Electric leakage detection system

Abstract

This electric leakage detection system comprises a plurality of power supply taps, a server device, and an external control terminal. In this electric leakage detection system, the plurality of power supply taps are connected in a tree configuration, with a power supply that supplies AC power being the most upstream. Each of the plurality of power supply taps comprises a plug unit, a connection unit, a switching unit, an electric leakage detection unit, a communication unit, and a control unit. The plug unit is a power input / output terminal on the upstream side of the power supply tap. The connection unit is a power input / output terminal on the downstream side of the power supply tap. The switching unit switches between conduction and interruption between the plug unit and the connection unit. The electric leakage detection unit detects an electric leakage current value flowing through the power supply tap. The communication unit performs data communication with the server device or the external control terminal. The control unit controls the conduction and interruption by the switching unit. The server device is connected to the communication units of the plurality of power supply taps via a network, receives the electric leakage current values of the plurality of power supply taps, and transmits the electric leakage current values to the external control terminal. On the basis of a combination of the electric leakage current values of the plurality of power supply taps, the external control terminal detects an electric leakage occurrence location in the system that is connected in the tree configuration.

Description

Leakage Detection System

[0001] The present invention relates to a technique for detecting leakage in a system to which a plurality of electrical devices are connected.

[0002] Patent Document 1 describes a submersible pump device. Devices used in water-related applications such as submersible pumps and devices with high power consumption are usually grounded using an earth wire. This ensures that even if leakage occurs, the user will not get an electric shock.

[0003] Japanese Unexamined Patent Application Publication No. 2018 - 168790

[0004] However, while an earth wire can prevent electric shock, it does not prevent leakage itself. Also, in cases where alternating current power is obtained from a temporary switchboard at a construction site or the like, or from a generator or portable power source, etc., there may be cases where grounding itself is not done, posing a risk of electric shock.

[0005] And when a system is equipped with a device as shown in Patent Document 1 and a plurality of devices are connected to an alternating current power source in a tree-like manner, it has been difficult to detect the leakage location.

[0006] Therefore, an object of the present invention is to detect the leakage location in a system to which a plurality of devices are connected.

[0007] The leakage detection system according to an embodiment of this invention includes a plurality of power taps, a cloud server, and an external control terminal. The leakage detection system is connected in a tree-like manner with a power source that supplies alternating current power by the plurality of power taps as the uppermost stream.

[0008] The plurality of power taps each include a plug portion, a connection portion, a switching portion, a leakage detection portion, a communication portion, and a control portion. The plug portion is the power input / output terminal on the upstream side of the power tap. The connection portion is the power input / output terminal on the downstream side of the power tap. The switching portion switches between conduction and interruption between the plug portion and the connection portion. The leakage detection portion detects the value of the leakage current flowing through the power tap. The communication portion performs data communication with the cloud server or the external control terminal. The control portion controls the conduction and interruption by the switching portion.

[0009] The cloud server connects to the communication ports of multiple power strips via a network, receives leakage current values ​​from the multiple power strips, and transmits these values ​​to an external control terminal. The external control terminal detects the location of the leakage current in the tree-like connected system based on the combination of leakage current values ​​from the multiple power strips.

[0010] This configuration utilizes the fact that the combination of leakage current values ​​of multiple power strips connected in a tree structure differs depending on the location of the leakage. For example, if the downstream power strip (the electrical equipment connected to the power strip) has a leakage current, the leakage current values ​​will be high in all power strips connected between this downstream power strip and the power source. Conversely, if a power strip in the middle of the tree has a leakage current, the leakage current values ​​of power strips downstream of this power strip will not be high.

[0011] By utilizing this principle, a leakage current detection system can measure the leakage current values ​​of multiple power strips and detect the location of the leakage.

[0012] According to this invention, it is possible to detect the location of a leakage current in a system in which multiple devices are connected.

[0013] Figure 1 is a configuration diagram showing an example of a leakage current detection system according to an embodiment of the present invention. Figure 2 is a diagram showing an example of a tree configuration of a leakage current detection system according to an embodiment of the present invention. Figures 3(A) and 3(B) are external perspective views of a power strip according to an embodiment of the present invention. Figure 4 is a circuit diagram showing an example of a circuit configuration of a power strip according to an embodiment of the present invention. Figure 5 is a diagram showing the concept of leakage current detection. Figure 6 is a table showing the relationship between the combination of whether or not there is leakage current in multiple power strips and the result of determining the location of the leakage current in a leakage current detection system according to an embodiment of the present invention. Figure 7 is a flowchart showing an example of a leakage current detection method according to an embodiment of the present invention. Figure 8 is a diagram showing another example of a tree configuration of a leakage current detection system according to an embodiment of the present invention. Figure 9 is a table showing the relationship between the combination of whether or not there is leakage current in multiple power strips and the result of determining the location of the leakage current in a leakage current detection system according to a second embodiment. Figure 10 is a flowchart showing an example of a leakage current detection method according to an embodiment of the present invention.

[0014] A leakage current detection system for electrical equipment according to an embodiment of the present invention will be described with reference to the figures.

[0015] Figure 1 is a configuration diagram showing an example of a leakage current detection system according to an embodiment of the present invention. Figure 2 is a diagram showing an example of a tree configuration of a leakage current detection system according to an embodiment of the present invention.

[0016] As shown in Figure 1, the leakage detection system 1 includes a plurality of power strips 101-112, an external control terminal 920, and a server device 930.

[0017] Multiple power strips 101-122 are placed, for example, at a construction site 91. The construction site 91 is equipped with multiple electrical devices EQ1-EQ16, multiple cable reels 911-916, and power jacks 901 (outlets).

[0018] Each of the multiple power strips 101-122 has the configuration of power strip 100 shown in Figures 3(A) and 3(B). Figures 3(A) and 3(B) are external perspective views of the power strip according to an embodiment of the present invention. Details of the circuit configuration of power strip 100 will be described later.

[0019] The power strip 100 comprises a cylindrical housing E100, a power jack J100, and a power plug P100. The housing E100 has an end face E1 at one end and an end face E2 at the other end. The power jack J100 is formed on end face E1. The power plug P100 is formed on end face E2. The power jack J100 and the power plug P100 are electrically connected via a relay switch 31 (see Figure 4, described later).

[0020] Each of the multiple cable reels 911-916 is equipped with one cable reel plug and multiple cable reel jacks. The cable reel plug is connected to the multiple cable reel jacks. In this way, the multiple cable reels 911-916 distribute power from the cable reel plug to the multiple cable reel jacks.

[0021] The power jack 901 is connected to a power source that supplies AC power. The power plug P100 of the power strip 101 is connected to the power jack 901. The power cord reel plug of the power cord reel 911 is connected to the power jack J100 of the power strip 101.

[0022] The power plugs P100 of the power strip 102 and P100 of the power strip 103 are connected to the multiple power cord jacks of the power cord reel 911, respectively.

[0023] The power jack J100 of the power strip 102 is connected to the power cord reel plug of the power cord reel 912.

[0024] The power plugs P100 of the power strip 104, P100 of the power strip 105, P100 of the power strip 106, and P100 of the power strip 107 are connected to the multiple power strip jacks of the power cord reel 912, respectively.

[0025] Electrical device EQ1 is connected to power jack J100 of power strip 104. Electrical device EQ2 is connected to power jack J100 of power strip 105. Electrical device EQ3 is connected to power jack J100 of power strip 106. Electrical device EQ4 is connected to power jack J100 of power strip 107.

[0026] The power jack J100 of the power strip 103 is connected to the power cord reel plug of the power cord reel 913.

[0027] The power plugs P100 of power strip 108, P100 of power strip 109, P100 of power strip 110, and P100 of power strip 111 are connected to the multiple power cord reel jacks of the power cord reel 913, respectively.

[0028] Electrical device EQ5 is connected to power jack J100 of power strip 108. Electrical device EQ6 is connected to power jack J100 of power strip 109. Electrical device EQ7 is connected to power jack J100 of power strip 110. Electrical device EQ8 is connected to power jack J100 of power strip 111.

[0029] The power plug P100 of the power strip 112 is connected to the power jack 901. The power cord reel plug of the cord reel 914 is connected to the power jack J100 of the power strip 112.

[0030] The power plugs P100 of the power strip 113 and P100 of the power strip 114 are connected to the multiple power cord jacks of the power cord reel 914, respectively.

[0031] The power jack J100 of the power strip 113 is connected to the power cord reel plug of the power cord reel 915.

[0032] The power plugs P100 of the power strip 115, P100 of the power strip 116, P100 of the power strip 117, and P100 of the power strip 118 are connected to the multiple power strip jacks of the power cord reel 915, respectively.

[0033] Electrical device EQ9 is connected to power jack J100 of power strip 115. Electrical device EQ10 is connected to power jack J100 of power strip 116. Electrical device EQ11 is connected to power jack J100 of power strip 117. Electrical device EQ12 is connected to power jack J100 of power strip 118.

[0034] The power jack J100 of the power strip 114 is connected to the power cord reel plug of the power cord reel 916.

[0035] The power plugs P100 of the power strip 119, P100 of the power strip 120, P100 of the power strip 121, and P100 of the power strip 122 are connected to the multiple power strip jacks of the power cord reel 916, respectively.

[0036] Electrical device EQ13 is connected to power jack J100 of power strip 119. Electrical device EQ14 is connected to power jack J100 of power strip 120. Electrical device EQ15 is connected to power jack J100 of power strip 121. Electrical device EQ16 is connected to power jack J100 of power strip 122.

[0037] With this connection arrangement, as shown in Figure 2, the multiple power strips 101-122, the multiple cable reels 911-916, and the multiple electrical devices EQ1-EQ16 are connected in a tree-like structure, with the power supply (power jack 901) supplying AC power as the upstream end and the multiple electrical devices EQ1-EQ16 as the downstream end. As a result, the multiple electrical devices EQ1-EQ16 are supplied with power from the power supply.

[0038] Multiple power strips 101 and 122 correspond to the upstream power strip. Multiple power strips 102, 103, 113, and 114 correspond to the midstream power strip. Multiple power strips 104-111 and 115-122 correspond to the downstream power strip.

[0039] Multiple cable reels 911 and 914 correspond to the upstream cable reels. Multiple cable reels 912, 913, 915, and 916 correspond to the downstream cable reels.

[0040] The relative positions of the multiple power strips 101-122 and the multiple cable reels 911-916 in this tree configuration are pre-stored, for example, by an external control terminal 920 or a server device 930.

[0041] The external control terminal 920 may be, for example, a desktop PC located in the control room 92, or a tablet PC carried by the administrator. The control room 92 is located in a different location from the construction site 91.

[0042] The server device 930 is located in a different location from the construction site 91. The server device 930 may be located in a different location from the control room 92, or it may be located in the control room 92.

[0043] Each of the power strips 101-122, the external control terminal 920, and the server device 930 is equipped with a communication function, which enables data communication. For example, the multiple power strips 101-122, the external control terminal 920, and the server device 930 can communicate data via the Internet, the network of a telecommunications company, and direct wireless communication including short-range wireless communication.

[0044] (Circuit Configuration of Power Tap 100 (101 - 122)) FIG. 4 is a circuit diagram showing an example of the circuit configuration of a power tap according to an embodiment of the present invention.

[0045] As shown in FIG. 4, the power tap 100 includes a power jack J100, a power plug P100, an AC - DC converter 210, a control unit 211, a current detection circuit 212, a voltage detection resistor 213, a leakage detection circuit 214, a communication unit 215, an antenna 216, a relay switch 31, a power wiring RP11, and a power wiring RP12. The control unit 211 includes a microcomputer 2111 and a leakage detection IC 2112. The relay switch 31 corresponds to the "switching unit". The power jack J100 corresponds to the "connection unit", and the power plug P100 corresponds to the "plug unit". The leakage detection circuit 214 corresponds to the "leakage detection unit".

[0046] The power wiring RP11 connects one terminal of the power jack J100 and one terminal of the power plug P100. The power wiring RP12 connects the other terminal of the power jack J100 and the other terminal of the power plug P100.

[0047] The power jack J100 and the power plug P100 are illustrated in a shape assuming single - phase 100V, but are not limited thereto. They may have a shape for single - phase 200V or a shape for overseas use.

[0048] The relay switch 31 is inserted (connected in series) into the power wiring RP12. The relay switch 31 may be composed of a semiconductor element such as a MOSFET.

[0049] The AC - DC converter 210 has AC - side terminals and DC - side terminals. The AC - side terminals are connected to the power wiring RP11. The DC - side terminals are connected to the control unit 211 and the communication unit 215. Although not shown, the power supply terminals of the operational amplifier of the current detection circuit 212 are also connected to the DC - type terminals. Thereby, the AC - DC converter 210 supplies driving DC power to the control unit 211, the communication unit 215, and the operational amplifier of the current detection circuit 212, respectively.

[0050] The current detection circuit 212 comprises a current detection resistor and an operational amplifier. The current detection resistor is inserted (connected in series) into the power supply wiring RP12. More specifically, the current detection resistor is connected to the power plug P100 side of the power supply wiring RP12 where the relay switch 31 is inserted. The input terminals of the operational amplifier are connected to both ends of the current detection resistor, and the output terminals of the operational amplifier are connected to the microcontroller 2111 of the control unit 211.

[0051] The current detection circuit 212 is not limited to a current detection resistor and operational amplifier; a non-contact type using a Hall element may also be used.

[0052] One terminal of the voltage detection resistor 213 is connected to the power supply wiring RP11. The other terminal of the voltage detection resistor 213 is connected to the microcontroller 2111 of the control unit 211.

[0053] The leakage current detection circuit 214 is configured, for example, by a zero-phase current transformer (ZCT). The output terminal of the leakage current detection circuit 214 is connected to the leakage current detection IC 2112 of the control unit 211.

[0054] The data output terminal of the microcontroller 2111 is connected to the communication unit 215. The microcontroller 2111 also has a first relay control signal output terminal. The first relay control signal output terminal is connected to the relay switch 31. The antenna 216 is connected to the communication unit 215.

[0055] The leakage current detection IC 2112 is connected to the microcontroller 2111. The leakage current detection IC 2112 has a second relay control signal output terminal. The second relay control signal output terminal is connected to the relay switch 31.

[0056] As a result, the relay switch 31 is controlled to conduct or disconnect by the control unit 211 (microcontroller 2111 or leakage detection IC 2112).

[0057] With this configuration, the power strip 100 operates, for example, as follows:

[0058] (Steady operation) When power is supplied to a device downstream of the power strip 100, the relay switch 31 is controlled to a conductive state. The current detection circuit 212 generates an output voltage corresponding to the current supplied to the device downstream through the power jack J100.

[0059] The microcontroller 2111 detects the current value flowing downstream to the power jack J100 from the output voltage of the current detection circuit 212.

[0060] Furthermore, a voltage detection resistor 213 is connected to the microcontroller 2111, and the voltage value of the downstream device connected to the power jack J100 is detected from the potential measured by the voltage detection resistor 213.

[0061] The microcontroller 2111 detects the detected current and voltage values ​​at a predetermined sampling period and outputs them as power information to the communication unit 215. The communication unit 215 transmits the power information to the server device 930 via the antenna 216.

[0062] Power information only needs to include the current value, for example, if the rated voltage of the downstream device is always constant. However, it is preferable that the power information includes both the current value and the voltage value.

[0063] When the microcontroller 2111 receives an electrical conduction control signal from the server device 930, it controls the relay switch 31 to maintain its conduction state. This ensures that power corresponding to the operation of the downstream device is supplied from the power source or from the upstream side to the downstream device.

[0064] When the microcontroller 2111 receives an electrical disconnection control signal (switching signal) from the server device 930, it controls the relay switch 31 to the disconnected state (open state). This disconnects the power supply or the power supply from the upstream side to the downstream device.

[0065] (Earth leakage detection and relay switch continuity and tripping control) Figure 5 shows the concept of earth leakage detection.

[0066] When the downstream device is connected to the power jack J100, and power is supplied to the downstream device from the power source on the power plug P100 side, current flows through the power wiring RP11 and RP12, as shown in Figure 5.

[0067] If there is no leakage current in the downstream equipment, the current value Iα flowing through power wiring RP11 and the current value Iβ flowing through power wiring RP12 will be the same. Therefore, the leakage current value ΔI, which is the difference between the forward current Iα and the return current Iβ, will be 0.

[0068] If a leakage current occurs in the downstream equipment and the current ILeak flows to ground, the current values ​​of Iα and Iβ will be different. Therefore, the leakage current value ΔI will be Iβ - Iα = ILeak ≠ 0.

[0069] The leakage current detection circuit 214 detects the leakage current value ΔI, which is the difference between the current value Iα flowing through the power wiring RP11 and the current value Iβ flowing through the power wiring RP12. The leakage current detection circuit 214 outputs the detected leakage current value ΔI to the leakage current detection IC 2112. The leakage current detection IC 2112 converts the leakage current value ΔI into digital data, for example, and passes it to the microcontroller 2111. The microcontroller 2111 transmits the leakage current value ΔI to the external server device 930 via the communication unit 215 and the antenna 216. The leakage current detection circuit 214 and the leakage current detection IC 2112 detect the leakage current value ΔI, for example, at predetermined sampling timings. The microcontroller 2111 sequentially transmits the detected leakage current value ΔI to the server device 930.

[0070] The server device 930 sequentially stores the received leakage current value ΔI. The server device 930 also transmits the received and stored leakage current value ΔI to the external control terminal 920.

[0071] The external control terminal 920 detects the leakage current corresponding to each of the multiple power strips 101-122 based on the received leakage current value ΔI.

[0072] For example, the following methods can be used to detect electrical leakage.

[0073] The external control terminal 920 has a threshold value for detecting leakage current set by the current value. The threshold value is set to a current value that is not zero. More specifically, the threshold value is set to a value that can detect an insulation failure downstream of the power strip from which the leakage current value ΔI was obtained. In other words, the threshold value is set based on the lower limit of the current value at which a user would be electrocuted if power were supplied as is, and is set lower than this lower limit by a predetermined margin based on measurement error.

[0074] The external control terminal 920 compares the threshold value with the leakage current value ΔI. If the leakage current value ΔI is greater than or equal to the threshold value, the external control terminal 920 determines that there is a leakage current downstream of the power strip from which the leakage current value ΔI was obtained. On the other hand, if the leakage current value ΔI is less than the threshold value, the external control terminal 920 determines that there is no leakage current downstream of the power strip from which the leakage current value ΔI was obtained.

[0075] The external control terminal 920 determines whether or not there is a ground fault for each of the multiple power strips 101-122.

[0076] The external control terminal 920 detects the location of a ground fault in the tree-like connected power transmission system based on a combination of the results of determining whether or not there is a ground fault in multiple power strips 101-122 (combination of ground fault current values).

[0077] Figure 6 is a table showing the relationship between the presence or absence of electrical leakage in multiple power strips and the determination result of the location of the electrical leakage in an electrical leakage detection system according to an embodiment of the present invention. In Figure 6, ○ indicates no electrical leakage, and × indicates electrical leakage. The determination result shows the location where the electrical leakage occurred.

[0078] Figure 6 shows the tree-like configuration shown in Figure 2, and there are three possible combinations of power strips with and without ground faults: patterns PT1-PT23.

[0079] In a tree-like configuration as shown in Figure 2, if the leakage current value ΔI is not zero and there is a leakage current at the downstream power tap, then the leakage current value ΔI will also be zero and there will be a leakage current at the upstream power tap in the power transmission system tree, and a leakage current will be detected.

[0080] On the other hand, even if the leakage current value ΔI is not zero and there is a leakage current at the upstream power strip, the leakage current value ΔI at the downstream power strip in the power transmission system tree will be 0, and it will be determined that there is no leakage current.

[0081] By utilizing this principle, the relationship between the presence or absence of leakage current in multiple power strips 101-122 shown in Figure 6 and the judgment result can be obtained.

[0082] The external control terminal 920 stores, for example, the table shown in Figure 6 in advance. The external control terminal 920 detects the location of a ground fault based on the results of determining whether or not there is a ground fault in the multiple power strips 101-122, and the relationship between the combination of whether or not there is a ground fault in the multiple power strips 101-122 and the determination results (the relationship shown in the table in Figure 6).

[0083] For example, the external control terminal 920 determines that there is no leakage current in all power strips 101-122 as pattern PT1, and therefore detects that there is no leakage current in the entire power transmission system.

[0084] Furthermore, for example, if the external control terminal 920 determines, as pattern PT2, that only power strip 101 has a ground fault and the other power strips 102-112 do not, it will detect that a ground fault has occurred in the electrical cable reel 911 downstream of power strip 101 and between it and the nearest power strip 102.

[0085] Furthermore, for example, if the external control terminal 920 determines, as pattern PT12, that there is a ground fault in multiple power strips 101, 103, and 111, and that there is no ground fault in the other multiple power strips 102, 104-110, and 112-122, it will detect that a ground fault has occurred in the electrical equipment EQ8 connected downstream of power strip 111.

[0086] In this way, the external control terminal 920 can detect the location of a power leakage in the power transmission system.

[0087] When the external control terminal 920 detects a power leakage point, it notifies the system of the location of the leakage. This notification is displayed, for example, on a display on the external control terminal 920, on the administrator's tablet device, or on a wearable device. This allows the administrator to easily identify the occurrence and location of the power leakage.

[0088] The external control terminal 920 transmits a switching signal indicating relay disconnection to the power strip that has been determined to be in a leakage state via the server device 930. Upon receiving the switching signal, the microcontroller 2111 of the power strip outputs a disconnection switching signal to the relay switch 31. As a result, the relay switch 31 is controlled to the disconnected state (open state), and the power supply to the downstream side is cut off. This prevents electric shock to the user.

[0089] (Earth leakage detection method 1) Figure 7 is a flowchart showing an example of an earth leakage detection method according to an embodiment of the present invention. Note that the specific details of each process shown in Figure 7 have been explained in the above description of the configuration, so only the necessary parts will be explained below.

[0090] Multiple power strips detect the leakage current value ΔI (S11). The multiple power strips transmit the leakage current value ΔI to the server device 930, and the server device 930 transmits the leakage current values ​​ΔI of the multiple power strips to the external control terminal 920.

[0091] The external control terminal 920 determines whether or not there is a leakage current for each of the multiple power strips using the leakage current value ΔI and a threshold value (S12).

[0092] The external control terminal 920 detects combinations of whether or not there is a ground fault in the multiple power strips 101-122 (S13).

[0093] The external control terminal 920 detects the location of a ground fault based on the combination of whether or not there is a ground fault in the multiple power strips 101-122 (S14).

[0094] (Another embodiment of the tree configuration) Figure 8 shows another example of the tree configuration of the leakage current detection system according to an embodiment of the present invention.

[0095] The tree configuration shown in Figure 8 differs from the tree configuration shown in Figure 2 in that only the power strip 101 is connected to the power jack 901 (outlet), that is, the cable reel 914 and the tree downstream of it in Figure 2 do not exist. Furthermore, the tree configuration shown in Figure 8 differs in that multiple electrical devices and the cable reel are connected in parallel to a single cable reel, each via a power strip. In the following, a detailed explanation of the connection relationships will be omitted, but the multiple power strips are connected so that the power plug P100 is on the upstream side of the power strip and the power jack J100 is on the downstream side of the power strip. Similarly, the multiple cable reels are connected so that the cable reel plug is on the upstream side of the cable reel and the cable reel jack is on the downstream side of the cable reel.

[0096] In the tree configuration shown in Figure 8, the power jack 901 is connected to the cable reel 911 via the power strip 101. The cable reel 912 is connected to the cable reel 911 via the power strip 102, and the cable reel 913 is connected via the power strip 103.

[0097] Electrical device EQ1 is connected to the power cord reel 912 via power strip 104, and electrical device EQ2 is connected via power strip 105. Furthermore, electrical device EQ3 is connected to the power cord reel 912 via power strip 106, and electrical device EQ4 is connected via power strip 107.

[0098] Electrical device EQ5 is connected to the power strip 108 via the power strip 108, electrical device EQ6 is connected to the power strip 109 via the power strip 109, and electrical device EQ7 is connected to the power strip 110. Furthermore, electrical device reel 914 is connected to the electrical device reel 913 via the power strip 111.

[0099] Electrical device EQ8 is connected to the power cord reel 914 via power strip 112, and electrical device EQ9 is connected via power strip 113. Electrical device EQ10 is connected to the power cord reel 915 via power strip 114, and electrical device EQ11 is connected via power strip 115.

[0100] Figure 9 is a table showing the relationship between the combination of whether or not a power strip has a power leak and the result of determining the location of the power leak in the power leak detection system according to the second embodiment.

[0101] As shown in Figure 9, the leakage detection system 1 can detect the relationship between the presence or absence of leakage current and the location of leakage current, even with an unbalanced tree configuration as shown in Figure 8. This allows the leakage detection system 1 to detect the location of leakage current even with an unbalanced tree configuration.

[0102] (Earth leakage detection method 2) Figure 10 is a flowchart showing an example of an earth leakage detection method according to an embodiment of the present invention.

[0103] Multiple power strips detect the leakage current value ΔI (S11). The multiple power strips transmit the leakage current value ΔI to the server device 930, and the server device 930 transmits the leakage current values ​​ΔI of the multiple power strips to the external control terminal 920.

[0104] The external control terminal 920 determines whether or not there is a leakage current for each of the multiple power strips using the leakage current value ΔI and a threshold value (S12).

[0105] If the external control terminal 920 determines that the power strip has a ground fault, and that it is the downstream power strip (S21: YES), it detects the combination of whether or not there is a ground fault in the multiple power strips 101-122 (S13).

[0106] The external control terminal 920 detects the location of a ground fault based on the combination of whether or not there is a ground fault in the multiple power strips 101-122 (S14).

[0107] If the external control terminal 920 determines that there is a ground fault, and the power strip is not the furthest downstream power strip (S21: NO), it will sequentially shut off multiple power strips downstream of the power strip where the ground fault was determined (S22).

[0108] The external control terminal 920, with each different power strip disconnected, measures the leakage current values ​​of the power strip that has been determined to have a leakage current, as well as multiple power strips downstream of that power strip (S23).

[0109] The external control terminal 920 detects the location of the leakage current based on the change in the leakage current value of these power strips (S24).

[0110] If the leakage current value does not change, the external control terminal 920 will again determine that a power strip has a leakage current if it was previously determined to have one. If the leakage current value changes, the external control terminal 920 will detect power strips with insulation deterioration in multiple downstream power strips based on this change.

[0111] For example, let's set the threshold for the leakage current value ΔI to 5 mA. When all power taps 101-115 are in a conductive state, the external control terminal 920 determines that power tap 111 (electrical cord reel 914) has a leakage current because the leakage current value of power tap 111 upstream of the electrical cord reel 914 in Figure 8 is 6 mA, which exceeds the threshold.

[0112] On the other hand, if the leakage current values ​​ΔI of the multiple power strips 112-115 downstream of power strip 111 are 2mA, 2mA, 1mA, and 1mA respectively, the external control terminal 920 determines that there is no leakage current for the multiple power strips 112-115.

[0113] When the external control terminal 920 confirms that power strip 111 is not the furthest downstream power strip, it controls the continuity and disconnection of multiple power strips 112-115 via the server device 930 so that the multiple power strips 112-115 downstream of power strip 111 (electric cord reel 914) are disconnected in rotation.

[0114] Multiple power strips 112-115 are controlled so that one is always in an interrupted state and the other three are always in a conductive state. Then, each of the multiple power strips 111-115 detects the leakage current value ΔI.

[0115] The external control terminal 920 acquires the leakage current value ΔI of multiple power strips 111-115, each with one power strip in the off state, in rotation.

[0116] Here, for example, if power strip 112 is in a disconnected state, or power strip 113 is in a disconnected state, and power strip 111 is not actually leaking current, then the leakage current value of power strip 111 will be 4 mA.

[0117] The external control terminal 920 detects that the leakage current value ΔI has changed to below a threshold, determines that the power strip 111 is not leaking, and determines that the electrical equipment EQ8 connected to the power strip 112 and the electrical equipment EQ9 connected to the power strip 113 are in a state of insulation deterioration.

[0118] In this way, by using leakage detection method 2, the leakage detection system 1 can prevent a false determination that a device has a leakage current even when the leakage current value ΔI of the device exceeds a threshold, while the device itself is not experiencing a leakage current and multiple downstream devices are experiencing insulation degradation. Furthermore, the leakage detection system 1 can detect devices that are experiencing insulation degradation but are not experiencing a leakage current.

[0119] 1: Leakage detection system 31: Relay switch 91: Construction site 92: Control room 100, 101-122: Power strip 210: AC-DC converter 211: Control unit 212: Current detection circuit 213: Voltage detection resistor 214: Leakage detection circuit 215: Communication unit 216: Antenna 901: Power jack 911-916: Cable reel 920: External control terminal 930: Server device 2111: Microcontroller 2112: Leakage detection IC E1: End face E100: Enclosure E2: End face EQ1-EQ16: Electrical equipment J100: Power jack P100: Power plug RP11, RP12: Power wiring

Claims

1. A leakage detection system comprising multiple power strips, a cloud server, and an external control terminal, wherein the multiple power strips are connected in a tree structure with a power source supplying AC power as the upstream source, and each of the multiple power strips comprises: a plug section which is the power input / output terminal on the upstream side of the power strip; a connection section which is the power input / output terminal on the downstream side of the power strip; a switching section which switches between continuity and disconnection between the plug section and the connection section; a leakage detection section which detects the leakage current value flowing through the power strip; a communication section which can communicate data with the cloud server or the external control terminal; and a control section which controls the continuity and disconnection by the switching section, wherein the cloud server is connected to the communication section of the multiple power strips via a network, receives the leakage current value of the multiple power strips, and transmits the leakage current value to the external control terminal, and the external control terminal detects the location of leakage in the tree-like connected system based on the combination of the leakage current values ​​of the multiple power strips.

2. The leakage detection system according to claim 1, wherein the external control terminal notifies the location of the leakage current occurrence.

3. The leakage detection system according to claim 1 or 2, wherein the external control terminal generates a switching signal to shut off the power strip corresponding to the location where the leakage current occurred, and the control unit of the power strip to be shut off controls the switching unit based on the switching signal.

4. The leakage detection system according to any one of claims 1 to 3, wherein the external control terminal detects the possibility of leakage in the plurality of power strips based on the leakage current value, and detects the location of the leakage based on the combination of the possibility of leakage.

5. The leakage detection system according to any one of claims 1 to 4, wherein, in the tree-connected system, if there are multiple power taps downstream of the power tap where a potential leakage is detected, the external control terminal sequentially shuts off the multiple power taps downstream of the power tap where a potential leakage is detected to detect a change in the leakage current value, and detects the location of the leakage based on the change in the leakage current value.

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