Contact assembly of a circuit breaker and related methods

Abstract

The application relates to the technical field of circuit breakers, and provides a contact assembly of a circuit breaker and a related method, a test method of the contact assembly comprising the following steps: before injecting a detection current, setting an output impedance as a high-impedance constant-current state; injecting a detection signal to a main circuit of the circuit breaker at a preset constant current; collecting port voltages at both ends of the main circuit of the circuit breaker in a preset sampling window in the high-impedance constant-current state; judging a contact sintering state of the circuit breaker according to a time sequence variation feature of the port voltages; if the port voltages are always lower than a first preset voltage threshold, it is determined that the contacts are sintered; and if the port voltages rise and exceed a second preset voltage threshold, it is determined that the contacts are normally disconnected. The test method of the contact assembly provided by the application can solve the technical problem that, in the related art, a capacitive element in a circuit breaker generates a transient charging pseudo short circuit at a moment of low-voltage direct-current injection, and causes a sintering detection error of the contacts.

Description

Technical Field

[0001] This application relates to the field of circuit breaker technology, and in particular to a contact assembly of a circuit breaker and related methods. Background Technology

[0002] The contact assembly of a circuit breaker is a contact-type switching mechanism located in the main circuit of the circuit breaker. It consists of a moving contact and a stationary contact forming the contact break. When the circuit is open, the moving contact and the stationary contact are physically separated, and the main circuit is disconnected. When the circuit is closed, the two are pressed together and conduction occurs, carrying the operating current. To prevent extremely high reverse voltage and arcing during DC interruption, an RC snubber network is usually connected in parallel across the contact break of a high-voltage DC circuit breaker. In addition, intelligent circuit breakers with self-generating power supply modules also include a front-end rectifier and filter network consisting of reverse polarity protection diodes and filter capacitors, which is connected in parallel to the main circuit. Furthermore, capacitive components are connected in parallel with the contact break when the circuit breaker is in the open state.

[0003] Contact sintering originates from metal fusion welding caused by an electric arc during the opening and closing process. When a circuit breaker carries or interrupts current, an electric arc is generated between the moving and stationary contacts at the moment of separation. The temperature at the center of the arc can reach thousands of degrees Celsius, causing localized melting of the contact surface material. If the breaking speed is insufficient or the arc is not extinguished adequately, the molten metal cools and solidifies rapidly when the contacts re-contact, forming metal bonds at the microscopic contact points, resulting in the moving and stationary contacts being welded together. Furthermore, contact bounce during closing, insufficient rated breaking capacity of the circuit breaker, and contact material migration and electrical wear after long-term service can all exacerbate this tendency to weld.

[0004] Therefore, contact sintering (i.e., the moving and stationary contacts cannot be separated due to metal adhesion) is a serious assembly defect in circuit breakers and must be detected and intercepted during the product off-line stage. However, during inspection, the RC absorption network and filter capacitors connected in parallel across the circuit breaker contact breaks generate a huge transient charging current the instant voltage is applied, and the equivalent impedance approaches zero. This is extremely similar in electrical characteristics to the zero-resistance state of contact sintering, which may lead to qualified products being mistakenly judged as sintered. If the capacitor is waited to charge to a steady state before judgment, the charging time of large-capacity filter capacitors (usually hundreds to thousands of microfarads) far exceeds the millisecond-level cycle time requirement of the production line, thus slowing down production capacity. Summary of the Invention

[0005] This application provides a contact assembly for a circuit breaker and a related method, which can improve the technical problem in the related art where the internal capacitive components of the circuit breaker generate a transient charging pseudo-short circuit at the moment of low-voltage DC injection, leading to misjudgment of contact sintering detection.

[0006] In a first aspect, embodiments of this application provide a contact assembly for a circuit breaker, applied to the circuit breaker, the contact assembly comprising: A moving contact, rotatably mounted on the housing of the circuit breaker; and A stationary contact is mounted on the housing of the circuit breaker. The moving contact and the stationary contact together form a contact break. When the circuit is open, the moving contact and the stationary contact are physically separated. When the circuit is closed, the moving contact and the stationary contact are pressed together to conduct electricity. The contact break is connected in series in the main circuit of the circuit breaker. The main circuit is the only path for the circuit breaker to carry the operating current. The current flows in from the incoming terminal and flows out from the outgoing terminal through the contact break. The contact break is a disconnectable node in the main circuit. The circuit breaker has at least one capacitive element, which is connected in parallel to both ends of the contact break. The circuit breaker is configured such that, when it is in the open state and an external testing system injects a constant detection current into the main circuit in a high-impedance constant-current state, the timing variation characteristics of the port voltages at both ends of the main circuit within the sampling window are used by the external testing system to determine the sintering state of the contact fracture.

[0007] The technical solutions described in this application embodiment have at least the following technical effects: The contact assembly of the circuit breaker provided in this application consists of a moving contact and a stationary contact forming a contact break. When the circuit is closed, the two contacts are pressed together to conduct, allowing the main circuit to carry the operating current. When the circuit is open, they are physically separated, forming a unique disconnectable node on the main circuit. Thus, in the open state, the physical fact of contact sintering or normal disconnection is mapped to the binary electrical state of the main circuit's on / off state. The capacitive element connected in parallel across the contact break utilizes the principle that its charging slope is modulated by the differential state of the contact break within the sampling window when a constant detection current is injected in a high-impedance constant-current state by an external testing system. This allows the time-series variation characteristics of the main circuit port voltage to directly reflect the sintering state of the contact break.

[0008] Secondly, embodiments of this application provide a testing method for a contact assembly, used to test the contact assembly of the circuit breaker described in the first aspect, the method comprising: Before injecting the detection current, the output impedance is set to a high-impedance constant current state; wherein, the high-impedance constant current state is a state in which the output equivalent impedance is above kiloohms and the output current is limited to a constant value. A detection signal is injected into the main circuit of the circuit breaker with a preset constant current; Under the high impedance constant current state, the port voltages at both ends of the main circuit of the circuit breaker are collected within a preset sampling window; The contact sintering state of the circuit breaker is determined based on the time-series change characteristics of the port voltage. If the port voltage is always lower than a first preset voltage threshold, the contact is determined to be sintered. If the port voltage rises and exceeds a second preset voltage threshold, the contact is determined to be normally open. The first preset voltage threshold is determined by multiplying a preset contact sintering resistance determination threshold with the constant current. The second preset voltage threshold is determined by the charging voltage of the capacitive element inside the circuit breaker at the end of the sampling window.

[0009] The technical solutions described in this application embodiment have at least the following technical effects: Before injecting the detection current, the output impedance is set to a high-impedance constant-current state (the output equivalent impedance rises to the kiloohm level or higher, and the output current is clamped to a constant value). When a detection signal is injected into the main circuit of the circuit breaker with a preset constant current, the capacitive element connected in parallel across the contact breaks has a very small charge accumulation in the sampling window due to the strict limitation of the charging current. Its transient equivalent impedance will not drop to zero, which is electrically equivalent to being "suspended and isolated". Under this high-impedance constant-current state, the timing sequence of the port voltages at both ends of the main circuit is collected in the preset sampling window. The two states of contact sintering and normal opening show a significant differentiation in voltage micro-state characteristics. If the contact is sintered, the port voltage is always maintained below the first preset voltage threshold determined by the product of the contact sintering resistance threshold and the constant current. If the contact is normally open, the constant current continuously charges the capacitive element, the port voltage continues to rise and exceeds the second preset voltage threshold determined by the charging voltage of the capacitive element at the end of the sampling window. This distinguishes between the two states of contact sintering and normal opening. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the contact assembly of a circuit breaker provided in an embodiment of this application; Figure 2 A flowchart illustrating the testing method for the contact assembly provided in this application embodiment; Figure 3 A flowchart illustrating step S300 in the test method for the contact assembly provided in this application embodiment; Figure 4 This is a flowchart illustrating step S400 in the test method for the contact assembly provided in this application embodiment.

[0012] The following are the labeling elements in the figure: 100. Circuit breaker contact assembly; 10. Moving contact; 20. Stationary contact. Detailed Implementation

[0013] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application. The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0015] The contact assembly of a circuit breaker is a contact-type switching mechanism located in the main circuit of the circuit breaker. It consists of a moving contact and a stationary contact forming the contact break. When the circuit is open, the moving contact and the stationary contact are physically separated, and the main circuit is disconnected. When the circuit is closed, the two are pressed together and conduction occurs, carrying the operating current. To prevent extremely high reverse voltage and arcing during DC interruption, an RC snubber network is usually connected in parallel across the contact break of a high-voltage DC circuit breaker. In addition, intelligent circuit breakers with self-generating power supply modules also include a front-end rectifier and filter network consisting of reverse polarity protection diodes and filter capacitors, which is connected in parallel to the main circuit. Furthermore, capacitive components are connected in parallel with the contact break when the circuit breaker is in the open state.

[0016] Contact sintering originates from metal fusion welding caused by an electric arc during the opening and closing process. When a circuit breaker carries or interrupts current, an electric arc is generated between the moving and stationary contacts at the moment of separation. The temperature at the center of the arc can reach thousands of degrees Celsius, causing localized melting of the contact surface material. If the breaking speed is insufficient or the arc is not extinguished adequately, the molten metal cools and solidifies rapidly when the contacts re-contact, forming metal bonds at the microscopic contact points, resulting in the moving and stationary contacts being welded together. Furthermore, contact bounce during closing, insufficient rated breaking capacity of the circuit breaker, and contact material migration and electrical wear after long-term service can all exacerbate this tendency to weld.

[0017] Therefore, contact sintering (i.e., the moving and stationary contacts cannot be separated due to metal adhesion) is a serious assembly defect in circuit breakers and must be detected and intercepted during the product off-line stage. However, during inspection, the RC absorption network and filter capacitors connected in parallel across the circuit breaker contact breaks generate a huge transient charging current the instant voltage is applied, and the equivalent impedance approaches zero. This is extremely similar in electrical characteristics to the zero-resistance state of contact sintering, which may lead to qualified products being mistakenly judged as sintered. If the capacitor is waited to charge to a steady state before judgment, the charging time of large-capacity filter capacitors (usually hundreds to thousands of microfarads) far exceeds the millisecond-level cycle time requirement of the production line, thus slowing down production capacity.

[0018] Based on this, in order to improve the technical problem in the related technology that the internal capacitive components of the circuit breaker generate transient charging pseudo-short circuits at the moment of low-voltage DC injection, leading to misjudgment of contact sintering detection, the embodiments of this application provide the following solution.

[0019] Please see Figure 1 This application provides a contact assembly 100 for a circuit breaker, which is disposed on the circuit breaker. The contact assembly includes a moving contact 10 and a stationary contact 20, wherein: The moving contact 10 is rotatably mounted on the circuit breaker.

[0020] The stationary contact 20 is installed on the circuit breaker. The moving contact 10 and the stationary contact 20 together form the contact break. When the circuit is broken, the moving contact 10 and the stationary contact 20 are physically separated. When the circuit is closed, the moving contact 10 and the stationary contact 20 are pressed together and connected. The contact break is connected in series in the main circuit of the circuit breaker. The main circuit is the only path for the circuit breaker to carry the working current. The current flows in from the incoming terminal and flows out from the outgoing terminal through the contact break. The contact break is a disconnectable node on the main circuit.

[0021] The circuit breaker has at least one capacitive element, which is connected in parallel to both ends of the contact break.

[0022] The circuit breaker is configured to use the timing variation characteristics of the port voltages at both ends of the main circuit within the sampling window to determine the sintering state of the contact fracture when it is in the open state and the external test system injects a constant detection current into the main circuit in a high-impedance constant current state.

[0023] It is understood that the contact assembly is a contact-type switching mechanism installed on the circuit breaker, consisting of a moving contact 10 and a stationary contact 20, used to realize the on-off control of the main circuit inside the circuit breaker. For example, the contact assembly can be a single-break contact assembly, a double-break contact assembly, etc.

[0024] The moving contact 10 is used to physically separate from the stationary contact 20 to disconnect the main circuit when the circuit is broken, and to press against the stationary contact 20 to connect the main circuit when the circuit is closed. For example, the moving contact 10 can be a copper alloy moving contact 10, a silver alloy moving contact 10, etc.

[0025] The stationary contact 20 is fixedly installed relative to the moving contact 10. It works with the moving contact 10 to separate and connect the contact points during opening and closing operations, respectively. For example, the stationary contact 20 can be a copper alloy stationary contact 20, a silver alloy stationary contact 20, etc.

[0026] The incoming terminal can be installed on the circuit breaker as the current inflow port of the main circuit. It is located on both sides of the contact break, along with the outgoing terminal, and is used to connect to the external circuit and introduce working current into the main circuit.

[0027] Outgoing terminals can be installed on the circuit breaker as current outflow ports of the main circuit. They are located on both sides of the contact break, respectively, and are used to output the working current flowing through the contact break to the external circuit.

[0028] When a constant detection current is injected into the main circuit by an external test system in a high-impedance constant current state, the charging behavior of the capacitive element is modulated by the differential constant detection current, so that the timing variation characteristics of the port voltage can reflect the sintering state of the contact break. For example, the capacitive element can be the absorption capacitor in an RC absorption network, the filter capacitor in a rectifier filter network, etc.

[0029] A circuit breaker is a complete device that carries contact assemblies. It provides a mounting base and electrical connection environment for the moving contact 10, stationary contact 20, capacitive elements, and main circuit. It also provides the breaking state of the contact joints when an external testing system performs testing. For example, a circuit breaker can be a high-voltage DC circuit breaker, an intelligent DC circuit breaker, etc.

[0030] As can be seen from the above, the contact assembly 100 of the circuit breaker provided in this application embodiment forms a contact break through the moving contact 10 and the stationary contact 20. When the circuit is closed, the two contacts are pressed together to conduct, allowing the main circuit to carry the working current. When the circuit is open, they are physically separated, forming a unique disconnectable node on the main circuit. Thus, in the open state, the physical fact of contact sintering or normal disconnection is mapped to the binary electrical state of the main circuit being open and closed. The capacitive element connected in parallel across the contact break utilizes the principle that its charging slope is modulated by the differential state of the contact break within the sampling window when a constant detection current is injected in a high-impedance constant current state by an external testing system. This allows the time-series change characteristics of the main circuit port voltage to directly reflect the sintering state of the contact break.

[0031] In some embodiments, the circuit breaker also includes a reverse connection protection diode.

[0032] The reverse polarity protection diode is connected in series between the capacitive component and the main circuit. The conduction direction of the reverse polarity protection diode is configured so that it conducts when the external test system injects a detection current with the positive polarity and cuts off when the detection current is injected with the reverse polarity, so as to form a high impedance isolation between the capacitive component and the main circuit.

[0033] It is understandable that a reverse polarity protection diode is connected in series between a capacitive component and the main circuit. Through its unidirectional conduction characteristic, it controls the electrical connection between the capacitive component and the main circuit, thereby providing isolation conditions for insulation testing. For example, a reverse polarity protection diode can be a silicon rectifier diode, a Schottky diode, a fast recovery diode, etc.

[0034] With this configuration, the conduction direction of the reverse connection protection diode is set as follows: when the external test system injects a detection current with the forward polarity, the reverse connection protection diode conducts, allowing the capacitive component to be connected to the detection circuit and participate in the generation of the timing change characteristics of the port voltage; when the external test system injects a detection current with the reverse polarity, the reverse connection protection diode is cut off, cutting off the electrical path between the capacitive component and the main circuit, so that a high impedance isolation state is formed between the two, thereby ensuring that the subsequent insulation test is not affected by the current shunting of the capacitive component.

[0035] In some embodiments, the circuit breaker also includes a readable identifier.

[0036] A readable identifier is set on the circuit breaker. The readable identifier is used to store internal topology information, which includes at least the nominal capacitance value of capacitive components.

[0037] It is understandable that the readable identifier and the capacitive component establish a data association through the nominal capacitance value in the internal topology information. This is used to load and adaptively configure the test parameters before the external test system performs the test, so that it can be adapted to different types of circuit breakers without manual intervention. For example, the readable identifier can be an RFID electronic tag, a QR code tag, a barcode tag, etc.

[0038] Internal topology information is used to provide external testing systems with the connection relationships and parameter data of the internal electrical components of the circuit breaker, enabling the external testing system to obtain the electrical characteristics of the circuit breaker based on the internal topology information and complete the adaptive configuration of the test parameters.

[0039] The nominal capacitance value is a parameter in the internal topology information used to characterize the design rated capacitance of capacitive components. It is used by external testing systems to compare the nominal capacitance value with the equivalent capacitance value obtained by inversion calculation before and after testing, thereby judging the assembly quality of capacitive components. For example, the nominal capacitance value can be a microfarad capacitance value, a nanofarad capacitance value, etc.

[0040] With this setup, during testing, the external testing system obtains the internal topology information by reading the readable identifier before testing, and then automatically completes the adaptive configuration of the test parameters based on parameters such as the nominal capacitance value. This allows the same testing system to be compatible with different models of circuit breakers without changing the hardware.

[0041] Please see Figure 2This application embodiment also provides a testing method for a contact assembly, used to test the contact assembly 100 of the circuit breaker described above. The testing method for the contact assembly includes: Before injecting the detection current, the output impedance is set to a high impedance constant current state; where the high impedance constant current state is a state in which the output equivalent impedance is above kiloohms and the output current is limited to a constant value. A detection signal is injected into the main circuit of the circuit breaker with a preset constant current; Under high impedance constant current conditions, the port voltages at both ends of the main circuit of the circuit breaker are collected within a preset sampling window; The contact sintering state of the circuit breaker is determined based on the time-series change characteristics of the port voltage. If the port voltage is always lower than the first preset voltage threshold, the contact is determined to be sintered. If the port voltage rises and exceeds the second preset voltage threshold, the contact is determined to be normally open. The first preset voltage threshold is determined by the product of the preset contact sintering resistance determination threshold and the constant current. The second preset voltage threshold is determined by the charging voltage of the capacitive element inside the circuit breaker at the end of the sampling window.

[0042] As can be seen from the above, the test method for the contact assembly provided in this application, by setting the output impedance to a high-impedance constant-current state (output equivalent impedance rises to the kiloohm level or above, and the output current is clamped to a constant value) before injecting the detection current, when a detection signal is injected into the main circuit of the circuit breaker with a preset constant current, the capacitive element connected in parallel across the contact break is extremely small in charge accumulation within the sampling window because the charging current is strictly limited, and its transient equivalent impedance will not drop to zero, electrically equivalent to being "suspended and isolated"; under this high-impedance constant-current state, Within a preset sampling window, the timing sequence of the port voltages at both ends of the main circuit is acquired. The two states of contact sintering and normal disconnection show significant differences in voltage micro-state characteristics. If the contact is sintered, the port voltage is always maintained below the first preset voltage threshold determined by the product of the contact sintering resistance threshold and the constant current. If the contact is normally disconnected, the constant current continuously charges the capacitive element, and the port voltage continues to rise and exceeds the second preset voltage threshold determined by the capacitive element charging voltage at the end of the sampling window. This distinguishes between the two states of contact sintering and normal disconnection.

[0043] To better understand the testing method for contact components provided in the embodiments of this application, the specific implementation process of the testing method for contact components provided in the embodiments of this application will be described by way of example below.

[0044] Figure 2 A schematic flowchart of a testing method for a contact assembly provided in an embodiment of this application is shown. The testing method for the contact assembly includes: S100 sets the output impedance to a high-impedance constant current state before injecting the detection current; where the high-impedance constant current state is a state in which the output equivalent impedance is above kiloohms and the output current is limited to a constant value.

[0045] It can be understood that before the detection current is injected, i.e. before the detection current is injected into the external test system, the external test system can serve as the main body for executing the test method of the contact assembly, and implement the steps in the test method of any number of contact assemblies.

[0046] The detection current is an excitation signal injected into the main circuit of the circuit breaker by an external testing system for contact sintering detection. Its amplitude is limited to a constant value in the range of microamps to milliamps so that the amount of charge accumulation in the capacitive element within the sampling window is strictly constrained. For example, the value of the detection current can be 0.5 milliamps to 5 milliamps.

[0047] Output impedance is the equivalent internal resistance presented by the external test system when injecting detection current into the main circuit. By setting it to the level of kilohms or above, the external test system is made to exhibit current source characteristics rather than voltage source characteristics, thereby changing the charging behavior of capacitive components. For example, the value of output impedance can be from 1 kilohm to 100 kilohms.

[0048] High impedance constant current is a working state of an external test system. In this state, the output equivalent impedance is above kiloohms and the output current is limited to a constant value. This allows the external test system to have both high internal resistance characteristics and constant current output capability. For example, high impedance constant current can be a state where the short-circuit output current is 1 mA when the open-circuit voltage is set to 12 volts, or a state where the short-circuit output current is 2 mA when the open-circuit voltage is set to 24 volts.

[0049] Output equivalent impedance is a parameter that characterizes the equivalent internal resistance of an external test system to the external circuit under high impedance constant current conditions. It is determined by the set value of the output impedance and is used to measure the ability of the external test system to suppress current changes in the main circuit. For example, the value of the output equivalent impedance can be 12 kΩ, 100 kΩ, etc.

[0050] The kilohm level is the order of magnitude range of the output equivalent impedance, indicating that its value is between 1 kilohm and 999 kilohms. It is used to ensure that the internal resistance of the external test system is much greater than the equivalent resistance of the contact break in both sintering and normal disconnection states, such as 1 kilohm, 10 kilohm, 100 kilohm, etc.

[0051] A constant value is the target amplitude of the output current that is limited under high impedance constant current conditions. It does not change with the load of the main circuit. It is used to ensure that the charging slope of the capacitive element and the port voltage change at both ends of the contact break are repeatable and calculable within the sampling window. For example, the constant value can be 0.5 mA to 5 mA.

[0052] Setting the output impedance to a high-impedance constant-current state can be achieved by adjusting the operating point of the linear metal-oxide-semiconductor field-effect transistor using a digital-to-analog converter to change the equivalent output impedance. For example, when the open-circuit voltage is set to 12 volts and the output current is limited to 1 mA, the equivalent output impedance = 12 / 1 = 12 kΩ. Alternatively, the equivalent output impedance can be set by switching the series resistance value at the output terminal using a programmable resistor network. For example, when the open-circuit voltage is set to 24 volts and the output current is limited to 2 mA, the equivalent output impedance = 24 / 2 = 12 kΩ, etc.

[0053] By setting the output impedance to a high-impedance constant-current state, i.e., the output equivalent impedance is above kiloohms and the output current is limited to a constant value, the operating mode of the external test system is switched from a low-impedance voltage source to a high-impedance current source before injecting the detection current. Through the strong suppression effect of the output equivalent impedance on the current change in the main circuit, the detection current is kept constant within the sampling window, thereby providing stable excitation conditions for the subsequent analysis of the time-series change characteristics of the port voltage.

[0054] S200 injects a detection signal into the main circuit of the circuit breaker with a preset constant current.

[0055] It can be understood that the detection signal is an electrical excitation injected into the main circuit for contact sintering detection. It uses constant current as a characteristic parameter to establish a current path in the main circuit and drive capacitive components to generate a charging response. The injection polarity of the detection signal is determined by the external test system based on the internal topology information of the circuit breaker. For example, the detection signal can be a positive polarity detection signal, a reverse polarity detection signal, etc.

[0056] The preset constant current refers to a set of parameters that are predetermined and configured based on the model characteristics of the circuit breaker before the detection signal is injected. This is used to ensure that the amplitude of the constant current and the duration of the subsequent sampling window match the nominal parameters of the capacitive components. For example, the preset constant current can be 1 mA for a circuit breaker with a nominal filter capacitor of 1000 microfarads, and 0.5 mA for a circuit breaker with a nominal filter capacitor of 470 microfarads.

[0057] The detection signal can be injected into the main circuit of the circuit breaker in several ways. First, the positive terminal of a high-impedance constant current source can be connected to the incoming terminal side of the main circuit via the test port, and the negative terminal to the outgoing terminal side, forming a detection circuit. Alternatively, an H-bridge electronic switch array can be used to select the conduction path and determine the injection polarity before injecting the signal into the main circuit via the test port. Taking a preset constant current of 1 mA as an example, when the circuit breaker is in the open state and the contacts are normally open, the detection signal charges the capacitive element. If the equivalent capacitance of the capacitive element is 1000 microfarads, then within a 200-microsecond sampling window, the rise in port voltage will be approximately 1*200 / 1000 = 0.2 volts.

[0058] By constraining the output characteristics of the external test system with a high-impedance constant current state, it is ensured that the constant current does not fluctuate with the load state of the main circuit within the sampling window, thereby providing an excitation source with a certain amplitude and stable waveform for the subsequent acquisition of the timing variation characteristics of the port voltage.

[0059] In one possible implementation, before injecting the detection signal into the main circuit of the circuit breaker in S200, the following steps are also included: S210, Obtain the internal topology information of the circuit breaker; wherein, the internal topology information includes the conduction direction of the reverse connection protection diode installed inside the circuit breaker.

[0060] It can be understood that the conduction direction is the direction in which the current flows forward through the PN junction inside the reverse polarity protection diode. This determines which polarity of the detection signal will cause the reverse polarity protection diode to conduct, thus connecting the capacitive component to the main circuit, and which polarity of the signal will cause the reverse polarity protection diode to cut off, thus isolating the capacitive component from the main circuit. For example, the conduction direction can be identified by the voltage detection pulse method, the circuit topology diagram analysis method, etc.

[0061] The internal topology information of a circuit breaker can be obtained in several ways. For example, after the circuit breaker enters the testing station, the external testing system sends a query request containing the circuit breaker's model identification code to the manufacturing execution system through a communication interface, and the manufacturing execution system returns the internal topology information corresponding to that model. Alternatively, the internal topology information stored on the circuit breaker can be read directly through a readable identifier.

[0062] By acquiring internal topology information, the conduction direction of the reverse polarity protection diode is loaded from the circuit breaker's model identification data before the detection signal is injected. The injection polarity of the detection signal is determined by the conduction direction. When the detection signal is injected with the forward polarity consistent with the conduction direction, the reverse polarity protection diode conducts and the capacitive element participates normally in the charging response of the detection circuit. When the subsequent insulation test is performed with the reverse polarity opposite to the conduction direction, the reverse polarity protection diode is cut off, forming a high impedance isolation between the capacitive element and the main circuit. Thus, the conduction and cut-off states of the reverse polarity protection diode are automatically switched at different stages of the detection process.

[0063] In one possible implementation, please refer to Figure 4 S210, Obtain the internal topology information of the circuit breaker, including: S211, obtain the type of the internal reverse polarity protection diode and its expected reverse cutoff voltage.

[0064] It is understandable that the type is a device category attribute of the internal reverse polarity protection diode, used to determine its reverse voltage withstand capability range and forward conduction characteristics. Different types of reverse polarity protection diodes have different expected reverse cutoff voltage and leakage current characteristics.

[0065] The expected reverse cutoff voltage is the upper limit of the voltage threshold before the internal reverse-biased diode transitions from the cutoff state to the conduction state under reverse bias. It is used as a reference benchmark to determine whether the internal reverse-biased diode has a soft breakdown or leakage fault when the output voltage is gradually increased. For example, the expected reverse cutoff voltage can be between 20 volts and 200 volts.

[0066] The type of internal reverse polarity protection diode and its expected reverse cutoff voltage can be obtained by querying the corresponding internal reverse polarity protection diode device model and its rated parameters from the pre-stored topology database of the manufacturing execution system according to the circuit breaker's model identification code, or by directly reading the device model data stored on the circuit breaker through a readable identifier.

[0067] By obtaining the type of the internal reverse polarity protection diode, the reverse voltage withstand capability of the internal reverse polarity protection diode is determined. By obtaining the expected reverse cutoff voltage, a reference threshold is provided for gradually increasing the output voltage of the second polarity in subsequent insulation testing. When the output voltage has not yet reached the expected reverse cutoff voltage, the leakage current abnormality occurs, indicating that the reverse characteristics of the internal reverse polarity protection diode have deteriorated. Thus, the safe test range of reverse voltage is limited to the rated withstand voltage range of the internal reverse polarity protection diode.

[0068] S212, when performing insulation testing on the circuit breaker, uses an H-bridge electronic switch array to progressively increase the output voltage of the second polarity in preset steps, and monitors the leakage current in real time.

[0069] It can be understood that the second polarity is the output polarity opposite to the conduction direction of the reverse polarity protection diode. Under this polarity, the reverse polarity protection diode is subjected to reverse bias voltage and is in the cut-off state, which is used to isolate the capacitive component from the main circuit, thereby eliminating the shunting effect of the capacitive component on the measurement result during insulation testing. For example, the voltage amplitude of the second polarity can be from -5 volts to -25 volts.

[0070] The output voltage is a DC voltage applied to the main circuit by the H-bridge electronic switch array with the second polarity. Its amplitude increases step by step in the insulation detection process with a preset step size to gradually approach the expected reverse cutoff voltage of the internal reverse connection protection diode to test its reverse withstand voltage characteristics. For example, the initial value of the output voltage can be 5 volts, 10 volts, etc.

[0071] The preset step size is a fixed voltage increment for each increase in the output voltage. It is used to control the rise rate of the output voltage and the test resolution. For example, the preset step size can be 5 volts, 10 volts, 20 volts, etc.

[0072] Leakage current is a small reverse current flowing through the PN junction of a reverse-biased diode when it is subjected to a reverse bias voltage. Its amplitude is maintained in the nanoamp to microamp range when the reverse-biased diode is normally off. If it increases abnormally, it indicates that the reverse characteristics of the reverse-biased diode have deteriorated. For example, the leakage current range can be less than 1 microamp, less than 10 microamp, etc.

[0073] The output voltage of the second polarity can be gradually increased by an H-bridge electronic switch array with a preset step size. This can be achieved by sending a pulse width modulation signal to the drive circuit of the H-bridge electronic switch array via a microcontroller (MCU), gradually increasing the duty cycle to raise the output voltage. For example, if the expected reverse cutoff voltage is 100 volts and the preset step size is 10 volts, the external test system can start from 10 volts and gradually increase it to 90 volts in increments of 10 volts, for a total of 9 stages. If a leakage current is detected to suddenly increase from the normal value of 0.5 microamps to 50 microamps when the output voltage is 60 volts, it is determined that the internal reverse connection protection diode has a soft breakdown or leakage fault below 60 volts. This fault threshold of 60 volts is lower than 60% of the expected reverse cutoff voltage of 100 volts. Alternatively, a step-increasing control voltage can be output to the gate driver of the H-bridge electronic switch array via a digital-to-analog converter, gradually increasing the output voltage in a discrete voltage step manner.

[0074] By controlling the H-bridge electronic switch array to output the voltage with the second polarity during insulation testing, the reverse-biased diode is turned off, isolating the capacitive components from the main circuit. The output voltage is gradually increased in preset steps while the leakage current is monitored in real time. As the output voltage gradually approaches the expected reverse cutoff voltage, the reverse characteristics of the internal reverse-biased diode are checked. If the leakage current increases abnormally when the output voltage is much lower than the expected reverse cutoff voltage, it can be determined that the internal reverse-biased diode has a soft breakdown or leakage fault.

[0075] S213: When the output voltage is lower than the expected reverse cutoff voltage, if a sudden change in leakage current is detected, it is determined that the reverse connection protection diode has a soft breakdown or leakage fault.

[0076] It is understandable that a sudden change is a phenomenon in which the leakage current amplitude jumps during the gradual increase of the output voltage. It is manifested as the increase in leakage current between two adjacent voltage steps exceeding the preset normal fluctuation range. It is used as an electrical signal indicator to determine the deterioration of the reverse characteristics of the internal anti-reverse diode. For example, the judgment condition of a sudden change can be that the leakage current increment exceeds 5 times the leakage current value of the previous stage, or the absolute value of the leakage current jumps from the nanoampere level to the microampere level.

[0077] Soft breakdown is a deterioration failure mode of the internal reverse polarity protection diode. It refers to the phenomenon that the PN junction of the internal reverse polarity protection diode exhibits a recoverable partial conduction phenomenon before the reverse bias voltage reaches the expected reverse cutoff voltage, resulting in an abnormal increase in leakage current.

[0078] Leakage fault is a deterioration fault mode of the internal reverse polarity protection diode. It refers to the phenomenon that the leakage current is continuously higher than the normal range under reverse bias, which reflects that the PN junction insulation performance of the internal reverse polarity protection diode has deteriorated.

[0079] A sudden change in leakage current can be detected by comparing the leakage current sampling values ​​collected at adjacent voltage steps. When the leakage current value of the later stage exceeds a preset multiple threshold of the leakage current value of the earlier stage, it is determined to be a sudden change. For example, when the preset step size is 10 volts and the preset multiple threshold of leakage current is 5 times, if the leakage current collected at an output voltage of 50 volts is 0.3 microamps and the leakage current collected at an output voltage of 60 volts is 12 microamps, then the ratio of the leakage current of 12 microamps in the later stage to the leakage current of 0.3 microamps in the earlier stage is 40, which exceeds the preset multiple threshold of 5 times. It is determined that the leakage current has changed suddenly at an output voltage of 60 volts. At this time, 60 volts is lower than the expected reverse cutoff voltage of 100 volts, so it is determined that the internal reverse connection protection diode has a soft breakdown or leakage fault. Alternatively, a first-order differential operation can be performed on the leakage current sequence collected at each stage. When the absolute value of the difference exceeds a preset differential threshold, it is determined to be a sudden change.

[0080] By comparing the changes in leakage current between adjacent stages in real time during the gradual increase of output voltage, it is determined whether the leakage current has undergone a sudden change that exceeds the normal fluctuation range. The output voltage corresponding to the sudden change is compared with the expected reverse cutoff voltage to determine the fault type of the internal reverse connection protection diode. If the sudden change occurs when the output voltage is lower than the expected reverse cutoff voltage, it indicates that the reverse cutoff capability of the internal reverse connection protection diode has failed prematurely within the rated voltage range, thus determining that the internal reverse connection protection diode has a soft breakdown or leakage fault.

[0081] S220, adjusts the injection polarity of the detection signal according to the conduction direction.

[0082] It can be understood that the injection polarity is the direction of the voltage applied to both ends of the main circuit by the detection signal, which is determined by the conduction direction of the reverse polarity protection diode. When the injection polarity is consistent with the conduction direction, the reverse polarity protection diode conducts and the capacitive element is connected to the detection circuit.

[0083] Adjusting the injection polarity of the detection signal according to the conduction direction can be achieved by controlling the MOSFETs in the upper left and lower right arms of the H-bridge electronic switch array to be turned on, while the other arms are turned off, so that test port A outputs positive and test port B outputs negative to match the conduction direction. For example, the external test system controls the H-bridge electronic switch array to output positive at test port A and negative at test port B. At this time, the detection signal is injected with positive polarity, the reverse connection diode is turned on, and the capacitive element is connected to the main circuit. When the preset constant current is 1 mA and the equivalent capacitance of the capacitive element is 1000 μF, the rise in port voltage within the 200 μs sampling window is approximately 1*200 / 1000=0.2 V. This rising trend is used to determine whether the contact break is normally opened in subsequent steps. Alternatively, it can be achieved by controlling the MOSFETs in the upper right and lower left arms of the H-bridge electronic switch array to be turned on, while the other arms are turned off, so that test port A outputs negative and test port B outputs positive to match the conduction direction, etc.

[0084] By obtaining the conduction direction of the reverse polarity protection diode recorded in the internal topology information, it is determined in which voltage direction the detection signal should be injected into the main circuit to enable the reverse polarity protection diode to conduct in the forward direction. The injection polarity is adjusted to be consistent with the conduction direction to ensure that the capacitive element is normally connected to the detection circuit and participates in the generation of the timing change characteristics of the port voltage during the contact sintering detection stage. At the same time, it provides a clear reference direction for the reverse polarity protection diode to be reverse cut off when the polarity is reversed in the future.

[0085] In one possible implementation, the internal topology information is obtained from the manufacturing execution system or a pre-stored topology database, and also includes: S200a, obtain the circuit breaker's model identification code from the manufacturing execution system.

[0086] It can be understood that a Manufacturing Execution System (MES) is a production process management platform deployed in an automated production line. It connects to an external testing system through a communication interface and stores the circuit breaker's model identification code and its corresponding internal topology information. This information is used to provide the external testing system with the circuit breaker's identification data and parameter configuration basis before testing. The communication method of the Manufacturing Execution System (MES) can be Ethernet communication, RS485 bus communication, etc.

[0087] The model identification code is a unique identification code assigned to a circuit breaker during the production process. It is used to uniquely identify the product model and batch information of the circuit breaker in the Manufacturing Execution System (MES). The model identification code can be a numerical sequence code, an alphanumeric mixed code, an RFID tag code, etc.

[0088] The model identification code of a circuit breaker can be obtained from the Manufacturing Execution System (MES) in several ways. For example, an external test system can send a data request message containing the test station number to the MES via an Ethernet interface, and the MES will return the model identification code of the circuit breaker at the current station. Alternatively, the external test system can scan the barcode or RFID tag on the circuit breaker to read its model identification code and then send a query request to the MES to obtain the corresponding internal topology information.

[0089] By establishing a communication connection between the external testing system and the Manufacturing Execution System (MES), the system automatically obtains the model identification code of the circuit breaker after it enters the testing station. The system then retrieves and loads the internal topology information that matches the circuit breaker from the pre-stored topology database based on the model identification code. This allows the external testing system to identify the model characteristics of the current circuit breaker without manual intervention. Based on the parameters of the capacitive components and the reverse polarity protection diodes corresponding to the model, the system adaptively configures the constant current value and sampling window duration used in subsequent testing steps.

[0090] The S200b adaptively configures the value of the constant current and the duration of the sampling window based on the model identification code.

[0091] Adaptive configuration can be understood as the process by which an external test system automatically calculates and sets test parameters based on the nominal parameters of capacitive components after obtaining the model identification code and loading the corresponding internal topology information. This allows the same external test system to adapt to circuit breakers with different capacitive component specifications without manual adjustment. The parameters involved in adaptive configuration may include the value of constant current, the duration of the sampling window, etc.

[0092] The sampling window is the time interval during which the external test system continuously collects the port voltages at both ends of the main circuit under high impedance constant current conditions. Its start time is the starting point of the port voltage collection after the detection signal is injected, and its end time is the ending point of the collection. It is used to limit the length of time for injecting charge into the capacitive element. For example, the duration of the sampling window can be from 100 microseconds to 500 microseconds.

[0093] The method for adaptively configuring the constant current value and sampling window duration based on the model identification code can be as follows: The constant current value is calculated based on the nominal capacitance values ​​of capacitive components stored in a pre-stored topology database according to a preset proportional relationship. Then, the sampling window duration is calculated back based on this value and the expected port voltage rise. For example, when the nominal capacitance value corresponding to the model identification code is 1000 microfarads, the preset constant current value is 1 milliampere, and the expected port voltage rise to 0.2 volts within the sampling window to meet the second preset voltage threshold requirement, then the sampling window... The sampling window duration is 0.2 * 1000 / 1 = 200 microseconds. Alternatively, the sampling window duration can be determined first based on the nominal capacitance value of the capacitive components stored in the pre-stored topology database. Then, the constant current value is calculated according to the constraint that the rise in port voltage does not exceed the forward conduction voltage of the reverse connection diode. For example, when the nominal capacitance value corresponding to the model identification code is 470 microfarads, if the constant current value is kept constant at 1 milliampere, the sampling window duration would be 0.2 * 470 / 1 = 94 microseconds to achieve the same 0.2 volt rise.

[0094] The nominal capacitance value of the capacitive component is loaded from the pre-stored topology database using the model identification code. The external test system automatically calculates the corresponding constant current value and sampling window duration based on the nominal capacitance value. Through adaptive configuration, the constant current value is matched with the sampling window duration. When the nominal capacitance value is large, the constant current value is increased or the sampling window duration is extended accordingly. When the nominal capacitance value is small, the constant current value is decreased or the sampling window duration is shortened accordingly. This ensures that the charging rise of the port voltage at the end of the sampling window is within a range that can be effectively distinguished by the second preset voltage threshold.

[0095] S300, under high impedance constant current state, collects the port voltage at both ends of the main circuit of the circuit breaker within a preset sampling window.

[0096] It can be understood that the port voltage is the voltage difference presented to the outside by the two ends of the main circuit under high impedance constant current state. It is generated when a constant current flows through the parallel network composed of the contact break and capacitive element. Its amplitude and trend of change depend on the differential modulation effect of the contact break sintering or normal open state on the equivalent impedance of the parallel network.

[0097] Data acquisition is the operation of an external test system to continuously convert the port voltage to digital and record the timing sequence through a high sampling unit. Discrete port voltage data points are acquired within the sampling window at a frequency not lower than the preset sampling rate. This data is used to construct a port voltage timing sequence that reflects the state of the contact break. The sampling rate can be not lower than 100 kHz (e.g., 100 kHz, 200 kHz, etc.).

[0098] The method for acquiring the port voltage at both ends of the main circuit of the circuit breaker can be to convert the differential voltage signal at both ends of the main circuit into a single-ended ground signal through a differential amplifier, and then send it to an analog-to-digital converter for continuous sampling at a preset sampling rate. For example, when the constant current is 1 mA under high impedance constant current state and the sampling window duration is 200 microseconds, the external test system samples the port voltage at a sampling rate of 100 kHz with a sampling interval of 10 microseconds, acquiring a total of 20 port voltage data points within the 200 microsecond sampling window; if the contact break is positive... If the equivalent capacitance of the normally disconnected capacitive element is 1000 microfarads, then the theoretical port voltage from the 1st to the 20th sampling point will rise approximately linearly from about 0 volts to 1 mA * 200 / 1000 = 0.2 volts. If the contact break is sintered, the port voltage values ​​at all 20 sampling points will remain below the first preset voltage threshold, for example, all below 1 * 50 = 50 microvolts. Alternatively, the high-voltage side signal at both ends of the main circuit can be electrically isolated from the low-voltage side sampling circuit by an isolation operational amplifier and then sampled by an analog-to-digital converter.

[0099] By sampling the port voltage at high speed within a preset sampling window, a set of time sequence data is obtained that can record the complete change process of the port voltage from the injection start time to the sampling window end time, providing the original data basis for distinguishing the sintering state and normal disconnection state of the contact fracture based on the time sequence change characteristics.

[0100] S400 determines the contact sintering state of the circuit breaker based on the time-series change characteristics of the port voltage. If the port voltage is always lower than the first preset voltage threshold, the contact is determined to be sintered. If the port voltage rises and exceeds the second preset voltage threshold, the contact is determined to be normally open. The first preset voltage threshold is determined by the product of the preset contact sintering resistance determination threshold and the constant current. The second preset voltage threshold is determined by the charging voltage of the capacitive element inside the circuit breaker at the end of the sampling window.

[0101] It can be understood that the timing variation characteristics are the amplitude evolution of the port voltage over time within the sampling window, including whether the port voltage shows an upward trend, the maximum value of the port voltage, and the comparison results with the first preset voltage threshold and the second preset voltage threshold. These are used as electrical criteria to distinguish between two states: contact break sintering and normal disconnection. The timing variation characteristics may include a flat low-level characteristic maintained at the microvolt level, a sloped characteristic that rises approximately linearly from zero volts, etc.

[0102] The first preset voltage threshold is the upper limit of the voltage used to determine the sintering of the contact break. It is determined by the product of the preset contact sintering resistance determination threshold and the constant current. When the port voltage is always lower than this value within the sampling window, it indicates that the equivalent resistance of the contact break is less than or equal to the contact sintering resistance determination threshold and is in the sintering state. For example, the value of the first preset voltage threshold can be from 10 microvolts to 200 microvolts.

[0103] The second preset voltage threshold is the lower limit of the voltage at which the contact breaks normally. It is determined by the charging voltage of the capacitive element inside the circuit breaker at the end of the sampling window. When the port voltage rises within the sampling window and exceeds this value, it indicates that the contact breaks have physically separated and a constant current is charging the capacitive element. For example, the value of the second preset voltage threshold can be 0.1 volts to 0.5 volts.

[0104] The contact sintering resistance threshold is a preset contact resistance boundary value used to distinguish between sintered contact breaks and normal disconnection. Below this resistance value, the contact break is considered to be in a sintered state. Its product with the constant current constitutes the first preset voltage threshold. The contact sintering resistance threshold is determined by the type of circuit breaker contact assembly, the rated current level, and the characteristics of the contact material. For example, the contact sintering resistance threshold can be between 10 milliohms and 200 milliohms.

[0105] The charging voltage is the voltage value accumulated at the end of the sampling window after the constant current continuously charges the capacitive element within the sampling window. It is determined by the value of the constant current, the duration of the sampling window, and the equivalent capacitance value of the capacitive element. It serves as the physical basis for determining the second preset voltage threshold. For example, the charging voltage can be calculated by multiplying the constant current by the sampling window duration and dividing by the equivalent capacitance value.

[0106] By performing time-series analysis on the port voltages collected within the sampling window, the system extracts whether the port voltage rises, the voltage range of the maximum value, and the comparison relationship with two preset voltage thresholds. By setting the first preset voltage threshold as the product of the contact sintering resistance judgment threshold and the constant current, the contact sintering judgment condition is directly related to the maximum allowable contact resistance of the contact break when sintering fails. By setting the second preset voltage threshold as the charging voltage of the capacitive element at the end of the sampling window, the normal contact disconnection judgment condition is directly related to the nominal parameters of the capacitive element and the duration of the sampling window. Thus, the sintering state and normal disconnection state of the contact break are distinguished in terms of electrical characteristics by two voltage thresholds with clear physical meaning.

[0107] In one possible implementation, please refer to Figure 4 In S400, after determining that the contact has opened normally, the following steps are taken: S400a controls the H-bridge electronic switch array to reverse the output polarity, thereby turning off the reverse connection protection diodes inside the circuit breaker and performing insulation testing on the circuit breaker.

[0108] It can be understood that reversing the output polarity is an operation that reverses the voltage direction applied by the external test system to the two ends of the main circuit from the first polarity to the second polarity by switching the combination of the conducting arms in the H-bridge electronic switch array. This is used to change the current flow direction when the detection signal is injected into the main circuit, so that the reverse connection protection diode switches from the forward conduction state to the reverse cutoff state. The triggering time for reversing the output polarity can be after the contact break is determined to be normally opened, or before the insulation test is performed, etc.

[0109] Insulation testing involves applying a DC test voltage to the contact break after the reverse polarity protection diode has been turned off and measuring the insulation resistance of the main circuit to ground or to the casing. It is used to assess the insulation integrity at both ends of the contact break when it is in an open state. The test voltage for insulation testing can be DC 500V, DC 1000V, etc.

[0110] The way to control the H-bridge electronic switch array to reverse the output polarity can be by sending complementary switching signals to the gate drivers of the four MOSFETs of the H-bridge electronic switch array through a microcontroller (MCU), so that the previously turned-on upper left and lower right bridge arm MOSFETs are turned off, and the previously turned-off upper right and lower left bridge arm MOSFETs are turned on. Alternatively, a pair of complementary enable signals can be generated by logic circuits to control the enable terminals of the two half-bridge drivers of the H-bridge electronic switch array respectively, so as to realize the hardware-level reversal of the output polarity.

[0111] By controlling the H-bridge electronic switch array to switch the combination of conducting bridge arms, the output polarity is flipped from positive to negative. By reversing the output polarity, the reverse polarity protection diode is subjected to reverse bias voltage and cut off, cutting off the electrical path between the capacitive component and the main circuit and forming a high impedance isolation between the two. This ensures that the DC test voltage applied for insulation detection is only applied to both ends of the contact break and is not affected by the current shunting of the capacitive component, thus allowing the insulation resistance measurement result to reflect the true insulation state of the contact break.

[0112] In one possible implementation, please refer to Figure 4 In S400a, insulation testing is performed on the circuit breaker, including: S400a1 injects a detection signal of the second polarity into the main circuit after the H-bridge electronic switch array reverses the output polarity.

[0113] It is understandable that by injecting a detection signal into the main circuit with the second polarity after reversing the output polarity of the H-bridge electronic switch array, and utilizing the characteristic that the second polarity is opposite to the conduction direction of the reverse polarity protection diode, the detection signal applies a reverse bias to the reverse polarity protection diode. By detecting the response characteristics of the port voltage under this reverse bias within the sampling window, it is determined whether the cutoff capability of the reverse polarity protection diode is normal under reverse bias conditions. Thus, without adding extra hardware or extra testing steps, the health status of the reverse polarity protection diode can be diagnosed simultaneously using the existing detection signal injection channel after polarity reversal.

[0114] S400a2, under the second polarity, if the collected port voltage is lower than the preset high resistance judgment threshold within the sampling window, it is determined that the anti-reverse connection diode inside the circuit breaker is in a breakdown short-circuit state.

[0115] It is understandable that the preset high-impedance judgment threshold is a port voltage judgment value used to distinguish between normal cutoff and short circuit breakdown of the anti-reverse diode under the second polarity. This threshold is set between the higher voltage level reached when the port voltage rises rapidly during normal cutoff and the lower voltage level where the port voltage hardly rises during short circuit breakdown. It is used to determine the cutoff capability of the anti-reverse diode by numerical comparison. The preset high-impedance judgment threshold can be determined by (constant detection current * sampling window duration / nominal capacitance value of absorption capacitor) * preset ratio. For example, the value of the preset high-impedance judgment threshold can be from 0.2 volts to 5 volts.

[0116] Breakdown short-circuit state is a failure mode of reverse polarity protection diode. It refers to the PN junction of the reverse polarity protection diode losing its unidirectional conduction characteristic and exhibiting a bidirectional conduction state that is close to a short circuit when an external reverse bias voltage is applied. In this state, the reverse polarity protection diode also conducts under the second polarity, causing the capacitive component to remain electrically connected to the main circuit and fail to be isolated. The causes of breakdown short-circuit state can be overvoltage surge breakdown, overheating damage, etc.

[0117] Another way to determine whether the anti-reverse connection diode is in a breakdown short-circuit state under the second polarity is to calculate the voltage rise slope of the port voltage within the sampling window. If the slope is lower than the preset slope threshold, it is determined to be a breakdown short circuit.

[0118] In one possible implementation, the equivalent output impedance corresponding to the high-impedance constant current state is 1kΩ to 100kΩ.

[0119] It is understandable that by setting the equivalent output impedance in the range of 1kΩ to 100kΩ, when the external test system injects a constant detection current into the main circuit, the amplitude of the constant detection current will not fluctuate significantly with the load change, because the equivalent output impedance is much greater than the equivalent resistance of the contact break in the near-zero resistance state in the sintering state and the equivalent impedance of capacitive charging in the normal disconnection state. At the same time, by clamping the upper limit of the charging current of the capacitive element through the equivalent output impedance, the amount of charge accumulation of the capacitive element in the sampling window is limited to a controllable range, avoiding the capacitive element from reaching saturation of the port voltage too early in the sampling window due to excessive charging, thus losing the ability to distinguish the micro-state characteristics between the sintering and normal disconnection states.

[0120] In one possible implementation, please refer to Figure 3 The testing methods for contact components also include: S500 calculates the equivalent capacitance of the internal capacitive elements of the circuit breaker using the voltage rise slope of the constant current and the port voltage.

[0121] It can be understood that the voltage rise slope is the rate at which the port voltage rises with time within the sampling window, determined by the physical process of constant current charging the capacitive element. When the contact breaks normally, the voltage rise slope is approximately equal to the constant current divided by the equivalent capacitance value of the capacitive element. This is used as an input parameter for inverting and calculating the equivalent capacitance value under the premise that the contact breaks normally. The voltage rise slope can be obtained by linearly fitting the port voltage time series collected within the sampling window to find the slope, or by taking the voltage difference between the first and last sampling points within the sampling window and dividing it by the time interval, etc.

[0122] The equivalent capacitance value is the total capacitance of all capacitive components connected in parallel within the circuit breaker, calculated using the voltage rise slope and constant current inversion. It is used to characterize the comprehensive capacitive characteristics of the capacitive components under actual testing conditions. Comparing the equivalent capacitance value with the nominal capacitance value can determine whether there are assembly problems such as incorrect installation, missing installation, or parameter drift of the capacitive components.

[0123] The equivalent capacitance value of the internal capacitive components of a circuit breaker can be calculated by using the voltage rise slope of the constant current and the port voltage. This can be achieved by performing linear regression fitting on the port voltage time series collected within the sampling window, taking the slope of the fitted line as the voltage rise slope, and then dividing the constant current by this slope to obtain the equivalent capacitance value. For example, if the constant current is 1 mA and the sampling window duration is 200 microseconds, and port voltage data is extracted from 20 sampling points, the voltage rise slope obtained through linear regression fitting is 0.99 V / s, then the equivalent capacitance value = 1 / 0. 99 = 1010 microfarads; alternatively, the voltage rise slope can be obtained by dividing the difference between the port voltage of the last sampling point and the first sampling point within the sampling window by the sampling window duration, and then dividing the constant current by this slope to obtain the equivalent capacitance value. For example, if the port voltage of the first sampling point is 0.002 volts and the port voltage of the 20th sampling point is 0.198 volts, then the voltage rise slope = (0.198 - 0.002) / 200 = 980 volts / second, and the equivalent capacitance value = 1 / 980 = 1020 microfarads. The results of the two calculation methods are basically the same.

[0124] Based on the physical premise that the constant current flows through the capacitive element and linearly charges it when the contact breaks normally, the equivalent capacitance value of all capacitive elements connected in parallel inside the circuit breaker is calculated by dividing the known amplitude of the constant current by the voltage rise slope extracted from the port voltage time sequence. By transforming the capacitive charging process, which was originally considered an interference source during the contact sintering test, into a data source for inverse calculation of capacitance value, the capacitance value of the capacitive element is measured synchronously using the same set of sampling data without adding extra test hardware or extending the test time. This achieves one-time acquisition and dual utilization of test data.

[0125] S600 compares the equivalent capacitance value with the pre-stored nominal capacitance value. When the deviation exceeds the preset tolerance range, it generates an assembly abnormality alarm signal.

[0126] It is understandable that the nominal capacitance value is the theoretical rated capacitance determined during the design phase of a capacitive component. It serves as a reference benchmark for judging the assembly quality of a capacitive component. When the deviation between the equivalent capacitance value and the nominal capacitance value exceeds the preset tolerance range, it indicates that the capacitive component may have an assembly abnormality.

[0127] The preset tolerance range is a pre-set upper limit for allowable deviations, used as a quantity limit to determine whether the assembly of capacitive components is abnormal. When the deviation exceeds this range, an assembly abnormality alarm signal is generated. For example, the preset tolerance range can be ±10%, ±20%, etc.

[0128] The equivalent capacitance value can be compared with the pre-stored nominal capacitance value by calculating the percentage relative deviation between the two values. When the percentage exceeds a preset tolerance range, an assembly abnormality alarm signal is generated. For example, if the nominal capacitance value is 1000 microfarads and the preset tolerance range is ±20%, and the calculated equivalent capacitance value is 1010 microfarads, then the deviation = |1010-1000| / 1000*100% = 1%. Since 1% is less than 20%, it does not exceed the preset tolerance range, the capacitive component assembly is normal, and no alarm is generated. It can calculate the absolute difference between the equivalent capacitance value and the nominal capacitance value. When the absolute value exceeds the preset absolute tolerance threshold, an assembly abnormality alarm signal is generated. For example, if the calculated equivalent capacitance value is 700 microfarads, then the deviation = |700-1000| / 1000*100% = 30%. 30% is greater than 20%, which exceeds the preset tolerance range, indicating that the capacitive component may not conform to the design specifications. The external testing system generates an assembly abnormality alarm signal and reports it to the manufacturing execution system, which automatically marks the circuit breaker as a defective product and intercepts it.

[0129] By comparing the equivalent capacitance value with the pre-stored nominal capacitance value and calculating the deviation between the two, the deviation is compared with the preset tolerance range to determine whether the actual assembly status of the internal capacitive components of the circuit breaker meets the design standards. If the deviation falls within the preset tolerance range, it indicates that the capacitance value of the capacitive component is consistent with the design value and the assembly status is normal. If the deviation exceeds the preset tolerance range, it indicates that the capacitive component may have assembly abnormalities such as incorrect installation, missing installation, or parameter drift. The external testing system generates an assembly abnormality alarm signal accordingly. By utilizing the port voltage timing data collected during the contact sintering detection process and without adding additional test actions and test time, the screening of the assembly quality of the capacitive components is completed simultaneously.

[0130] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0131] Corresponding to the test method for the contact assembly in the above embodiments, this application also provides an external test system, the various parts of which can implement the various steps of the test method for the contact assembly. Figure 4 A structural block diagram of the external testing system provided in the embodiments of this application is shown. For ease of explanation, only the parts related to the embodiments of this application are shown.

[0132] External test systems may include: digital-to-analog converters (DACs), linear MOSFETs, H-bridge electronic switch arrays, high-speed sampling units, processing units, communication interfaces, and test ports.

[0133] The digital-to-analog converter (DAC) converts digital control words into analog voltages to adjust the gate bias of MOSFETs. Linear MOSFETs are driven by the DAC, programmably reconstructing the output impedance to the kilohm to ten-thousand-ohm range, achieving a high-impedance constant-current state. The H-bridge electronic switching array is a full-bridge composed of four high-speed MOSFETs, reversing the output polarity in microseconds to allow the internal reverse-connection protection diodes of the circuit breaker to withstand reverse voltage, cut off, and create a megahm-level high-impedance isolation window. The high-speed sampling unit consists of a differential amplifier and an analog-to-digital converter (ADC). The differential amplifier is used to acquire the port voltages across the main circuit of the circuit breaker, and the ADC is used for... It provides timing sequence data required to distinguish between the sintering state and the normal disconnection state of the contact fracture surface by analyzing the timing change characteristics of the port voltage within a microsecond time window. The processing unit can be an MCU, FPGA, etc., to implement each step of the test method for the contact assembly. The processing unit communicates with the production process management platform (manufacturing execution system) deployed in the automated production line through a communication interface to obtain the model identification code and report the test results or alarm signals. The test port is divided into port A and port B, which are physically connected to the two ends of the main circuit of the circuit breaker and are used to inject test signals and collect port voltage.

[0134] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A contact assembly for a circuit breaker, used in the circuit breaker, characterized in that, The contact assembly includes: A moving contact, rotatably mounted on the housing of the circuit breaker; and A stationary contact is mounted on the housing of the circuit breaker. The moving contact and the stationary contact together form a contact break. When the circuit is open, the moving contact and the stationary contact are physically separated. When the circuit is closed, the moving contact and the stationary contact are pressed together to conduct electricity. The contact break is connected in series in the main circuit of the circuit breaker. The main circuit is the only path for the circuit breaker to carry the operating current. The current flows in from the incoming terminal and flows out from the outgoing terminal through the contact break. The contact break is a disconnectable node in the main circuit. The circuit breaker has at least one capacitive element, which is connected in parallel to both ends of the contact break. The circuit breaker is configured such that, when it is in the open state and an external testing system injects a constant detection current into the main circuit in a high-impedance constant-current state, the timing variation characteristics of the port voltages at both ends of the main circuit within the sampling window are used by the external testing system to determine the sintering state of the contact fracture.

2. The contact assembly of the circuit breaker as described in claim 1, characterized in that, The circuit breaker also includes: A reverse polarity protection diode is connected in series between the capacitive element and the main circuit. The conduction direction of the reverse polarity protection diode is configured to conduct when the external test system injects a detection current with positive polarity and to cut off when the detection current is injected with reverse polarity, so as to form a high impedance isolation between the capacitive element and the main circuit.

3. The contact assembly of the circuit breaker as described in claim 1, characterized in that, The circuit breaker also includes: A readable identifier is provided on the circuit breaker. The readable identifier is used to store internal topology information, which includes at least the nominal capacitance value of the capacitive element.

4. A test method for a contact assembly, characterized in that, The method for testing the contact assembly as described in any one of claims 1 to 3 includes: Before injecting the detection current, the output impedance is set to a high-impedance constant current state; wherein, the high-impedance constant current state is a state in which the output equivalent impedance is above kiloohms and the output current is limited to a constant value. A detection signal is injected into the main circuit of the circuit breaker with a preset constant current; Under the high impedance constant current state, the port voltages at both ends of the main circuit of the circuit breaker are collected within a preset sampling window; The contact sintering state of the circuit breaker is determined based on the time-series change characteristics of the port voltage. If the port voltage is always lower than a first preset voltage threshold, the contact is determined to be sintered. If the port voltage rises and exceeds a second preset voltage threshold, the contact is determined to be normally open. The first preset voltage threshold is determined by multiplying a preset contact sintering resistance determination threshold with the constant current. The second preset voltage threshold is determined by the charging voltage of the capacitive element inside the circuit breaker at the end of the sampling window.

5. The test method for the contact assembly as described in claim 4, characterized in that, Also includes: The equivalent capacitance value of the internal capacitive element of the circuit breaker is calculated using the voltage rise slope of the constant current and the port voltage. The equivalent capacitance value is compared with the pre-stored nominal capacitance value. When the deviation exceeds the preset tolerance range, an assembly abnormality alarm signal is generated.

6. The test method for the contact assembly as described in claim 4, characterized in that, After the determination contact is normally disconnected, the following is included: The output polarity of the H-bridge electronic switch array is reversed to cut off the reverse connection protection diode inside the circuit breaker and to perform insulation detection on the circuit breaker.

7. The test method for the contact assembly as described in claim 6, characterized in that, Before injecting the detection signal into the main circuit of the circuit breaker, the method further includes: Obtain the internal topology information of the circuit breaker; wherein, the internal topology information includes the conduction direction of the reverse connection protection diode disposed inside the circuit breaker; The injection polarity of the detection signal is adjusted according to the conduction direction.

8. The test method for the contact assembly as described in claim 7, characterized in that, The internal topology information is obtained from the manufacturing execution system or a pre-stored topology database, and also includes: Obtain the model identification code of the circuit breaker from the manufacturing execution system; The value of the constant current and the duration of the sampling window are adaptively configured according to the model identification code.

9. The test method for the contact assembly as described in claim 6, characterized in that, The insulation test performed on the circuit breaker includes: After the H-bridge electronic switch array reverses the output polarity, a detection signal of the second polarity is injected into the main circuit; Under the second polarity, if the collected port voltage is lower than the preset high resistance judgment threshold within the sampling window, it is determined that the anti-reverse connection diode inside the circuit breaker is in a breakdown short-circuit state.

10. The test method for the contact assembly as described in claim 9, characterized in that, Obtaining the internal topology information of the circuit breaker includes: Obtain the type of the internal reverse polarity protection diode and its expected reverse cutoff voltage; When performing the insulation test on the circuit breaker, the output voltage of the second polarity is gradually increased by the H-bridge electronic switch array in a preset step size, and the leakage current is monitored in real time. If a sudden change in leakage current is detected when the output voltage is lower than the expected reverse cutoff voltage, it is determined that the reverse connection protection diode has a soft breakdown or leakage fault.

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