For split type arc fault detectors, slaves, masters and detectors

Abstract

This invention discloses a slave unit, a master unit, and a detector for a split-type arc fault detector. The detector includes a master unit and one or more slave units connected to it. The slave unit is mounted on the line to be protected between the circuit breaker and the load, and is used to detect whether an arc fault exists on the line to be protected, and transmit the arc fault detection result to the master unit in the form of a digital signal. The master unit is connected to the circuit breaker on the line to be protected, and processes the arc fault based on the received arc fault detection result. This invention adopts a split master-slave structure, and the two communicate with each other via digital signals, which not only solves the problem of traditional arc fault detectors occupying too much rail space, but also ensures the data processing speed of the master unit. In addition, the line does not need to be disconnected when installing the slave unit, reducing the number of contacts and lowering the possibility of arc faults.

Description

Technical Field

[0001] The invention relates to a fault arc detection technology, in particular to a slave machine, a host machine and a detector for a split type fault arc detector. Background Art

[0002] At present, arc fault is one of the main causes of electrical fires. As a monitoring device for electrical fires, arc fault detectors can effectively reduce the probability of electrical fires in the monitored area. Therefore, the number of arc fault detectors installed is increasing, and it has become an indispensable part of civilian-grade industrial electricity safety.

[0003] Traditional arc fault detectors are generally installed on the rails in the final distribution box and placed at the rear end of the circuit breaker or leakage protector. The specific connection structure is as follows: Figure 1 As shown, the arc fault detector 1 is mounted on the guide rail in the distribution box and connected to the line to be protected between the circuit breaker and the load. With the increase in the types and number of electrical equipment, in order to avoid damage to electrical equipment caused by arc faults, the number of lines that need to use arc fault detectors is also increasing. The number of arc fault detectors that need to be installed on the guide rails of the corresponding distribution box is also increasing, resulting in exceeding the capacity of the original distribution box. As a result, additional distribution boxes specifically used to install arc fault detectors have to be added, which will not only increase the difficulty of maintaining the arc detector itself and other electrical equipment in the distribution box, but also increase the maintenance cost. Therefore, its customer acceptance is low. At the same time, the traditional arc fault detector is an independent product, which consists of four parts: power supply system, arc inspection system, bus system, sound and light alarm, etc. The single cost is relatively high. As the number of installations in a distribution box continues to increase, the total cost increases accordingly, which is also one of the reasons for the low customer acceptance.

[0004] In addition, combined Figure 1 It can be seen that during the installation of traditional fault detectors, it is necessary to disconnect the line between the original circuit breaker and the load, and connect the fault arc detector between the load and the circuit breaker. This installation method will add more contacts, which will increase more safety hazards from a safety perspective.

[0005] In the prior art, the patent with the authorization announcement number CN207866965U and the name of the patent is a split-type arc fault detection system, which discloses the following technical contents: the split-type arc fault detection system includes a control unit, an alarm unit and multiple split-type arc detection units, and the multiple split-type arc detection units are arranged in the same arc fault detector, so as to achieve the technical effect of using one control unit to perform arc detection on multiple lines at the same time. In the split-type arc fault detection system, the structure of "multiple arc detection units corresponding to multiple control units" is improved to "multiple arc detection units corresponding to one control unit". This improvement can reduce the occupied space of the arc fault detector to a certain extent, but as the number of lines to be protected increases, the structure is prone to the following problems:

[0006] 1. Since the control unit is connected to multiple arc detection units and has many internal wirings, its installation and maintenance are difficult. When the number of lines to be protected is large, the number of arc detection units in the system cannot be increased without limit. In order to adapt to the number of lines to be protected, the number of fault arc detection systems must be increased. Therefore, it is difficult to fundamentally solve the problem of space occupation.

[0007] 2. Since the control unit needs to respond to and process the detection signals of multiple arc detection units, the amount of calculation is large. Therefore, its response and processing speed will be reduced, which will also affect the accuracy of the system's judgment of fault arcs, resulting in delays or even missing the best arc extinguishing time;

[0008] 3. Analog signals are used for signal transmission. In order to ensure the timeliness and quality of data transmission, the signal transmission distance is short, so it is not suitable for remote monitoring.

[0009] Based on this, the above-mentioned disclosed patent can alleviate the problem of space occupation and cost increase caused by a small increase in the number of lines to be protected to a certain extent. However, with the widespread application of electrical equipment, the number of lines to be protected has increased sharply. It can neither fundamentally solve the problem of space occupation existing in the prior art, nor guarantee the response speed and accuracy of fault arc judgment. It can also not solve the problem of increased contacts in the line to be protected due to the connection of the fault detector between the load and the circuit breaker due to the circuit breaker. Moreover, due to the display of the analog signal transmission method, it is difficult to monitor the line to be protected over a long distance.

[0010] In view of this, the above technical problems need to be solved urgently. Summary of the invention

[0011] In order to solve the above technical problems, the present invention provides a slave, a host and a detector for a split-type fault arc detector. The present invention adopts a split master-slave structure, and the two communicate through digital signals, which not only solves the problem that traditional fault arc detectors occupy more guide rail space; but also ensures the data processing speed of the host. In addition, when installing the slave, it is only necessary to pass the live wire on the line to be protected through the slave without disconnecting the line. Compared with the prior art, the number of contacts is reduced and the possibility of fault arc occurrence is reduced.

[0012] In order to achieve the above object, one aspect of the present invention provides a slave for a split type fault arc detector, the slave is mounted on a line to be protected between a circuit breaker and a load, and comprises a slave housing, an arc detection unit and a first communication unit located in the slave housing,

[0013] The arc detection unit is used to detect and judge the type of arc and convert the detection result of the fault arc into a digital signal;

[0014] The first communication unit is connected to the arc detection unit and is used to transmit the digital signal to the host.

[0015] Preferably, the arc detection unit comprises a circuit board and an arc detection coil, the arc detection coil is located at the upper end of the slave housing, the circuit board is located at the lower end of the slave housing, and the arc detection coil and the circuit board are arranged adjacent to each other above and below;

[0016] A through hole is provided on the slave housing along the axial position of the arc detection coil, so as to mount the slave on the line to be protected between the circuit breaker and the load.

[0017] Preferably, the circuit board comprises an arc detection board and a power supply board, and the power supply board and the arc detection board are stacked on the lower end of the arc detection coil along the radial direction of the arc detection coil.

[0018] Preferably, the upper ends of the arc detection board and the power board are provided with an arc-shaped notch adapted to the size of the arc detection coil, and the arc detection coil is clamped in the arc-shaped notch.

[0019] Preferably, the upper end of the slave housing is used to place the arc detection coil, and its edge is an arc shape adapted to the outer diameter of the arc detection coil;

[0020] The lower end of the slave housing is used for placing the stacked arc detection board and the power supply board, and the edge thereof is in a right angle shape.

[0021] Preferably, the slave uses software to simulate the half-wave period of the arc to obtain a curve of the arc changing with time, and then identify the fault arc.

[0022] Preferably, a data interface is provided on one side of the lower end of the slave housing at a position corresponding to the arc detection board.

[0023] Another aspect of the present invention provides a host for a split-type arc fault detector, the host comprising a host housing and a main control unit, a second communication unit, an alarm unit and a power supply unit located therein;

[0024] The second communication unit is connected to the main control unit and is used to receive a digital signal sent by the slave as a fault arc detection result, and transmit the digital signal to the main control unit;

[0025] The main control unit is used to process the fault arc according to the received digital signal and communicate with the host computer;

[0026] The alarm unit is connected to the main control unit and responds to an indication signal from the main control unit to alarm an arc fault;

[0027] The power supply unit is connected to the main control unit and is used to supply power to the host and the slave.

[0028] Preferably, a third communication unit is further included, and the third communication unit is connected to the main control unit and the host computer respectively to serve as a communication channel between the main control unit and the host computer.

[0029] In another aspect of the present invention, a split-type arc fault detector is provided, which includes a slave as described above and a host as described above, wherein the slave is mounted on a line to be protected between a circuit breaker and a load, performs arc fault detection on the line to be protected, and transmits the detection result to the host in the form of a digital signal, and the host processes the arc fault according to the digital signal, and preferably transmits the arc fault information to a host computer.

[0030] Preferably, the host and the slave are connected via two buses.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1) The present invention adopts a split master-slave structure. During installation, only the master is installed on the rail of the distribution box, and the slave is mounted on the line to be protected between the circuit breaker and the load. Even if a single master is connected to multiple slaves, it will not occupy more rail space, which fundamentally solves the problem that the traditional fault arc detector occupies more rail space;

[0033] 2) Since the host and the slave communicate through digital signals, the host only needs to process the received digital signals accordingly. Therefore, not only the transmission distance is long, but also the one-to-many structure of a single host connecting multiple slaves does not affect the data processing speed of the host, which can effectively ensure the efficiency of arc fault processing. In addition, the use of digital signal communication reduces the wiring, reduces the difficulty of installation and wiring of the arc fault detector, and is conducive to reducing maintenance costs. In addition, when the number of lines to be detected is increased, only the number of slaves needs to be increased accordingly, saving material costs.

[0034] 3) When installing the slave, it is only necessary to pass the line to be protected (the live wire) through the slave without disconnecting the line. Compared with the prior art, the number of contacts is reduced, and the possibility of arc fault is reduced;

[0035] 4) The power supply and detection parts inside the slave are divided into two circuit boards, and the two circuit boards are stacked and arranged adjacent to the arc detection coil, thereby reducing the size of the slave and further saving space. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings in the specification, which constitute a part of the present application, are used to provide a further understanding of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute a limitation on the present application.

[0037] Figure 1 This is the connection structure diagram of the traditional arc fault detector;

[0038] Figure 2 It is a structural principle diagram of a split-type arc fault detector in the first embodiment of the present invention;

[0039] Figure 3 This is a connection structure diagram of the split type arc fault detector in the working state in the first embodiment of the present invention;

[0040] Figure 4 It is an exploded view of the split-type fault arc detection slave in the first embodiment of the present invention.

[0041] Figure 5 It is a schematic diagram of an arc detection circuit of a split-type fault arc detection slave in the first embodiment of the present invention;

[0042] FIG6( a ) is a schematic diagram of the series arc principle;

[0043] Fig. 6(b) is a schematic diagram of the parallel arc principle;

[0044] FIG6( c ) is a schematic diagram of the principle of arc leakage;

[0045] Figure 7 This is an example waveform diagram of the current and voltage of a series fault arc;

[0046] Figure 8 This is an example waveform diagram of the current and voltage of a parallel fault arc;

[0047] Fig. 9 This is a flowchart of the split-type fault arc detection slave performing fault arc detection in the first embodiment of the present invention;

[0048] Fig.10 It is a software flow chart of the split-type arc fault detection slave performing arc fault detection in the first embodiment of the present invention.

[0049] Among them, 1. Fault arc detector; 2. Guide rail; 3. Circuit breaker; 4. Load;

[0050] 11. Host; 12. Slave;

[0051] 111, main control unit; 112, second communication unit; 113, third communication unit; 114, power supply unit; 115, alarm unit;

[0052] 121. Slave housing; 122. Power board; 123. Arc detection board; 124. Arc detection coil; 125. Through hole; 126. Data interface; 1241. First communication unit. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0054] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0055] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0056] In addition, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0057] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0060] Embodiment 1

[0061] A split type arc fault detector, such as Figure 2 , Figure 3 As shown, it includes a host 11 and one or more slaves 12 connected thereto; wherein:

[0062] The slave 12 is mounted on the line to be protected between the circuit breaker 3 and the load 4, and is used to detect whether there is a fault arc on the line to be protected, and transmit the fault arc detection result to the host 11 in the form of a digital signal; specifically:

[0063] In this embodiment, the slave 12 includes a slave housing 121 and an arc detection unit and a first communication unit 1241 located therein and interconnected. The arc detection unit is used to detect the type of arc on the line to be protected, determine whether the detected arc is a non-fault arc or a fault arc, and transmit the fault arc detection result to the main control unit 111 of the host 11 in the form of a digital signal. The first communication unit 1241 is used to provide an information transmission channel for the arc detection unit.

[0064] like Figure 4 As shown, in this embodiment, the arc detection unit of the slave part includes a circuit board and an arc detection coil 124. In order to minimize the size of the slave, the circuit board of the slave is divided into two parts: a power board 122 and an arc detection board 123. The power board 122 and the arc detection board 123 are stacked at the lower end of the arc detection coil 124 along the radial direction of the arc detection coil 124. A through hole 125 is provided on the slave housing 121 at an axial position corresponding to the center of the arc detection coil 124, and the live wire of the circuit to be protected passes through the through hole 125. It should be noted that Figure 1 As shown, when installing the conventional arc fault detector 1, it is necessary to cut the connection between the circuit breaker 3 and the load 4, that is, it is necessary to disconnect the wire to install the conventional arc fault detector 1. The installation process is relatively complicated, and disconnecting the wire will increase more contacts, which will cause many hidden dangers, such as increasing the probability of arc fault. Figure 4 It can be seen that the slave 12 of the split arc fault detector does not need to disconnect the circuit breaker 3 and the load 4, and only needs to pass the live wire of the circuit to be tested through the through hole 125 through the slave, thereby achieving unbroken installation. This wiring structure not only simplifies the installation process in engineering implementation, but also can well avoid the safety hazards caused by the increase of contacts.

[0065] In this embodiment, in order to further reduce the volume of the slave machine 12, the upper ends of the arc detection board 123 and the power board 122 are provided with an arc-shaped notch adapted to the size of the arc detection coil 124, and the arc detection coil 124 is clamped in the arc-shaped notch to reduce the longitudinal dimension of the slave machine housing 121.

[0066] The lower edge of the slave housing 121 is in a right angle shape, for placing the stacked arc detection board and power board 122 ; the upper edge is in an arc shape adapted to the outer diameter of the arc detection coil 124 , for placing the arc detection coil 124 .

[0067] A data interface 126 is provided at a position corresponding to the arc detection board 123 on one side of the lower end of the slave housing 121 , so as to facilitate program burning and debugging of the arc detection board 123 .

[0068] In this embodiment, the host 11 is connected to the circuit breaker 3 on the line to be protected, and processes the arc fault according to the received arc fault detection result (in the form of digital signal). Figure 2 As shown, the host 11 includes a host housing and a main control unit 111, a second communication unit 112, an alarm unit 115 and a power supply unit 114 located therein, wherein:

[0069] The main control unit 111 is used to process the fault arc according to the received fault arc information and communicate with the host computer;

[0070] The second communication unit 112 is connected to the main control unit 111 and is used to provide an information transmission channel for the main control unit 111; the alarm unit 115 is connected to the main control unit 111 and responds to the indication signal of the main control unit 111 to alarm the fault arc;

[0071] The power supply unit 114 is connected to the main control unit 111 and is used to supply power to the host 11 and the slave 12. In this embodiment, the power supply unit 114 adopts an ACDC switching power supply module encapsulated with a high thermal conductivity resin and an aluminum shell. The power supply module has the characteristics of high power, small size, high conversion efficiency, better performance, multiple protections, and stability and reliability. While ensuring power supply, the width of the host 11 on the distribution cabinet rail 2 is as small as possible.

[0072] The host 11 of the split arc fault detector 1 provided in this embodiment also retains the RS485 bus interface and relay output interface of the traditional arc fault detector 1, and also adds a third communication unit 113, which can be connected by wireless networks in various forms, such as WiFI / LoRa / NB-IoT, etc. The host 11 adopts a unified interface standard, and the interface corresponds to a PCB board of fixed size. The connection method of the wireless network can be selected according to the on-site situation, which plays an active role in some engineering projects that are inconvenient to lay wires; the addition of the third communication unit 113 also promotes the seamless connection between the product and smart fire protection and smart cities, and makes it more convenient for customers to understand the alarm information, statistical information and other information that customers are eager to know from the mobile client. It is more convenient for customers to use.

[0073] The host 11 and the slave 12 are connected through a two-bus system. The two-bus system is a technology that combines the power supply line and the signal line into one, relative to the four-wire system (two power supply lines and two communication lines), and the signal and power supply share one bus. The two-bus system has the characteristics of strong anti-interference, long communication distance, non-polarity wiring, topological wiring, and low cable requirements. It not only meets the data transmission requirements, but also provides power for the slave 12, thereby avoiding two more power supply lines. The transmission distance of the two-bus system is determined according to the power consumption of the host power supply. The maximum transmission distance can reach 3000m, which exceeds the maximum transmission distance of the RS485 bus or CAN bus used in industry; in addition, the two-bus system has clear requirements for cables and strong anti-interference; the power supply and signal do not need to be isolated, saving isolation costs.

[0074] In this embodiment, the host 11 is installed on the guide rail 2 of the distribution box, and the width of the guide rail 2 occupied is 5P (90mm). It will not continuously increase the width of the guide rail 2 as the number of loads increases. According to the installation method of the traditional fault arc detector 1, the width of the guide rail 2 occupied by one load 4 is at least 2P (36mm). As the number of loads increases, the width of the space occupied by the guide rail 2 increases by multiples of 2P (36mm), far exceeding the current fixed width of 5P.

[0075] (90mm), so when the conventional arc fault detector 1 is installed, when the number of loads 4 is large, the guide rail 2 of the distribution box is difficult to bear in terms of space, and the cost is also increased due to the increase in the difficulty of installation and maintenance. The split type arc fault detector 1 provided in this embodiment makes up for the shortcomings of the conventional arc fault detector 1 well, and reduces the material, installation and maintenance costs.

[0076] In summary, the present embodiment adopts a split master-slave structure. During installation, only the host 11 needs to be installed on the distribution box rail 2, and the slave 12 is mounted on the line to be protected between the circuit breaker 3 and the load 4. Even if a single host is connected to multiple slaves, it will not occupy more space on the rail 2, which fundamentally solves the problem that the traditional arc fault detector 1 occupies more space on the rail 2. Moreover, since the host 11 and the slave 12 communicate through digital signals, the host 11 only needs to process the received digital signals accordingly. Therefore, the one-to-many structure of a single host 11 connecting multiple slaves 12 does not affect the data processing speed of the host 11, and can effectively ensure the arc fault processing efficiency. Moreover, digital communication is performed between the host 11 and the slave 12, so there are fewer wirings, which reduces the difficulty of installation and wiring of the arc fault detector 1, and is conducive to reducing maintenance costs. In addition, when the number of lines to be detected is increased, only the number of slaves 12 needs to be increased accordingly, saving material costs.

[0077] In addition, the power supply and detection parts inside the slave 12 are divided into two circuit boards, and the two circuit boards are stacked and arranged adjacent to the arc detection coil 124, thereby reducing the volume of the slave 12 and further saving space.

[0078] Further explanation:

[0079] The main feature that distinguishes this embodiment from the prior art is not only the split structure and the structure of the master and slave machines themselves, but also that after the fault arc detector is set to a split structure, information is transmitted between the master and the slave in the form of digital signals, and the premise is that the slave part performs arc detection on the line to be detected, determines whether the detected arc is a fault arc, and transmits the arc as a detection result to the master in the form of a digital signal. Based on this, the slave part independently completes the arc detection and type judgment work; the master only detects the frequency of occurrence of the fault arc based on the digital signal, and performs subsequent processing on the fault arc based on the frequency (including sending information about the line where the fault arc is located to the upper computer, controlling the alarm unit to alarm, and storing and displaying the fault arc information, etc.).

[0080] 1. Further explanation of the slave:

[0081] In this embodiment, the arc detection board is provided with a slave controller and an arc detection circuit. Figure 5 From the disclosed circuit schematic diagram of the arc detection circuit in the slave machine, it can be seen that the arc detection circuit is connected to the arc detection coil at the upper end of the slave machine housing through the two terminals A+ and A-, performs arc detection on the circuit to be detected, and amplifies the detected arc information before sending it to the slave machine controller through the output terminal B1. Based on this, the overall working principle of the slave machine is: the arc detection circuit detects the current change in the arc detection coil and transmits the detection result to the slave machine controller, and the slave machine controller determines whether there is an arc in the circuit to be detected and whether the existing arc is a fault arc according to the change of the current over time.

[0082] In order to make the technical solution of this embodiment more complete, the classification and identification method of the fault arc are specifically described below:

[0083] In this field, "bad arc" refers specifically to "fault arc", which occurs in electrical systems at unpredictable times and locations, and is difficult to control in terms of scale and duration. It is also non-periodic and prone to persist, develop, and spread, ultimately causing damage to equipment and lines, and eventually leading to electrical fires.

[0084] In the prior art, arc faults are divided into three categories:

[0085] a) The arc caused by the breakage of the live conductor or poor contact is also called "series arc" because the arc is in series with the load. The structural principle corresponding to this type of arc is shown in Figure 6(a);

[0086] b) The arc between the live conductors (phase line and phase line, phase line and neutral line) is also called "arc short circuit". Because the arc is in parallel with the normal load on the line, it is also called "parallel arc". The structural principle corresponding to this type of arc is shown in Figure 6(b);

[0087] c) The arc between the charged conductor and the grounding conductor (PE line, grounded equipment conductive shell, etc.), also known as "arcing grounding fault" or "arcing leakage". The structural principle corresponding to this arc is shown in Figure 6(c);

[0088] Taking the series fault arc as an example, the waveforms of its current and voltage changing with time can be found in Figure 7 The current and voltage waveforms are in phase, and a flat shoulder waveform appears near each current zero crossing. This is due to the arc ignition and extinguishing process at each zero crossing. The voltage waveform is approximately a rectangular wave outside the arc ignition and extinguishing parts. For series faults, due to the arc voltage in series, the effective value of the current I 2 t is lower than the rated current of the line, so it will not cause the overcurrent protection device to operate, and therefore it is more likely to cause an electrical fire.

[0089] Taking the parallel fault arc as an example, see Figure 8 Since this type of fault arc generally occurs intermittently, the waveforms of the arc current and voltage are also intermittent. The effective current value and rated current value are smaller than those in the direct short circuit case, and a shoulder also appears in the current waveform during the arcing period.

[0090] In the traditional arc detection method, when detecting the arc, the traditional fault arc detector uses the period of the AC voltage zero crossing as the unit of measurement of the half-wave period N. The half-wave period N involved here refers to the period of the voltage zero crossing change in a 50Hz power supply environment, which is 10ms. In this way, 1s of timing is performed. Therefore, this method needs to rely on AC power to complete. In this embodiment, since the traditional fault arc detection function is moved to the slave part of the split-type fault arc detector, in order to solve the measurement problem of the half-wave period, a software simulation method is used to determine the half-wave period time, which can not only ensure the timing accuracy of 1s, but also get rid of the dependence on AC power. In addition, the zero-crossing detection circuit can be removed to simplify the circuit routing on the arc detection board. See Fig. 9 In this embodiment, the specific method of performing arc detection by the split-type fault arc detector is as follows:

[0091] S01: The slave performs arc detection on the transmission line, takes the moment when the arc is first detected as the timing starting point, uses the internal clock of the slave control chip to continuously perform half-wave period sampling on the current in the transmission line within a preset period;

[0092] The preset period is determined according to the half-wave period of the current carried in the transmission line. Taking 220V mains electricity as an example, its half-wave period is 10ms, and the preset period must be an integer multiple of 10ms. Generally, when the half-wave period is 10ms, the preset period is set to 1s.

[0093] S02: Recording parameter characteristics of the detected current changes in the transmission line;

[0094] Among them, the parameter characteristics include the sampling time t and the current amplitude A and phase ω in the transmission line corresponding to the sampling time; the reference data includes the amplitude A0 and phase ω0 of the current carried in the transmission line corresponding to the half-wave cycle sampling point when it is not disturbed by the arc.

[0095] S03: Compare the parameter characteristics with the pre-stored reference data to determine whether there is an arc within the half-wave period;

[0096] If each parameter in the parameter feature exceeds the standard data range of the corresponding item in the reference data, it is determined that an arc exists in the half-wave cycle.

[0097] S04: Determine whether there is a fault arc based on the periodicity and number of arcs occurring within a preset period.

[0098] If the occurrence of arcs within a preset period is not periodic, and the number of arcs that occur is greater than a critical number, then a fault arc exists within the preset period.

[0099] It should be noted that the alarm rule for mains fault arc in the prior art is: if the half-wave arc reaches 14 cycles or more within 1 second, and the detected arc is not periodic, it is determined to be a fault arc. Therefore, the slave part needs to detect the periodicity and frequency of the fault arc to determine whether it is a fault arc. Based on this, the software implementation flow of the above process can be found in Fig.10 This embodiment uses software to simulate the half-wave cycle to perform fault arc detection, so that the fault arc detection process is no longer dependent on the AC zero crossing point, simplifies the circuit structure, and also provides technical support for the development of the fault arc detection device towards a split structure.

[0100] When the arc detection unit in the slave machine detects the presence of a fault arc in the transmission line, the detection result is converted into a digital signal and transmitted to the host part through the first communication unit. The host part controls the circuit breaker to perform the circuit breaking action, and when necessary, after the host receives the digital signal sent by the slave machine, it sends the information of the line to be protected where the fault arc occurs to the upper computer through the third communication unit 113.

[0101] In addition, in other embodiments, the arc detection unit in the slave machine may also be directly connected to the alarm unit in the master machine. When the arc detection unit detects the presence of a fault arc, the alarm unit is directly triggered to sound an alarm.

[0102] 2. Further explanation of the host:

[0103] The host polls the slave to obtain digital signals and detects whether there is a fault arc in the line where the slave is installed. If there is a fault arc, the corresponding circuit breaker is controlled to perform a circuit breaking action. Otherwise, the host continues to poll the slave to obtain digital signals.

[0104] This embodiment adopts a split master-slave structure. During installation, only the master is installed on the rail of the distribution box, and the slave is mounted on the line to be protected between the circuit breaker and the load. Even if a single master is connected to multiple slaves, it will not occupy more rail space, which fundamentally solves the problem of traditional fault arc detectors occupying more rail space.

[0105] Since the host and the slave communicate through digital signals, the host only needs to process the received digital signals accordingly. Therefore, not only the transmission distance is long, but also the one-to-many structure of a single host connecting multiple slaves does not affect the data processing speed of the host, which can effectively ensure the efficiency of arc fault processing. In addition, the use of digital signal communication reduces the wiring, which reduces the difficulty of installation and wiring of the arc fault detector and helps to reduce maintenance costs. In addition, when the number of lines to be detected is increased, only the number of slaves needs to be increased accordingly, saving material costs.

[0106] When installing the slave, it is only necessary to make the line to be protected (the live wire) pass through the slave without disconnecting the line. Compared with the prior art, the number of contacts is reduced, and the possibility of arc fault is reduced;

[0107] The power supply and detection parts inside the slave are divided into two circuit boards, and the two circuit boards are stacked and arranged adjacent to the arc detection coil, thereby reducing the size of the slave and further saving space.

[0108] Need to explain:

[0109] The above is only one embodiment of the present invention. It should be understood by those skilled in the art that the embodiments of the present invention can be provided as methods, systems or computer program products. Therefore, the present invention can be implemented in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware.

[0110] In addition, it should be noted that:

[0111] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0112] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0113] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A slave device for a split type arc fault detector, characterized in that: The device is mounted on the line to be protected between the circuit breaker and the load, and comprises a slave housing, an arc detection unit and a first communication unit located in the slave housing. The arc detection unit is used to detect and judge the type of arc and convert the detection result of the fault arc into a digital signal; The first communication unit is connected to the arc detection unit and is used to transmit the digital signal to the host; The arc detection unit includes a circuit board and an arc detection coil, wherein the arc detection coil is located at the upper end of the slave housing, the circuit board is located at the lower end of the slave housing, and the arc detection coil and the circuit board are arranged adjacent to each other up and down; The slave housing is provided with a through hole along the axial position of the arc detection coil, so as to mount the slave on the line to be protected between the circuit breaker and the load; The circuit board includes an arc detection board and a power supply board, and the power supply board and the arc detection board are stacked on the lower end of the arc detection coil along the radial direction of the arc detection coil; The power board is connected to the power supply unit of the host of the split-type arc fault detector through two buses; The fault arc detection method is as follows: S01: The slave performs arc detection on the transmission line, takes the moment when the arc is first detected as the timing starting point, uses the internal clock of the slave control chip to continuously perform half-wave period sampling of the current in the transmission line within a preset period; wherein the preset period is determined according to the half-wave period of the current carried in the transmission line, such as if the half-wave period is 10ms, the preset period must be an integer multiple of 10ms; S02: Recording the parameter characteristics of the detected current change in the transmission line; wherein the parameter characteristics include the sampling time t and the current amplitude A and phase ω in the transmission line corresponding to the sampling time; the reference data include the amplitude A0 and phase ω0 of the current carried in the transmission line in a state without arc interference, corresponding to the half-wave cycle sampling point; S03: Compare the parameter characteristics with the pre-stored reference data to determine whether there is an arc in the half-wave period: if each parameter in the parameter characteristics exceeds the standard data range of the corresponding item in the reference data, it is determined that there is an arc in the half-wave period; S04: Determine whether there is a fault arc based on the periodicity and number of arcs occurring within a preset period: If the occurrence of arcs within the preset period is not periodic and the number of arcs occurring is greater than a critical number, then there is a fault arc within the preset period.

2. The slave device for split-type arc fault detector according to claim 1, characterized in that: The upper ends of the arc detection plate and the power supply plate are both provided with an arc-shaped notch adapted to the size of the arc detection coil, and the arc detection coil is clamped in the arc-shaped notch.

3. The slave device for split-type arc fault detector according to claim 2, characterized in that: The upper end of the slave housing is used to place the arc detection coil, and its edge is an arc shape adapted to the outer diameter of the arc detection coil; The lower end of the slave housing is used for placing the stacked arc detection board and the power supply board, and the edge thereof is in a right angle shape.

4. The slave device for split-type arc fault detector according to claim 1, characterized in that: The slave uses software to simulate the half-wave period of the arc to obtain the curve of the arc changing with time, and then identify the fault arc.

5. A host for a split type arc fault detector, used in conjunction with a slave for a split type arc fault detector as claimed in any one of claims 1 to 4, characterized in that: It includes a host housing and a main control unit, a second communication unit, an alarm unit and a power supply unit located therein; The second communication unit is connected to the main control unit and is used to receive a digital signal sent by the slave as a fault arc detection result, and transmit the digital signal to the main control unit; The main control unit is used to process the fault arc according to the received digital signal and communicate with the host computer; The alarm unit is connected to the main control unit and responds to an indication signal from the main control unit to alarm an arc fault; The power supply unit is connected to the main control unit and is used to supply power to the host and the slave.

6. The host for split type arc fault detector according to claim 5, characterized in that: It also includes a third communication unit, which is connected to the main control unit and the host computer respectively to serve as a communication channel between the main control unit and the host computer.

7. A split type arc fault detector, characterized in that: It comprises a slave as described in any one of claims 1 to 4 and a host as described in any one of claims 5 to 6, wherein the slave is mounted on a line to be protected between a circuit breaker and a load, performs arc fault detection on the line to be protected, and transmits the detection result to the host in the form of a digital signal, and the host processes the arc fault according to the digital signal.

8. A split type arc fault detector according to claim 7, characterized in that: The host and the slave are connected via two buses.

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