Arc fault detection system and distribution board

Abstract

To reduce the number of circuit components.SOLUTION: An arc fault detection system 1 comprises a first detection unit 10, a plurality of second detection units 20, and a determination unit 30. It is possible that a current flowing in each of a plurality of branch circuits BC1 passes through in a common path unit 40. The first detection unit 10 detects first information related to at least one of a first current I1 flowing in the common path unit 40 and a first voltage generated in the common path unit 40. Each of the plurality of second detection units 20 detects second information related to at least one of a second current I2 flowing in a corresponding branch circuit BC1 among the plurality of branch circuits BC1 and a second voltage generated in a corresponding branch circuit BC1 among the plurality of branch circuits BC1. The determination unit 30 determines whether there is an arc failure in each of the plurality of branch circuits BC1 on the basis of the first information detected by the first detection unit 10 and the plurality of pieces of second information detected respectively by the plurality of second detection units 20.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an arc fault detection system and a distribution board. More specifically, the present disclosure relates to an arc fault detection system for detecting the presence or absence of an arc fault in a branch circuit and a distribution board.

Background Art

[0002] Patent Document 1 discloses a circuit breaker for a distribution board housed as an internal component in a distribution board cabinet. The circuit breaker for a distribution board includes a primary terminal, a secondary terminal, and a cutoff unit that cuts off power supply to a load connected to the secondary terminal when the current value between the primary terminal and the secondary terminal exceeds a predetermined current value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, when detecting an arc fault due to disconnection or short circuit of wiring connected to each of a plurality of circuit breakers for a distribution board, it was necessary to provide a circuit necessary for detecting an arc fault in each of the plurality of circuit breakers for a distribution board.

[0005] An object of the present disclosure is to provide an arc fault detection system and a distribution board capable of reducing the number of circuit components.

Means for Solving the Problems

[0006] An arc fault detection system according to one aspect of the present disclosure is an arc fault detection system that detects the presence or absence of an arc fault in each of a plurality of branch circuits branching from a main circuit connected to an AC power supply. The arc fault detection system comprises a common path section, a first detection section, a plurality of second detection sections, and a determination section. The common path section is through which the current flowing to each of the plurality of branch circuits can pass. The first detection section detects first information relating to at least one of a first current flowing through the common path section and a first voltage generated in the common path section. The plurality of second detection sections are provided corresponding to each of the plurality of branch circuits. Each of the plurality of second detection sections detects second information relating to at least one of a second current flowing through the corresponding branch circuit and a second voltage generated in the corresponding branch circuit. The determination section determines the presence or absence of an arc fault in each of the plurality of branch circuits based on the first information detected by the first detection section and the plurality of second information detected by each of the plurality of second detection sections. The frequency range detected by the first detection unit is higher than the frequency range detected by the second detection unit.

[0007] A distribution board according to one aspect of the present disclosure comprises the arc fault detection system, a main circuit breaker provided in the main circuit, a plurality of branch circuit breakers provided in each of the plurality of branch circuits, and a housing. The housing houses the arc fault detection system, the main circuit breaker, and the plurality of branch circuit breakers. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an arc fault detection system and a distribution board that can reduce the number of circuit components. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic circuit diagram of a distribution board equipped with an arc fault detection system according to one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic circuit diagram showing the specific configuration of the distribution board mentioned above. [Figure 3]Figure 3 is a front view of the same distribution board with the cover removed. [Figure 4] Figure 4 is an exploded perspective view showing the main components of the distribution board shown above. [Figure 5] Figure 5 is an exploded perspective view showing the main components of the distribution board shown above. [Figure 6] Figure 6 is a schematic circuit diagram of a distribution board equipped with an arc fault detection system according to Modification Example 1. [Modes for carrying out the invention]

[0010] Hereinafter, an arc fault detection system according to an embodiment and a distribution board equipped therewith will be described in detail with reference to the drawings. However, the configuration described in the following embodiments is merely one example of this disclosure. This disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of this disclosure can be achieved. Furthermore, the figures described in the following embodiments are schematic diagrams, and the dimensional ratios of the size of each component do not necessarily reflect the actual dimensional ratios.

[0011] (Embodiment) (1) Overview Figure 1 is a schematic circuit diagram of the arc fault detection system 1 and the distribution board 100 equipped therewith according to this embodiment.

[0012] The arc fault detection system 1 detects the presence or absence of an arc fault in each of the multiple branch circuits BC1 that branch off from the main circuit MC1 connected to the AC power supply 2.

[0013] The arc fault detection system 1 comprises a common path section 40, a first detection section 10, a plurality of second detection sections 20, and a determination section 30.

[0014] The common path section 40 allows current flowing through each of the multiple branch circuits BC1 to pass through.

[0015] The first detection unit 10 detects first information regarding at least one of the first current I1 flowing through the common path unit 40 and the first voltage generated in the common path unit 40.

[0016] The plurality of second detection units 20 are provided corresponding to each of the plurality of branch circuits BC1.

[0017] Each of the plurality of second detection units 20 detects second information regarding at least one of the second current I2 flowing through the corresponding branch circuit BC1 among the plurality of branch circuits BC1 and the second voltage generated in the corresponding branch circuit BC1 among the plurality of branch circuits BC1.

[0018] The determination unit 30 determines the presence or absence of an arc fault in each of the plurality of branch circuits BC1 based on the first information detected by the first detection unit 10 and the plurality of second information detected by the plurality of second detection units 20 respectively.

[0019] The arc fault detection system 1 of the present embodiment is used, for example, to detect an arc fault in each of a plurality of branch circuits BC1 branched from the main circuit MC1 in a distribution board 100 for housing (for single-family houses or apartment houses). The "arc fault" referred to in the present disclosure can be caused, for example, by a wire abnormality such as insulation deterioration or semi-breakage in a pair of electric wires L30 included in the branch circuit BC1. The "semi-breakage" referred to in the present disclosure means a state where the wire is on the verge of breaking. Specifically, if each of the pair of electric wires L30 is a stranded wire, it is a state where some of the plurality of strands constituting the stranded wire are broken. An arc fault may include, as an example, an abnormal event in which an arc (so-called parallel arc) occurs due to a short circuit between a pair of electric wires L30. Further, an arc fault may include, as an example, an abnormal event in which an arc (so-called series arc) occurs due to semi-breakage of one of a pair of electric wires L30. Note that the magnitude of the current flowing through the electric wire L30 due to a parallel arc is about several tens to several hundreds of A, whereas in the case of a series arc, the current flows through the load device LD1, so the magnitude of the current flowing through the electric wire L30 due to a series arc is about several A to 30 A.

[0020] In the present disclosure, the main circuit MC1 may include, for example, a main electric circuit L10 connected to an AC power supply 2 and a main breaker B1 connected between the AC power supply 2 and the main electric circuit L10. The main electric circuit L10 shown in FIG. 1 is, for example, a single-phase three-wire power distribution system and includes an electric circuit L11 as the L1 phase, an electric circuit L12 as the L2 phase, and an electric circuit L13 as the N phase.

[0021] Each of the plurality of branch circuits BC1 may include, for example, a branch electric circuit L20 branched from the main electric circuit L10, a branch breaker B2 connected to the terminal of the branch electric circuit L20, a pair of electric wires L30 connecting between the branch breaker B2 and the load device LD1, and the load device LD1. In the present disclosure, since a single-phase three-wire power distribution system is adopted, the plurality of branch circuits BC1 may include a plurality of first branch circuits BC11 branched from the electric circuit L11 of the L1 phase and the electric circuit L13 of the N phase, and a plurality of second branch circuits BC12 branched from the electric circuit L12 of the L2 phase and the electric circuit L13 of the N phase.

[0022] The common path section 40 is a path through which the second current I2 flowing through each of the multiple branch circuits BC1 can pass. The common path section 40 includes at least a circuit through which the second current I2 flowing through each of the multiple branch circuits BC1 can pass, and further includes an impedance element connected in series with the circuit. Here, the statement that the second current I2 flowing through each of the multiple branch circuits BC1 can pass through the common path section 40 means that the second current I2 flowing through each branch circuit BC1 can flow bidirectionally through the common path section 40. Note that it is not essential that all of the second current I2 can pass through the common path section 40; it is sufficient that at least some of the current components of the second current I2 (for example, high-frequency components or low-frequency components) can pass through the common path section 40. In this disclosure, since a plurality of branch circuits BC1 comprises a plurality of first branch circuits BC11 and a plurality of second branch circuits BC12, the common path section 40 may include a first common path section 40A through which the second current I2 flowing through each of the plurality of first branch circuits BC11 can pass, and a second common path section 40B through which the second current I2 flowing through each of the plurality of second branch circuits BC12 can pass. The first common path section 40A is a circuit that electrically connects the L1 phase circuit L11 and the N phase circuit L13, and the second current I2 flowing through each of the plurality of first branch circuits BC11 can pass through the first common path section 40A. The second common path section 40B is a circuit that electrically connects the L2 phase circuit L12 and the N phase circuit L13, and the second current I2 flowing through each of the plurality of second branch circuits BC12 can pass through the second common path section 40B.

[0023] In this case, if an arc fault occurs in any of the branch circuits BC1, an arc current is generated due to the arc fault, and a portion of the arc current flows through the common path section 40. Therefore, the first information detected by the first detection unit 10 changes due to the arc fault that occurred in the branch circuits BC1, so the determination unit 30 can use the first information to determine whether or not an arc fault has occurred. In other words, the first information includes information about the second current flowing through each of the multiple branch circuits BC1. In this embodiment, the determination unit 30 uses the first information detected by the first detection unit 10 and the multiple pieces of second information detected by the multiple second detection units 20 to determine whether or not an arc fault has occurred in each of the multiple branch circuits BC1. If both the first information and the second information used to determine whether or not an arc fault has occurred are to be detected in each of the multiple branch circuits BC1, it is necessary to provide a first detection unit and a second detection unit in each of the multiple branch circuits BC1. In contrast, in the arc fault detection system 1 of this embodiment, the first detection unit 10 detects the first information in the common path section 40 through which the current flowing through each of the multiple branch circuits BC1 can pass. Therefore, the arc fault detection system 1 of this embodiment has the advantage of reducing the number of circuit components constituting the arc fault detection system 1 compared to the case in which a first detection unit for detecting first information is provided in each of the multiple branch circuits BC1.

[0024] (2) Details Hereinafter, the arc fault detection system 1 and the distribution board 100 equipped with the arc fault detection system 1 according to this embodiment will be described with reference to Figures 1 to 5.

[0025] The housing 101 of the distribution board 100 (see Figure 3) is installed and used in residential facilities such as detached houses or apartment buildings. However, the facilities in which the distribution board 100 is installed are not limited to residential facilities such as detached houses or apartment buildings, and may also be installed in non-residential buildings (for example, factories, commercial buildings, office buildings, hospitals, schools, etc.).

[0026] In the following explanation, unless otherwise specified, the X-axis direction in Figure 3 is defined as the left-right direction, and the Z-axis direction as the up-down direction. Furthermore, the directions perpendicular to the X-axis and Z-axis directions are defined as the front-back direction. Additionally, the positive direction in the X-axis direction is defined as the right side, and the positive direction in the Z-axis direction is defined as the up side. However, these directions are merely examples and are not intended to limit the direction in which the arc fault detection system 1 and the distribution board 100 may be used. Also, the arrows indicating directions in the drawings are for illustrative purposes only and do not represent actual movement.

[0027] (2.1) Distribution board First, the distribution board 100 will be described with reference to Figures 1 and 3 to 5. As shown in Figures 1 and 3, the distribution board 100 comprises an arc fault detection system 1, a main circuit breaker B1 provided in the main circuit MC1, a plurality of branch circuit breakers B2 provided in each of the plurality of branch circuits BC1, and a housing 101. The housing 101 houses the arc fault detection system 1, the main circuit breaker B1, and the plurality of branch circuit breakers B2. The housing 101 also houses a monitoring unit 110 that monitors power consumption, etc., in the main circuit MC1 and the plurality of branch circuits BC1. It should be noted that it is not mandatory for the housing 101 to house the monitoring unit 110, and the monitoring unit 110 can be omitted as appropriate.

[0028] The housing 101 of the distribution board 100 comprises a box-shaped body 102 (see Figure 3) with an open front, and a cover that closes the opening of the body 102. Note that the cover is not shown in Figure 3. The housing 101 is mounted to a mounting target, such as a building wall or a component of the building. The housing 101 may be mounted partially or entirely embedded in a mounting hole provided in the wall.

[0029] As shown in Figure 3, the enclosure 101 houses a main circuit breaker B1, multiple branch circuit breakers B2, and a monitoring unit 110, among other things. The main circuit breaker B1, multiple branch circuit breakers B2, and monitoring unit 110 are attached to the body 102 either directly or via mounting parts. Figure 3 shows the arrangement of the main circuit breaker B1, multiple branch circuit breakers B2, and monitoring unit 110 inside the enclosure 101, but this arrangement is just one example and can be changed as appropriate.

[0030] The main circuit breaker B1 comprises, for example, a box-shaped body 130 made of synthetic resin. The main circuit breaker B1 includes a primary terminal 131 to which the wire L40 from the AC power supply 2 is connected, a secondary terminal to which the three conductive bars constituting the main circuit L10 are connected, and a contact connected between the primary terminal 131 and the secondary terminal. In addition, a handle 132 for manually switching the contact on / off is provided on the front of the body 130 of the main circuit breaker B1.

[0031] Furthermore, the main circuit breaker B1 is equipped with a protection circuit that opens its contacts when it detects a leakage current flowing through the main circuit L10. The protection circuit may also have a function to detect an abnormal condition in which an overcurrent such as a short-circuit current or overload current flows through the main circuit L10, and may open its contacts when it detects an overcurrent flowing through the main circuit L10. The protection circuit may also have a function to detect a phase loss in the neutral wire in a single-phase three-wire wiring system, and may open its contacts when it detects a phase loss in the neutral wire. The main circuit breaker B1 may also be equipped with a limiter function that opens its contacts when a current exceeding a predetermined limit value flows through it.

[0032] The secondary terminals of the main circuit breaker B1 protrude laterally from the right side of the main circuit breaker B1 body 130. Three conductive bars 141, 142, and 143 (see Figures 4 and 5) that constitute the main circuit L10 are connected to the secondary terminals of the main circuit breaker B1. Specifically, conductive bar 141, which constitutes the L1 phase circuit L11, conductive bar 142, which constitutes the L2 phase circuit L12, and conductive bar 143, which constitutes the N phase circuit L13 are connected to the secondary terminals of the main circuit breaker B1. Each conductive bar 141, 142, and 143 is formed from a conductive material into a long plate shape that is elongated in the left-right direction, and is positioned in the center in the vertical direction inside the housing 101, on the right side of the main circuit breaker B1.

[0033] In this embodiment, the three conductive bars 141, 142, and 143 and the multiple branch breakers B2 are mounted on a base 150 made of, for example, synthetic resin. A current measuring instrument 170 for measuring the current flowing through each of the multiple branch circuits BC1 is also mounted on the base 150. This base 150 is attached to the body 102 via, for example, a metal support member 160. In other words, the three conductive bars 141, 142, and 143 and the multiple branch breakers B2 are attached to the body 102 via the base 150 and the support member 160.

[0034] On the front of the base 150, a pair of support columns 151 (see Figure 4) are provided, each projecting forward from the center in the vertical direction at both the left and right ends. On the front of the base 150, L1-phase conductive bars 141 and L2-phase conductive bars 142 are arranged on both the upper and lower sides of the pair of support columns 151. The L1-phase conductive bar 141 and L2-phase conductive bar 142 are arranged along the left-right direction on the front of the base 150. In addition, an N-phase conductive bar 143 is attached to the front of the base 150 so as to span across the front ends of the pair of support columns 151.

[0035] Furthermore, multiple branch breakers B2 can be arranged side by side in the left-right direction in the mounting spaces SP1 and SP2 on both the upper and lower sides of the front of the base unit 150, with the N-phase conductive bar 143 in between.

[0036] The body 200 of the branch breaker B2 (see Figure 5) is formed in the shape of a rectangular parallelepiped, with dimensions in the left-right direction being smaller than dimensions in the up-down and front-back directions. The body 200 of the branch breaker B2 has three outlets 201 openings on the side facing the N-phase conductive bar 143 when the branch breaker B2 is installed in the mounting space SP1 or SP2. The three outlets 201 are arranged in a front-to-back direction on one side of the body 200. Inside the body 200, plug-in terminals are housed at positions corresponding to two of the three outlets 201. In the 100V branch breaker B2, plug-in terminals are housed at positions corresponding to two of the outlets 201, excluding the central outlet 201 in the front-to-back direction. In the 200V branch breaker B2, plug-in terminals are housed at positions corresponding to two of the outlets 201, excluding the frontmost outlet 201.

[0037] Furthermore, the body 200 of the branch breaker B2 is equipped with a quick-connect terminal on the end opposite to the end with three sockets 201, to which the wire L30 from the load device LD1 is connected.

[0038] The conductive bar 141 comprises a flat plate portion 1411 positioned on the front surface of the base 150, and a plurality of connection terminals 1412 formed by bending the ends of the flat plate portion 1411. The plurality of connection terminals 1412 are arranged side by side in the left-right direction, with half of the connection terminals 1412 protruding downwards and the other half protruding upwards. The plurality of connection terminals 1412 protruding downwards and the plurality of connection terminals 1412 protruding upwards are each spaced at the same interval as the width dimension of one branch breaker B2.

[0039] Furthermore, the conductive bar 142 comprises a flat plate portion 1421 positioned on the front surface of the base 150, and a plurality of connection terminals 1422 formed by bending the ends of the flat plate portion 1421. The plurality of connection terminals 1422 are arranged in a left-right direction, with half of the plurality of connection terminals 1422 protruding downwards and the other half protruding upwards. The plurality of connection terminals 1422 protruding downwards and the plurality of connection terminals 1422 protruding upwards are each spaced at the same interval as the width dimension of one branch breaker B2.

[0040] Here, the three sockets 201 of the branch breaker B2, which is placed in the upper mounting space SP1, are connected in order from the front: the N-phase conductive bar 143, the L2-phase conductive bar 142's connection terminal 1422, and the L1-phase conductive bar 141's connection terminal 1412. Therefore, when a 100V branch breaker B2 is placed in the mounting space SP1, this branch breaker B2 is connected to the L1-phase conductive bar 141 and the N-phase conductive bar 143, respectively. In other words, the branch breaker B2 placed in the upper mounting space SP1 becomes the branch breaker B2 of the first branch circuit BC11. Also, when a 200V branch breaker B2 is placed in the mounting space SP1, this branch breaker B2 is connected to the L1-phase conductive bar 141 and the L2-phase conductive bar 142, respectively.

[0041] Furthermore, the three sockets 201 of the branch breaker B2 located in the lower mounting space SP2 are, in order from the front, connected to the N-phase conductive bar 143, the L1-phase conductive bar 141's connection terminal 1412, and the L2-phase conductive bar 142's connection terminal 1422. Therefore, when a 100V branch breaker B2 is placed in the mounting space SP2, this branch breaker B2 is connected to the L2-phase conductive bar 142 and the N-phase conductive bar 143, respectively. In other words, the branch breaker B2 located in the lower mounting space SP2 becomes the branch breaker B2 of the second branch circuit BC12. Also, when a 200V branch breaker B2 is placed in the mounting space SP2, this branch breaker B2 is connected to the L1-phase conductive bar 141 and the L2-phase conductive bar 142, respectively.

[0042] Furthermore, two current measuring instruments 170 are mounted on the front side of the base 150, spanning between a pair of support columns 151. One of the two current measuring instruments 170 is positioned below the pair of support columns 151, and the other is positioned above the pair of support columns 151. Since the two current measuring instruments 170 have similar configurations, the current measuring instrument 170 positioned below the pair of support columns 151 (see Figure 5) will be used as an example for explanation.

[0043] The current measuring instrument 170 includes a substrate 171 positioned such that the normal to the main surface is parallel to the vertical direction. The substrate 171 is formed in the shape of a rectangular plate, with its left-right dimension being larger than its front-back dimension. The substrate 171 is provided with multiple circular through holes 172 into which multiple connection terminals 1422 are inserted, and multiple rectangular through holes 173 into which multiple connection terminals 1412 are inserted. Multiple current sensors 21 are provided around the multiple through holes 172 located on the rear side of the substrate 171.

[0044] In the current measuring instrument 170 positioned below the pair of support columns 151, multiple connection terminals 1422 are inserted into multiple through holes 172 in the substrate 171. Therefore, multiple current sensors 21 can measure the current flowing through each of the multiple connection terminals 1422, that is, the value of the second current I2 flowing through each of the multiple second branch circuits BC12.

[0045] Furthermore, in the current measuring instrument 170 positioned above the pair of support columns 151, multiple connection terminals 1412 are inserted into multiple through holes 172 in the substrate 171. Therefore, multiple current sensors 21 can measure the current flowing through each of the multiple connection terminals 1412, that is, the second current I2 flowing through each of the multiple first branch circuits BC11.

[0046] Here, each current sensor 21 is a Rogowski coil consisting of a coreless air-core coil that produces an output corresponding to the current passing through the connection terminals 1412 or 1422, which are routed through the through-hole 172. The current measuring instrument 170 calculates the value of the second current I2 flowing through each of the multiple branch circuits BC1 based on the output of each current sensor 21. Note that the current sensor 21 is not limited to a Rogowski coil, but may also be a current transformer, Hall element, magnetoresistive element, GMR (Giant Magnetic Resistances) element, shunt resistor, or other sensor.

[0047] (2.2) Arc detection system Next, the arc fault detection system 1 will be described with reference to Figures 1 to 5. As described above, the arc fault detection system 1 comprises a common path section 40, a first detection section 10, a plurality of second detection sections 20, and a determination section 30.

[0048] In this embodiment, the branch circuit BC1 includes a plurality of first branch circuits BC11 that branch off from the L1 phase circuit L11 and the N phase circuit L13, and a plurality of second branch circuits BC12 that branch off from the L2 phase circuit L12 and the N phase circuit L13.

[0049] Therefore, in this embodiment, a first common path section 40A is provided between the L1 phase circuit L11 and the N phase circuit L13, through which the second current I2 flowing through each of the multiple first branch circuits BC11 can pass, and a second common path section 40B is provided between the L2 phase circuit L12 and the N phase circuit L13, through which the second current I2 flowing through each of the multiple second branch circuits BC12 can pass.

[0050] Figure 2 is a schematic circuit diagram showing the specific configuration of the arc fault detection system 1. Since the first branch circuit BC11 and the second branch circuit BC12 have similar configurations, the second branch circuit BC12 and the circuit for detecting the presence or absence of an arc fault in the second branch circuit BC12 are not shown or explained.

[0051] In the specific circuit example shown in Figure 2, the common path section 40 includes a capacitor C1. Specifically, the first common path section 40A includes a circuit connecting the L1 phase circuit L11 and the N phase circuit L13, and a capacitor C1 connected in series with this circuit. Since the impedance of capacitor C1 decreases with increasing frequency, the high-frequency components of the current (second current I2) flowing through each of the multiple first branch circuits BC11 can pass through the first common path section 40A. In this disclosure, the high-frequency components of the second current I2 are current components in the frequency range higher than the lower limit frequency (for example, a frequency of several kHz to several tens of kHz). The low-frequency components of the second current I2 are current components in the frequency range below the lower limit frequency. Note that the common path section 40 may include a high-pass filter that can pass through the current generated during an arc fault instead of capacitor C1.

[0052] A current sensor 11, such as a Rogowski coil, is provided in the circuit constituting the first common path section 40A. The current sensor 11 is, for example, a coreless air-core coil formed on the surface of a substrate having a through-hole, surrounding the through-hole. The current sensor 11 is positioned with a portion of the circuit connecting the L1 phase circuit L11 and the N phase circuit L13 (i.e., a portion of the circuit constituting the first common path section 40A) inserted into the through-hole provided in the substrate.

[0053] In the specific circuit example shown in Figure 2, the first detection unit 10 is comprised of a high-frequency detection unit 12 that uses a current sensor 11 to detect the current value of the high-frequency current flowing through the first common path section 40A. In other words, the high-frequency detection unit 12, as the first detection unit 10, detects the current value of the high-frequency current flowing through the first common path section 40A as first information. To put it another way, the first detection unit 10 of this embodiment detects first information regarding the first current I1 flowing through the common path section 40 using a Rogowski coil provided in the common path section 40 (for example, the first common path section 40A in Figure 2). More specifically, the first detection unit 10 detects the current value of the first current I1 flowing through the common path section 40 as first information using a Rogowski coil provided in the common path section 40. Since the first detection unit 10 detects first information regarding the first current I1 using a Rogowski coil, it can be made smaller compared to cases where a current transformer or the like is used as a sensor to detect the first current I1.

[0054] Furthermore, in the specific circuit example shown in Figure 2, a low-frequency detection unit 22 provided in each of the multiple first branch circuits BC11 detects second information regarding the second current I2 flowing through each of the multiple first branch circuits BC11 using a current sensor 21 provided in each of the multiple branch circuits L20. Here, the second detection unit 20 is composed of the low-frequency detection units 22 provided in each of the multiple first branch circuits BC11. In other words, each of the multiple second detection units 20 uses a Rogowski coil provided in the corresponding branch circuit BC1 among the multiple branch circuits BC1 to detect the aforementioned second information regarding the second current I2 flowing through the corresponding branch circuit BC1 among the multiple branch circuits BC1. Since the second detection unit 20 detects the second current I2 using a Rogowski coil, it can be made smaller compared to the case where a current transformer or the like is used as a sensor for detecting the second current I2. Furthermore, the second detection unit 20, which is the low-frequency detection unit 22, detects the magnitude of the low-frequency component contained in the second current I2, that is, the current value of the low-frequency current, as second information. The low-frequency detection unit 22 includes, for example, a low-pass filter that attenuates the high-frequency component contained in the output of the current sensor 21, and detects the current value of the low-frequency current flowing through the first branch circuit BC11 from the signal after it has passed through the low-pass filter.

[0055] The determination unit 30 primarily consists of, for example, a computer system having one or more processors and memory. The functions of the determination unit 30 are realized when the processor of the computer system executes a program recorded in the memory of the computer system. The program may be recorded in memory, provided via a telecommunication line such as the Internet, or provided on a non-temporary recording medium such as a memory card.

[0056] The determination unit 30 receives first information detected by the high-frequency detection unit 12 (first detection unit 10) and multiple pieces of second information detected by multiple low-frequency detection units 22 (second detection unit 20). Based on the first information detected by the high-frequency detection unit 12 and the multiple pieces of second information detected by the multiple low-frequency detection units 22, the determination unit 30 determines whether or not there is an arc fault in the multiple branch circuits BC1. Specifically, the determination unit 30 determines that an arc fault has occurred in the branch circuit BC1 that is the target of detection by the low-frequency detection unit 22 if the current value of the high-frequency current detected by the high-frequency detection unit 12 is equal to or greater than a predetermined first threshold current, and the current value of the low-frequency current detected by the low-frequency detection unit 22 is equal to or greater than a predetermined second threshold current. Furthermore, the determination unit 30 determines that no arc fault has occurred in the branch circuit BC1, which is the target of detection by the low-frequency detection unit 22, if the current value of the high-frequency current detected by the high-frequency detection unit 12 is less than a predetermined first threshold current, or if the current value of the low-frequency current detected by the low-frequency detection unit 22 is less than a second threshold current.

[0057] Here, the frequency range detected by the first detection unit 10 is higher than the frequency range detected by the second detection unit 20. In other words, the frequency range of the first current I1, which is detected by the high-frequency detection unit 12 (the first detection unit 10), is higher than the frequency range of the second current I2, which is detected by the low-frequency detection unit 22 (the second detection unit 20). Therefore, the determination unit 30 determines whether or not an arc fault has occurred in each of the multiple branch circuits BC1 based on the second information regarding the second current and the first information regarding the first current, which has a higher frequency range than the second current. In this way, the determination unit 30 can determine whether or not an arc fault has occurred in each of the multiple branch circuits BC1 based on two pieces of information (first information and second information) with different frequency ranges, and can determine whether or not an arc fault has occurred more accurately. Furthermore, although the first detection unit 10, which detects first information in a higher frequency range than the second detection unit 20, requires higher performance components than the second detection unit 20, the manufacturing cost of the arc fault detection system 1 can be reduced because the first detection unit 10 is shared not just for detecting arc faults in one but multiple branch circuits BC1.

[0058] The determination unit 30 outputs the determination result of the arc fault to the output unit 50. The output unit 50 includes, for example, a display unit such as a liquid crystal display or a 7-segment LED. When the determination unit 30 determines that an arc fault has occurred in any of the branch circuits BC1, it displays information about the branch circuit BC1 where the arc fault occurred (for example, the circuit number or name assigned to the branch circuit BC1) on the display unit. This allows the arc fault detection system 1 to inform the user of information about the branch circuit BC1 where the arc fault occurred. The output unit 50 is not limited to a display unit; it may also be a speaker that outputs the determination result as sound, or a communication device that transmits the determination result to an information terminal such as a smartphone held by the user.

[0059] Furthermore, the arc fault detection system 1 includes a body 70 (see Figure 3) that houses the first detection units 10A and 10B, the determination unit 30, and the output unit 50. The body 70 of the arc fault detection system 1 is installed, for example, inside the housing 101 of the distribution board 100, in the space to the left of the main breaker B1. The mounting position of the body 70 of the arc fault detection system 1 can be changed as appropriate. The second detection unit 20 is located outside the body 70 of the arc fault detection system 1, but it may also be housed inside the body 70.

[0060] (3) Variant The above embodiments are merely one of many embodiments of this disclosure. The above embodiments can be modified in various ways depending on the design, etc., as long as they achieve the objectives of this disclosure.

[0061] The following lists modifications of the above embodiment. The modifications described below can be combined and applied as appropriate. In the following, the above embodiment may also be referred to as the basic configuration.

[0062] The arc fault detection system 1 in this disclosure includes a computer system. The computer system mainly consists of a processor and memory as hardware. The processor executes a program recorded in the computer system's memory, thereby realizing the function of the arc fault detection system 1 as the executing entity. The program may be pre-recorded in the computer system's memory, provided via a telecommunication line, or provided on a non-temporary recording medium such as a memory card, optical disk, or hard disk drive that is readable by the computer system. The processor of the computer system consists of one or more electronic circuits including semiconductor integrated circuits (ICs) or large-scale integrated circuits (LSIs). The integrated circuits referred to here, such as ICs or LSIs, are named differently depending on the degree of integration, and include integrated circuits called system LSIs, VLSIs (Very Large Scale Integration), or ULSIs (Ultra Large Scale Integration). Furthermore, FPGAs (Field-Programmable Gate Arrays) that are programmed after the manufacture of the LSI, or logic devices that allow for the reconfiguration of junction relationships or circuit compartments within the LSI, can also be used as processors. Multiple electronic circuits may be integrated onto a single chip or distributed across multiple chips. Multiple chips may be integrated onto a single device or distributed across multiple devices. The computer system referred to herein includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller also consists of one or more electronic circuits, including semiconductor integrated circuits or large-scale integrated circuits.

[0063] Furthermore, it is not essential for the arc fault detection system 1 to have multiple functions integrated into a single housing; the components of the arc fault detection system 1 may be distributed across multiple housings. Moreover, at least some of the functions of the arc fault detection system 1, for example, some of the functions of the determination unit 30, may be implemented by the cloud (cloud computing), etc.

[0064] Furthermore, in the above embodiment, where "greater than or equal to" is used in the comparison of two values ​​such as measurement data, it may also be used as "greater than". In other words, whether or not the case where the two values ​​are equal is included in the comparison of two values ​​can be arbitrarily changed depending on the setting of the reference value, etc., so there is no technical difference between "greater than or equal to" and "greater than". Similarly, where "less than" is used, it may also be used as "less than or equal to".

[0065] (3.1) Variation 1 The arc fault detection system 1 and the distribution board 100 equipped therewith according to Modification 1 will be described with reference to Figure 6. Note that the arc fault detection system 1 of Modification 1 has the same configuration as the basic arc fault detection system 1, except that it includes a receiving unit 60. Therefore, common components are denoted by the same reference numerals, and their descriptions are omitted.

[0066] Of the multiple branch circuits BC1, multiple outlet devices 300 are connected to a common branch circuit BC1. Each of the multiple outlet devices 300 connected to the common branch circuit BC1 is equipped with a third detection unit 310 and a transmission unit 320.

[0067] The third detection unit 310 detects third information relating to at least one of the third current I3 flowing through each of the multiple outlet devices 300, and the third voltage generated at each of the multiple outlet devices 300. Here, the third detection unit 310 detects third information relating to the third current I3 flowing through each of the multiple outlet devices 300, for example, detecting the current value of the third current I3 as third information.

[0068] The transmitting unit 320 transmits the detection result from the third detection unit 310. The transmitting unit 320 communicates wirelessly with the receiving unit 60 of the arc fault detection system 1. For communication between the transmitting unit 320 and the receiving unit 60, it is preferable to use wireless communication that conforms to standards such as Wi-Fi®, Bluetooth®, ZigBee®, or unlicensed low-power radio (specified low-power radio).

[0069] The outlet device 300 and the branch circuit breaker B2 are connected via the electric wire L30. The outlet device 300 is equipped with an electric wire connection terminal to which the electric wire L30 is connected. The outlet device 300 is also equipped with a blade receptacle to which the plug of the load device LD1, which is provided on the electric wire L50 from the load device LD1, is detachably connected. When the plug of the load device LD1 is plugged into the blade receptacle of the outlet device 300, the power supplied from the branch circuit breaker B2 is supplied to the load device LD1 via the outlet device 300.

[0070] The receiving unit 60 of the arc fault detection system 1 receives the detection result from the third detection unit 310 transmitted from the transmitting unit 320. The determination unit 30 then determines whether or not there is an arc fault in each of the multiple outlet devices 300 based on the first information detected by the first detection unit 10, the multiple pieces of second information detected by the multiple second detection units 20, and the detection result from the third detection unit 310 received by the receiving unit 60.

[0071] Specifically, the determination unit 30 determines that an arc fault has occurred in the branch circuit BC1, which is the target of detection by the second detection unit 20, if the current value of the first current I1 detected by the first detection unit 10 is equal to or greater than a predetermined first threshold current, and the current value of the second current I2 detected by the second detection unit 20 is equal to or greater than a predetermined second threshold current. Here, it is assumed that the determination unit 30 has pre-configured information on the branch circuit BC1 to which multiple outlet devices 300 are connected. When the determination unit 30 determines that an arc fault has occurred in the branch circuit BC1 to which multiple outlet devices 300 are connected, it further determines, based on multiple pieces of third information transmitted from the transmission units 320 of the multiple outlet devices 300, whether or not the arc fault occurred in the wire connected to which outlet device 300. In other words, the determination unit 30 compares the current value of the third current I3 with a predetermined third threshold current based on the third information received from each outlet device 300. If the current value of the third current I3 is equal to or greater than the third threshold current, the determination unit 30 determines that an arc fault has occurred in the wires connected to the outlet device 300 (such as the wire L30 connecting the branch breaker B2 and the outlet device 300, and the wire L50 connecting the outlet device 300 and the load equipment LD1). If the current value of the third current I3 is less than the third threshold current, the determination unit 30 determines that no arc fault has occurred in the wires connected to the outlet device 300.

[0072] Thus, in the modified example 1, when multiple outlet devices 300 are connected to the branch circuit BC1, the determination unit 30 determines whether or not an arc fault has occurred in the wire connected to which outlet device 300, making it possible to pinpoint the location of the arc fault more precisely.

[0073] (3.2) Other variations In the above embodiment, the first information is information relating to the first current I1, but the first information may also be information relating to the first voltage generated in the common path section 40. If the first detection unit 10 detects the voltage value of the first voltage generated in the common path section 40 as the first information, for example, a shunt resistor for current detection through which the first current flows can be connected in series with the common path section 40, and the voltage value of the first voltage generated in the common path section 40 can be detected from the voltage across the shunt resistor.

[0074] Furthermore, in the above embodiment, the second information is information regarding the current value of the second current I2 flowing through each of the multiple branch circuits BC1, but the second information may also be information regarding the second voltage generated in each of the multiple branch circuits BC1. When the second detection unit 20 detects the second voltage generated in each of the multiple branch circuits BC1, for example, a shunt resistor for current detection through which the second current flows can be connected in series with each of the multiple branch circuits BC1, and the voltage value of the second voltage can be detected from the voltage across the shunt resistor.

[0075] Furthermore, if the first information includes information about the first voltage and the second information includes information about the second voltage, the determination unit 30 should determine that an arc fault has occurred in the corresponding branch circuit BC1 if the voltage value of the first voltage is higher than the first threshold voltage and the voltage value of the second voltage is higher than the second threshold voltage. Also, if the voltage value of the first voltage is less than or equal to the first threshold voltage, or if the voltage value of the second voltage is less than or equal to the second threshold voltage, the determination unit 30 should determine that no arc fault has occurred in the corresponding branch circuit BC1.

[0076] Here, it is preferable that the frequency range of the first voltage detected by the first detection unit 10 is higher than the frequency range of the second voltage detected by the second detection unit 20, and the determination unit 30 can more accurately determine whether or not an arc fault has occurred in each of the multiple branch circuits BC1 based on the second information and the first information which has a higher frequency range than the second information.

[0077] The first detection unit 10 may detect both information regarding the first current I1 and information regarding the first voltage as first information, and the second detection unit 20 may detect both information regarding the second current I2 and information regarding the second voltage as second information.

[0078] Furthermore, in the basic configuration and modified example 1 described above, the frequency range detected by the first detection unit 10 is higher than the frequency range detected by the second detection unit 20. However, the first detection unit 10 and the second detection unit 20 may be configured such that the frequency range detected by the first detection unit 10 is lower than the frequency range detected by the second detection unit 20.

[0079] In the basic configuration and modified example 1 described above, the power distribution system is a single-phase three-wire system, but the power distribution system can also be a single-phase two-wire system or a three-phase three-wire system.

[0080] The shape and size of the distribution board 100 described in the basic configuration and modified example 1 above, as well as the number of internal components (main breaker B1, branch breaker B2, etc.) housed in the enclosure 101, the number of branch circuits BC1, etc., can be changed as appropriate. In addition, the configuration and arrangement of the current sensor 21 provided in the second detection unit 20 and the current sensor 11 provided in the first detection unit 10 can also be changed as appropriate.

[0081] (summary) Based on the embodiments described above, the following aspects are disclosed.

[0082] The first embodiment of the arc fault detection system (1) is an arc fault detection system (1) that detects the presence or absence of an arc fault in each of the multiple branch circuits (BC1, BC11, BC12) that branch off from a main circuit (MC1) connected to an AC power supply (2). The arc fault detection system (1) comprises a common path section (40, 40A, 40B), a first detection section (10, 10A, 10B), a plurality of second detection sections (20, 20A, 20B), and a determination section (30). The common path section (40, 40A, 40B) is through which the current flowing to each of the multiple branch circuits (BC1, BC11, BC12) can pass. The first detection unit (10, 10A, 10B) detects first information relating to at least one of the first current (I1) flowing through the common path section (40, 40A, 40B) and the first voltage generated in the common path section (40, 40A, 40B). Multiple second detection units (20, 20A, 20B) are provided corresponding to each of the multiple branch circuits (BC1, BC11, BC12). Each of the multiple second detection units (20, 20A, 20B) detects second information relating to at least one of the second current (I2) flowing through the corresponding branch circuit (BC1, BC11, BC12) and the second voltage generated in the corresponding branch circuit (BC1, BC11, BC12) among the multiple branch circuits (BC1, BC11, BC12). The determination unit (30) determines whether or not there is an arc fault in each of the multiple branch circuits (BC1, BC11, BC12) based on the first information detected by the first detection unit (10, 10A, 10B) and the multiple pieces of second information detected by the multiple second detection units (20, 20A, 20B).

[0083] According to this embodiment, the number of circuit components can be reduced compared to the case in which multiple first detection units are provided, each corresponding to a multiple branch circuit (BC1, BC11, BC12) and each detecting first information.

[0084] In the second embodiment of the arc fault detection system (1), in the first embodiment, the frequency range to be detected by the first detection unit (10, 10A, 10B) is higher than the frequency range to be detected by the second detection unit (20, 20A, 20B).

[0085] According to this embodiment, the determination unit (30) determines the presence or absence of an arc fault in each of the multiple branch circuits (BC1, BC11, BC12) based on first and second information in different frequency ranges. Therefore, it is possible to determine the presence or absence of an arc fault more accurately compared to the case where the presence or absence of an arc fault is determined based on first and second information in the same frequency range. Furthermore, although the first detection unit (10, 10A, 10B), which detects first information in a higher frequency range than the second detection unit (20, 20A, 20B), requires higher performance components than the second detection unit (20, 20A, 20B), the manufacturing cost of the arc fault detection system (1) can be reduced because this first detection unit (10, 10A, 10B) is shared for detecting arc faults in multiple branch circuits (BC1, BC11, BC12).

[0086] In the third embodiment of the arc fault detection system (1), in the first or second embodiment, the first detection unit (10, 10A, 10B) uses a Rogowski coil provided in the common path section (40, 40A, 40B) to detect first information relating to the first current (I1) flowing through the common path section (40, 40A, 40B).

[0087] According to this embodiment, the first detection unit (10, 10A, 10B) detects the first current (I1) using a Rogowski coil, which allows for miniaturization compared to the case where a current transformer is used as the sensor for detecting the first current (I1).

[0088] In the arc fault detection system (1) of the fourth embodiment, in any of the first to third embodiments, each of the plurality of second detection units (20, 20A, 20B) uses a Rogowski coil provided in the corresponding branch circuit (BC1, BC11, BC12) among the plurality of branch circuits (BC1, BC11, BC12) to detect second information relating to the second current (I2) flowing through the corresponding branch circuit (BC1, BC11, BC12) among the plurality of branch circuits (BC1, BC11, BC12).

[0089] According to this embodiment, the second detection unit (20, 20A, 20B) detects the second current (I2) using a Rogowski coil, which allows for miniaturization compared to the case where a current transformer is used as the sensor for detecting the second current (I2).

[0090] In the fifth embodiment of the arc fault detection system (1), in any of the first to fourth embodiments, the common path section (40, 40A, 40B) includes a capacitor (C1).

[0091] According to this embodiment, the capacitor (C1) allows the high-frequency components of the current flowing through each of the multiple branch circuits (BC1, BC11, BC12) to pass through the common path section (40, 40A, 40B).

[0092] In the sixth embodiment of the arc fault detection system (1), in any of the first to fifth embodiments, each of a plurality of outlet devices (300) connected to a common branch circuit (BC1, BC11, BC12) among a plurality of branch circuits (BC1, BC11, BC12) includes a third detection unit (310) that detects third information relating to at least one of a third current flowing through each of the plurality of outlet devices (300) and a third voltage generated at each of the plurality of outlet devices (300), and a transmitting unit (320) that transmits the detection result of the third detection unit (310). The arc fault detection system (1) includes a receiving unit (60) that receives the detection result of the third detection unit (310) transmitted from the transmitting unit (320). The determination unit (30) determines whether or not there is an arc fault in each of the multiple outlet devices (300) based on the first information detected by the first detection unit (10, 10A, 10B), the multiple second pieces of information detected by the multiple second detection units (20, 20A, 20B), and the detection result of the third detection unit (310) received by the receiving unit (60).

[0093] According to this embodiment, it is possible to determine which of the multiple outlet devices (300) connected to a common branch circuit (BC1, BC11, BC12) is experiencing an arc fault.

[0094] The seventh embodiment of the distribution board (100) comprises an arc fault detection system according to any of the first to sixth embodiments, a main circuit breaker (B1) provided in the main circuit (MC1), a plurality of branch circuit breakers (B2) provided in each of the plurality of branch circuits (BC1, BC11, BC12), and a housing (101). The housing (101) houses the arc fault detection system (1), the main circuit breaker (B1), and the plurality of branch circuit breakers (B2).

[0095] According to this embodiment, the number of circuit components can be reduced compared to the case in which multiple first detection units are provided, each corresponding to a multiple branch circuit (BC1, BC11, BC12) and each detecting first information.

[0096] Not limited to the above embodiments, various configurations (including modifications) of the arc fault detection system (1) according to the above embodiment can be embodied in the detection method, (computer) program, or non-temporary recording medium on which the program is recorded.

[0097] The configurations relating to the second to sixth aspects are not essential to the arc fault detection system (1) and can be omitted as appropriate. [Explanation of Symbols]

[0098] 1. Arc Fault Detection System 2 AC power supply 10, 10A, 10B First detection unit 20, 20A, 20B Second detection unit 30 Judgment section 40 Common Route Section 40A First Common Route Section 40B Second Common Route Section 60 Receiver 100-unit distribution board 101 cabinets 300 outlet device 310 Third detection unit 320 Transmitter B1 Main circuit breaker B2 Branch Circuit Breaker BC1 Branch Circuit BC11 First Branch Circuit BC12 Second Branch Circuit C1 Capacitor I1 1st current I2 2nd current MC1 main circuit

Claims

1. An arc fault detection system that detects the presence or absence of arc faults in each of the multiple branch circuits branching off from a main circuit connected to an AC power source, A common path section through which the current flowing to each of the aforementioned multiple branch circuits can pass, A first detection unit detects first information relating to at least one of a first current flowing through the common path and a first voltage generated in the common path, A plurality of second detection units are provided corresponding to each of the plurality of branch circuits, It comprises a determination unit and, Each of the plurality of second detection units detects second information relating to at least one of the second current flowing through the corresponding branch circuit among the plurality of branch circuits, and the second voltage generated in the corresponding branch circuit among the plurality of branch circuits. The determination unit determines whether or not there is an arc fault in each of the plurality of branch circuits based on the first information detected by the first detection unit and the plurality of second information detected by each of the plurality of second detection units. The frequency range to be detected by the first detection unit is higher than the frequency range to be detected by the second detection unit. Arc fault detection system.

2. The first detection unit detects the first information relating to the first current flowing through the common path using a Rogowski coil provided in the common path. The arc fault detection system according to claim 1.

3. Each of the plurality of second detection units detects the second information relating to the second current flowing through the corresponding branch circuit among the plurality of branch circuits using a Rogowski coil provided in the corresponding branch circuit among the plurality of branch circuits. The arc fault detection system according to claim 1.

4. The common path includes a capacitor, The arc fault detection system according to claim 1.

5. Each of the multiple outlet devices connected to a common branch circuit among the multiple branch circuits, A third detection unit detects third information relating to at least one of the third current flowing through each of the plurality of outlet devices and the third voltage generated at each of the plurality of outlet devices. The system comprises a transmitting unit that transmits the detection result of the third detection unit, The arc fault detection system includes a receiving unit that receives the detection result of the third detection unit transmitted from the transmitting unit, The determination unit determines whether or not there is an arc fault in each of the plurality of outlet devices based on the first information detected by the first detection unit, the plurality of second information detected by each of the plurality of second detection units, and the detection result of the third detection unit received by the receiving unit. The arc fault detection system according to claim 1.

6. An arc fault detection system according to any one of claims 1 to 5, The main circuit breaker provided in the main circuit, Multiple branch breakers provided in each of the aforementioned multiple branch circuits, The system comprises the arc fault detection system, the main circuit breaker, and a housing that accommodates the plurality of branch circuit breakers. Distribution board.

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