Arc detection system, arc detection method, and program recording medium

Abstract

The arc detection system (100) includes an acquisition unit (11) and a judgment unit (12). The acquisition unit (11) acquires the measurement result of the current (I1) flowing in the feeder line (L1) powered by the DC power supply (2). The judgment unit (12) determines whether an arc fault has occurred based on the components of a specific frequency band in the measurement result of the current (I1) acquired by the acquisition unit (11). If the judgment unit (12) determines that an arc fault has occurred when the components of the specific frequency band are above a threshold for a specific time longer than the time during which an arc may occur when the device (3) is installed or removed from the feeder line (L1).

Description

Technical Field

[0001] This invention relates to an arc detection system, an arc detection method, and a program recording medium for determining the possibility of an arc fault occurring in a feeder line. Background Art

[0002] Patent Document 1 discloses an arc detection unit for detecting electric arcs. This arc detection unit includes: a voltage detection unit that measures the voltage between an input wire fed into a terminal block and an output wire discharged from the terminal block; and a current detection unit that measures the current in the output wire discharged from the terminal block. Furthermore, this arc detection unit identifies electrical noise and electric arcs within the terminal block by simultaneously detecting changes in both the voltage value of the voltage detection unit and the current value of the current detection unit.

[0003] (Existing technical literature)

[0004] (Patent Document)

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-7765 Summary of the Invention

[0006] This invention provides an arc detection system, an arc detection method, and a program recording medium that can easily prevent false detection of arc faults.

[0007] One aspect of the present invention relates to an arc detection system comprising an acquisition unit and a determination unit. The acquisition unit acquires a measurement result of a current flowing in a feeder line powered by a DC power supply. The determination unit determines whether an arc fault has occurred based on a specific frequency band component in the current measurement result acquired by the acquisition unit. If the determination unit determines that an arc fault has occurred for a specific time when the component of the specific frequency band is above a threshold, longer than the time during which an arc could occur when the device is installed or removed from the feeder line, the arc fault is considered to have occurred.

[0008] One embodiment of the present invention relates to an arc detection method comprising an acquisition step and a judgment step. In the acquisition step, a measurement result of a current is obtained, the current being a current flowing in a feeder line powered by a DC power source. In the judgment step, a judgment is made as to whether an arc fault has occurred based on a specific frequency band component in the current measurement result obtained in the acquisition step. In the judgment step, if a specific time during which the component of the specific frequency band is above a threshold is longer than the time during which an arc might occur when the device is installed or removed from the feeder line, the arc fault is judged to have occurred.

[0009] One embodiment of the present invention relates to a program recording medium that records a program for causing one or more processors to execute the above-described arc detection method.

[0010] One embodiment of the present invention has the advantage of easily preventing false detection of arc faults. Attached Figure Description

[0011] Figure 1 This is a schematic diagram showing the overall configuration of the arc detection system according to Embodiment 1.

[0012] Figure 2A This is a schematic diagram illustrating the operation of the suppression circuit in the arc detection system according to Embodiment 1.

[0013] Figure 2B This is a schematic diagram illustrating the operation of the suppression circuit in the arc detection system according to Embodiment 1 when the device is attached to or detached from the feeder line.

[0014] Figure 3A This is a schematic diagram illustrating the operation of the suppression circuit in the arc detection system according to Embodiment 1 when the device is attached to or detached from the feeder line.

[0015] Figure 3B This is a schematic diagram illustrating the operation of the suppression circuit in the arc detection system according to Embodiment 1 when the device is attached to or detached from the feeder line.

[0016] Figure 4 This is a flowchart illustrating an example of the operation of the arc detection system according to Embodiment 1.

[0017] Figure 5 This is a schematic diagram showing the overall configuration of the arc detection system according to Embodiment 2. Detailed Implementation

[0018] The embodiments of the present invention will now be described with reference to the accompanying drawings. The embodiments described below are all specific examples of the present invention. Therefore, the numerical values, shapes, materials, constituent elements, the arrangement of constituent elements, connection methods, steps, and the order of steps shown in the following embodiments are all examples and are not intended to limit the present invention.

[0019] Furthermore, the diagrams are schematic diagrams, not rigorous illustrations. Also, in each diagram, substantially identical components are given the same symbols, and repetitive explanations are omitted or simplified.

[0020] (Implementation Method 1)

[0021] [constitute]

[0022] use Figure 1The arc detection system described in Implementation Method 1 will be explained. Figure 1 This is a schematic diagram showing the overall configuration of the arc detection system 100 according to Embodiment 1.

[0023] The arc detection system 100 is primarily used to determine whether an arc fault has occurred in the feeder line L1, which is powered by the DC power supply 2. That is, the feeder line L1 may be damaged or broken due to external factors or years of aging, and such damage could lead to an arc (arc discharge), resulting in the possibility of an arc fault. Therefore, the arc detection system 100 is mainly used to detect potential arc faults in the feeder line L1.

[0024] Specifically, the arc detection system 100 is used in a so-called DC (Direct Current) distribution network 200. The DC distribution network 200 is configured to include one or more feeder lines L1. Figure 1 In the diagram, only one feeder line L1 is shown. The DC distribution network 200 is supplied with DC power by the DC power supply 2. Each feeder line L1 consists of a feeder line connected to the positive terminal of the output side of the DC power supply 2 and a feeder line connected to the negative terminal of the output side of the DC power supply 2.

[0025] Here, when the DC distribution network 200 has only one feeder line L1, the feeder line L1 is supplied with DC power by the DC power source 2. Furthermore, when the DC distribution network 200 has multiple feeder lines L1, one end of each of the multiple feeder lines L1 is connected to more than one branch point. Therefore, if DC power is supplied to any one feeder line L1 by the DC power source 2, the DC power will also be supplied to the other feeder lines L1 via more than one branch point.

[0026] In Embodiment 1, the DC power supply 2 is a power converter equipped with an AC / DC converter 21. The DC power supply 2 converts the alternating current output from the power system 300 into direct current and outputs the converted direct current to the feeder line L1 connected to the DC power supply 2. When the DC distribution network 200 has multiple feeder lines L1, the direct current output to that feeder line L1 is also output to other feeder lines L1. In addition, in Embodiment 1, the DC power supply 2 can be any configuration that outputs direct current, and can be a distributed power source such as a solar cell or a power source such as a battery, or a combination of these power sources and a power converter (e.g., a power converter equipped with a DC / DC converter circuit).

[0027] Each feeder line L1 is, for example, constructed from a conduit rail, and can accommodate one or more devices 3. That is, one or more devices 3 can be freely positioned at any location on each feeder line L1. Of course, the placement of each feeder line L1, capable of accommodating one or more devices 3, can be predetermined. In Embodiment 1, although each feeder line L1 is positioned on the ceiling of the facility, it can also be installed on the floor, walls, or furniture of the facility.

[0028] Device 3 has a load 31 and a pair of connection terminals 32. Device 3 can be mounted and detached from feeder line L1 via the pair of connection terminals 32. Specifically, when mounting device 3 onto feeder line L1, with the pair of connection terminals 32 of device 3 inserted into the guide rail (feeder line L1), device 3 is rotated clockwise or counterclockwise by a predetermined angle (e.g., 90 degrees) from the insertion direction. Accordingly, the pair of connection terminals 32 are fixed in contact with a pair of connecting conductors L11 disposed on feeder line L1, thus connecting device 3 to feeder line L1 electrically and mechanically.

[0029] To remove device 3 from feeder line L1, rotate device 3 by a predetermined angle in the opposite direction to the direction described above, viewed from the insertion direction of device 3. This releases the contact between the pair of connecting terminals 32 and the pair of connecting conductors L11, allowing device 3 to be removed from feeder line L1. With device 3 installed on feeder line L1, load 31 receives and is driven by DC power supplied by DC power supply 2 via feeder line L1.

[0030] In Embodiment 1, although device 3 is a lighting fixture, it could also be a speaker, camera, sensor, or USB PD (USB Power Delivery). In other words, device 3 can be any device other than a lighting fixture, as long as the load 31 can accept and drive DC power. Furthermore, although in Embodiment 1, the devices 3 connected to each feed line L1 are all lighting fixtures, and there is only one type, the types of devices 3 connected to each feed line L1 can be multiple. For example, the devices connected to each feed line L1 could be lighting fixtures, speakers, cameras, sensors, or USB PD. These devices 3 can all be connected to one feed line L1, or they can be connected separately to multiple feed lines L1.

[0031] The arc detection system 100 includes an acquisition unit 11, a judgment unit 12, a notification unit 13, a stop unit 14, and a suppression circuit 4 as functional components for determining whether an arc fault has occurred. In Embodiment 1, the acquisition unit 11, judgment unit 12, notification unit 13, and stop unit 14 are provided in the DC power supply 2, and the suppression circuit 4 is provided in each device 3. In the DC power supply 2, the arc detection system 100 is, for example, a microcomputer or a device equipped with a microcomputer. The microcomputer is a semiconductor integrated circuit, etc., having ROM (Read Only Memory) and RAM (Random Access Memory) for storing programs, a processor (CPU) for executing programs, a timer, an A / D converter, and a D / A converter. Any one of the acquisition unit 11, judgment unit 12, notification unit 13, and stop unit 14 can be implemented by the processor executing the above-described program.

[0032] The acquisition unit 11 acquires the measurement result of the current I1 flowing in the feeder line L1, which is powered by the DC power supply 2. In Embodiment 1, the acquisition unit 11 acquires the measurement result of the measured current I1 by sampling and measuring with an ammeter 22 at a predetermined period (sampling period). That is, the acquisition unit 11 acquires the measurement result of the current I1 at the predetermined period from the ammeter 22. The ammeter 22 is installed between the DC power supply 2 and the feeder line L1 to measure the current flowing in the feeder line on the negative side of the feeder line L1 (that is, the current I1 flowing in the feeder line L1). Alternatively, the ammeter 22 may be built into the DC power supply 2.

[0033] The determination unit 12 determines whether an arc fault has occurred based on the components of a specific frequency band in the measurement result of the current I1 obtained by the acquisition unit 11. Specifically, the determination unit 12 performs frequency analysis on the measurement result of the current I1 obtained by the acquisition unit 11. Frequency analysis refers to, for example, calculating the spectrum of the measurement result of the current I1 by performing a Fourier transform (in this case, FFT) on the time waveform of the measurement result of the current I1. Furthermore, the determination unit 12 determines whether an arc fault has occurred by referring to the calculated spectrum. The specific frequency band includes, for example, the frequency band of noise generated in the event of an arc fault. As an example, the specific frequency band is tens of kHz, which is a relatively high frequency band. In addition, the frequency of the noise generated in the above case can be determined experimentally.

[0034] Here, the determination unit 12 compares a specific time when a component of a specific frequency band exceeds a threshold with a preset threshold time (e.g., 1 second). If the specific time is longer than the threshold time, it determines that an arc fault has occurred. The threshold time is preset based on the time during which an arc may occur when the device 3 is installed or removed from the feeder line L1. In other words, if the determination unit 12 determines that an arc fault has occurred when the specific time during which a component of a specific frequency band exceeds the threshold is longer than the time during which an arc may occur when the device 3 is installed or removed from the feeder line L1, the following will explain the process of determining the occurrence of an arc fault in this way.

[0035] The two types of arcs that may occur in the DC distribution network 200 are: arcs caused by a broken or nearly broken feeder line L1, and arcs that may occur momentarily when installing or removing device 3 from feeder line L1. Specifically, if the installation of device 3 onto feeder line L1 is not smooth, the load 31 of device 3 may repeatedly switch between being connected to and disconnected from feeder line L1 for a short period, potentially causing contact bounce. Furthermore, during contact bounce, an arc may occur when the load 31 is momentarily disconnected from feeder line L1 while current is flowing. Similarly, contact bounce may occur when device 3 is removed from feeder line L1. Again, during contact bounce, an arc may occur when the load 31 is momentarily disconnected from feeder line L1 while current is flowing. Such arcs caused by contact bounce can occur not only in the DC distribution network 200 but also in the AC distribution network. However, in an AC distribution network, since the current flowing in the feeder line is alternating current, there is a moment when the current becomes zero. Therefore, the duration of the arc caused by contact chatter tends to be shorter. Specifically, the duration of the arc will be less than half of the AC current cycle. On the other hand, in a DC distribution network 200, since the current flowing in the feeder line L1 is direct current, and the current does not become zero, the duration of the arc caused by contact chatter tends to be longer. Especially when the distance between the electrode of device 3 and the electrode of feeder line L1 is not ideal and device 3 is installed on feeder line L1, the arc will be difficult to extinguish.

[0036] Here, an arc caused by a broken or nearly broken feeder line L1 is more likely to be the cause of an arc fault, while an arc caused by contact chatter can be extinguished within a short period of time and is unlikely to be the cause of an arc fault. Therefore, in the arc detection system 100, it is desirable not to detect short-term arcs caused by contact chatter, but to primarily determine the occurrence of an arc caused by a broken or nearly broken feeder line L1 as the occurrence of an arc fault.

[0037] Therefore, in Embodiment 1, a suppression circuit 4 is provided in each device 3 to meet the above requirements. The suppression circuit 4 is configured to connect the load 31 to the feeder line L1 after a delay time when the device 3 is installed on the feeder line L1, as will be described in detail later. Accordingly, it is estimated that after the device 3 is indeed installed on the feeder line L1, the load 31 is connected to the feeder line L1, making it difficult for the load 31 to momentarily disconnect from the feeder line L1 under the current flow conditions described above, thus making it difficult for an arc caused by contact bounce to occur.

[0038] Furthermore, the suppression circuit 4 is configured to disconnect the electrical connection between the device 3 and the feeder line L1 before removing the device 3 from the feeder line L1 when it is to be removed from the feeder line L1, as will be described in detail later. Accordingly, since the device 3 is removed from the feeder line L1 after it has been removed from the feeder line L1, it is difficult for the load 31 to momentarily disconnect from the feeder line L1 under the current flow conditions described above, resulting in a low likelihood of arcing caused by contact bounce.

[0039] Furthermore, if the specific time for a component of a particular frequency band to exceed a threshold is longer than the aforementioned delay time (threshold time), the determination unit 12 determines that the arc is not caused by contact jitter, but rather by a break or near break in the feeder line L1, i.e., an arc fault occurs. In other words, in Embodiment 1, the specific time is longer than the delay time. Here, in the absence of the suppression circuit 4, it is assumed that an arc caused by contact jitter is possible within a period equivalent to the delay time. Thus, the specific time being longer than the delay time is equivalent to the specific time being longer than the arc occurrence time that may occur when the device 3 is attached to or detached from the feeder line L1.

[0040] Furthermore, if the device 3 is not equipped with a suppression circuit 4, an arc may occur due to contact jitter when the device 3 is installed or removed from the feeder line L1. However, since the arc caused by contact jitter generally disappears within a short time, the determination unit 12 will not determine that an arc fault has occurred even if an arc caused by contact jitter occurs. However, there are exceptions where an arc caused by contact jitter can be the cause of an arc fault. Since the specific time in this case is longer than the threshold time, the determination unit 12 can determine that an arc fault has occurred even in such cases.

[0041] The notification unit 13 may notify the surrounding area of ​​an arc fault, for example, by illuminating a light or emitting a buzzer. Furthermore, the notification unit 13 may also notify the owner or manager of the arc detection system 100 of an arc fault by sending information indicating that an arc fault has occurred to an information terminal. As an example, the information terminal may include portable terminals such as smartphones or tablets, as well as personal computers.

[0042] If the determination unit 12 determines that an arc fault has occurred, the stopping unit 14 stops the current flowing in the feeder line L1. Accordingly, if an arc discharge occurs due to an arc fault, the arc discharge disappears.

[0043] The stopping unit 14 stops the current flowing in the feeder line L1, for example, by controlling a switch connected to the feeder line L1. The switch can be, for example, a mechanical switch or a semiconductor switch. A mechanical switch can be, for example, a relay or a circuit breaker, while a semiconductor switch can be, for example, a transistor or a diode.

[0044] Furthermore, the switch connected to the feeder line L1 can be either directly connected to the feeder line L1 or indirectly connected to the feeder line L1. For example, this switch is used to implement the AC / DC conversion function in the AC / DC converter 21. Even if this switch is not directly connected to the feeder line L1, it is still indirectly connected to the feeder line L1, and therefore can be a switch connected to the feeder line L1. The stop unit 14 stops the operation of opening the switch, for example, by controlling the switch, thereby stopping the current flowing in the feeder line L1.

[0045] Alternatively, the switch can be configured to toggle between turning the DC power supply 2 on and off. In this case, the stop unit 14 controls the switch to turn off the DC power supply 2, thereby stopping the current flowing in the feeder line L1.

[0046] Alternatively, the switch can be installed on the feeder line L1, allowing switching between connecting and disconnecting the feeder line L1. For example, the stop unit 14 can control the switch to disconnect the feeder line L1, thereby stopping the current flowing in the feeder line L1.

[0047] The suppression circuit 4 is used to suppress electric arcs that may occur when the device 3 is installed or removed from the feeder line L1. The suppression circuit 4 includes a first switch SW1, a second switch SW2, and a drive circuit 41. In embodiment 1, the suppression circuit 4 is provided between a pair of connection terminals 32 and the load 31 of each device 3.

[0048] The first switch SW1 connects or disconnects the circuit L2 between the load 31 of device 3 and the feeder line L1. Circuit L2 consists of a circuit connecting the positive terminal 32 of one pair of connection terminals 32 to the positive terminal of the load 31, and a circuit connecting the negative terminal 32 of one pair of connection terminals 32 to the negative terminal of the load 31. When the first switch SW1 is in the ON state, the pair of connection terminals 32 are electrically connected to the load 31 because circuit L2 is connected. In this state, when device 3 is installed on feeder line L1, power (i.e., current flows) is supplied to the load 31 by feeder line L1. On the other hand, when the first switch SW1 is in the OFF state, the pair of connection terminals 32 are electrically isolated from the load 31 because circuit L2 is disconnected. In this state, even if device 3 is installed on feeder line L1, feeder line L1 does not supply power to the load 31 (i.e., no current flows).

[0049] In embodiment 1, the first switch SW1 is an n-channel enhancement-mode MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). That is, the first switch SW1 is a field-effect transistor. Furthermore, in... Figure 1 In the diagram, the symbol for the diode between the drain and source terminals represents the parasitic diode of the first switch SW1, as described later. Figure 5 Similarly, the drain of the first switch SW1 is connected to the negative terminal of the load 31, the source of the first switch SW1 is connected to the negative terminal of one of the pair of connection terminals 32, and the gate of the first switch SW1 is connected to the drive circuit 41.

[0050] After the device 3 is connected to the circuit L2 and a delay time has elapsed, the drive circuit 41 drives the first switch SW1 to turn on the circuit L2. In Embodiment 1, the drive circuit 41 is connected to the gate of the first switch SW1 and includes a CR filter 42 that applies the charging voltage of the capacitor C1 to the gate of the first switch SW1. The delay time is determined by the time constant of the CR filter 42.

[0051] Specifically, the drive circuit 41 includes a first resistor R1, a second resistor R2, a capacitor C1, and a Zener diode ZD1. The first resistor R1, the second resistor R2, and the capacitor C1 constitute a CR filter 42. One end of the first resistor R1 is connected to the positive terminal 32 of a pair of connection terminals 32 and the positive terminal of the load 31, and the other end of the first resistor R1 is connected to the gate of the first switch SW1. One end of the second resistor R2 is connected to the gate of the first switch SW1, and the other end of the second resistor R2 is connected via the second switch SW2 to the negative terminal 32 of a pair of connection terminals 32. One end of the capacitor C1 is connected to the gate of the first switch SW1, and the other end of the capacitor C1 is connected to the source of the first switch SW1. The Zener diode ZD1 is connected between the gate and source of the first switch SW1 to suppress excessively large voltages applied between the gate and source of the first switch SW1.

[0052] Alternatively, the Zener diode ZD1 can be replaced with a resistor whose voltage division ratio with the first resistive element R1 is pre-set, so that there is sufficient voltage between the gate and source of the first switch SW1 to switch to the on state. Furthermore, the Zener diode ZD1 can also be connected in parallel with a resistor. The same applies to Embodiment 2 described later.

[0053] In the CR filter 42, when the second switch SW2 is in the off state, the time constant and delay time are determined based on the resistance value of the first resistor element R1 and the capacitance value of the capacitor C1. Conversely, in the CR filter 42, when the second switch SW2 is in the on state, the time constant and delay time are determined based on the resistance value of the second resistor element R2 and the capacitance value of the capacitor C1. Furthermore, when the second switch SW2 is in the on state, although a voltage division by the first resistor element R1 and the second resistor element R2 is fixedly applied between the gate and source of the first switch SW1, this voltage division is not large enough to turn on the first switch SW1. The same applies to Embodiment 2 described later. Moreover, in Embodiment 1, the delay time is set such that no power is supplied to the device 3 during periods when contact jitter may occur when the device 3 is attached to or detached from the feed line L1.

[0054] The second switch SW2 is configured to switch the gate of the first switch SW1 and the circuit L2 from a short-circuit state to an open state. In Embodiment 1, the second switch SW2 is a normally open push-button switch, exposed outside the device 3. The second switch SW2 switches to the on state (i.e., short-circuit state) only when the user presses the button, and remains in the off state (i.e., open state) when the user does not press the button. One end of the second switch SW2 is connected to the gate of the first switch SW1 via the second resistor element R2, and the other end of the second switch SW2 is connected to the negative terminal of a pair of connection terminals 32.

[0055] The following uses Figures 2A to 3B The operation of suppression circuit 4 will be explained. Figures 2A to 3B Each of these is a schematic diagram illustrating the operation of the suppression circuit 4 when device 3 is attached to or detached from feeder line L1. Additionally, in Figures 2A to 3B In order to make the conduction and cutoff of the first switch SW1 simple and easy to understand visually, the diagram of the first switch SW1 is made similar to... Figure 1 The differences.

[0056] First, the operation of the suppression circuit 4 when device 3 is installed on feeder line L1 will be explained. Here, it is assumed that the user operates the second switch SW2 while installing device 3 on feeder line L1. Figure 3B As shown, at the moment when a pair of connection terminals 32 of device 3 contacts a pair of connection conductors L11 of feed line L1 (hereinafter referred to as the "contact moment"), the first switch SW1 is in the off state, and circuit L2 is open. Furthermore, although device 3 is electrically connected to feed line L1 at the contact moment, because the second switch SW2 is in the on state, no charging current I11 flows in capacitor C1, and the first switch SW1 is not turned on.

[0057] Here, the user operates the second switch SW2 while inserting device 3 into feeder line L1 and rotating it at a predetermined angle, thereby electrically and mechanically connecting device 3 to feeder line L1. This completes the installation of device 3 onto feeder line L1. Afterward, the user releases the second switch SW2, thus turning it off. In other words, as long as the user operates the second switch SW2, that is, until the installation of device 3 onto feeder line L1 is completed, the first switch SW1 is essentially not turned on.

[0058] like Figure 2AAs shown, if the second switch SW2 is turned off, the capacitor C1 begins to charge by allowing the charging current I11 to flow through the first resistive element R1 to the capacitor C1 in the CR filter 42 of the drive circuit 41. The capacitor C1 charges according to a time constant based on the resistance value of the first resistive element R1 and the electrostatic capacitance value of the capacitor C1.

[0059] And, as Figure 2B As shown, by fully charging capacitor C1, once the charging voltage of capacitor C1 (that is, the voltage between the gate and source of the first switch SW1) reaches the specified voltage, the first switch SW1 is turned on, and circuit L2 is connected. Accordingly, the feeder line L1 can provide power to the load 31.

[0060] Thus, by turning on the first switch SW1 after a delay period following the moment when the device 3 is connected to the circuit L2 (here, the moment when the second switch SW2 is turned off), the suppression circuit 4 enables the feeder line L1 to supply power to the load 31 after the aforementioned moment and the delay period. Therefore, even if contact jitter occurs when the device 3 is installed on the feeder line L1, power will not be supplied from the feeder line L1 to the load 31 during the period of contact jitter, thereby suppressing the occurrence of arcing caused by contact jitter.

[0061] Furthermore, when the device 3 is installed on the feeder line L1, there is a possibility that the user may forget to operate the second switch SW2. In this case, the charging current I11 begins to flow into the capacitor C1 from the moment of contact. However, even in this case, since the suppression circuit 4 turns on the first switch SW1 after a delay from the moment the device 3 is connected to the circuit L2 (the moment of contact), the feeder line L1 supplies power to the load 31 after the aforementioned moment and the delay time. Therefore, even if contact bounce occurs in this case, since the feeder line L1 has difficulty supplying power to the load 31 during the contact bounce, it is expected that the arcing caused by contact bounce can be suppressed.

[0062] Next, the operation of the suppression circuit 4 when device 3 is removed from feeder line L1 will be explained. Here, it is assumed that the user operates the second switch SW2 while removing device 3 from feeder line L1. Figure 3AAs shown, during the period before device 3 is removed from feed line L1, the second switch SW2 is turned on. Then, in the CR filter 42 of the drive circuit 41, the discharge current I12 flows from capacitor C1 to feed line L1 via the second resistive element R2, and capacitor C1 begins to discharge. Capacitor C1 discharges according to a time constant based on the resistance value of the second resistive element R2 and the electrostatic capacitance value of capacitor C1.

[0063] And, as Figure 3B As shown, once the charging voltage of capacitor C1 (that is, the voltage between the gate and source of the first switch SW1) falls below the specified voltage due to the full discharge of capacitor C1, the first switch SW1 is turned off, and circuit L2 is disconnected. Accordingly, feeder line L1 cannot supply power to load 31. After this, the electrical connection between device 3 and feeder line L1 is severed by removing device 3 from feeder line L1, thus separating a pair of connection terminals 32 of device 3 from a pair of connection conductors L11 of feeder line L1.

[0064] Thus, the suppression circuit 4 disconnects the device 3 from the feeder line L1 before it is removed from the feeder line L1 by turning off the first switch SW1 after a delay from the moment the second switch SW2 is turned on. Therefore, even if contact jitter occurs when the device 3 is removed from the feeder line L1, power will not be supplied from the feeder line L1 to the load 31 during the contact jitter period, thereby suppressing the occurrence of arcing caused by contact jitter.

[0065] Alternatively, there is a possibility that device 3 may be removed from feeder line L1 before the delay time has elapsed. In this case, although an arc may occur at the moment device 3 is removed from feeder line L1, the arc occurrence time can be shortened compared to the case where suppression circuit 4 is not present. As a result, it can be considered that the arc caused by contact bounce is suppressed.

[0066] Here, in the CR filter 42, it is desirable that the resistance value of the second resistor element R2 is smaller than that of the first resistor element R1. The smaller the resistance value of the second resistor element R2 is compared to the resistance value of the first resistor element R1, the shorter the delay time until the first switch is turned off. Furthermore, the shorter the delay time, the lower the probability of installing or removing the device 3 from the feeder line L1 before the delay time, and the less likely it is to generate an arc due to contact bounce. However, this delay time is not necessarily better the shorter it is; in the case of an extremely short delay time, an arc may be generated due to the instantaneous turn-off of the first switch SW1. Therefore, it is desirable, for example, that the delay time is approximately tens of milliseconds.

[0067] On the other hand, when installing device 3 onto feeder line L1, since load 31 can be connected to feeder line L1 after it is estimated that device 3 has indeed been installed, the delay time until the first switch SW1 is turned on can be longer. However, if this delay time is made extremely long, the time from when device 3 is installed onto feeder line L1 to when load 31 is actually driven will be too long, which may feel unnatural to the user. Therefore, it is desirable, for example, that the delay time is approximately several hundred milliseconds.

[0068] [Work]

[0069] The following uses Figure 4 An example of the operation of the arc detection system 100 according to Embodiment 1 will be described. Figure 4 This is a flowchart illustrating an example of the operation of the arc detection system 100 according to Embodiment 1.

[0070] First, the acquisition unit 11 acquires the measurement result of the current I1 over a predetermined period from the ammeter 22 (S1). Processing S1 corresponds to the acquisition step ST1 of the arc detection method. Then, the judgment unit 12 determines whether an arc fault has occurred based on the components of a specific frequency band in the measurement result of the current I1 acquired by the acquisition unit 11 (S2). Here, the judgment unit 12 makes the determination by performing frequency analysis on the measurement result of the current I1 acquired by the acquisition unit 11.

[0071] Specifically, the determination unit 12 compares the components of the specific frequency band with a threshold. If the components of the specific frequency band are above the threshold and the specific time for which this state persists is longer than the threshold time, then it is determined that an arc fault has occurred (S3 "Yes"). On the other hand, if the specific time does not reach the threshold time or the components of the specific frequency band are below the threshold, the determination unit 12 determines that no arc fault has occurred (S3 "No"). Processing S2 and S3 corresponds to the determination step ST2 of the arc detection method.

[0072] If the determination unit 12 determines that an arc fault has occurred (S3 "Yes"), the stopping unit 14 stops the power supply from the DC power supply 2 to the feeder line L1 by stopping the current flowing in the feeder line L1 (S4). Furthermore, the notification unit 13 notifies that an arc fault has occurred (S5). On the other hand, if the determination unit 12 determines that no arc fault has occurred (S3 "No"), the processing of the arc detection system 100 ends. Hereinafter, the above series of processes S1 to S5 are repeated.

[0073] [advantage]

[0074] Hereinafter, the advantages of the arc detection system 100 according to Embodiment 1 will be explained while comparing it with the comparative arc detection system. The comparative arc detection system immediately determines that an arc fault has occurred as long as a component of a specific frequency band in the measurement result of the current I1 obtained by the acquisition unit 11 is higher than a threshold. In this respect, the comparative arc detection system differs from the arc detection system 100 according to Embodiment 1.

[0075] First, the conditions required for an arc detection system will be explained. If an arc occurs due to a break or near break in the feeder line L1, ignoring this situation could lead to a fire due to excessive heating of the broken or near-broken section, which may sometimes generate sparks. Therefore, it is crucial that the arc detection system can quickly detect the occurrence of an arc (i.e., the occurrence of an arc fault) and stop supplying power to the feeder line L1 before a fire occurs. For example, the UL (Underwriters Laboratories) standard requires detection of an arc fault within two seconds of its occurrence.

[0076] Even a comparative arc detection system can detect arc faults. However, in a comparative arc detection system, not only are arcs caused by a broken or nearly broken wire in the feeder line L1 classified as arc faults, but arcs caused by contact jitter are also classified as arc faults. In other words, even arcs unlikely to cause an arc fault are incorrectly classified as arc faults by the comparative arc detection system. Thus, because the comparative arc detection system classifies every arc as an arc fault, it may be inconvenient for users. For example, it might notify the user of an arc fault every time the device 3 is installed or removed from the feeder line L1, which would be annoying. Furthermore, suppose the comparative arc detection system is configured to automatically stop supplying power from the DC power supply 2 to the feeder line L1 when an arc fault is detected. In this configuration, there is a possibility that the power supply to the feeder line L1 will stop whenever the device 3 is attached to or detached from the feeder line L1, which would be annoying to the user.

[0077] On the other hand, in the arc detection system 100 according to Embodiment 1, an arc caused by a break or near break in the feeder line L1 is judged as an arc fault, but an arc caused by contact jitter is generally not judged as an arc fault. In other words, in the arc detection system 100 according to Embodiment 1, the likelihood of judging an arc that is unlikely to cause an arc fault as an arc fault is low. In other words, in the arc detection system 100 according to Embodiment 1, since it is not necessary to detect arcs that may occur when the device 3 is installed or removed from the feeder line L1—that is, phenomena that occur only temporarily and are unlikely to cause an arc fault—the arc detection system 100 has the advantage of easily preventing false detection of arc faults. Therefore, the phenomena described above, which may occur in the comparative arc detection system, are unlikely to occur in the arc detection system according to Embodiment 1. In other words, in the arc detection system 100 according to Embodiment 1, since the user is notified or power supply to the feeder line L1 is stopped only when a phenomenon that is considered to have a significant impact on the user occurs, that is, when an arc fault occurs, the user is notified or power supply to the feeder line L1 is stopped, thus having the advantage of being convenient for the user to use.

[0078] (Implementation Method 2)

[0079] [constitute]

[0080] The following uses Figure 5 The arc detection system 100 according to Embodiment 2 will be described. Figure 5 This is a schematic diagram showing the overall configuration of the arc detection system 100 according to Embodiment 2. Figure 5 The diagram for DC power supply 2 is omitted. Therefore, in Figure 5 The illustrations of the acquisition unit 11, judgment unit 12, notification unit 13, and stop unit 14, which are components of the arc detection system 100, are omitted here. In the arc detection system 100 according to Embodiment 2, the configuration of the suppression circuit 4A differs from that of the suppression circuit 4 in the arc detection system 100 according to Embodiment 1. The following description mainly focuses on the differences from Embodiment 1, while appropriately omitting descriptions of the parts identical to those in Embodiment 1.

[0081] In Embodiment 2, the suppression circuit 4A is the same as the suppression circuit 4 in Embodiment 1, and also includes a first switch SW1, a second switch SW2, and a drive circuit 41. However, in the suppression circuit 4A of Embodiment 2, the arrangement of each component of the first switch SW1, the second switch SW2, and the drive circuit 41 is different from that of the suppression circuit 4 in Embodiment 1. Furthermore, the drive circuit 41 of Embodiment 2 is also different from the suppression circuit 4 of Embodiment 1, and includes a power supply circuit 43.

[0082] The first switch SW1 is the same as in Embodiment 1, and is an n-channel enhancement-mode MOSFET. The drain of the first switch SW1 is connected to the positive terminal of one of the pair of connection terminals 32, and the source of the first switch SW1 is connected to the positive terminal of the load 31. The gate of the first switch SW1 is connected to the drive circuit 41.

[0083] The second switch SW2 is the same as that in Embodiment 1, and is a normally closed push-button switch. One end of the second switch SW2 is connected to the gate of the first switch SW1 via the second resistor element R2, and the other end of the second switch SW2 is connected to the positive terminal 32 of a pair of connection terminals 32.

[0084] The driving circuit 41 includes a first resistive element R1, a second resistive element R2, a capacitor C1, a Zener diode ZD1, and a power supply circuit 43. The first resistive element R1, the second resistive element R2, and the capacitor C1 form a CR filter 42. One end of the first resistive element R1 is connected to the gate of the first switch SW1, and the other end of the first resistive element R1 is connected to the high-voltage side of the pair of output terminals 432 of the power supply circuit 43. One end of the second resistive element R2 is connected to the gate of the first switch SW1, and the other end of the second resistive element R2 is connected via the second switch SW2 to the positive side of the pair of connection terminals 32. One end of the capacitor C1 is connected to the gate of the first switch SW1, and the other end of the capacitor C1 is connected to the source of the first switch SW1. The Zener diode ZD1 is connected between the gate and source of the first switch SW1 to suppress excessively large voltages applied between the gate and source of the first switch SW1.

[0085] The power supply circuit 43 has a pair of input terminals 431 and a pair of output terminals 432, which are electrically isolated from each other. The power supply circuit 43 generates a drive voltage for driving the gate of the first switch SW1 based on the voltage applied to the input terminals 431, and outputs the generated drive voltage from the output terminals 432. The input terminals 431 are respectively connected to a pair of connection terminals 32. The high-voltage output terminal 432 is connected to the gate of the first switch SW1 via a first resistor element R1, and the low-voltage output terminal 432 is connected to the positive terminal of the load 31.

[0086] In the CR filter 42, when the second switch SW2 is in the off state, the time constant and the delay time are determined based on the resistance value of the first resistor element R1 and the electrostatic capacitance value of the capacitor C1. On the other hand, in the CR filter 42, when the second switch SW2 is in the on state, the time constant and the delay time are determined based on the resistance value of the second resistor element R2 and the electrostatic capacitance value of the capacitor C1.

[0087] The operation of the suppression circuit 4A will now be explained. First, the operation of the suppression circuit 4A when the device 3 is installed onto the feeder line L1 will be explained. Here, it is assumed that the user is operating the second switch SW2 while installing the device 3 onto the feeder line L1. At the moment when a pair of connection terminals 32 of the device 3 contacts a pair of connection conductors L11 of the feeder line L1 (hereinafter referred to as the "contact moment"), the first switch SW1 is in the off state, and circuit L2 is disconnected. Furthermore, although the device 3 is electrically connected to the feeder line L1 at the contact moment, since the second switch SW2 is in the on state, no charging current flows in the capacitor C1, and the first switch SW1 does not conduct.

[0088] Here, the user operates the second switch SW2 while inserting device 3 into feeder line L1 and rotating it at a predetermined angle, thereby electrically and mechanically connecting device 3 to feeder line L1. This completes the installation of device 3 onto feeder line L1. Afterward, the user releases the second switch SW2, thus turning it off. In other words, as long as the user operates the second switch SW2, that is, until the installation of device 3 onto feeder line L1 is completed, the first switch SW1 is essentially not turned on.

[0089] When the second switch SW2 is turned off, a voltage is applied to a pair of input terminals 431 of the power supply circuit 43 via the feed line L1, thereby generating a drive voltage and outputting the generated drive voltage from a pair of output terminals 432. Accordingly, in the CR filter 42 of the drive circuit 41, capacitor C1 begins to charge by allowing the charging current to flow through the first resistive element R1 to capacitor C1. Capacitor C1 charges according to a time constant based on the resistance value of the first resistive element R1 and the electrostatic capacitance value of capacitor C1.

[0090] Furthermore, by fully charging capacitor C1, once the charging voltage of capacitor C1 (that is, the voltage between the gate and source of the first switch SW1) reaches the specified voltage, the first switch SW1 is turned on, and circuit L2 is connected. Accordingly, the feeder line L1 can provide power to the load 31.

[0091] Next, the operation of the suppression circuit 4A when device 3 is removed from feed line L1 will be explained. Here, it is assumed that the user operates the second switch SW2 while removing device 3 from feed line L1. During the period before device 3 is removed from feed line L1, the second switch SW2 is turned on. Then, in the CR filter 42 of the drive circuit 41, the discharge current flows from capacitor C1 to feed line L1 via the second resistive element R2, and capacitor C1 begins to discharge. Capacitor C1 discharges according to a time constant based on the resistance value of the second resistive element R2 and the electrostatic capacitance value of capacitor C1.

[0092] Furthermore, once the charging voltage of capacitor C1 (i.e., the voltage between the gate and source of the first switch SW1) falls below the specified voltage due to the full discharge of capacitor C1, the first switch SW1 is turned off, and circuit L2 is disconnected. Accordingly, feeder line L1 cannot supply power to load 31. After this, the electrical connection between device 3 and feeder line L1 is severed by removing device 3 from feeder line L1, thereby separating a pair of connection terminals 32 of device 3 from a pair of connection conductors L11 of feeder line L1.

[0093] As described above, in the arc detection system 100 according to Embodiment 2, the suppression circuit 4A operates in the same way as the suppression circuit 4 in Embodiment 1. Furthermore, except for the suppression circuit 4A, the configuration of the arc detection system 100 according to Embodiment 2 is the same as that of the arc detection system 100 according to Embodiment 1. Therefore, the arc detection system 100 according to Embodiment 2 can achieve the same effects as the arc detection system 100 according to Embodiment 1.

[0094] (Other implementation methods)

[0095] While embodiments 1 and 2 have been described above, the present invention is not limited to embodiments 1 and 2. Hereinafter, variations of embodiments 1 and 2 will be listed. The variations to be described below can also be appropriately combined.

[0096] In embodiments 1 and 2, although the ammeter 22 is a device installed outside the arc detection system 100, it can also be built into the arc detection system 100.

[0097] In embodiments 1 and 2, although the arc detection system 100 is provided in the DC power supply 2, it is not limited thereto. For example, the arc detection system 100 can also be connected to the feeder line L1 as a device other than the DC power supply 2. In this case, as long as the arc detection system 100 is configured to communicate with the DC power supply 2 via wired or wireless communication, it can provide an instruction to the DC power supply 2 according to the determination result of the determination unit 12.

[0098] In embodiments 1 and 2, although the determination unit 12 extracts components of a specific frequency band by performing frequency analysis on the measurement result of the current I1 obtained by the acquisition unit 11, it is not limited to this. For example, the determination unit 12 may also extract frequency components of a specific frequency band by passing the measurement result of the current I1 obtained by the acquisition unit 11 through a filter (e.g., a bandpass filter) instead of performing frequency analysis.

[0099] In embodiments 1 and 2, although the second switch SW2 is configured to switch between on and off via manual operation by the user, it is not limited to this. For example, the second switch SW2 may also be configured to automatically switch between on and off depending on whether the device 3 is attached to or removed from the feeder line L1. For example, the second switch SW2 may also be configured to temporarily switch to a short-circuit state at least when the device 3 is removed from the feeder line L1.

[0100] The following is a specific example of the above configuration. In this specific example, the second switch SW2 is configured as a normally closed push-button switch that switches to the off state (open state) when a specified force is applied. That is, the second switch SW2 maintains a conducting state (short-circuit state) when the device 3 is not installed on the feeder line L1, and switches to the off state by applying a specified force when the device 3 is installed on the feeder line L1.

[0101] The operation of the second switch SW2 in the above specific example will now be explained. When installing device 3 onto feeder line L1, firstly, device 3 is inserted into feeder line L1. At this moment, the second switch SW2 remains in the ON state. Afterward, device 3 is rotated by a predetermined angle, thereby connecting device 3 to feeder line L1. At this time, as device 3 rotates, a predetermined force is applied to the second switch SW2 by device 3 and feeder line L1. Accordingly, the second switch SW2 switches to the OFF state. Furthermore, the second switch SW2 remains in the OFF state while device 3 is installed on feeder line L1.

[0102] To remove device 3 from feeder line L1, first, rotate device 3 by the specified angle opposite to its installation angle. At the moment rotation of device 3 begins, the second switch SW2 is released from the force exerted by device 3 and feeder line L1, thus switching to the ON state. Furthermore, during the rotation of device 3, the load 31 is disengaged from feeder line L1.

[0103] In this configuration, the second switch SW2 automatically switches between on and off states based on whether the device 3 is attached to or detached from the feeder line L1, without direct user operation. Furthermore, the second switch SW2 switches to the on state before the device 3 is removed from the feeder line L1 (that is, it temporarily switches to a short-circuit state at least when the device 3 is removed from the feeder line L1). In this configuration, similar to the case where the user operates the second switch SW2 when the device 3 is removed from the feeder line L1, the electrical connection between the device 3 and the feeder line L1 is severed before the device 3 is removed. Therefore, in this configuration, even if contact bounce occurs when the device 3 is removed from the feeder line L1, power will not be supplied from the feeder line L1 to the load 31 during the contact bounce period, thus suppressing the occurrence of arcing caused by contact bounce.

[0104] In embodiments 1 and 2, the suppression circuits 4 and 4A may not have the second switch SW2. Furthermore, in embodiments 1 and 2, the arc detection system 100 may not have the notification unit 13 and the stop unit 14. That is, the arc detection system 100 only needs to have the function of detecting the occurrence of arc faults; the notification unit 13 and the stop unit 14 can be implemented by other systems.

[0105] In embodiments 1 and 2, although each device 3 is provided with suppression circuits 4 and 4A, this is not a limitation. For example, suppression circuits 4 and 4A may be provided only in a portion of the multiple devices 3. Furthermore, suppression circuits 4 and 4A may not be provided in any single device 3. That is, the arc detection system 100 may not have suppression circuits 4 and 4A. Also, for example, suppression circuits 4 and 4A may not be provided in the devices 3, but rather in a connector used to connect the devices 3 to the feed line L1.

[0106] For example, the present invention can be implemented not only as an arc detection system 100, but also as an arc detection method including the steps (processes) performed on each constituent element constituting the arc detection system 100.

[0107] Specifically, the arc detection method includes an acquisition step ST1 and a judgment step ST2. In the acquisition step ST1, the measurement result of the current I1 flowing in the feeder line L1 powered by the DC power supply 2 is obtained. In the judgment step ST2, a judgment is made as to whether an arc fault has occurred based on the specific frequency band components of the current I1 measured in the acquisition step ST1. In the judgment step ST2, if the specific frequency band component reaches a threshold value for a period longer than the time during which an arc could occur when the device 3 is installed or removed from the feeder line L1, an arc fault is judged to have occurred.

[0108] For example, these steps can also be performed by a computer (computer system) having more than one processor. Furthermore, the present invention can be implemented as a program for causing a computer to execute the steps included in these methods. Further, the present invention can also be implemented by a non-transitory recording medium such as a CD-ROM, which is a computer-readable recording program. Specifically, the program causes more than one processor to execute the above-described arc detection method.

[0109] Although at least a portion of the arc detection system 100 described in the above embodiments is implemented by microcomputer-executed software, it can also be implemented by executing software on a general-purpose computer such as a personal computer. Furthermore, at least a portion of the arc detection system 100 can also be implemented by hardware consisting of dedicated electronic circuits such as A / D converters, logic circuits, gate arrays, and D / A converters.

[0110] Furthermore, the suppression circuits 4 and 4A in embodiments 1 and 2 may be distributed separately from the arc detection system 100 and sold individually on the market. That is, the suppression circuits 4 and 4A include a first switch SW1 and a drive circuit 41. The first switch SW1 connects or disconnects the circuit L2 between the feeder line L1, which is powered by the DC power supply 2, and the load 31 of the device 3 that can be attached to and detached from the feeder line L1. The drive circuit 4 drives the first switch SW1 to turn on the circuit L2 after a delay time has elapsed after the device 3 has been connected to the circuit L2.

[0111] Furthermore, the suppression circuits 4 and 4A can also be configured as follows: the first switch SW1 is a field-effect transistor; the driving circuit 41 further includes a CR filter 42 connected to the gate of the first switch SW1 and applying the charging voltage of capacitor C1 to the gate of the first switch SW1; the delay time is determined by the time constant of the CR filter 42.

[0112] Furthermore, the suppression circuits 4 and 4A can also be configured as follows: the suppression circuits 4 and 4A further include a second switch SW2 that switches the gate of the first switch SW1 and the circuit L2 from one of a short-circuit state and an open state to the other.

[0113] Furthermore, the suppression circuits 4 and 4A can also be configured as follows: the second switch SW2 is configured to temporarily switch to a short-circuit state at least when the device 3 is removed from the feeder line L1.

[0114] Furthermore, the suppression circuits 4 and 4A can be configured such that the delay time is set to prevent power from being supplied to the device 3 during the period when contact jitter may occur when the device 3 is attached to or detached from the feeder line L1.

[0115] The suppression circuits 4 and 4A described above have the following advantages: they make it difficult to generate an electric arc that may be caused by contact jitter when the device 3 is installed or removed from the feeder line L1.

[0116] In addition, the first switch SW1 is not limited to a field-effect transistor; for example, it can also be a relay.

[0117] Furthermore, the present invention includes all forms obtained by performing various modifications that can be conceived by those skilled in the art on various embodiments, as well as forms achieved by combining constituent elements and functions without departing from the spirit of the present invention.

[0118] (Summarize)

[0119] As described above, the arc detection system 100 includes an acquisition unit 11 and a determination unit 12. The acquisition unit 11 acquires the measurement result of the current I1 flowing in the feeder line L1, which is powered by the DC power supply 2. The determination unit 12 determines whether an arc fault has occurred based on the components of a specific frequency band in the measurement result of the current I1 acquired by the acquisition unit 11. If the specific time during which the components of the specific frequency band are above a threshold is longer than the time during which an arc might occur when the device 3 is installed or removed from the feeder line L1, the determination unit 12 determines that an arc fault has occurred.

[0120] With such an arc detection system 100, since it is not necessary to detect arcs that may occur when the device 3 is installed or removed from the feeder line L1, that is, phenomena that occur only temporarily and are not likely to cause arc faults, such an arc detection system 100 has the advantage of easily preventing false detection of arc faults.

[0121] Furthermore, the arc detection system 100 further includes, for example, suppression circuits 4 and 4A to suppress arcs that may occur when the device 3 is attached to or detached from the feeder line L1. Suppression circuits 4 and 4A include a first switch SW1 and a drive circuit 41. The first switch SW1 connects or disconnects the circuit L2 between the load 31 of the device 3 and the feeder line L1. The drive circuit 41 drives the first switch SW1 to connect the circuit L2 after a delay following the connection of the device 3 to the circuit L2.

[0122] With this arc detection system 100, since the load 31 of the device 3 is connected to the feeder line L1 after the device 3 is estimated to be installed on the feeder line L1, it is difficult for the load 31 to momentarily disconnect from the feeder line L1 when current is flowing. As a result, the arc detection system 100 has the following advantages: it is difficult to generate an arc that may occur due to contact bounce when the device 3 is installed or removed from the feeder line L1.

[0123] Furthermore, in the arc detection system 100, the first switch SW1 is, for example, a field-effect transistor. The drive circuit 41 further includes a CR filter 42 connected to the gate of the first switch SW1 and applying the charging voltage of capacitor C1 to the gate of the first switch SW1. The delay time is determined by the time constant of the CR filter 42.

[0124] With this arc detection system 100, since the load 31 of the device 3 is connected to the feeder line L1 after the device 3 is estimated to be installed on the feeder line L1, it is difficult for the load 31 to momentarily disconnect from the feeder line L1 when current is flowing. As a result, the arc detection system 100 has the following advantages: it is difficult to generate an arc that may occur due to contact bounce when the device 3 is installed or removed from the feeder line L1.

[0125] Furthermore, in the arc detection system 100, the suppression circuits 4 and 4A further include, for example, a second switch SW2 that switches the gate of the first switch SW1 and the circuit L2 from a short-circuit state to an open state.

[0126] With this arc detection system 100, the electrical connection between the device 3 and the feeder line L1 can be severed before the device 3 is removed from the feeder line L1 by operating the second switch SW2 when the device 3 is removed from the feeder line L1. Therefore, the arc detection system 100 has the advantage that since power is not supplied from the feeder line L1 to the load 31 during periods when contact jitter may occur, the occurrence of arcs caused by contact jitter can be suppressed.

[0127] Furthermore, in the arc detection system 100, the second switch SW2 is configured, for example, to temporarily switch to a short-circuit state at least when the device 3 is removed from the feeder line L1.

[0128] Such an arc detection system 100 has the following advantages: when the device 3 is removed from the feeder line L1, the electrical connection between the device 3 and the feeder line L1 is automatically disconnected before the device 3 is removed from the feeder line L1.

[0129] Furthermore, in the arc detection system 100, the delay time is, for example, set such that no power is supplied to the device 3 during the period when contact jitter may occur when the device 3 is attached to or detached from the feeder line L1. This specific time is longer than the delay time.

[0130] Such an arc detection system 100 has the following advantages: it easily prevents the occurrence of an arc caused by contact bounce from being mistakenly identified as an arc fault.

[0131] Furthermore, the arc detection method includes, for example, an acquisition step ST1 and a judgment step ST2. In the acquisition step ST1, the measurement result of the current I1 flowing in the feeder line L1 powered by the DC power supply 2 is obtained. In the judgment step ST2, a judgment is made as to whether an arc fault has occurred based on the components of a specific frequency band in the measurement result of the current I1 obtained in the acquisition step ST1. In the judgment step ST2, if the time when the components of the specific frequency band are above a threshold is longer than the time during which an arc might occur when the device 3 is installed or removed from the feeder line L1, an arc fault is judged to have occurred.

[0132] This arc detection method eliminates the need to detect arcs that may occur when the device 3 is installed or removed from the feeder line L1, which are temporary occurrences that are unlikely to cause an arc fault. Therefore, this arc detection method has the advantage of easily preventing false detections of arc faults.

[0133] Furthermore, the program recording medium may contain, for example, a program that enables one or more processors to execute the aforementioned arc detection method.

[0134] Since such a program recording medium does not require detection of arcing that may occur when the device 3 is installed or removed from the feeder line L1, i.e., such a temporary phenomenon that is not enough to cause an arcing fault, such a program recording medium has the advantage of easily preventing false detection of arcing faults.

[0135] Explanation of symbols

[0136] 100 Arc Detection System

[0137] 11. Obtained by the department

[0138] 12 Judgment Department

[0139] 2 DC power supply

[0140] 3 Equipment

[0141] 31 Load

[0142] 4. 4A Suppression Circuit

[0143] 41 Drive Circuit

[0144] 42 CR filter

[0145] C1 capacitor

[0146] I1 current

[0147] L1 feeder line

[0148] L2 circuit

[0149] Steps to obtain ST1

[0150] ST2 Judgment Steps

[0151] SW1 First Switch

[0152] SW2 Second Switch

Claims

1. An arc detection system, The arc detection system includes: The obtaining unit obtains a measurement result of the current, said current being the current flowing in a feeder line powered by a DC power source; and The judgment unit determines whether an arc fault has occurred based on the components of a specific frequency band in the current measurement results obtained by the acquisition unit. The determination unit determines that an arc fault has occurred if the time during which a component of the specific frequency band exceeds a threshold is longer than the time during which an arc might occur when the device is installed or removed from the feeder line. The specific frequency band is tens of kHz.

2. The arc detection system as described in claim 1, The arc detection system further includes a suppression circuit that suppresses arcs that may occur when the device is installed or removed from the feeder line. The suppression circuit includes a first switch and a drive circuit. The first switch connects or disconnects the circuit between the load of the device and the feeder line. After the device is connected to the circuit and a delay time has elapsed, the drive circuit drives the first switch to turn on the circuit.

3. The arc detection system as described in claim 2, The first switch is a field-effect transistor. The driving circuit further includes a CR filter, which is connected to the gate of the first switch and applies a capacitor charging voltage to the gate of the first switch. The delay time is determined by the time constant of the CR filter.

4. The arc detection system as described in claim 3, The suppression circuit further includes a second switch that switches the gate of the first switch and the circuit from a short-circuit state to an open state.

5. The arc detection system as described in claim 4, The second switch is configured to temporarily switch to the short-circuit state at least when the device is removed from the feeder.

6. The arc detection system as described in any one of claims 2 to 5, The delay time is set such that no power is supplied to the device during the period when contact jitter may occur when the device is being attached to or detached from the feeder cable. The time for a component of the specific frequency band to be above the threshold is longer than the delay time.

7. An arc detection method, comprising: The step is to obtain a measurement result of the current, which is the current flowing in the feeder line powered by a DC power source; as well as The judgment step involves determining whether an arc fault has occurred based on the specific frequency band components in the current measurement results obtained in the acquisition step. In the judgment step, if the time for a component of the specific frequency band to be above a threshold is longer than the time during which an arc might occur when the device is installed or removed from the feeder line, it is determined that an arc fault has occurred. The specific frequency band is tens of kHz.

8. A program recording medium, The program recording medium records a program that causes one or more processors to execute the arc detection method of claim 7.

Images