Circuit determination system, circuit interruption system, and distribution board

Abstract

To provide a circuit determination system, a circuit cutoff system, and a distribution board capable of suppressing a trouble caused by re-turning on a switch.SOLUTION: A circuit determination system 1 controls a switch SW that conducts and cuts off an electric path La. The circuit determination system 1 includes a current detection unit 11 and a control unit 13. The current detection unit 11 detects a load current I1 flowing through the electric path La. The control unit 13 controls the switch SW so as to be capable of switching between an off state in which the electric path La is cut off and an on state in which the electric path La is conducted. The control unit 13 sets a period from when the switch SW is switched to the on state to when a predetermined time elapses until the switch SW is switched to the off state as a determination period. The control unit 13 performs determination processing of determining whether to switch the switch SW to the on state again based on a waveform of the load current I1 detected by the current detection unit 11 in the determination period.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a circuit determination system, a circuit interruption system, and a distribution board. [Background technology]

[0002] The shutdown system of Patent Document 1 includes an acquisition unit and a shutdown control unit. The acquisition unit acquires information on the duration of a power outage that occurs in a grid power source. The shutdown control unit turns off the contacts of a breaker connected to the grid power source when the duration of the power outage exceeds a predetermined threshold time. By including this configuration, the shutdown system prevents a situation in which power is restored to the breaker when no one is nearby after a power outage caused by a disaster. In other words, it becomes possible to prevent problems that may occur when power is restored to the breaker. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-53304 Summary of the Invention [Problem to be solved by the invention]

[0004] When a breaker (switch) is turned on again after an overcurrent or power outage occurs, it is necessary to prevent problems caused by the re-closing. However, the circuit breaker system of the above-mentioned Patent Document 1 turns off the contacts of the breaker when a power outage occurs, but does not disclose how to prevent problems caused by the re-closing of the breaker (switch).

[0005] Therefore, an object of the present disclosure is to provide a circuit determination system, a circuit interruption system, and a distribution board that can suppress problems caused by re-closing a switch. [Means for solving the problem]

[0006] A circuit determination system according to one aspect of the present disclosure controls a switch that connects and disconnects an electric path. The circuit determination system includes a current detection unit and a control unit. The current detection unit detects a load current flowing through the electric path. The control unit controls the switch to be switchable between an off state that disconnects the electric path and an on state that connects the electric path. The control unit defines a determination period as a period from when the switch is switched to the on state until when a predetermined time has elapsed and the switch is switched to the off state. The control unit performs a determination process to determine whether or not the switch can be switched to the on state again, based on the waveform of the load current detected by the current detection unit during the determination period.

[0007] A circuit interruption system according to one aspect of the present disclosure includes the circuit determination system described above and the switch.

[0008] A distribution board according to one aspect of the present disclosure includes the circuit breaker system described above and a housing that houses the circuit breaker system. [Effects of the Invention]

[0009] As described above, the present disclosure has the effect of suppressing trouble caused by re-closing a switch. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a circuit breaker system including a circuit determination system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing a distribution board equipped with the circuit breaker system. [Figure 3] FIG. 3 is a front view of the housing of the distribution board. [Figure 4] Figure 4A shows the waveforms when the power is re-closed after the fault point has been completely restored, and Figure 4B shows the waveforms when the power is re-closed when the fault point has not been completely restored. [Figure 5]Fig. 5A is a waveform diagram when the first inspection is started before the fault point has been completely restored, and Fig. 5B is a waveform diagram when the first inspection is started after the fault point has been completely restored. [Figure 6] FIG. 6 is a waveform diagram showing the relationship between the phase and phase range of the AC voltage. [Figure 7] FIG. 7 is a waveform diagram when the second inspection is started. [Figure 8] FIG. 8 is a block diagram showing a distribution board according to a first modified example. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following embodiments generally relate to a circuit determination system, a circuit interruption system, and a distribution board. More specifically, the embodiments relate to a circuit determination system, a circuit interruption system, and a distribution board that control switches that connect and disconnect electric circuits. Note that the following embodiments are merely examples of embodiments of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0012] The DC device circuit determination system, circuit interruption system, and distribution board according to the embodiments are primarily used in apartment buildings, detached houses, office buildings, commercial buildings, hotels, factories, stores, etc. However, the circuit determination system, circuit interruption system, and distribution board according to the embodiments may also be used in facilities other than those described above, and may be installed indoors or outdoors.

[0013] (Embodiment) (1) Overview of the circuit determination system, circuit interruption system, and distribution board FIG. 1 shows the configuration of a circuit determination system 1 according to this embodiment. The circuit determination system 1 controls a switch SW that connects and disconnects an electric circuit La. The circuit determination system 1 includes a current detection unit 11 and a control unit 13. The current detection unit 11 detects a load current I1 that flows through the electric circuit La. The control unit 13 controls the switch SW to be switchable between an OFF state that disconnects the electric circuit La and an ON state that connects the electric circuit La. The control unit 13 defines a determination period as a period from when the switch SW is switched to the ON state until a predetermined time has elapsed and the switch SW is switched to the OFF state. The control unit 13 then performs a determination process to determine whether or not the switch SW can be switched to the ON state again, based on the waveform of the load current I1 detected by the current detection unit 11 during the determination period.

[0014] 1, the circuit breaker system 100 includes a circuit determination system 1 and a switch SW. The circuit breaker system 100 preferably further includes an operation unit 15.

[0015] As shown in FIG. 2, the distribution board 200 includes the circuit breaker system 100 and a housing 2 that houses the circuit breaker system 100.

[0016] The circuit determination system 1, the circuit interruption system 100, and the distribution board 200 having the above-described configuration perform a determination process to determine whether or not the switch SW can be switched on again during a determination period before the switch SW is turned on again. Therefore, the circuit determination system 1 can prevent problems caused by turning the switch SW on again.

[0017] (2) Details The circuit determination system 1 of this embodiment is used in a distribution board 200 shown in Fig. 2. The distribution board 200 is installed in a customer facility F1 such as a detached house, an apartment building, a factory, a store, an office, an office building, a commercial building, a stadium, a hospital, or a school. The distribution board 200 distributes commercial power (AC power) supplied from a commercial power system PS to multiple loads LD in the customer facility F1.

[0018] (2.1) Distribution board The distribution board 200 includes a rectangular box-shaped housing 2. The housing 2 houses a main breaker 3, a plurality of branch breakers 4, and a control device 5. A rectangular opening 2a is formed in the front of the housing 2, and a cover (not shown) is attached to the opening 2a so that it can be opened and closed freely. The cover is movable between a closed position that covers the opening 2a and an open position that exposes the opening 2a to the front. The housing 2 is attached to, for example, a wall or a pillar of a building.

[0019] The housing 2 accommodates a main breaker 3, a plurality of branch breakers 4, and a control device 5. The main breaker 3, the plurality of branch breakers 4, and the control device 5 are attached to the bottom plate of the housing 2 (a plate member facing the opening 2a) directly or via an attachment member or the like. Note that Fig. 2 shows an example of the arrangement of the main breaker 3, the plurality of branch breakers 4, and the control device 5 inside the housing 2. Note that this arrangement can be changed as appropriate.

[0020] A power supply line L0, which supplies commercial power from the power grid PS, is laid outside the customer facility F1, and the power supply line L0 connects to a main power line L1 at the customer facility F1. The main power line L1 is drawn into the housing 2. The commercial power is supplied from the main power line L1 to a load LD outside the housing 2 via a main breaker 3 and branch breakers 4.

[0021] The primary terminal of the main breaker 3 is connected to the main electric circuit L1 drawn into the housing 2. The secondary terminal of the main breaker 3 is connected to the main electric circuit L1 inside the housing 2. The main electric circuit L1 is composed of bus bars, electric wires, etc.

[0022] The main electric circuit L1 connected to the secondary terminal of the main breaker 3 branches into multiple branch electric circuits L2 within the housing 2. Multiple branch breakers 4 are connected to the multiple branch electric circuits L2, respectively. The branch breakers 4 connect and cut off the branch electric circuits L2 to which they are connected. Specifically, the primary terminal of the branch breaker 4 is connected to the branch electric circuit L2 branched from the main electric circuit L1. The secondary terminal of the branch breaker 4 is connected to the branch electric circuit L2 extended outside the housing 2. A load LD of the customer facility F1 is connected to the branch electric circuit L2 extended outside the housing 2. The branch electric circuit L2 is composed of bus bars, electric wires, etc.

[0023] The load LD includes electrical equipment directly connected to the branch electric circuit L2, as well as electrical equipment indirectly connected to the branch electric circuit L2 via an outlet connected to the branch electric circuit L2. Examples of electrical equipment include heating appliances, cooking appliances, lighting appliances, and air conditioning equipment.

[0024] As described above, commercial power is supplied to each of the loads LD via the power supply line L0, the main breaker 3, the main electric line L1, the branch electric line L2, the branch breaker 4, and the branch electric line L2.

[0025] (2.2.1) Main breaker The main breaker 3 has a contact 3a electrically connected between the primary terminal and the secondary terminal of the main breaker 3. In this embodiment, the contact 3a of the main breaker 3 is a mechanical contact having a fixed contact and a movable contact. The main breaker 3 has a handle 3b on its front for turning the contact 3a on or off. When the handle 3b is turned on, the contact 3a is turned on, and the main breaker 3 conducts the main electric circuit L1. When the handle 3b is turned off, the contact 3a is turned off, and the main breaker 3 interrupts the main electric circuit L1. Furthermore, the main breaker 3 has a function for detecting overcurrents such as short-circuit currents or overload currents. When the main breaker 3 detects overcurrents such as short-circuit currents or overload currents, it forcibly opens the contact 3a to interrupt the main electric circuit L1.

[0026] (2.2.2) Branch breaker The branch breaker 4 functions as the circuit breaking system 100 shown in Fig. 1. That is, the branch breaker 4 shown in Fig. 2 includes the circuit determination system 1, the switch SW, and the operation unit 15 of the circuit breaking system 100.

[0027] The switch SW is a semiconductor switch, such as a field effect transistor (FET), an insulated gate bipolar transistor (IGBT), a bipolar transistor, or a solid state relay (SSR). In this embodiment, the switch SW is a normally-off semiconductor switch that is turned off when the voltage or current of the drive signal Y1 becomes zero. The switch SW is connected between the primary terminal and the secondary terminal of the branch breaker 4. That is, the branch electric circuit L2 in FIG. 2 corresponds to the electric circuit La in FIG. 1. When the switch SW is turned on, the branch electric circuit L2 is conductive, and when the switch SW is turned off, the branch electric circuit L2 is interrupted. The switch SW receives a drive signal Y1 (see FIG. 1) from the circuit determination system 1 and is switched on and off by the drive signal Y1. If the magnitude of the voltage or current of the drive signal Y1 is the level of the drive signal Y1, the switch SW is turned on when the level of the drive signal Y1 is equal to or greater than a threshold, and the switch SW is turned off when the level of the drive signal Y1 is less than the threshold.

[0028] As shown in FIG. 1, the circuit determination system 1 includes a circuit block 10, a current detection unit 11, and a voltage detection unit 12.

[0029] The circuit block 10 includes a control unit 13 and a drive unit 14. The operating power source for the control unit 13 and the drive unit 14 is commercial power supplied from a branch electric circuit L2 on the primary side of the branch breaker 4. In addition, if the current detection unit 11 includes a CT (Current Transformer) or the like, the operating power source for the current detection unit 11 is also commercial power supplied from the branch electric circuit L2 on the primary side of the branch breaker 4.

[0030] The drive unit 14 drives the switch SW to turn on and off in accordance with instructions from the control unit 13. Specifically, the drive unit 14 outputs a drive signal Y1 to the switch SW, and drives the switch SW to turn on and off using the drive signal Y1. For example, the drive unit 14 turns on the switch SW by setting the drive signal Y1 to an H level (e.g., 10 V). The drive unit 14 turns off the switch SW by setting the drive signal Y1 to an L level (e.g., 0 V).

[0031] The control unit 13 controls the on / off state of the switch SW in response to the operation of the operation unit 15 and an instruction signal from the control device 5. Specifically, the control unit 13 controls the on / off state of the switch SW by controlling the drive unit 14. That is, the control unit 13 controls the switch SW so that it can be switched between an off state in which the branch electric circuit L2 is interrupted and an on state in which the branch electric circuit L2 is conductive.

[0032] The operation unit 15 is a button or the like for manually switching the switch SW on or off, and is provided on the front surface of the branch breaker 4. The control unit 13 controls the drive signal Y1 output from the drive unit 14 in response to operation of the operation unit 15. When the operation unit 15 is turned on, the control unit 13 sets the drive signal Y1 to an H level to turn on the switch SW. When the operation unit 15 is turned off, the control unit 13 sets the drive signal Y1 to an L level to turn off the switch SW. In this embodiment, the operation unit 15 is a push-button switch that performs momentary operation, but the operation unit 15 may have another structure.

[0033] The control unit 13 also communicates with the control device 5 via the communication line W1, and can control the on / off of the switch SW in response to an instruction signal from the control device 5. The control unit 13 controls the drive signal Y1 output from the drive unit 14 in response to the instruction signal from the control device 5. When receiving an on instruction signal from the control device 5, the control unit 13 sets the drive signal Y1 to H level to turn on the switch SW. When receiving an off instruction signal from the control device 5, the control unit 13 sets the drive signal Y1 to L level to turn off the switch SW. The control unit 13 also outputs a monitor signal indicating the state (on state or off state) of the switch SW to the control device 5.

[0034] The current detection unit 11 detects the load current I1 flowing through the branch electric circuit L2. The current detection unit 11 includes a CT, a shunt resistor, or the like. The current detection unit 11 may be provided on either the primary side or the secondary side of the branch breaker 4. In FIG. 2, the current detection unit 11 is provided on the secondary side of the branch breaker 4. The current detection unit 11 outputs a load current signal Y2 to the control unit 13 as a detection result of the load current I1. The load current signal Y2 indicates the magnitude (current value) of the load current I1. The control unit 13 has a function of detecting an overcurrent such as a short-circuit current or an overload current based on the load current signal Y2. When the control unit 13 detects an overcurrent such as a short-circuit current or an overload current, it turns off the switch SW to interrupt the branch electric circuit L2.

[0035] Furthermore, the control unit 13 generates waveform data (current waveform data) of the load current I1 based on the load current signal Y2. The control unit 13 performs a determination process to determine whether or not the switch SW can be switched on again based on the current waveform data during a determination period described below. The details of the determination process will be described later.

[0036] The voltage detection unit 12 detects the AC voltage Vi applied to the branch electric circuit L2 on the primary side of the branch breaker 4. The voltage detection unit 12 includes a voltage dividing resistor and the like. The voltage detection unit 12 outputs a voltage signal Y3 to the control unit 13 as a detection result of the AC voltage Vi. The voltage signal Y3 indicates the magnitude (voltage value) of the AC voltage Vi. The control unit 13 then monitors the phase of the AC voltage Vi based on the voltage signal Y3. The control unit 13 sets the start timing of a determination period for performing a determination process, which will be described later, based on the phase of the AC voltage Vi. The determination period will be described in detail later.

[0037] (2.2.3) Control device The control device 5 monitors and controls each of the multiple branch breakers 4. The control device 5 outputs an ON instruction signal to a branch breaker 4, thereby setting the drive signal Y1 of that branch breaker 4 to H level and turning on the switch SW. The control device 5 outputs an OFF instruction signal to a branch breaker 4, thereby setting the drive signal Y1 of that branch breaker 4 to L level and turning off the switch SW. In addition, the branch breaker 4 outputs a monitoring signal indicating the state (ON state or OFF state) of the switch SW of that branch breaker 4 to the control device 5. The control device 5 can monitor the state of the branch breaker 4 based on the monitoring signal.

[0038] Furthermore, the control device 5 communicates with the operation terminal 6 to relay the monitoring and control of each of the multiple branch breakers 4 by the operation terminal 6. The operation terminal 6 targets at least one of the multiple branch breakers 4 as a control target and transmits to the control device 5 an instruction signal (on instruction signal or off instruction signal) instructing the state (on state or off state) of the target branch breaker 4. The control device 5 outputs the instruction signal received from the operation terminal 6 to the target branch breaker 4. The target branch breaker 4 turns on or off its switch SW in response to the instruction signal. The control device 5 also notifies the operation terminal 6 of the state of each of the multiple branch breakers 4, allowing the operation terminal 6 to display the state of each of the multiple branch breakers 4 on its screen. The operation terminal 6 is an information terminal such as a smartphone, tablet terminal, or personal computer owned by a user of the customer facility F1, and is equipped with input / output devices such as an LCD screen, touch panel, mouse, and keyboard.

[0039] The communication between the control device 5 and the operation terminal 6 may be either wireless or wired. The wireless communication is wireless communication that complies with standards such as Wi-Fi (registered trademark), a mobile phone network, Bluetooth (registered trademark), ZigBee (registered trademark), or low-power radio that does not require a license (specified low-power radio). The wired communication is wired communication via, for example, a twisted pair cable, a dedicated communication line, or a LAN (Local Area Network) cable.

[0040] (3) Normal operation Normally, the power system PS is energized, and the main breaker 3 and the branch breakers 4 are turned on. In this case, commercial power from the power system PS is supplied to multiple loads LD via the power supply line L0, the main breaker 3, the main electric line L1, the branch electric line L2, the branch breaker 4, and the branch electric line L2.

[0041] The main breaker 3 turns the contact 3a on and off in response to the operation of the handle 3b, thereby switching the main electric circuit L1 between conduction and interruption. When the main breaker 3 detects an overcurrent, it forcibly opens the contact 3a to interrupt the main electric circuit L1. Normally, the contact 3a of the main breaker 3 is on, and the main electric circuit L1 is conductive.

[0042] The branch breaker 4 can switch between conducting and interrupting the branch electric circuit L2 by turning the switch SW on and off in response to the operation of the operation unit 15. Furthermore, when the branch breaker 4 detects an overcurrent, it turns the switch SW off to interrupt the branch electric circuit L2. Normally, the switch SW of the branch breaker 4 is on, and the branch electric circuit L2 is conducting.

[0043] (4) Operation when power is turned back on When reclosing the branch breaker 4 by switching the branch breaker 4 from an OFF state to an ON state again, the control unit 13 of the branch breaker 4 performs a test input by turning on the switch SW for a determination period. Then, during the determination period, the control unit 13 performs a determination process to determine whether or not reclosing is possible. At this time, because the switch SW is a semiconductor switch, it is easy to shorten the determination period.

[0044] Furthermore, in this embodiment, by performing the following first determination process or second determination process, it becomes possible to make a determination in a shorter time than when using conventional disaggregation techniques to distinguish current waveforms.

[0045] (4.1) Restarting after an overcurrent interruption When the control unit 13 of the branch breaker 4 detects an overcurrent, such as a short-circuit current or an overload current, based on the load current signal Y2, it turns off the switch SW to interrupt the branch electric circuit L2. After the user restores the fault point that caused the overcurrent, the switch SW of the branch breaker 4 must be turned on again to re-close the circuit. However, if the fault point is unclear or if all of the multiple fault points have not been restored, an overcurrent will occur again when the branch breaker 4 is re-closed.

[0046] FIG. 4A is a waveform diagram showing the results when power is reclosed after the fault point has been completely restored. It shows an example of the waveforms of the load current I1 flowing through the load LD and the load voltage V1 applied to the load LD. The load voltage V1 corresponds to the AC voltage Vi applied to the load LD via the branch breaker 4. In FIG. 4A, at time t1, an overcurrent OC1 occurs in the load current I1, turning the switch SW of the branch breaker 4 off. Then, at time t2, power is reclosed by switching the switch SW back on. In this case, the fault point has been completely restored, no overcurrent occurs in the load current I1 after time t2, and commercial power is supplied to the load LD.

[0047] Figure 4B is a waveform diagram showing the waveforms of the load current I1 flowing through the load LD and the load voltage V1 applied to the load LD when the fault point has not yet been fully restored. In Figure 4B, an overcurrent OC2 occurs in the load current I1 at time t11, turning the switch SW of the branch breaker 4 off. Then, at time t12, the switch SW is turned on again and the power is reclosed. In this case, the fault point has not yet been fully restored, and even when the power is reclosed at time t12, an overcurrent OC3 occurs in the load current I1, turning the switch SW of the branch breaker 4 off again.

[0048] Therefore, the circuit determination system 1 provided in the branch breaker 4 of this embodiment performs the following first determination process as a determination process performed when the branch breaker 4 is re-closed. The first determination process is a process for determining whether an overcurrent accident has occurred in the branch electric circuit L2 due to a short circuit in the branch electric circuit L2 or a failure in the load LD. The control unit 13 performs the first determination process when it detects an ON operation of the operation unit 15 or receives an instruction signal from outside the distribution board 200.

[0049] (First determination process) When the branch breaker 4 is to be re-closed, the user of the customer facility F1 turns on the operation unit 15 of the branch breaker 4 or operates the operation terminal 6 to send an ON instruction signal from the operation terminal 6. After the control unit 13 of the branch breaker 4 turns off the switch SW due to an overcurrent, if the control unit 13 detects the ON operation of the operation unit 15 or receives an ON instruction signal, the control unit 13 performs a first inspection input to turn on the switch SW for a first determination period Ta. The first determination period Ta is the period from when the switch SW is switched on to when a predetermined time has elapsed and the switch SW is switched off, and corresponds to the determination period described above. The first determination period Ta is, for example, several tens of microseconds.

[0050] Then, the control unit 13 determines whether or not it is possible to switch the switch SW back to the on state, based on the waveform of the load current I1 detected by the current detection unit 11 during the first determination period Ta.

[0051] For example, the control unit 13 preferably includes a learning model created by machine learning such as deep learning that uses a large amount of waveform data of the load current I1 as training data. The learning model is constructed by deep learning using, for example, a convolutional neural network (CNN) or a fully convolutional network (FCN). The learning model receives the waveform data of the load current I1 and determines whether or not an overcurrent accident has occurred. Note that the algorithm executed by the control unit 13 is not limited to a specific algorithm. The learning model may also be a model using other algorithms such as multiple regression analysis or a support vector machine. If the waveform of the load current I1 during the first determination period Ta is not an allowable waveform (or is an unallowable waveform), the control unit 13 determines that an overcurrent accident has occurred and does not permit the switch SW to be switched on again. If the waveform of the load current I1 during the first determination period Ta is an allowable waveform (or is not an unallowable waveform), the control unit 13 determines that an overcurrent accident has not occurred and permits the switch SW to be switched on again.

[0052] Furthermore, control unit 13 may determine whether or not to switch switch SW back to the on state based on the rate of increase (amount of increase per unit time) of load current I1 during first determination period Ta. If the rate of increase of load current I1 during first determination period Ta is equal to or greater than a first threshold, control unit 13 determines that an overcurrent accident has occurred and does not permit switch SW to be switched back to the on state. If the rate of increase of load current I1 during first determination period Ta is less than the first threshold, control unit 13 determines that an overcurrent accident has not occurred and permits switch SW to be switched back to the on state.

[0053] Furthermore, control unit 13 may determine whether or not to switch switch SW back to the on state based on the absolute value of load current I1 during first determination period Ta. If the absolute value of load current I1 during first determination period Ta is equal to or greater than a second threshold, control unit 13 determines that an overcurrent accident has occurred and does not permit switch SW to be switched back to the on state. If the absolute value of load current I1 during first determination period Ta remains less than the second threshold, control unit 13 determines that an overcurrent accident has not occurred and permits switch SW to be switched back to the on state.

[0054] 5A is a waveform diagram showing an example of the waveforms of the load current I1 flowing through the load LD and the load voltage V1 applied to the load LD when the fault point has not been completely restored and the first determination process is performed. In FIG. 5A, an overcurrent OC11 occurs in the load current I1 at time t21, turning off the switch SW of the branch breaker 4. Then, the control unit 13 switches the switch SW to the on state at time t22 and performs the first determination process, maintaining the switch SW in the on state for a first determination period Ta. As a result of performing the first determination process during the first determination period Ta, the control unit 13 determines that an overcurrent fault has occurred and does not allow the switch SW to be switched on again.

[0055] FIG. 5B is a waveform diagram showing an example of the waveforms of the load current I1 flowing through the load LD and the load voltage V1 applied to the load LD when the first inspection is initiated after the fault point has been completely restored and the first determination process is performed. In FIG. 5B, an overcurrent OC21 occurs in the load current I1 at time t31, turning off the switch SW of the branch breaker 4. Then, the control unit 13 switches the switch SW to the on state at time t32 and performs the first inspection, maintaining the switch SW in the on state for the first determination period Ta. As a result of performing the first determination process during the first determination period Ta, the control unit 13 determines that no overcurrent fault has occurred and permits the switch SW to be switched on again. If the control unit 13 permits the switch SW to be switched on again, at time t33, a certain time after the end of the first determination period Ta, the control unit 13 controls the drive unit 14 to switch the drive signal Y1 from low to high, thereby turning on the switch SW. That is, if the control unit 13 permits the switch SW to be switched back to the on state, the drive unit 14 switches the switch SW back to the on state.

[0056] As described above, the circuit determination system 1 performs the first determination process to determine whether an overcurrent accident, in which an overcurrent occurs, has occurred in the branch electric circuit L2 while the load LD is connected to the branch electric circuit L2. Then, the circuit determination system 1 controls the re-closing of the switch SW based on the determination result of the first determination process. As a result, the circuit determination system 1 can prevent problems caused by the re-closing of the switch SW after the occurrence of an overcurrent accident.

[0057] It is preferable that the control unit 13 sets the start timing ta of the determination period Ta to be different from the timings at which the phase of the AC voltage Vi becomes 0 degrees, 90 degrees, 180 degrees, and 360 degrees. The start timing ta of the determination period Ta corresponds to the above-mentioned times t22 (see FIG. 5A) and t32 (see FIG. 5B).

[0058] FIG. 6 shows the waveform of the AC voltage Vi. The magnitude of the AC voltage Vi is zero at phases 0, 180, and 360 degrees, and peaks at phases 90 and 270 degrees. Therefore, if the start timing ta of the determination period Ta coincides with phase 90 or 270 degrees of the AC voltage Vi, the load current I1 during the first determination period Ta will be too large if an overcurrent accident occurs. Furthermore, if the start timing ta of the determination period Ta coincides with phases 0, 180, or 360 degrees of the AC voltage Vi, the load current I1 will be less likely to flow during the first determination period Ta, even if an overcurrent accident occurs. This may prevent accurate determination of whether an overcurrent accident has occurred.

[0059] Therefore, the control unit 13 monitors the phase of the AC voltage Vi based on the voltage signal Y3 output by the voltage detection unit 12. The control unit 13 sets the start timing ta of the determination period Ta to be different from the timings at which the phase of the AC voltage Vi is 0 degrees, 90 degrees, 180 degrees, and 360 degrees. For example, the start timing ta of the determination period Ta is set within a phase range of the AC voltage Vi in which the load current I1 during the first determination period Ta does not become too large and in which it is possible to accurately determine whether or not an overcurrent accident has occurred. Specifically, the start timing ta of the determination period Ta is set within a phase range G1 (see FIG. 6) of the AC voltage Vi between 30 degrees and 60 degrees. In this case, the circuit determination system 1 can improve the accuracy of the first determination process.

[0060] Furthermore, it is preferable that the control unit 13 repeats the first determination process multiple times, and that the start timing of the determination period Ta in each of the multiple first determination processes is different from one another. In this case, the circuit determination system 1 can further improve the accuracy of the first determination process.

[0061] For example, assume that the control unit 13 repeats the first determination process four times. In this case, the control unit 13 sets the start timing of the determination period Ta for each of the four first determination processes to within the phase range G1 of the AC voltage Vi (see FIG. 6 ). The control unit 13 then sets the start timing of the determination period Ta for the first determination process to when the phase of the AC voltage Vi is 30 degrees. The control unit 13 sets the start timing of the determination period Ta for the second determination process to when the phase of the AC voltage Vi is 40 degrees. The control unit 13 sets the start timing of the determination period Ta for the third determination process to when the phase of the AC voltage Vi is 50 degrees. The control unit 13 sets the start timing of the determination period Ta for the fourth determination process to when the phase of the AC voltage Vi is 60 degrees. That is, as the number of first determination processes increases, the control unit 13 gradually delays the phase of the AC voltage Vi that coincides with the start timing of the determination period Ta from 30 degrees toward 60 degrees. The first determination process may be performed one to four times within the same cycle of the AC voltage Vi, or may be performed over multiple cycles (for example, four cycles) of the AC voltage Vi.

[0062] (4.2) Restarting after power outage When the power system PS experiences a power outage, the supply of commercial power from the distribution board 200 to the load LD in the customer facility F1 stops. In the distribution board 200, the operating power source for the control unit 13 and drive unit 14 of the branch breaker 4 is commercial power supplied from the branch electric circuit L2 on the primary side of the branch breaker 4. Therefore, when the power system PS experiences a power outage, the control unit 13 and drive unit 14 stop operating, so the drive signal Y1 for driving the switch SW becomes 0 V (L level), and the switch SW is turned off. In other words, when the power system PS experiences a power outage, the branch electric circuit L2 is shut off.

[0063] When power is restored to the power system PS and power is supplied to the power supply line L0, the main breaker 3, and the main power line L1, the switch SW of the branch breaker 4 that was turned off due to the power outage remains in the off state even after power is restored. In other words, immediately after power is restored, the supply of commercial power to the load LD is stopped. Therefore, in order to supply commercial power to the load LD after power is restored to the power system PS, it is necessary to re-close the switch SW of the branch breaker 4 by switching it back on.

[0064] However, the multiple loads LD in the customer facility F1 may include a heat-generating load LDb (see FIG. 2) that generates heat when in operation. In this embodiment, the heat-generating load LDb is assumed to be a resistive load such as an electric space heater or an electric heater. After a power outage occurs due to a disaster such as an earthquake, fire, or landslide, operating the heat-generating load LDb may pose a risk of secondary disasters such as fire.

[0065] Therefore, the circuit determination system 1 provided in the branch breaker 4 of this embodiment performs the following second determination process as a determination process performed when the branch breaker 4 is re-closed. The second determination process is a process for determining whether the load LD connected to the branch electric circuit L2 is a heat-generating load LDb that generates heat during operation. The control unit 13 performs the second determination process when it detects an ON operation of the operation unit 15 or receives an instruction signal from outside the distribution board 200.

[0066] (Second determination process) When the branch breaker 4 is to be re-closed, the user of the customer facility F1 turns on the operation unit 15 of the branch breaker 4 or operates the operation terminal 6 to transmit an ON instruction signal from the operation terminal 6. When the control unit 13 of the branch breaker 4 detects the ON operation of the operation unit 15 or receives the ON instruction signal after the switch SW is turned off due to a power outage, the control unit 13 performs a second inspection, turning on the switch SW for a second determination period Tb. The second determination period Tb is the period from when the switch SW is turned on until a predetermined time has elapsed and the switch SW is turned off, and corresponds to the determination period described above. The second determination period Tb is preferably a period corresponding to, for example, two cycles of the AC voltage Vi. For example, if the frequency of the power grid PS is 50 Hz, the second determination period Tb is 40 msec. If the frequency of the power grid PS is 60 Hz, the second determination period Tb is 33.3 msec.

[0067] FIG. 7 is a waveform diagram showing an example of the waveforms of the load current I1 flowing through the load LD and the load voltage V1 applied to the load LD when the second inspection is initiated and the second determination process is performed. In FIG. 7, a power outage occurs at time t41, and the switch SW of the branch breaker 4 is turned off. Then, the control unit 13 switches the switch SW to the on state at time t42 and performs the second inspection in which the switch SW is maintained in the on state for a second determination period Tb. The control unit 13 performs the second determination process to determine whether or not the switch SW can be switched on again based on the waveform of the load current I1 detected by the current detection unit 11 during the second determination period Tb. Then, if the result of the second determination process during the second determination period Tb shows that the load LD is not a heat-generating load LDb, the control unit 13 allows the switch SW to be switched on again. If the result of the second determination process during the second determination period Tb shows that the load LD is a heat-generating load LDb, the control unit 13 does not allow the switch SW to be switched on again.

[0068] In this embodiment, the heat generating load LDb is a resistive load such as an electric space heater or an electric heater, and the waveform of the load current I1 is a sine wave (or an approximately sine wave). Therefore, the control unit 13 uses the distortion rate of the waveform of the load current I1 relative to a sine wave to determine whether the waveform of the load current I1 is a sine wave.

[0069] Specifically, as the second determination process, the control unit 13 preferably calculates the distortion rate of the waveform of the load current I1 relative to a sine waveform, and determines that the load LD is a heat-generating load LDb if the distortion rate is less than a third threshold, and determines that the load LD is not a heat-generating load LDb if the distortion rate is equal to or greater than the third threshold. In this embodiment, it is assumed that the heat-generating load LDb is a resistive load, and the load current I1 flowing through the heat-generating load LDb to which the load voltage V1 is applied has a sine waveform. In other words, if the load current I1 flowing through the load LD has a sine waveform or a waveform close to a sine waveform, the load LD is likely to be a heat-generating load LDb. The control unit 13 previously stores waveform data of a sine wave to be compared with the waveform of the load current I1.

[0070] The third threshold value compared with the distortion factor is set to, for example, 5%. The third distortion factor of the waveform of the load current I1 flowing through the heat-generating load LDb, which is an ideal resistive load, is 0%. However, assuming that the load current I1 flowing through the actual heat-generating load LDb contains about 10% fifth-order harmonics, it is preferable to set the third threshold value to 5% (or about 5%).

[0071] If the control unit 13 determines that the distortion rate of the waveform of the load current I1 during the second determination period Tb is equal to or greater than the third threshold and that the load LD is not a heat-generating load LDb, it permits the switch SW to be switched on again.If the control unit 13 determines that the distortion rate of the waveform of the load current I1 during the second determination period Tb is less than the third threshold and that the load LD is a heat-generating load LDb, it does not permit the switch SW to be switched on again.

[0072] Then, if the control unit 13 permits the switch SW to be switched on again, at time t43, which is a certain time after the end of the second determination period Tb, the control unit 13 controls the drive unit 14 to switch the drive signal Y1 from L level to H level, thereby turning on the switch SW. In other words, if the control unit 13 permits the switch SW to be switched on again, the drive unit 14 switches the switch SW to the on state again.

[0073] As described above, the circuit determination system 1 performs the second determination process to determine whether the load LD connected to the branch electric circuit L2 is a heat-generating load LDb while connecting the load LD to the branch electric circuit L2. Then, the circuit determination system 1 controls the re-opening of the switch SW based on the determination result of the second determination process. As a result, the circuit determination system 1 can suppress problems caused by the heat-generating load LDb restarting when power is restored after a power outage.

[0074] The second determination period Tb may be any period that allows the distortion rate of the load current I1 to be calculated, and therefore may have a length of at least half a cycle of the AC voltage Vi. However, in order to accurately calculate the distortion rate in the second determination period Tb, given design constraints such as the time required to start detecting the load current I1, it is preferable that the second determination period Tb be a period equivalent to two cycles of the AC voltage Vi.

[0075] Furthermore, it is preferable that the start timing tb (corresponding to time t42 in FIG. 7) of the second determination period Tb is set to a zero crossing of the AC voltage Vi (0 degrees, 180 degrees, and 360 degrees of the phase of the AC voltage Vi). Then, the control unit 13 sets the phase of the sine wave to be compared with the waveform of the load current I1 to be the same phase as the AC voltage Vi. In this case, the control unit 13 can accurately distinguish between the load LD, which is a capacitive load or an inductive load (a load in which the phase of the load current I1 is shifted from the phase of the AC voltage Vi), and the heat-generating load LDb, which is a resistive load. As a result, the accuracy of determining the heat-generating load LDb is improved.

[0076] Of the first and second determination processes, the control unit 13 may be configured to perform only the first determination process or only the second determination process. Furthermore, the control unit 13 may be configured to perform the second determination process after performing the first determination process, or to perform the first determination process after performing the second determination process.

[0077] (5) First Modification It is preferable that the control unit 13 performs at least one of a first determination process and a second determination process after the seismic sensor detects an earthquake. The distribution board 200 shown in FIG. 8 further includes a seismic sensor 7. The seismic sensor 7 senses seismic motion, and when an earthquake of a magnitude equal to or greater than a set value occurs, outputs an earthquake signal to the control unit 13 via the communication line W2. The control unit 13 determines whether an earthquake has occurred based on the earthquake signal output by the seismic sensor 7.

[0078] For example, suppose that the control unit 13 detects an overcurrent after determining that an earthquake has occurred and turns off the switch SW to interrupt the branch electric circuit L2. In this case, after the user restores the fault point that caused the overcurrent, the control unit 13 executes the first determination process described above when the switch SW of the branch breaker 4 is turned on again. That is, the control unit 13 controls the branch breaker 4 so that it does not re-close unless the fault point has been completely restored after the occurrence of an overcurrent due to an earthquake. Therefore, when an overcurrent accident occurs due to an earthquake, the occurrence of a secondary disaster such as a fire caused by re-closing the switch SW can be suppressed.

[0079] Furthermore, if a power outage occurs after determining that an earthquake has occurred, the control unit 13 executes the second determination process described above. That is, after a power outage occurs due to an earthquake, the control unit 13 controls so that the branch breaker 4 connected to the heat-generating load LDb is not re-closed. Therefore, when an earthquake causes a heat-generating load LDb such as an electric space heater or an electric heater to fall over or when a flammable object such as a blanket covers the heat-generating load LDb, it is possible to prevent the occurrence of a secondary disaster such as a fire due to re-closing the breaker.

[0080] The seismic sensor 7 may be provided in any of the circuit determination system 1, the main breaker 3, the branch breaker 4, and the control device 5. The seismic sensor 7 may also be provided outside the distribution board 200 and transmit an earthquake signal to the control unit 13 in the distribution board 200 via wireless communication or wired communication.

[0081] (6) Second Modification It is preferable that the control unit 13 performs the second determination process when the waveform (current waveform) of the load current I1 is an AC waveform.

[0082] In this case, before performing the second determination process, the control unit 13 determines whether the waveform of the load current I1 detected by the current detection unit 11 is an AC waveform. If the waveform of the load current I1 is an AC waveform, the control unit 13 performs the second determination process. On the other hand, if the waveform of the load current I1 is not an AC waveform, the control unit 13 determines that the load LD is not a heat-generating load LDb. In other words, the control unit 13 can narrow down the loads LD to be subjected to the second determination process from multiple loads LD.

[0083] (7) Third Modification The control unit 13 may determine whether or not there is a leakage current in the branch electric circuit L2 and the load LD by comparing the waveform of the load current I1 with the waveform during a leakage current. In this case, the control unit 13 stores in advance waveform data of the load current I1 during a leakage current.

[0084] (8) Fourth Modification The circuit determination system 1 may include a notification unit. If the above-described determination process denies permission to switch the switch SW back on, the notification unit notifies the user that permission is not granted. The notification unit includes at least one of a screen that visually notifies the user, a speaker that audibly notifies the user, and a communication device that transmits a signal containing the notification content to an information terminal carried by the user.

[0085] The circuit determination system 1 may be provided outside the branch breaker 4. In this case, the circuit determination system 1 may be provided either inside the distribution board 200 or outside the distribution board 200.

[0086] The control unit 13 preferably includes a computer system. That is, in the control unit 13, a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) reads and executes programs stored in memory, thereby realizing some or all of the functions of the control unit 13. The control unit 13 mainly includes a processor that operates according to a program. The type of processor is not important as long as it can realize functions by executing a program. The processor is composed of one or more electronic circuits, including a semiconductor integrated circuit (IC) or an LSI (Large Scale Integration). Although the terms IC and LSI are used here, the term may be changed depending on the degree of integration, and may also be called a system LSI, a VLSI (Very Large Scale Integration), or an ULSI (Ultra Large Scale Integration). Field programmable gate arrays (FPGAs), which are programmed after the LSI is manufactured, or reconfigurable logic devices that can reconfigure the connections within the LSI or set up circuit partitions within the LSI, can also be used for the same purpose. Multiple electronic circuits may be integrated on a single chip or on multiple chips. The plurality of chips may be arranged in a concentrated manner or in a dispersed manner.

[0087] The control unit 13 is not limited to being implemented by a single computer device, but may be implemented by multiple computers linked to each other. Furthermore, the control unit 13 may be configured as a cloud computing system.

[0088] The switch SW is not limited to a semiconductor switch, but may be any normally-off switch, and may be a mechanical relay having a mechanical contact, other than a semiconductor switch.

[0089] Furthermore, the circuit determination system 1, the circuit interruption system 100, and the distribution board 200 may be configured by appropriately combining the above-described embodiments and modifications.

[0090] (9) Summary As described above, the circuit determination system (1) according to the first aspect of the embodiment controls the switch (SW) that connects and disconnects the electric circuit (La, L2). The circuit determination system (1) includes a current detection unit (11) and a control unit (13). The current detection unit (11) detects the load current (I1) flowing through the electric circuit (La, L2). The control unit (13) controls the switch (SW) to be switchable between an OFF state that disconnects the electric circuit (La, L2) and an ON state that connects the electric circuit (La, L2). The control unit (13) defines a period from when the switch (SW) is switched ON to when a predetermined time has elapsed and the control unit (13) switches the switch (SW) OFF as a determination period (Ta, Tb). The control unit (13) performs a determination process to determine whether or not to switch the switch (SW) ON again, based on the waveform of the load current (I1) detected by the current detection unit (11) during the determination period (Ta, Tb).

[0091] The above-described circuit determination system (1) can prevent trouble caused by re-closing the switch (SW).

[0092] In the circuit determination system (1) of the second aspect according to the embodiment, in the first aspect, the control unit (13) preferably determines whether or not an overcurrent accident in which an overcurrent occurs in the electric circuit (La, L2) as the determination process. If an overcurrent accident has not occurred, the control unit (13) permits the switch (SW) to be switched on again. If an overcurrent accident has occurred, the control unit (13) does not permit the switch (SW) to be switched on again.

[0093] The circuit determination system (1) described above can prevent trouble caused by re-closing a switch (SW) after an overcurrent accident occurs.

[0094] The circuit determination system (1) of the third aspect of the embodiment is preferably the second aspect, further including a voltage detection unit (12) that detects the AC voltage (Vi) applied to the electric circuit (La, L2). The control unit (13) sets the start timing (ta) of the determination period (Ta) to be different from the timings at which the phase of the AC voltage (Vi) becomes 0 degrees, 90 degrees, 180 degrees, and 360 degrees.

[0095] The above-described circuit determination system (1) can improve the accuracy of the first determination process.

[0096] In the circuit determination system (1) of the fourth aspect according to the embodiment, in the third aspect, the control unit (13) preferably repeats the determination process multiple times, and the control unit (13) makes the start timing of the determination period (Ta) in each of the multiple determination processes different from each other.

[0097] The above-described circuit determination system (1) can further improve the accuracy of the first determination process.

[0098] In the circuit determination system (1) of the fifth aspect according to the embodiment, in the first aspect, the control unit (13) preferably determines, as the determination process, whether the load (LD) connected to the electric circuit (La, L2) is a heat-generating load (LDb) that generates heat during operation. If the load (LD) is not a heat-generating load (LDb), the control unit (13) allows the switch (SW) to be switched on again. If the load (LD) is a heat-generating load (LDb), the control unit (13) does not allow the switch (SW) to be switched on again.

[0099] The circuit determination system (1) described above can suppress trouble caused by the heat generating load (LDb) that restarts when the switch (SW) is turned on again.

[0100] In the circuit determination system (1) of the sixth aspect according to the embodiment, in the fifth aspect, the heat generating load (LDb) is preferably an electric space heater or an electric heater.

[0101] The circuit determination system (1) described above can prevent trouble caused by an electric space heater or electric heater that is restarted by turning on the switch (SW) again.

[0102] In the circuit determination system (1) of the seventh aspect according to the embodiment, in the fifth or sixth aspect, the heat generating load (LDb) is preferably a resistive load.

[0103] The above-described circuit determination system (1) can easily determine whether the load (LD) is a heat-generating load (LDb) or not based on the waveform of the load current (I1).

[0104] In a circuit determination system (1) according to an eighth aspect of the present embodiment, in any one of the fifth to seventh aspects, an AC voltage (Vi) is applied to the electric circuit (La, L2). The control unit (13) preferably determines a distortion rate of the waveform of the load current (I1) relative to a sine waveform as the determination process. If the distortion rate is less than a threshold, the control unit (13) determines that the load (LD) is a heat-generating load (LDb), and if the distortion rate is equal to or greater than the threshold, the control unit (13) determines that the load (LD) is not a heat-generating load (LDb).

[0105] The above-described circuit determination system (1) can improve the accuracy of the second determination process.

[0106] In the circuit determination system (1) of the ninth aspect according to the embodiment, in any one of the fifth to eighth aspects, it is preferable that the control unit (13) performs the second determination process when the waveform of the load current (I1) is an AC waveform.

[0107] The above-described circuit determination system (1) can narrow down the loads (LD) to be subjected to the second determination process from among a plurality of loads (LD).

[0108] In the circuit determination system (1) of the tenth aspect according to the present embodiment, in any one of the first to ninth aspects, the switch (SW) is preferably a semiconductor switch.

[0109] The above-described circuit determination system (1) can easily achieve a reduction in the determination period (Ta, Tb).

[0110] In the circuit determination system (1) of the eleventh aspect of the embodiment, in any one of the first to tenth aspects, it is preferable that the control unit (13) is arranged inside the distribution board (200) and performs the determination process when an instruction signal is received from outside the distribution board (200).

[0111] The circuit determination system (1) described above can remotely instruct the execution of the determination process.

[0112] The circuit determination system (1) according to a twelfth aspect of the present invention is preferably any one of the first to eleventh aspects, further comprising a drive unit (14) that drives the switch (SW). If the control unit (13) permits the switch (SW) to be switched back to the on state, the drive unit (14) switches the switch (SW) back to the on state.

[0113] The above-described circuit determination system (1) can perform on / off control of the switch (SW) based on the result of the determination process, and can therefore execute the process from the determination process to re-closing.

[0114] In the circuit determination system (1) of the thirteenth aspect of the embodiment, in any one of the first to twelfth aspects, it is preferable that the control unit (13) performs the determination process after the seismic sensor (7) detects an earthquake.

[0115] The circuit determination system (1) described above can prevent secondary disasters from occurring after an earthquake.

[0116] A circuit breaker system (100) according to a fourteenth aspect of the embodiment includes the circuit determination system (1) according to any one of the first to thirteenth aspects and a switch (SW).

[0117] The above-described circuit breaker system (100) can prevent trouble caused by re-closing the switch (SW).

[0118] The system includes a distribution board (200) according to a fifteenth aspect of the embodiment, a circuit breaker system (100) according to the fourteenth aspect, and a housing (2) that houses the circuit breaker system (100).

[0119] The distribution board (200) described above can prevent trouble caused by cycling the switch (SW). [Explanation of symbols]

[0120] 200 Distribution board 100 Circuit Breaker System 1 Circuit Judgment System 11 Current detection section 12 Voltage detection section 13 Control Unit 14 Drive unit 7. Seismic Sensor La electric circuit L2 branch circuit (electric circuit) SW switch I1 load current Vi AC voltage Ta 1st judgment period (judgment period) Tb Second judgment period (judgment period) ta start timing LD load LDb heat load

Claims

1. A circuit determination system for controlling a switch that turns on and off an electric circuit, a current detection unit that detects a load current flowing through the electrical path; a control unit that controls the switch so as to be switchable between an OFF state that interrupts the electric path and an ON state that conducts the electric path, The control unit a determination period is a period from when the switch is turned on until when a predetermined time has elapsed and the switch is turned off; A determination process is performed to determine whether or not the switch can be switched back to the on state based on the waveform of the load current detected by the current detection unit during the determination period. Circuit determination system.

2. The control unit As the determination process, it is determined whether or not an overcurrent accident in which an overcurrent occurs in the electric circuit has occurred; If the overcurrent fault has not occurred, allowing the switch to be switched back to the on state; If the overcurrent fault occurs, the switch is not allowed to be switched back to the on state. The circuit determination system according to claim 1 .

3. Further, a voltage detection unit is provided to detect an AC voltage applied to the electric circuit, The control unit causes the start timing of the determination period to be different from the timings at which the phase of the AC voltage becomes 0 degrees, 90 degrees, 180 degrees, and 360 degrees. The circuit determination system according to claim 2 .

4. The control unit Repeating the determination process multiple times, The start timing of the determination period in each of the plurality of determination processes is made different from one another. The circuit determination system according to claim 3.

5. The control unit As the determination process, it is determined whether or not the load connected to the electric circuit is a heat-generating load that generates heat during operation; If the load is not the heat-generating load, then allowing the switch to be switched back to the on state; If the load is the heat-generating load, the switch is not allowed to be switched back to the on state. The circuit determination system according to claim 1 .

6. The heat generating load is an electric space heater or an electric heater. The circuit determination system according to claim 5.

7. The heat generating load is a resistive load. The circuit determination system according to claim 5.

8. An AC voltage is applied to the electric circuit, The control unit performs the determination process by: determining a distortion rate of the load current waveform relative to a sine waveform; If the distortion rate is less than a threshold value, the load is determined to be the heat-generating load; If the distortion rate is equal to or greater than the threshold value, the load is determined to not be a heat-generating load. The circuit determination system according to claim 5 .

9. The control unit performs the determination process when the waveform of the load current is an AC waveform. The circuit determination system according to claim 5 .

10. The switch is a semiconductor switch. The circuit determination system according to claim 1 .

11. The control unit Located inside the distribution board, When an instruction signal is received from outside the distribution board, the determination process is performed. The circuit determination system according to claim 1 .

12. Further, a driving unit that drives the switch is provided. If the control unit allows the switch to be switched back to the on state, the driving unit switches the switch back to the on state. The circuit determination system according to claim 1 .

13. The control unit performs the determination process after the seismic sensor detects an earthquake. The circuit determination system according to claim 1 .

14. A circuit determination system according to any one of claims 1 to 13; The switch Circuit Breaker System.

15. The circuit interruption system of claim 14; a housing for housing the circuit interruption system; Distribution board.

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