters of the resistor and the capacitor, which can effectively filter out high-frequency interference signals and make the output signal smoother and more stable.

[0032] Preferably, the VP and VN signals output by the isolation circuit are respectively input to the positive input terminal IN+ and the negative input terminal IN- of the operational amplifier chip IC3 in the operational amplifier circuit; the operational amplifier chip amplifies the signals, and its output terminal OUT is connected to the signal filtering module through the 25th resistor R25. The output signal ADC_LS and the output reference REFV of the metering chip form a sampling signal, which is filtered by a filter circuit composed of the 63rd resistor R63 in series with the 51st capacitor C51 and the 78th resistor R78 in series with the 53rd capacitor C53, and then transmitted to the metering chip to complete the monitoring and sampling of the residual current. At the same time, the 3rd bidirectional diode VD3 conducts when the signal voltage is too high, protecting the signal against overvoltage and preventing damage to the ADC port by excessive voltage; Embodiment 3: The difference from the above embodiment is that an intelligent miniature circuit breaker residual current monitoring and protection circuit described in this embodiment is further connected with a circuit breaker tripping device and a circuit breaker MCU detection unit; As Figure 1 shown, in this embodiment, the output terminal of the residual current protection circuit is connected to the input terminal of the circuit breaker tripping device.

[0033] When the residual current in the residual current protection circuit is abnormal, the residual current protection circuit outputs a control signal to the circuit breaker tripping device, driving the circuit breaker tripping device to quickly cut off the circuit, thereby ensuring personal safety and normal operation of the equipment.

[0034] The output of the circuit breaker MCU detection unit is connected to the circuit breaker tripping device, and drives the tripping device to act according to the tripping current set manually, and this current is generally less than the action current of the protection circuit when needed.

[0035] The residual current monitoring circuit provides accurate residual current data for the circuit breaker MCU detection unit. After receiving the sampling signal, the circuit breaker MCU detection unit compares it with the internally set residual current threshold to support the circuit breaker MCU detection unit to realize real-time monitoring, comparison and judgment of the residual current in the circuit and control the circuit breaker tripping device to act when the residual current exceeds the set threshold, thereby realizing the residual current protection function; at the same time, the MCU can also perform data analysis, storage and transmission on the sampling signal for users to perform real-time monitoring and troubleshooting.

[0036] The residual current monitoring circuit further includes two series resistors connected to both ends of the input signal: the 109th resistor R109 and the 110th resistor R110, and the middle of the two series resistors is grounded, The 109th resistor and the 110th resistor are used for subsequent circuit debugging, function expansion or accessing the circuit to adjust circuit parameters when other resistors fail, and the 109th resistor and the 110th resistor are connected in parallel at the back end of the bidirectional voltage stabilizing tube.

[0037] When debugging the circuit, the 109th resistor R109 and the 110th resistor R110 can select resistors with appropriate resistance values according to actual needs and access them. By changing the resistance value of the circuit, parameters such as the size and gain of the signal can be adjusted. When expanding functions, the resistance value of the resistor to be accessed can be determined according to the requirements of the new function for the circuit parameters. When other resistors fail, a spare resistor with a resistance value close to that of the faulty resistor can be selected and accessed to ensure the normal operation of the circuit.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An intelligent miniature circuit breaker residual current monitoring protection circuit, characterized in that: The monitoring protection circuit comprises a residual current transformer (CT1), a residual current protection circuit, an isolation circuit and a residual current monitoring circuit; the input end of the residual current protection circuit is connected to the residual current transformer (CT1); the residual current monitoring circuit is connected to the residual current transformer (CT1) through the isolation circuit, and its output is connected to the circuit breaker MCU detection unit; The output end of the residual current transformer (CT1) is sampled by the sixth resistor (R6) and the thirty-sixth resistor (R36) connected in series and used as an input signal of the residual current protection circuit; The residual current protection circuit has a signal processing chip (U7) as its core, and the input signal is connected to the input end of the signal processing chip after being filtered by a resistor sampling capacitor; The isolation circuit comprises an isolation operational amplifier chip (R15) and its peripheral circuits, the input signal of the isolation circuit comprises a signal sampled by a sixth resistor (R6) at the output end of the current transformer, the signal being connected to the input end of the isolation operational amplifier chip (U15) after being filtered by a resistor-capacitor circuit; The residual current monitoring circuit comprises a signal amplification module and a filtering protection module. The input signal is connected to the output end of the isolation operational amplifier chip (U15), enters the residual current monitoring circuit through a current limiting resistor, and is transmitted to the metering chip in the circuit breaker MCU detection unit.

2. The intelligent miniature circuit breaker residual current monitoring protection circuit according to claim 1 is characterized in that: The residual current protection circuit also includes a sampling filter module and an overvoltage protection module; the two ends of the input signal of the sampling filter module are respectively connected to the two input ends of the signal processing chip via the fourth resistor (R4) and the seventh resistor (R7), and the signal sampling front end is filtered via a resistor-capacitor circuit composed of the fourth resistor (R4), the fifth capacitor (C5), the seventh resistor (R7), and the sixth capacitor (C6); the seventh resistor (R7), the fifth capacitor (C5) and an input end (VR) of the signal processing chip (U7) are interconnected, and the input end (VR) of the signal processing chip is connected to the grounded ninth capacitor (C9); the overvoltage protection module includes a sixth bidirectional voltage regulator (D6), and the sixth bidirectional voltage regulator (D6) is connected in parallel with the sixth capacitor (C6).

3. The intelligent miniature circuit breaker residual current monitoring protection circuit according to claim 1 is characterized in that: The two ends of the input signal of the isolation circuit are respectively transmitted to the isolation operational amplifier chip (U15) via a resistor-capacitor filtering network composed of a 17th resistor (R17), a 19th resistor (R19), a 61st capacitor (C61), a 73rd capacitor (C73), and an 87th capacitor (C87), wherein the 17th resistor (R17) and the 19th resistor (R19) are respectively connected to two input pins of the isolation operational amplifier chip (U15), and the 73rd capacitor (C73) is also connected in parallel between the two input pins of the isolation operational amplifier chip, and the two ends of the 73rd capacitor (C73) are respectively grounded through the 61st capacitor (C61) and the 87th capacitor (C87).

4. The intelligent miniature circuit breaker residual current monitoring protection circuit according to claim 1 is characterized in that: In the residual current monitoring circuit, the two ends of the input signal of the signal amplification module are connected to the positive input terminal (IN+) and the reverse input terminal (IN-) of the operational amplifier chip (IC3) via the 23rd resistor (R23) and the 29th resistor (R29), respectively. The reverse input terminal (IN-) of the operational amplifier chip (IC3) is connected to its output terminal (OUT) via the feedback resistor 27th resistor (R27), and the output terminal (OUT) is connected to an input terminal (ADC_LS) of the filtering protection module via a low-pass filtering circuit composed of the 25th resistor (R25) and the 89th capacitor (C89). The operational amplifier chip The positive input terminal (IN+) of (IC3) is connected to the output reference (REFV) of the metering chip in the circuit breaker MCU detection unit through the 22nd resistor (R22); the filtering protection module includes two lines, and the two lines are connected to the metering chip in the circuit breaker monitoring circuit through two resistor-capacitor circuits composed of the 63rd resistor (R63) and the 51st capacitor (C51), and the 78th resistor (R78) and the 53rd capacitor (C53), respectively. The front ends of the two resistor-capacitor circuits of the filtering protection module are connected to a third bidirectional voltage regulator (VD3), and the third bidirectional voltage regulator (VD3) is located between the two resistor-capacitor circuits.

5. The intelligent miniature circuit breaker residual current monitoring protection circuit according to claim 1, characterized in that: The output end of the residual current protection circuit is connected to the input end of the circuit breaker release.

6. The intelligent miniature circuit breaker residual current monitoring protection circuit according to claim 1, characterized in that: The output of the circuit breaker MCU detection unit is connected to the circuit breaker release, and the release is driven to operate according to the manually set tripping current.

7. The intelligent miniature circuit breaker residual current monitoring protection circuit according to claim 1, characterized in that: The residual current monitoring circuit further includes two series resistors connected at both ends of the input signal: a 109th resistor (R109) and a 110th resistor (R110), wherein the two series resistors are grounded in between.

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