Electric leakage monitoring device and leakage current detection method

Abstract

To provide an electric leakage monitoring device and a leakage current detection method capable of widening an object capable of monitoring a leakage current.SOLUTION: A pair of two individual current transformers 21, 22 (an individual measuring instrument) of an electric leakage measuring instrument 20 (an electric leakage monitoring device) individually measure a current flowing through a pair of positive electrode wire 12 and a negative electrode wire 13. A total of the measured current indicates a value of a leakage current generated on a downstream side of the individual current transformers 21, 22. In particular, according to the individual current transformers 21, 22, even when the positive electrode line 12 and the negative electrode line 13 are separated from each other, a total of the current flowing through the positive electrode line 12 and the negative electrode line 13 can be calculated, and the leakage current can be monitored. As a result, the range of targets that can be monitored for the leakage current by the electric leakage measuring instrument 20 can be widened.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a leakage current monitoring device and leakage current detection method for monitoring leakage current in an electric circuit, and more particularly to a leakage current monitoring device and leakage current detection method that can monitor a wide range of objects for leakage current. [Background technology]

[0002] An electric circuit supplies DC or AC power from an upstream power source to downstream load equipment via a set of multiple power lines, and the load equipment is operated by the supplied power. A leakage current monitoring device is known for monitoring this electric circuit as the measurement object and for monitoring leakage current from the measurement object to the ground or other objects.

[0003] In the leakage current monitoring device disclosed in Patent Document 1, a set of three power lines passes through a single current transformer, and the current transformer measures the total current flowing through those power lines. If there is no leakage current downstream of the current transformer, essentially all of the current passing through the current transformer toward the load equipment passes through the current transformer again and returns from the load equipment to the upstream side. Therefore, in this case, the measurement result by the current transformer (the total current flowing through one set of power lines) is essentially approximately 0 A. In contrast, if a leakage current occurs downstream, bypassing the current transformer, the current transformer measures a current of the same magnitude but in the opposite direction to the leakage current. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4159590 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the above-mentioned conventional leakage current monitoring device, for example, if the positions of a pair of power lines are far apart, it may be impossible to pass the pair of power lines through a single current transformer. In this case, the leakage current of the measurement target cannot be measured with a leakage current monitoring device using a current transformer. In other words, the conventional leakage current monitoring device has the problem that the targets that can be monitored for leakage current are limited.

[0006] SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a leakage current monitoring device and a leakage current detection method that can monitor a wide range of objects for leakage current. [Means for solving the problem]

[0007] In order to achieve this object, the leakage current monitoring device of the present invention monitors the leakage current of a measurement object that includes a set of multiple power lines that supplies load power from upstream to downstream, and a load device that operates using the load power supplied from the set of power lines, The power supply lines are provided at a distance from each other on the upstream side and the downstream side of the pair of power supply lines, and the power supply lines are provided at a distance from each other on the downstream side of the pair of power supply lines. The measurement object in The leakage current that occurs can be monitored 2 The power supply device has one or more measuring units, one of which is formed by a set of multiple individual measuring devices that individually measure the current flowing through each of the set of multiple power supply lines.

[0008] Note that "load power" may be DC power or AC power, and the AC power may be single-phase or three-phase. Furthermore, "monitoring leakage current" does not only mean calculating the leakage current occurring in the measurement object using a leakage monitoring device, but also includes transmitting the measurement results necessary for calculating the leakage current from the leakage monitoring device to an external control device, etc., so that the leakage current can be calculated on that external control device.

[0009] As another means for achieving the above object, the earth leakage monitoring device of the present invention comprises: This device monitors the leakage current of a measurement object that has a set of multiple power lines that supply load power from upstream to downstream, a load device that operates using the load power supplied from the set of power lines, a housing that houses the load device, and a grounding wire that grounds the housing, and is equipped with two or more measurement units that can monitor the leakage current that occurs within a specified range of the measurement object, one of which is formed by a set of multiple individual measuring instruments that individually measure the current flowing through each of the set of multiple power lines, and one of the measurement units is formed by a grounding side measuring instrument that measures the current flowing through the grounding wire. Another aspect of the present inventionThe leakage current monitoring device monitors the leakage current of a measurement object that includes a set of multiple power lines that supply load power from upstream to downstream and a load device that operates using the load power supplied from the set of power lines, and includes an upstream measuring instrument that measures the current flowing through one of the power lines, and a downstream measuring instrument that measures the current flowing through the power line whose current is measured by the upstream measuring instrument, downstream of the measurement position of the upstream measuring instrument.

[0010] The leakage current detection method of the present invention is a method for detecting a leakage current of a measurement object that includes a set of multiple power lines that supplies load power from upstream to downstream and a load device that operates with the load power supplied from the set of power lines, and the method includes measuring the current flowing through each of the set of multiple power lines. Individual The individual measurement steps are performed by measuring instruments individually, and the summation step is performed by adding up the multiple currents measured individually in the individual measurement steps. , downstream of the position where the individual measuring instrument is arranged The measurement object occurred in Detecting leakage current No. 1 a detection step; a second detection step of detecting a leakage current occurring in the object to be measured downstream of a measurement unit provided on one set of the power lines at a position upstream or downstream of the position where the individual measurement devices are arranged; It is equipped with: Another leakage current detection method of the present invention is a method for detecting leakage current in a measurement object that has a set of multiple power lines that supply load power from upstream to downstream, a load device that operates using the load power supplied from the set of power lines, a housing that houses the load device, and a grounding wire that grounds the housing, and includes an individual measurement step in which the current flowing through each of the set of multiple power lines is measured individually using an individual measuring instrument, a summing step in which the multiple currents measured individually in the individual measurement step are summed, a detection step in which the leakage current of the measurement object is detected based on the current summed in the summing step, and a grounding side measurement step in which the current flowing through the grounding wire is measured using a grounding side measuring instrument.

[0011] Another leakage current detection method of the present invention is a leakage current detection method for detecting leakage current in a measurement object that has a set of multiple power lines that supply load power from upstream to downstream and a load device that operates using the load power supplied from the set of power lines, and includes a measurement step in which currents flowing at two different points on one of the power lines are measured individually using a measuring instrument, a difference step in which the difference between the currents measured at the two points in the measurement step is calculated, and a detection step in which the leakage current in the measurement object is detected based on the difference in current calculated in the difference step. [Effects of the Invention]

[0012] The earth leakage monitoring device according to claim 1 is configured to: Two power supply lines are installed separately on the upstream and downstream sides of a pair of power lines.By more than one measuring unit , downstream of the position where each measurement unit is located Measurement target in This monitors the leakage current that occurs. One of the measurement sections is made up of a set of multiple individual measuring instruments. This set of individual measuring instruments individually measures the current flowing through each of the multiple power lines in the measurement target.

[0013] For example, if there is no leakage current in the object being measured, basically all of the current that passes through one part of a set of power lines toward the load equipment will return upstream from the load equipment through another part of the set of power lines, so the total current measured by one set of individual measuring instruments (the total current flowing through one set of power lines) will be approximately 0 A. Note that the "total current measured by one set of individual measuring instruments" is the sum of the current flowing upstream, which is a positive value, and the current flowing downstream, which is a negative value.

[0014] On the other hand, as with conventional technology, if a leakage current occurs downstream of the measurement position of an individual meter (the position where the current is measured by the individual meter), the sum of the currents measured by a set of individual metering devices indicates the value of that leakage current. In this way, the leakage current monitoring device can monitor leakage currents occurring downstream of the measurement position of the individual metering devices using a set of individual metering devices (measurement unit).

[0015] In particular, with the leakage current monitoring device of the present invention, the current flowing through each of a pair of power lines is measured individually by individual measuring instruments, so that even if the power lines are separated from each other, the total current flowing through the pair of power lines can be calculated and leakage current can be monitored. As a result, the leakage current monitoring target can be expanded.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021] Furthermore, by having two or more measuring units,For example, the leakage current occurring between the upstream measurement unit and the downstream measurement unit can be measured from the difference between the measurement results of the upstream measurement unit and the downstream measurement unit, making it easier to analyze the cause of the leakage current.

[0022] Claim 2 According to the earth leakage monitoring device described in claim 1 In addition to the effects of the above-described leakage current monitoring device, the following effect is achieved. One of the measurement units is formed by a zero-phase meter that collectively measures the magnetic fields generated in multiple power lines of a set when current is passed through them, and measures the total current flowing through those power lines based on that magnetic field. This allows the zero-phase meter to measure the total current at a location where, for example, each of a set of power lines is bundled together, making it difficult to measure the current using individual meters. As a result, the degree of freedom in arranging the measurement unit is improved, making it easier to analyze the cause of leakage current.

[0023] Claim 3 According to the earth leakage monitoring device described in claim 1 or 2 In addition to the effects of the leakage current monitoring device described above, the present invention provides the following effects. A set of power lines includes an upstream main line and multiple sets of branch lines branching off from the main line. Multiple load devices are connected to each set of branch lines. A measurement unit located on the main line upstream of the multiple sets of branch lines can easily monitor (measure or calculate) the total leakage current of the load devices connected to the multiple sets of branch lines. Furthermore, because a separate measurement unit is located on a set of branch lines, the leakage current of the load devices connected to that set of branch lines can be monitored without being affected by the leakage current of load devices connected to other branch lines. Furthermore, by comparing the measurement results of the measurement unit on the main line side and the measurement unit on the branch lines side, it is easier to analyze the cause of the leakage current.

[0024] Claim 4 The earth leakage monitoring device The earth leakage monitoring device monitors leakage current occurring within a predetermined range of an object to be measured, which operates a load device using load power supplied from a set of multiple power lines, using two or more measurement units. One of the measurement units is formed by a set of multiple individual meters. This set of individual meters individually measures the current flowing through each of the set of multiple power lines of the object to be measured. Therefore, similar to the effect achieved by the earth leakage monitoring device described in claim 1, the earth leakage monitoring device can monitor leakage current occurring downstream from the measurement position of the set of individual meters (measurement units), and can widen the range of objects that can be monitored for leakage current by the earth leakage monitoring device. The object to be measured comprises a housing that houses a load device and a ground wire that grounds the housing. One of the two or more measurement units is formed by a ground-side measuring instrument that measures the current flowing through the ground wire. This ground-side measuring instrument can measure the leakage current that occurs between the load device and the housing. By comparing this measurement result with the measurement result from a set of individual measuring instruments (leakage current that occurs downstream from the measurement position of the individual measuring instruments), it is easier to analyze the cause of the leakage current.

[0025] Claim 5 The disclosed leakage current monitoring device monitors leakage current in a measurement object that operates a load device using load power supplied from a set of multiple power lines. An upstream measuring instrument measures the current flowing through one of the set of multiple power lines. Furthermore, a downstream measuring instrument measures the current flowing through the power line downstream of the measurement position of the upstream measuring instrument. If there is a difference between the measurement results of the upstream measuring instrument and the downstream measuring instrument, it can be determined that a leakage current has occurred between them. In this way, the leakage current monitoring device can monitor leakage current without measuring the current of each of the set of multiple power lines, thereby broadening the scope of objects that can be monitored for leakage current.

[0026] Claim 6 According to the leakage current detection method described above, the same effect as that of the leakage current monitoring device described in claim 1 can be obtained. According to the leakage current detection method of claim 7, the same effects as those achieved by the leakage current monitoring device of claim 4 are achieved.

[0027] Claim 8 According to the leakage current detection method described in claim 5 Similar to the effect of the leakage current monitoring device described above, the leakage current of the measurement object can be detected without measuring the current of each of a set of multiple power lines, thereby widening the range of objects that can be monitored for leakage current. [Brief explanation of the drawings]

[0028] [Figure 1] 1 is a circuit diagram showing a schematic diagram of an electric circuit of a leakage current monitor (leakage current measuring instrument) and an object to be measured in a first embodiment. [Figure 2] Graph (a) shows the change over time in the current measured by the individual current transformers and the zero-phase current transformer, and graph (b) shows the change over time in the leakage current. [Figure 3] FIG. 2 is a block diagram showing the electrical configuration of the earth leakage measuring instrument. [Figure 4] 10 is a flowchart of a main process executed by a CPU of the earth leakage measuring device. [Figure 5] 10 is a flowchart of a peak detection process. [Figure 6] 10 is a flowchart of an average detection process. [Figure 7] 10 is a flowchart of a cycle collection process. [Figure 8] FIG. 10 is a circuit diagram that schematically illustrates an electric circuit of a leakage current monitor and an object to be measured in a second embodiment. [Figure 9] 10 is a graph showing changes in leakage current over time. [Figure 10] FIG. 2 is a block diagram showing the electrical configuration of a vehicle that is an object to be measured. [Figure 11] 3 is a flowchart of a main process executed by a CPU of the vehicle control device. [Figure 12] FIG. 10 is a circuit diagram that schematically illustrates an electric circuit of a leakage current monitor and an object to be measured in a third embodiment. [Figure 13] FIG. 10 is a circuit diagram that schematically illustrates an electric circuit of a leakage current monitor and an object to be measured in a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Preferred embodiments will now be described with reference to the accompanying drawings. First, a leakage current measuring instrument 20 and a measurement object 10 as a leakage current monitoring device in a first embodiment will be described with reference to Fig. 1. Fig. 1 is a circuit diagram that schematically shows the electric circuits of the leakage current measuring instrument 20 and the measurement object 10.

[0030] The measurement object 10 includes a battery 11 that outputs DC power (load power), a positive wire 12 connected to the positive electrode of the battery 11, a negative wire 13 connected to the negative electrode of the battery 11, and a load device 14 that operates with the DC power supplied from the battery 11 via the positive wire 12 and the negative wire 13. Examples of the measurement object 10 include automobiles, industrial vehicles, railroad cars, aircraft, and ships that are powered by electricity. Other examples of the measurement object 10 include indoor and outdoor wiring or electrical equipment, electrical appliances, etc. in homes, facilities, factories, etc.

[0031] Battery 11 is a DC power supply that outputs DC power of a predetermined voltage (for example, approximately 800 V). Positive line 12 and negative line 13 are a pair of power lines for supplying DC power from upstream battery 11 to downstream load device 14, and are each connected to load device 14. Current flows from positive line 12 to load device 14, and current flows from load device 14 to negative line 13. In this specification, the power supply side of battery 11 or the like is referred to as "upstream" and the power consumption side of load device 14 or the like is referred to as "downstream," rather than the direction of current.

[0032] The load device 14 is an electric circuit that operates on DC power. Examples of the load device 14 include a DC motor and an inverter. The load device 14 is housed in a housing 14a that is grounded (earthed) via a grounding wire 18.

[0033] The ground wire 18 is an electric wire connected to a ground electrode embedded in the ground. However, if the measurement target 10 is a vehicle, the "ground" refers to a connection to a large conductor such as the frame of the vehicle, and the large conductor does not necessarily have to be connected to the ground.

[0034] In this embodiment, not only the housing 14a but also the negative electrode line 13 is grounded via a grounding wire 18. The grounding wire 18 connected to the housing 14a and the negative electrode line 13 may be the same electric wire, or may be separate electric wires connected to each other via the earth.

[0035] In such a measurement object 10, leakage current may occur due to deterioration of insulation resistance in various parts. Note that, regardless of whether leakage current occurs or not, the electric circuit is formed so that the current flowing out of the positive side of the battery 11 is basically the same as the current flowing in from the negative side. Therefore, for example, if leakage current occurs from the load device 14 to the housing 14a, the leakage current will return to the battery 11 from the negative line 13 via the ground wire 18.

[0036] A leakage current measuring instrument 20 for monitoring such leakage current is provided in the measurement object 10. The leakage current measuring instrument 20 includes an individual current transformer 21 through which the positive electrode wire 12 passes, an individual current transformer 22 through which the negative electrode wire 13 passes, a zero-phase current transformer 23 through which both the positive electrode wire 12 and the negative electrode wire 13 pass, and a reference detection unit 24 that measures the voltage (potential difference) between the positive electrode wire 12 and the negative electrode wire 13.

[0037] The individual current transformers (individual measuring instruments) 21, 22 and the zero-phase current transformer (zero-phase measuring instrument) 23 are each measuring instruments configured as annular current transformers through which the electric wire to be measured passes, and measure the value of the current flowing through the passed portion. More specifically, a current transformer measures the magnetic field generated at the passed portion of the electric wire when current is passed through it, and measures (calculates) the value of the current based on that magnetic field. The individual current transformers 21, 22 and the zero-phase current transformer 23 in this embodiment are configured to be able to measure DC current values, but since their configuration is well known, their description will be omitted. Furthermore, of the currents measured in this manner, those flowing from upstream to downstream are considered to have positive values, and those flowing from downstream to upstream are considered to have negative values.

[0038] The upstream side of the positive electrode wire 12 passes through individual current transformer 21, and measures current A1 at the position where it passes through. The downstream side (load device 14 side) of the position where the grounding wire 18 is connected of the negative electrode wire 13 passes through individual current transformer 22, and measures current A2 at the position where it passes through. The positive electrode wire 12 and the negative electrode wire 13 at the positions where they pass through these individual current transformers 21, 22 are separated by an amount that makes it difficult to pass through one current transformer together.

[0039] The zero-phase-sequence current transformer 23 passes through the positive and negative electrode wires 12 and 13 downstream of where they pass through the individual current transformers 21 and 22, and measures a total current A3, which is the sum of the currents in the positive and negative electrode wires 12 and 13 at the position where they pass through. Note that because the currents in the positive and negative electrode wires 12 and 13 flow in opposite directions, the total current A3 is the difference between the absolute values ​​of these currents. Similarly, the sum of current A1 and current A2 is the difference between the absolute value of current A1 and the absolute value of current A2. Furthermore, the positive and negative electrode wires 12 and 13 at the position where they pass through the zero-phase-sequence current transformer 23 are close enough to each other to maintain insulation from each other.

[0040] The reference detection unit 24 is a known voltmeter, and is connected to the positive electrode line 12 and the negative electrode line 13 so as to measure the voltage V1 of the battery 11. Since the positive electrode line 12 and the negative electrode line 13 have no branches, the voltage V1 of the battery 11 is essentially substantially the same as the voltage between the positive electrode line 12 and the negative electrode line 13 at the positions where the individual current transformers 21, 22 are located. In other words, the reference detection unit 24 measures the voltage V1 at the positions of the individual current transformers 21, 22.

[0041] A method for monitoring leakage current (leakage current detection method) using such leakage current measuring instrument 20 will be described with reference to Fig. 1 and Fig. 2. Fig. 2(a) is a graph showing the time-dependent changes in currents A1 and A2 and total current A3 measured by individual current transformers 21 and 22 and zero-phase current transformer 23, respectively. Fig. 2(b) is a graph showing the time-dependent changes in leakage current value L1 (hereinafter abbreviated as "leakage value L1") calculated according to currents A1 and A2, and the time-dependent changes in leakage current value L2 (hereinafter abbreviated as "leakage value L2") calculated according to total current A3.

[0042] The vertical axis of the graphs in Figures 2(a) and 2(b) represents the absolute value of current [A]. The horizontal axis of the graphs in Figures 2(a) and 2(b) represents time [s]. Furthermore, in the graph in Figure 2(a), the change over time of the current A1 of the individual current transformer 21 is shown by a solid line, the change over time of the current A2 of the individual current transformer 22 is shown by a dashed line, and the change over time of the total current A3 of the zero-phase current transformer 23 is shown by a two-dot chain line. In the graph in Figure 2(b), the change over time of the leakage current value L1 is shown by a solid line, and the change over time of the leakage current value L2 is shown by a two-dot chain line. Furthermore, in the graphs in Figures 2(a) and 2(b), the overlapping lines are slightly shifted to make the graphs easier to read.

[0043] When no leakage current is occurring in the measurement object 10, essentially all of the current that flows from the battery 11 through the positive electrode line 12 (individual current transformer 21) to the load device 14 returns from the load device 14 through the negative electrode line 13 (individual current transformer 22) to the battery 11. Therefore, during the time when no leakage current is occurring, the absolute values ​​of the currents A1 and A2 of the individual current transformers 21 and 22 are the same in the graph of Fig. 2(a), and the leakage value L1 is 0 A in the graph of Fig. 2(b).

[0044] On the other hand, for example, if only leakage current occurs from the load device 14 to the housing 14a and no other leakage current occurs, the leakage current passes through the grounding wire 18, bypasses the individual current transformer 22 and the zero-phase-sequence current transformer 23, and returns to the battery 11 from the negative wire 13. In other words, the current that passes through the individual current transformer 21 and the zero-phase-sequence current transformer 23 toward the load device 14 is divided into a normal route that passes through the individual current transformer 22 and the zero-phase-sequence current transformer 23, and a leakage current route that returns to the battery 11 without passing through them.

[0045] 2(a), the current A2 of the individual current transformer 22 is lower than the current A1 of the individual current transformer 21. Therefore, the graph of FIG. 2(b) shows the leakage current value L1 that has occurred in the object to be measured 10 downstream of the individual current transformers 21 and 22 based on the sum (difference in absolute values) of the currents A1 and A2 during the same time period. Similarly, the total current A3 of the zero-phase-sequence current transformer 23 increases during the time when the leakage current has occurred, and the leakage current value L2 that has occurred in the object to be measured 10 downstream of the zero-phase-sequence current transformer 23 is shown based on the total current A3.

[0046] As shown in Figure 2(a), when the currents A1 and A2 of the individual current transformers 21 and 22 fluctuate, their sum also fluctuates slightly. Similarly, when the currents of the positive electrode line 12 and the negative electrode line 13 passing through the zero-phase current transformer 23 fluctuate, the sum of these currents, that is, the total current A3, fluctuates slightly. These currents A1 and A2 and the total current A3 fluctuate mainly according to the voltage V1 of the battery 11. Figure 2(a) shows the voltage V1 at the time when the currents A1 and A2 were acquired above the graphs of the currents A1 and A2. The voltage V1 of the battery 11 fluctuates depending on the remaining charge of the battery 11, its deterioration over time, and other factors.

[0047] The graph in Figure 2(b) shows the corrected (converted) leakage current values ​​L1 and L2 when the voltage V1 is 800 V. Specifically, when the voltage V1 is 800 V, the sum of the currents A1 and A2 is used as the corrected leakage current value L1, and the total current A3 is used as the corrected leakage current value L2.

[0048] When the voltage V1 is 600V, the corrected leakage current value L1 is calculated by multiplying the sum of the currents A1 and A2 by approximately 1.33 (=800V / 600V), and the corrected leakage current value L2 is calculated by multiplying the sum of the currents A1 and A2 by approximately 1.33 (=800V / 900V). When the voltage V1 is 900V, the corrected leakage current value L1 is calculated by multiplying the sum of the currents A1 and A2 by approximately 0.89 (=800V / 900V), and the corrected leakage current value L2 is calculated by multiplying the sum of the currents A1 and A2 by approximately 0.89 (=800V / 900V). Therefore, when determining whether the leakage current values ​​L1 and L2 exceed the threshold, the determination can be prevented from being affected by fluctuations in the voltage V1. In other words, this correction based on the voltage V1 can widen the range in which leakage current detection accuracy can be ensured.

[0049] Furthermore, since the individual current transformers 21, 22 and the zero-phase current transformer 23 are separated on the upstream and downstream sides, the cause of the leakage current can be easily analyzed by comparing the leakage current values ​​L1, L2 according to the measurement results.

[0050] Specifically, according to the leftmost peak (part P1) in the graph of Fig. 2(b), the leakage current value L1 occurring in the object to be measured 10 downstream of the individual current transformers 21 and 22 is the same as the leakage current value L2 occurring in the object to be measured 10 downstream of the zero-phase-sequence current transformer 23. From this, it can be inferred that a leakage current has occurred in the object to be measured 10 only downstream of the zero-phase-sequence current transformer 23.

[0051] 2(b), only leakage current L1 has occurred, but not leakage current L2. This suggests that leakage current has occurred from the negative electrode wire 13 upstream of the zero-phase-sequence current transformer 23 and downstream of the individual current transformer 22 to the ground or the like.

[0052] According to the two peaks (parts P3 and P4) on the right side of the graph in Figure 2(b), leakage current L2 is smaller than leakage current L1. From this, it is estimated that leakage current L2 occurs downstream of zero-phase-sequence current transformer 23, and that the leakage current occurring in negative electrode wire 13 between zero-phase-sequence current transformer 23 and individual current transformer 22 is the difference between leakage current L1 and leakage current L2. In other words, it is estimated that leakage current occurs in at least two locations in this case.

[0053] The route of the leakage current changes depending on the location where the leakage current occurs, and the way in which currents A1 and A2 (leakage value L1) and total current A3 (leakage value L2) fluctuate also changes. For example, it is possible that current A2 fluctuates according to voltage V1 regardless of whether or not leakage current occurs, and when leakage current occurs, only current A1 increases relative to current A2 by the amount of the leakage current.

[0054] Furthermore, when both currents A1 and A2 fluctuate according to voltage V1 and current A2 drops relative to current A1, it can be estimated from the measurement results of leakage current measuring instrument 20 that a leakage current has occurred downstream of individual current transformers 21 and 22 at the point when current A2 drops, without having to calculate leakage current value L1.

[0055] As described above, the earth leakage measuring instrument 20 can monitor (calculate) the leakage current occurring downstream of the individual current transformers 21, 22 from the measurement results of the individual current transformers 21, 22, and can monitor the leakage current occurring downstream of the zero-phase-sequence current transformer 23 from the measurement results of the zero-phase-sequence current transformer 23. That is, in the earth leakage measuring instrument 20, one measurement unit capable of monitoring the leakage current is configured by one pair of the individual current transformers 21, 22, and another measurement unit capable of monitoring the leakage current is configured by one zero-phase-sequence current transformer 23.

[0056] In particular, with the measurement unit using individual current transformers 21 and 22, the positive electrode line 12 and the negative electrode line 13 pass through each individually, so even if the positive electrode line 12 and the negative electrode line 13 are separated from each other, the sum of the currents A1 and A2 flowing through them can be calculated, and leakage current can be monitored. As a result, the range of objects for which leakage current can be monitored by leakage current measuring instrument 20 can be expanded.

[0057] Furthermore, the number of current transformers can be reduced by using the zero-phase-sequence current transformer 23 instead of the individual current transformers 21 and 22. Furthermore, even in a position where the positive and negative wires 12 and 13 are bundled together and cannot be individually passed through the individual current transformers 21 and 22, the total current at that position can be measured by the zero-phase-sequence current transformer 23. As a result, the degree of freedom in the placement of the measuring unit that monitors the leakage current can be improved, making it easier to analyze the cause of the leakage current.

[0058] Next, the control of the earth leakage measuring instrument 20 will be described in more detail with reference to Figures 3 to 7. Figure 3 is a block diagram showing the electrical configuration of the earth leakage measuring instrument 20. The earth leakage measuring instrument 20 has a CPU 25, a flash ROM 26, and a RAM 27, which are each connected to an input / output port 29 via a bus line 28. The input / output port 29 is further connected to a communication device 30, individual current transformers 21 and 22, a zero-phase current transformer 23, and a reference detection unit 24, respectively.

[0059] The communication device 30 is connected to an external control device 40, and transmits and receives information to and from the external control device 40. The external control device 40 is a device that analyzes the cause of leakage current based on the measurement results of the individual current transformers 21, 22, the zero-phase-sequence current transformer 23, and the reference detection unit 24. Furthermore, a load device 14 is connected to the external control device 40, and the external control device 40 is configured to be able to analyze the cause of leakage current using the operating state of the load device 14, etc.

[0060] The CPU 25 is a computing device that controls each component connected via a bus line 28. The flash ROM 26 is a rewritable nonvolatile memory that stores programs executed by the CPU 25, fixed value data, and the like, and includes a monitoring program 26a, a unique number memory 26b, a peak detection memory 26c, a short-term change detection memory 26d, a long-term change detection memory 26e, and a cycle collection memory 26f. Note that instead of the flash ROM 26, a storage device such as an SSD or HDD may be used.

[0061] When the monitoring program 26a is executed by the CPU 25, the main processing of Fig. 4 is executed. The unique number memory 26b is a memory that stores the unique number of the earth leakage measuring instrument 20. This unique number is part of the information for identifying the measurement object 10 whose leakage current is monitored by the earth leakage measuring instrument 20. This unique number is necessary when there are multiple earth leakage measuring instruments 20 connected to the external control device 40. On the other hand, when there is only one earth leakage measuring instrument 20, there is no need to identify the measurement object 10 by the unique number, and so the unique number memory 26b may be omitted.

[0062] The peak detection memory 26c, the short-term change detection memory 26d, the long-term change detection memory 26e, and the cycle collection memory 26f are all memories for storing data relating to the leakage current values ​​L1 and L2 until they are transmitted to the external control device 40. That is, each of these memories 26c to 26f stores data that is permitted to be transmitted to the external control device 40.

[0063] The RAM 27 is a memory for rewritably storing various work data, flags, etc. when the CPU 25 executes a program, and is provided with an upstream ring buffer 27a, a downstream ring buffer 27b, an upstream average ring buffer 27c, a downstream average ring buffer 27d, and a voltage ring buffer 27e.

[0064] The upstream ring buffer 27a is configured as a known ring buffer and stores the leakage current value L1 calculated every 1 ms for the past minute by correcting the sum of the currents A1 and A2 with the voltage V1. Specifically, the upstream ring buffer 27a stores (overwrites) the latest leakage current value L1 at the latest position in multiple storage areas. This latest position is the storage area where the leakage current value L1 from one minute ago is stored, and the multiple storage areas correspond to the latest positions in order. Furthermore, the upstream ring buffer 27a is configured so that the time when each leakage current value L1 was stored (the time when the leakage current value L1 was calculated) can be determined by using the latest position as the current time.

[0065] Each ring buffer 27b-27e is configured identically to the upstream ring buffer 27a, except for the content of the data stored and the storage capacity. The downstream ring buffer 27b stores the leakage current value L2 calculated every 1 ms for the past minute by correcting the total current A3 with the voltage V1. The upstream average ring buffer 27c stores the average value M1 obtained by averaging all leakage current values ​​L1 measured over the past minute for the past 10 minutes. The downstream average ring buffer 27d stores the average value M2 obtained by averaging all leakage current values ​​L2 measured over the past minute for the past 10 minutes. The voltage ring buffer 27e stores the voltage V1 measured by the reference detection unit 24 every 1 ms for the past 10 minutes.

[0066] Next, the main processing executed by the CPU 25 of the earth leakage measuring instrument 20 will be described with reference to Fig. 4 to Fig. 7. Fig. 4 is a flowchart of the main processing of the earth leakage measuring instrument 20. Fig. 5 is a flowchart of the peak detection processing S20. Fig. 6 is a flowchart of the average detection processing S21. Fig. 7 is a flowchart of the cycle collection processing S22.

[0067] The main processing of the earth leakage measuring instrument 20 is executed every 1 ms while the power of the earth leakage measuring instrument 20 is on. The peak detection processing S20, the average detection processing S21, and the cycle collection processing S22 are executed during this main processing of the earth leakage measuring instrument 20.

[0068] 4, the main process first acquires a current A1 measured by the individual current transformer 21 (S11). Next, a current A2 measured by the individual current transformer 22 is acquired (S12). Next, a total current A3 measured by the zero-phase-sequence current transformer 23 is acquired (S13). Next, a voltage V1 measured by the reference detection unit 24 is acquired, and the voltage V1 is stored in the voltage ring buffer 27e (S14).

[0069] In this series of steps S11 to S14, the currents A1 and A2, the total current A3, and the voltage V1 are measured at the same time. This is to accurately calculate the leakage current values ​​L1 and L2 that occurred during the measurements. However, the currents A1 and A2, the total current A3, and the voltage V1 measured in steps S12 to S14 may be measured at different times.

[0070] After the process of S14, the reference voltage Vs, which is the reference value of the voltage V1, is set to 800 V (S15). The reference voltage Vs may be set according to the voltage of the battery 11 in the normal state. For example, if the normal voltage is 350 to 450 V, the reference voltage Vs is set to 400 V in the process of S15.

[0071] After the process of S15, based on these values, the sum (difference in absolute values) of current A1 and current A2 is corrected to the value at reference voltage Vs to calculate leakage current value L1 = (A1 + A2) Vs / V1 (S16). This calculated leakage current value L1 is temporarily stored in the latest position of upstream ring buffer 27a (S17).

[0072] Next, the total current A3 is corrected to the value at the reference voltage Vs to calculate a leakage current value L2=A3·Vs / V1 (S18). This calculated leakage current value L2 is temporarily stored in the latest position of the downstream ring buffer 27b (S19).

[0073] Thereafter, based on the temporarily stored leakage current values ​​L1 and L2, a peak detection process S20, an average detection process S21, and a cycle collection process S22 are sequentially executed to determine whether or not to store data relating to the leakage current values ​​L1 and L2 so that the data can be transmitted to the external control device 40.

[0074] The peak detection process S20 in Fig. 5 will be described with reference to Fig. 2(b). When the leakage current value L1 temporarily stored in the upstream ring buffer 27a is a value that is suspected to be abnormal or that requires a caution or warning, the peak detection process S20 stores the leakage current value L1 in the peak detection memory 26c for analysis by the external control device 40. Note that, because the leakage current value L2 is generally equal to or less than the leakage current value L1, the peak detection process S20 does not use the leakage current value L2 to determine whether or not to store the leakage current value L1, and when the leakage current value L1 is stored in the peak detection memory 26c, the leakage current value L2 at the same time is also stored in the peak detection memory 26c.

[0075] In the peak detection process S20, first, it is determined whether the leakage current value L1 stored in the latest position of the upstream ring buffer 27a has changed from below the threshold to above the threshold, i.e., whether the leakage current value L1 at the previous position is below the threshold and the leakage current value L1 at the latest position is above the threshold (S41). An example of this threshold is 1 mA. If the leakage current value L1 is above the threshold, it is suspected that an abnormal leakage current is occurring in the measurement object 10 monitored by the leakage current measuring instrument 20. However, the threshold may be set to a value smaller than the value that is determined to be abnormal so that a caution or warning can be issued to prevent the occurrence of an abnormal leakage current. Alternatively, the threshold may be set to a value greater than 1 mA.

[0076] In the process of S41, if the leakage current value L1 at the latest position changes from less than the threshold to greater than or equal to the threshold (S41: Yes), it is checked whether the start position S (see FIG. 2(b)) for specifying the range to be stored in the peak detection memory 26c has not been set (S42). Note that if the leakage current value L1 remains less than the threshold for 15 seconds or more, the start position S is not set (cleared).

[0077] If the start position S has not been set (S42: Yes), the start position S is set to the position 15 seconds before the most recent position where the leakage current value L1 became equal to or greater than the threshold value among the multiple memory positions in the upstream ring buffer 27a (S43), and the peak detection process S20 is terminated.

[0078] In the process of S41, if the leakage current value L1 at the latest position has not changed from less than the threshold to greater than or equal to the threshold (S41: No), it is determined whether the leakage current value L1 stored at the latest position of the upstream ring buffer 27a has changed from greater than or equal to the threshold to less than the threshold (S45).If the leakage current value L1 has changed from greater than or equal to the threshold to less than the threshold (S45: Yes), since the start position S has already been set in the process of S43, the end position E (see FIG. 2(b)) corresponding to the start position S is set (S46), and the peak detection process S20 is terminated.

[0079] Specifically, in the process of S46, among the multiple memory positions in the upstream ring buffer 27a, the position 15 seconds after the most recent position where the leakage current value L1 became less than the threshold is set as the end position E. The range from the start position S to the end position E in the upstream ring buffer 27a is the range to be stored in the peak detection memory 26c.

[0080] At the start of the peak detection process S20, if the leakage current value L1 at the latest position does not cross the threshold value (S41: No and S45: No), it is checked whether a new leakage current value L1 has been stored at the end position E of the upstream ring buffer 27a (S47). That is, in the process of S47, it is checked whether 15 seconds have passed since the leakage current value L1 became less than the threshold value and remained less than the threshold value.

[0081] If a new leakage value L1 is stored at the end position E in the process of S47 (S47: Yes), all leakage values ​​L1 within the range to be stored in the peak detection memory 26c are now stored, and the leakage values ​​L1 from the start position S to the end position E are stored in the peak detection memory 26c (S48). Furthermore, in the process of S48, the times corresponding to these leakage values ​​L1, and the leakage values ​​L2 and voltage V1 at those times are stored in the peak detection memory 26c in association with the leakage value L1. These leakage values ​​L2 and voltage V1 are stored in the upstream ring buffer 27a and voltage ring buffer 27e, respectively.

[0082] Although not shown, the peak detection memory 26c specifically includes a time memory in which the time is stored, an L1 memory in which the leakage current value L1 is stored, an L2 memory in which the leakage current value L2 is stored, and a voltage memory in which the voltage V1 is stored.

[0083] The times stored in the time memory are the times when the currents A1 and A2 for calculating the leakage value L1 were measured (acquired), the times when the total current A3 for calculating the leakage value L2 was measured, and the times when the voltage V1 was measured. That is, the leakage values ​​L1, L2, and voltage V1 are associated with each other by time and stored in the peak detection memory 26c. This makes it possible to analyze the cause of the leakage value L1 (leakage current value) being so high that it is suspected to be an abnormality by comparing the leakage values ​​L1 and L2 with each other and with the voltage V1.

[0084] After the process of S48, the settings of the start position S and the end position E are cleared (S49) so that a new start position S can be set in the processes of S41 to S43, and the peak detection process S20 is terminated.

[0085] Here, we will explain what happens when, after the start position S is set in the process of S43, the leakage current value L1 falls below the threshold value (S45: Yes), and the end position E is set in the process of S46, the leakage current value L1 at the latest position goes from below the threshold value to equal to or greater than the threshold value (S41: Yes) before the leakage current value L1 is stored at the end position E. That is, we will explain how to set the end position when, for example, peaks P3 and P4 occur consecutively within a short period of time, as shown in Figure 2(b).

[0086] In this case, when the process proceeds to S42, both the start position S and the end position E have already been set (S42: No), so the start position S does not need to be reset in the process of S43, and only the end position E is cleared so that it can be reset (S44, see the dashed line in FIG. 2(b)), and the peak detection process S20 ends. Thereafter, if the latest leakage value L1 again changes from above the threshold to below the threshold (S45: Yes), the end position E is reset (S46), and the leakage value L1 from the start position S to the end position E can be stored in the peak detection memory 26c by the processes of S47 and S48.

[0087] In this way, even if there are consecutive periods in which the leakage current L1 is equal to or greater than the threshold value over a short period of time, the leakage current L1 for multiple consecutive periods above the threshold value and for 15 seconds before and after each period can be stored in the peak detection memory 26c. This avoids a situation in which some of the multiple ranges in which the leakage current L1 is equal to or greater than the threshold value are not stored in the peak detection memory 26c. Furthermore, compared to a case in which the start position S and end position E are individually set for each of the multiple ranges in which the leakage current L1 is equal to or greater than the threshold value, the peak detection process S20 can be simplified and duplicate data can be prevented from being stored in the peak detection memory 26c.

[0088] If a new leakage value L1 is not stored at the end position E in the process of S47 (S47: No), it is confirmed whether the position where the next leakage value L1 is to be stored in the upstream ring buffer 27a is the start position S (S50). If the next storage position is not the start position S (S50: No), the peak detection process S20 is terminated.

[0089] On the other hand, if the next storage position is the start position S (S50: Yes), the storage of new leakage values ​​L1, L2 in the upstream ring buffer 27a and downstream ring buffer 27b from the next time onwards will cause the leakage values ​​L1, L2 to be stored in the peak detection memory 26c to be erased, starting with the oldest. Therefore, just before the old leakage values ​​L1, L2 are erased (S50: Yes), all leakage values ​​L1 stored in the upstream ring buffer 27a, the times corresponding to those leakage values ​​L1, and the leakage values ​​L2 and voltage V1 at those times are stored in the peak detection memory 26c in association with one another (S51).

[0090] If a new leakage value L1 is stored at the end position E in the peak detection process S20 after the process of S51 (S47: Yes), in the process of S48, the leakage value L1 stored in the upstream ring buffer 27a immediately after the process of S51 is set as a new start position S, and the leakage value L1 after the process of S51 and the like are stored in the peak detection memory 26c. Therefore, by the processes of S50 and S51, the leakage value L1 that is equal to or greater than the threshold, the leakage values ​​L1 for 15 seconds before and after that, and the leakage value L2 at the same time can all be stored in the peak detection memory 26c without increasing the capacity of the upstream ring buffer 27a and the downstream ring buffer 27b.

[0091] Next, the average detection process S21 will be described with reference to Fig. 6. The average detection process S21 is a process for storing an average value M1 (an average value of all leakage values ​​L1 measured within one minute) and an average value M2 (an average value of all leakage values ​​L2 measured within one minute) in the short-term change detection memory 26d and the long-term change detection memory 26e, respectively, in order to analyze the short-term or long-term increase trends of the leakage values ​​L1 and L2 using the external control device 40, while eliminating the influence of momentary increases in the leakage values ​​L1 and L2 due to noise, etc. As with the peak detection process S20, the average detection process S21 does not use the average value M2 based on the leakage value L2 to determine whether or not storage is necessary, and when the average value M1 is stored in the short-term change detection memory 26d or the long-term change detection memory 26e, the average value M2 for the same time is also stored in each memory 26d, 26e.

[0092] As shown in Fig. 6, in the average detection process S21, first, it is confirmed whether one minute has passed since the previous calculation of the average values ​​M1 and M2, i.e., whether all values ​​in the upstream ring buffer 27a and the downstream ring buffer 27b, which respectively store the leakage current values ​​L1 and L2 for the past minute, have been updated (S61). Note that immediately after powering on the earth leakage measuring instrument 20, invalid values ​​are stored in the memories of the upstream ring buffer 27a and the downstream ring buffer 27b, and the process of S61 immediately after powering on checks whether all invalid values ​​have been updated with the leakage current values ​​L1 and L2. If, in the process of S61, one minute has not passed since the previous calculation of the average values ​​M1 and M2 or since powering on (S61: No), the average detection process S21 is terminated, and one minute is awaited.

[0093] On the other hand, if one minute has passed since the previous calculation of the average values ​​M1 and M2 or the power was turned on (S61: Yes), the values ​​in the upstream ring buffer 27a and the downstream ring buffer 27b have all been updated, so the leakage values ​​L1 for the most recent minute stored in the upstream ring buffer 27a are averaged to calculate an average value M1, and this average value M1 is stored in the upstream average ring buffer 27c (S62). Similarly, the leakage values ​​L2 for the most recent minute stored in the downstream ring buffer 27b are averaged to calculate an average value M2, and this average value M2 is stored in the downstream average ring buffer 27d (S63).

[0094] Next, the rate of change of the average value M1 for the most recent minute relative to the average value M1 from 2 to 1 minute ago stored in the upstream average ring buffer 27c (the average value M1 calculated in the process of S62 1 minute ago, which is the average of the multiple leakage values ​​L1 calculated from 2 to 1 minute ago) is calculated as the short-term rate of change (S64). Specifically, the short-term rate of change is calculated as follows: (short-term rate of change) = ((average value M1 for the most recent minute) - (average value M1 from 2 to 1 minute ago)) / (average value M1 from 2 to 1 minute ago).

[0095] It is then confirmed whether the calculated short-term change rate is equal to or greater than a change threshold value (S65). The change threshold value is set to, for example, 1.1 to eliminate noise, but may be changed as long as it is a number equal to or greater than 1.

[0096] If the short-term change rate is equal to or greater than the change threshold value in the processing of S65 (S65: Yes), the average values ​​M1 for the most recent two minutes stored in the upstream average ring buffer 27c (all average values ​​M1 calculated in the processing of S62 for the most recent two minutes), the time corresponding to these average values ​​M1, and the average value M2 and voltage V1 at that time are associated with each other and stored in the short-term change detection memory 26d (S66), and the processing proceeds to S67.

[0097] The average value M2 at the time corresponding to the average value M1 for the most recent two minutes is the average value M2 for the most recent two minutes stored in downstream average ring buffer 27d (all average values ​​M2 calculated in the process of S63 for the most recent two minutes). The voltage V1 at the time corresponding to the average value M1 for the most recent two minutes is the voltage V1 for the most recent two minutes stored in voltage ring buffer 27e.

[0098] Although not shown, the short-term variation detection memory 26d specifically includes a time memory for storing time, an M1 memory for storing average value M1, an M2 memory for storing average value M2, and a voltage memory for storing voltage V1. That is, the short-term variation detection memory 26d is obtained by replacing the L1 memory and L2 memory of the peak detection memory 26c with an M1 memory and an M2 memory. The M1 memory and M2 memory store the average values ​​M1 and M2 in association with the time when the oldest leakage values ​​L1 and L2 used to calculate the average values ​​M1 and M2 were calculated.

[0099] If the short-term change rate is less than the change threshold in the process of S65 (S65: No), the process skips the process of S66 and proceeds to the process of S67. This makes it possible to analyze the increasing trend of the short-term average value M1 while excluding cases where the short-term change rate is decreasing or where the short-term change rate is only slightly increasing due to noise or the like.

[0100] In the process of S67, the long-term change rate is calculated as the rate of change of the average value M1 for the most recent minute relative to the average value M1 for 10 to 9 minutes ago stored in the upstream average ring buffer 27c (the average value M1 calculated in the process of S62 9 minutes ago, which is the average of the multiple leakage values ​​L1 calculated for 10 to 9 minutes ago). Specifically, the long-term change rate is calculated as follows: (long-term change rate) = ((average value M1 for the most recent minute) - (average value M1 for 10 to 9 minutes ago)) / (average value M1 for 10 to 9 minutes ago).

[0101] It is then confirmed whether the calculated long-term change rate is equal to or greater than a change threshold value (e.g., 1.1) (S68). If the long-term change rate is equal to or greater than the change threshold value (S68: Yes), the average values ​​M1 for the most recent 10 minutes stored in the upstream average ring buffer 27c (all average values ​​M1 calculated in the process of S63 for the most recent 10 minutes), the time corresponding to these average values ​​M1, and the average value M2 and voltage V1 at that time are stored in the long-term change detection memory 26e in association with each other (S69), and the average detection process S21 is terminated.

[0102] The average value M2 at the time corresponding to the average value M1 for the most recent 10 minutes is the average value M2 for the most recent 10 minutes stored in downstream average ring buffer 27d (all average values ​​M2 calculated in the process of S63 for the most recent 10 minutes). The voltage V1 at the time corresponding to the average value M1 for the most recent 10 minutes is the voltage V1 for the most recent 10 minutes stored in voltage ring buffer 27e. Furthermore, long-term change detection memory 26e has the same configuration as short-term change detection memory 26d.

[0103] If the long-term change rate is less than the change threshold in the process of S68 (S68: No), the process of S69 is skipped and the average detection process S21 is terminated. This makes it possible to analyze the increasing trend of the long-term average value M1 while excluding cases where the long-term change rate is decreasing or where the long-term change rate is only slightly increasing due to noise, etc.

[0104] Next, the cycle collection process S22 will be described with reference to Fig. 7. The cycle collection process S22 is a process for periodically storing the leakage current values ​​L1 and L2 in the cycle collection memory 26f even when no abnormality is present, in order to analyze fluctuations in the leakage current values ​​L1 and L2 over an extremely long period, such as several months or several years.

[0105] 7, in the cycle collection process S22, first, it is confirmed whether a periodic collection timing has arrived (S71). In this embodiment, the periodic collection timing is set to every hour, but the collection timing may be changed as appropriate.

[0106] If the periodic collection timing has not arrived (S71: No), the cycle collection process S22 is terminated and the process waits for the arrival of the collection timing. On the other hand, if the periodic collection timing has arrived (S71: Yes), all leakage values ​​L1 (for the most recent minute) stored in the upstream ring buffer 27a, all leakage values ​​L2 (for the most recent minute) stored in the downstream ring buffer 27b, the times corresponding to the leakage values ​​L1 and L2, and the voltage V1 at those times are associated with each other and stored in the cycle collection memory 26f (S72), and the cycle collection process S22 is terminated. Note that in the process of S72, the voltage V1 at the time corresponding to the leakage values ​​L1 and L2 is the voltage V1 for the most recent minute stored in the voltage ring buffer 27e.

[0107] By periodically acquiring the leakage current value L1, it is possible to analyze the long-term increase trend of the leakage current over several months or years. For example, by approximating the change over time of the past measured value of the leakage current value L1 using the least squares method, it is possible to calculate the change over time of the predicted value of the leakage current value L1. From this change over time of the predicted value, it is possible to analyze the approximate date and time when the leakage current value L1 will exceed a threshold value (e.g., 1 mA). This makes it possible to plan schedules for maintenance of the measurement object 10 and to plan the ordering of equipment or parts that need to be replaced. Furthermore, by acquiring the leakage current value L2 and voltage V1 at the same time as acquiring the leakage current value L1, it is possible to analyze the location of equipment or parts that need to be replaced based on each of these values.

[0108] Returning to Fig. 4, after the cycle collection process S22, the unsent data stored in the peak detection memory 26c, short-term change detection memory 26d, long-term change detection memory 26e, and cycle collection memory 26f, and the unique number stored in the unique number memory 26b are transmitted to the external control device 40 (S23).

[0109] When the external control device 40 receives each of these data, it stores the data in a memory provided for each unique number (measurement object 10). The memories of the external control device 40 are substantially the same as the memories 26c to 26f of the earth leakage measuring device 20. The external control device 40 uses the data received from the earth leakage measuring device 20 to perform an analysis of the cause of the leakage current, etc. It is preferable to use AI data analysis for this analysis.

[0110] The data of each of the memories 26c to 26f transmitted in the process of S23 is data including the leakage current values ​​L1, L2 themselves or data including average values ​​M1, M2 obtained by averaging the leakage current values ​​L1, L2, and is data that is permitted to be transmitted to and stored in the external control device 40. Therefore, the processes of S41 to S47, S50 in Fig. 5, the processes of S64, S65, S67, S68 in Fig. 6, and the process of S71 in Fig. 7, which determine whether to store each piece of data in each of the memories 26c to 26f, can be said to be processes for determining whether to transmit each piece of data to (store) it in the external control device 40.

[0111] In particular, the processes of S41 to S47 and S50 in Fig. 5 and the processes of S64, S65, S67 and S68 in Fig. 6 can be said to be processes that determine, based on the leakage value L1, whether data related to the leakage values ​​L1 and L2 should be transmitted to (stored in) the external control device 40. Furthermore, the processes of S48 and S51 in Fig. 5, the processes of S66 and S69 in Fig. 6 and the process of S72 in Fig. 7 can be said to be processes that make each piece of data that has been determined to be transmitted to (stored in) the external control device 40 transmittable (storable) to the external control device 40.

[0112] This makes it possible to select data that is effective for analyzing leakage current from data relating to leakage values ​​L1 and L2, for example, and transmit (store) it to the external control device 40, thereby reducing the frequency and amount of transmission from the leakage measuring device 20 to the external control device 40. Furthermore, it is possible to reduce the amount of data stored in the leakage measuring device 20 and the external control device 40 per given time, making it easier to make the leakage measuring device 20 and the external control device 40 smaller and less expensive.

[0113] After the processing of S23, other processing is executed (S24), and the main processing of the earth leakage measuring instrument 20 is terminated. The processing of S24 may include processing to change the reference voltage Vs, processing to change the threshold value used in the peak detection processing S20, and processing based on a signal received from the external control device 40. For example, if an operation to change the threshold value used in the peak detection processing S20 is performed by the external control device 40 and the earth leakage measuring instrument 20 receives a signal of this change from the external control device 40 via the communication device 30, the processing of S24 executes processing to change the threshold value in accordance with the received signal.

[0114] Next, a second embodiment will be described with reference to Figures 8 to 11. In the first embodiment, a leakage measuring instrument 20 (leakage monitoring device) that measures the leakage current of a measurement object 10 having one load device 14 will be described. In contrast, in the second embodiment, a leakage monitoring device that measures the leakage current of a measurement object (vehicle 19) having three load devices 15 to 17 will be described. Note that the same parts as in the first embodiment will be given the same reference numerals and the following description will be omitted.

[0115] 8 is a circuit diagram showing a schematic diagram of an electric circuit of the earth leakage monitoring device and the object to be measured in the second embodiment. The earth leakage monitoring device of the second embodiment is composed of an earth leakage measuring instrument 50 and a control device 60 of the object to be measured (see FIG. 10).

[0116] The measurement object in the second embodiment is a vehicle 19 (for example, a pile driver) that is driven by electricity, and a vehicle body 19b is supported by a plurality of wheels 19a so that it can run. Note that, since the vehicle body 19b is a large conductor, "grounding" in the second embodiment refers to electrically connecting to the vehicle body 19b, as described above.

[0117] The vehicle 19 includes a battery 11 that outputs DC power (load power), a positive electrode line 12 connected to the positive electrode of the battery 11, a negative electrode line 13 connected to the negative electrode of the battery 11, and a plurality of load devices 15, 16, and 17 that are each operated by DC power supplied from the battery 11 via the positive electrode line 12 and the negative electrode line 13.

[0118] The positive line 12 and the negative line 13 are a pair of power lines for supplying DC power from the upstream battery 11 to the downstream load devices 15 to 17. The positive line 12 includes a main electric line 12a connected to the battery 11 and a plurality of branch electric lines 12b, 12c, and 12d branching off from the main electric line 12a. Similarly, the negative line 13 includes a main electric line 13a connected to the battery 11 and a plurality of branch electric lines 13b, 13c, and 13d branching off from the main electric line 13a.

[0119] The main electric wires 12a and 13a are similarly configured as a pair to collect the upstream sides of pairs of power lines branching out toward the multiple load devices 15 to 17. The branch electric wires 12b and 13b are connected to the load device 15, respectively, and configure a downstream pair of the power lines. Similarly, the branch electric wires 12c and 13c are connected to the load device 16, respectively, and configure a downstream pair of the power lines, and the branch electric wires 12d and 13d are connected to the load device 17, respectively, and configure a downstream pair of the power lines. In this way, the pair of power lines in this embodiment branches out from the upstream pair into multiple pairs downstream.

[0120] Examples of the load devices 15 to 17 include an inverter, a control device 60 (see FIG. 10), a DC motor, etc. The load devices 15 to 17 are housed in housings 15a, 16a, and 17a, respectively, which are grounded via a ground wire 18. When a leakage current occurs from the load devices 15 to 17 to the housings 15a to 17a, even if the negative electrode wire 13 is not grounded, the leakage current returns to the negative electrode of the battery 11, for example, from the ground wire 18 through the vehicle body 19b, the surface of the housing of the battery 11, etc.

[0121] In the second embodiment, similarly to the first embodiment, the negative electrode line 13 may be grounded by the grounding line 18. In this case, the leakage current is more likely to return to the negative electrode line 13 through the grounding line 18, and the route of the leakage current is more easily determined, making it easier to analyze the cause of the leakage current. Therefore, information on whether the negative electrode line 13 is grounded may be included in the operating state data described below.

[0122] The earth leakage measuring instrument 50 is a device for monitoring leakage current occurring in the vehicle 19, which is the measurement object, and is mounted on the vehicle 19. The earth leakage measuring instrument 50 includes an individual current transformer 21 through which the main electric wire 12a passes, an individual current transformer 22 through which the main electric wire 13a passes, an individual current transformer 51 through which the branch electric wire 12b passes, an individual current transformer 52 through which the branch electric wire 13b passes, an individual current transformer 53 through which the branch electric wire 12c passes, an individual current transformer 54 through which the branch electric wire 13c passes, an individual current transformer 55 through which the branch electric wire 12d passes, an individual current transformer 56 through which the branch electric wire 13d passes, and a reference detection unit 24 that measures the voltage between the positive electrode wire 12 and the negative electrode wire 13. Each of the individual current transformers (individual measuring instruments) 51 to 56 is a measuring instrument made up of a ring-shaped current transformer through which the electric wire to be measured passes, and measures the value of the current flowing through the passed-through portion.

[0123] As explained in the first embodiment, a set of individual current transformers 21 and 22 constitutes a single measurement unit that can monitor (calculate) a leakage current within a predetermined range by summing up the currents A1 and A2 that are the measurement results of each. Furthermore, a set of individual current transformers 51 and 52, a set of individual current transformers 53 and 54, and a set of individual current transformers 55 and 56 each constitute a single measurement unit that can monitor (calculate) a leakage current within a predetermined range by summing up the currents that are the measurement results, similar to the set of individual current transformers 21 and 22.

[0124] The measurement unit using individual current transformers 21 and 22 can easily calculate the sum of leakage current value L1 occurring downstream of itself, which is leakage current value L2 to L4 occurring in each of load devices 15 to 17, and the value of leakage current occurring between individual current transformers 21 and 22 and individual current transformers 51 to 56. The measurement unit using individual current transformers 51 and 52 can calculate leakage current value L2 occurring downstream of itself, which is leakage current value L2 occurring in load device 15, without being affected by leakage current values ​​L3 and L4 of other load devices 16 and 17.

[0125] Similarly, the measurement unit using individual current transformers 53 and 54 can calculate leakage current value L3 occurring in load device 16 without being affected by leakage current values ​​L2 and L4. Furthermore, the measurement unit using individual current transformers 55 and 56 can calculate leakage current value L4 occurring in load device 17 without being affected by leakage current values ​​L2 and L3.

[0126] In this way, the leakage current measuring instrument 50 can calculate the leakage current values ​​L1 to L4 at a plurality of locations, and by comparing these values, it is possible to easily analyze the cause of the leakage current occurring in the vehicle 19. This analysis method will be described with reference to FIG.

[0127] Figure 9 is a graph showing the changes over time in leakage current values ​​L1 to L4. The vertical and horizontal axes of this graph are the same as those of the graph in Figure 2(b) described in the first embodiment. In the graph in Figure 9, the changes over time in leakage current value L1 are shown by a solid line, the changes over time in leakage current value L2 by a dashed line, the changes over time in leakage current value L3 by a dashed line, and the changes over time in leakage current value L4 by a dashed line. Furthermore, in this graph, the lines that actually overlap are shown slightly shifted from one another to make the graph easier to read.

[0128] According to the leftmost peak (part P5) of the graph in Fig. 9, the leakage current value L1 due to individual current transformers 21 and 22 and the leakage current value L2 due to individual current transformers 51 and 52 are the same, and the leakage current value L3 due to individual current transformers 53 and 54 and the leakage current value L4 due to individual current transformers 55 and 56 are 0 A. From this, it can be estimated that leakage current has occurred in vehicle 19 only downstream of individual current transformers 51 and 52 (at load device 15).

[0129] According to the peaks (part P6) in the center of the left and right of the graph in Fig. 9, leakage current L2 is 0 A, and the sum of leakage current L3 and L4 is equal to leakage current L1. From this, it is estimated that leakage current has occurred in vehicle 19 downstream of individual current transformers 53 and 54 (load device 16) and downstream of individual current transformers 55 and 56 (load device 17).

[0130] According to the rightmost peak (part P7) of the graph in Figure 9, leakage current L1 rises in two stages as it moves to the right. In the first stage, the sum of leakage current L2 and L3 is equal to leakage current L1, and leakage current L4 is 0 A. In the second stage, leakage current L2 and L3 remain unchanged from the first stage, but leakage current L4 rises. From this, it can be inferred that while leakage current was occurring in vehicle 19 downstream of individual current transformers 51 and 52 and downstream of individual current transformers 53 and 54, further leakage current began to occur downstream of individual current transformers 55 and 56.

[0131] Furthermore, not only when the sum of leakage current values ​​L2, L3, and L4 matches leakage current value L1, but also when they do not match, it is estimated that leakage current has occurred in vehicle 19 downstream of individual current transformers 21 and 22 and upstream of individual current transformers 51 to 56.

[0132] Next, the control device 60 constituting a part of the earth leakage monitoring device will be described in more detail with reference to Fig. 10. Fig. 10 is a block diagram showing the electrical configuration of a measurement object (vehicle 19) equipped with the control device 60. The control device 60 has a CPU 61, an HDD 62, and a RAM 63, which are each connected to an input / output port 65 via a bus line 64. The input / output port 65 is further connected to the battery 11, a cab 66, a traveling device 67, a position detection device 68, a speed sensor 69, a temperature sensor 70, a humidity sensor 71, an earth leakage meter 50, a forecast lamp 72, and an alarm lamp 73.

[0133] The CPU 61 is a computing device that controls each unit connected via a bus line 64. The HDD 62 is a rewritable non-volatile memory that stores programs executed by the CPU 61, various data, etc., and is provided with a control program 62a, a leakage data memory 62b, and an operating status memory 62c. Note that a storage device such as a flash ROM or SSD may be used instead of the HDD 62.

[0134] When the control program 62a is executed by the CPU 61, the main processing of Fig. 11 is executed. The earth leakage data memory 62b is a memory for storing each piece of data received from the earth leakage measuring instrument 50. The operating status memory 62c is a memory for storing operating status data, which will be described later.

[0135] The cab 66 is a device operated by an operator to operate the vehicle 19, and is located in the cab. The traveling device 67 is a device that causes the vehicle 19 to travel based on the operation of the cab 66. The cab 66 and the traveling device 67 correspond to part of the load devices 15 to 17.

[0136] The position detection device 68 is a device that detects the current position of the vehicle 19, and in this embodiment is configured with a GPS receiver that acquires the current position of the vehicle 19 using a GPS. The position detection device 68 is not limited to a GPS receiver, and it is of course possible to adopt other position detection devices. Examples of other position detection devices include a signal receiver that detects the position using a signal emitted from a signal device installed on the ground.

[0137] The speed sensor 69 is a sensor for detecting the traveling speed of the vehicle 19. The traveling speed of the vehicle 19 may be calculated from the position information of the position detection device 68, so that the position detection device 68 also functions as the speed sensor 69. The temperature sensor 70 is a sensor for detecting the temperature (air temperature) around the vehicle 19. The humidity sensor 71 is a sensor for detecting the humidity around the vehicle 19. The temperature sensor 70 and the humidity sensor 71 do not have to be mounted on the vehicle 19.

[0138] The forecast lamp 72 is a device that emits yellow light to advise a worker to perform maintenance on the vehicle 19. The warning lamp 73 is a device that emits red light to notify a worker that maintenance is required on the vehicle 19. The forecast lamp 72 and the warning lamp 73 are located in the driver's cab of the vehicle 19.

[0139] The earth leakage measuring instrument 50 of the second embodiment executes substantially the same processes as those of the first embodiment shown in FIGS. 4 to 7. The following describes in detail the processes of the earth leakage measuring instrument 50 that differ from those of the first embodiment. First, instead of the process of S13 in FIG. 4, the currents measured by the individual current transformers 51 to 56 are acquired. Instead of the processes of S18 and S19, the earth leakage values ​​L2 to L4 are calculated and stored in ring buffers individually provided for the earth leakage values ​​L2 to L4. In the process of S23, untransmitted data is transmitted to the control device 60 instead of the external control device 40.

[0140] Furthermore, in the processes of S48 and S51 in Fig. 5, in addition to the leakage values ​​L1 and L2 and the voltage V1, leakage values ​​L3 and L4 are also stored in the peak detection memory 26c. Instead of the process of S63 in Fig. 6, leakage values ​​L2 to L4 for the most recent minute are respectively averaged to calculate average values ​​M2 to M4, and the average values ​​M2 to M4 are stored in ring buffers individually provided for each of the average values ​​M2 to M4. In the processes of S66 and S69, in addition to the average values ​​M1 and M2 and the voltage V1, average values ​​M3 and M4 are also stored in the short-term change detection memory 26d or the long-term change detection memory 26e. In the process of S72 in Fig. 7, in addition to the leakage values ​​L1, L2 and the voltage V1, leakage values ​​L3 and L4 are also stored in the cycle collection memory 26f.

[0141] Next, the main processing executed by the CPU 61 of the control device 60 will be described with reference to Fig. 11. Fig. 11 is a flowchart of the main processing of the control device 60. The main processing of the control device 60 is executed when the control device 60 of the vehicle 19 is powered on.

[0142] 11, the main process first acquires various types of operating status data and stores them in the operating status memory 62c (S81). This operating status data includes the control status of the load devices 15 to 17 (the driver's cab 66 and the traveling device 67), the current position of the vehicle 19 detected by the position detection device 68, the traveling speed of the vehicle 19 detected by the speed sensor 69, the temperature detected by the temperature sensor 70, the humidity detected by the humidity sensor 71, and the time at which these were detected. Note that the operating status data is not limited to these data, and weather information and worker information acquired from external devices may also be used.

[0143] After the process of S81, the unreceived data stored in the peak detection memory 26c, short-term change detection memory 26d, long-term change detection memory 26e, and cycle collection memory 26f of the earth leakage measuring instrument 50 is acquired from the earth leakage measuring instrument 50 and stored in the earth leakage data memory 62b (S82). Note that this unreceived data is the data transmitted by the earth leakage measuring instrument 50 in the process of S23 in FIG. 4.

[0144] After the process of S82, the latest leakage value L1 is obtained from the leakage meter 50 to determine whether the forecast lamp 72 or the warning lamp 73 needs to be turned on (S83). Next, judgment values ​​a and b are set to be compared with the leakage value L1 (S84). The judgment value a is set to 0.8 mA, for example. The judgment value b is set to a value greater than the judgment value a, for example, 1 mA. Note that these judgment values ​​a and b may be changed as appropriate.

[0145] After the process of S84, the leakage current value L1 is compared with the determination values ​​a and b (S85). If the leakage current value L1 is less than the determination values ​​a and b (S85: less than a, b), the leakage current value L1 is sufficiently small and there is no need to turn on the forecast lamp 72 and the warning lamp 73, so other processing is executed (S88) and the processing from S81 onwards is repeated. Note that the processing of S88 may include various processing for operating the vehicle 19 and processing for changing the determination values ​​a and b set in the processing of S84.

[0146] In the process of S85, if the leakage value L1 is equal to or greater than the judgment value a but less than the judgment value b (S85: equal to or greater than a but less than b), the leakage value L1 is on the rise, so the warning lamp 72 is turned on (S86), and the process proceeds to S88. By turning on the warning lamp 72, the operator in the cab is advised to perform maintenance on the vehicle 19.

[0147] In the processing of S85, if the leakage value L1 is equal to or greater than the judgment values ​​a and b (S85: a and b or greater), there is a possibility that an abnormal leakage current is occurring in the vehicle 19, so the warning lamp 73 is turned on (S87) and the processing proceeds to S88. By turning on the warning lamp 73, the operator in the cab is notified that maintenance of the vehicle 19 is required.

[0148] When the warning lamp 73 lights up, for example, some functions of the vehicle 19 may be restricted or the power to the vehicle 19 may be disabled. This prevents the vehicle 19 from breaking down and becoming immobile due to leakage current while traveling or during work.

[0149] As described above, the leakage current monitoring device configured by the control device 60 and the leakage current measuring instrument 50 can monitor the leakage current value L1 to notify the operator of the timing of maintenance of the vehicle 19 or of any abnormalities in the vehicle 19, thereby enabling the safe operation of the vehicle 19. When performing maintenance on the vehicle 19, the leakage current values ​​L1 to L4 and the voltage V1, which are associated with each other and stored in the leakage current data memory 62b, can be analyzed by an external device or the like to easily identify the cause of the leakage current.

[0150] Furthermore, the leakage current values ​​L1-L4 and voltage V1 stored in leakage data memory 62b and the operating status data stored in operating status memory 62c are correlated by time. By analyzing these data using an external device, it becomes easier to identify the cause of the leakage current. For example, if leakage current value L1 becomes equal to or exceeds threshold values ​​a and b only when the brakes are applied, it can be assumed that there is an abnormality in the brake-related electrical circuit.

[0151] The operating condition data also includes the temperature and humidity outside the vehicle 19. The insulation resistance values ​​of various parts of the vehicle 19 vary depending on the temperature and humidity, and the leakage current values ​​L1 to L4, which depend on the insulation resistance values, also vary depending on the temperature and humidity. Therefore, by comparing the temperature and humidity with the leakage current values ​​L1 to L4, it is possible to estimate whether the fluctuations in the leakage current values ​​L1 to L4 are due to the temperature and humidity or other changes.

[0152] Next, a third embodiment will be described with reference to Fig. 12. In the first embodiment, a leakage current measuring instrument 20 (leakage monitoring device) that monitors leakage current in a measurement object 10 equipped with a load device 14 that operates on DC power was described. In contrast, in the third embodiment, a leakage current measuring instrument 90 (leakage monitoring device) that monitors leakage current in a measurement object 80 equipped with a load device 85 that operates on AC power will be described. Note that parts that are the same as those in the first and second embodiments are given the same reference numerals, and the following description will be omitted.

[0153] 12 is a circuit diagram that schematically shows an electric circuit of a leakage measuring instrument 90 as a leakage monitoring device in the third embodiment and a measurement object 80. The measurement object 80 includes an AC power supply 81 that outputs three-phase AC power (power for a load), a set of three power lines 82, 83, and 84 that are connected to the AC power supply 81, and a load device 85 that is connected to the power lines 82 to 84.

[0154] The AC power supply 81 is a three-phase, four-wire generator that supplies three-phase AC power to power lines 82 to 84. A neutral line 81a extending from the neutral point of the AC power supply 81 is grounded. Single-phase AC currents with the same voltage but shifted in phase by 120° relative to the neutral line 81a flow through the power lines 82 to 84. Therefore, if no leakage current is occurring in the measurement object 80, the total current through the power lines 82 to 84 will basically be approximately 0 A.

[0155] The load device 85 is an electric circuit that operates by three-phase AC power supplied from the AC power source 81 via the power lines 82 to 84. Examples of the load device 85 include a three-phase motor and a converter. The load device 85 is housed in a housing 85a that is grounded via the ground line 18. For example, if a leakage current occurs between the load device 85 and the housing 85a, the leakage current passes through the ground line 18 and the neutral line 81a, and the total current passing through the power lines 82 to 84 becomes unbalanced by the amount of the leakage current.

[0156] The earth leakage measuring instrument 90 is a device for monitoring this leakage current. The earth leakage measuring instrument 90 includes three individual current transformers 91, 92, and 93 through which each of the three power supply wires 82 to 84 passes, and a ground-side current transformer 94 through which the ground wire 18 passes.

[0157] Each of the individual current transformers (individual measuring instruments) 91 to 93 and the ground side current transformer (ground side measuring instrument) 94 is a measuring instrument configured as a ring-shaped current transformer through which the electric wire to be measured passes, and measures the value of the current flowing through the passed-through part. The individual current transformers 91 to 93 and the ground side current transformer 94 in this embodiment are configured to be able to measure the value of AC current, but since their configuration is known, a description thereof will be omitted.

[0158] As in the first and second embodiments, a set of the individual current transformers 91-93 constitutes a single measurement unit that can monitor (calculate) a predetermined range of leakage current by summing up the currents that are the measurement results of each. Specifically, the measurement unit made up of the individual current transformers 91-93 can calculate the value of the leakage current (leakage value L1) that occurs downstream of itself (on the load device 85 side). In contrast, the ground-side current transformer 94 is a measurement unit that directly monitors (measures) the value of the leakage current that passes through the ground wire 18.

[0159] In this way, the leakage current measuring instrument 90 can easily analyze the cause of leakage current in the measurement object 80 by comparing the leakage current value from the individual current transformers 91-93 with the leakage current value from the ground-side current transformer 94. For example, if the leakage current value from the individual current transformers 91-93 and the leakage current value from the ground-side current transformer 94 are the same, it can be inferred that leakage current is occurring mainly between the load device 85 and the housing 85a, and that the insulation resistance between them has deteriorated. Furthermore, if the leakage current value from the individual current transformers 91-93 and the leakage current value from the ground-side current transformer 94 are different, it can be inferred that leakage current is occurring somewhere other than between the load device 85 and the housing 85a.

[0160] Next, a fourth embodiment will be described with reference to Fig. 13. In the first to third embodiments, leakage meters 20, 50, 90 (leakage monitoring devices) were described that calculate leakage current from the sum of currents flowing through a set of multiple power lines (a set of two positive and negative lines 12 and 13, or a set of three power lines 82-84). In contrast, in the fourth embodiment, a leakage measurement device 100 (leakage monitoring device) will be described that calculates leakage current by comparing the currents on the upstream and downstream sides of one power line 82 of a set of power lines 82-84. Note that the same parts as in the first to third embodiments are given the same reference numerals, and the following description will be omitted.

[0161] 13 is a circuit diagram that schematically shows an electric circuit of a leakage current measuring instrument 100 as a leakage current monitoring device in the fourth embodiment and an object to be measured 80. The leakage current measuring instrument 100 includes an upstream current transformer 101 through which one power line 82 passes, and a downstream current transformer 102 through which the power line 82 passes on the downstream side of the upstream current transformer 101. Both the upstream current transformer (upstream measuring instrument) 101 and the downstream current transformer (downstream measuring instrument) 102 are measuring instruments formed from annular current transformers through which the electric wire to be measured passes, and measure the value of the current flowing through the passed portion.

[0162] The current measured by the upstream current transformer 101 is compared with the current measured by the downstream current transformer 102, and if there is no difference between them, it can be determined that no leakage current has occurred between the upstream current transformer 101 and the downstream current transformer 102. On the other hand, if there is a difference between the currents measured by the upstream current transformer 101 and the downstream current transformer 102, it can be determined that a leakage current has occurred between the upstream current transformer 101 and the downstream current transformer 102.

[0163] In this way, the earth leakage measuring instrument 100 can monitor leakage current without measuring the current in each of the three power lines 82 to 84, thereby broadening the scope of objects that can be monitored for leakage current. In particular, the earth leakage measuring instrument 100 can monitor leakage current occurring in one power line 82 without being affected by leakage current occurring between the load device 85 and the housing 85a. As a result, for example, by combining the earth leakage measuring instrument 100 with the earth leakage measuring instrument 90 of the third embodiment, it becomes easier to analyze the cause of leakage current occurring in the object under measurement 80 by comparing the measurement results of each.

[0164] Although the present invention has been described above based on the embodiments, it is not limited to the above-described embodiments, and it is easily conceivable that various improvements and modifications are possible without departing from the spirit of the present invention. For example, the voltage output from the battery 11 or the AC power supply 81 may be changed as appropriate, the battery 11 may be replaced with a DC power supply such as a DC generator or converter, and the AC power supply 81 may be replaced with an inverter or a transformer. Furthermore, the power line or electric wire in this specification is not limited to a flexible linear conductor, but may also be a rod-shaped or plate-shaped conductor such as a bus bar (copper bar), or a combination of these conductors.

[0165] In addition, the intervals at which currents A1, A2, etc. are acquired (the intervals at which the main process is executed), the intervals at which operating state data is acquired, the intervals at which average values ​​M1, M2, etc. of leakage current values ​​L1, L2 are calculated, the ranges of currents A1, A2 used to calculate the average values ​​M1, M2, the storage capacities of each ring buffer 27a-27e, and the ranges stored in peak detection memory 26c when leakage current value L1, etc. exceeds a threshold may be changed as appropriate. Furthermore, the average value M1 before change used to calculate the short-term and long-term change rates in average detection process S21 of FIG. 6 may be changed as appropriate. Specifically, for example, the rate of change of the average value M1 for the most recent minute relative to the average value M1 from 5 to 4 minutes ago (the average value of multiple leakage current values ​​L1 calculated from 5 to 4 minutes ago) may be used as the short-term and long-term change rates.

[0166] Some of the configurations of the above embodiments may be combined with each other, or some of the configurations may be omitted. For example, the measurement unit using the zero-phase-sequence current transformer 23 in the first embodiment may be replaced with at least one of the measurement units using the individual current transformers 21, 22, and 51-56 in the second embodiment, or with the measurement unit using the individual current transformers 91-93 in the third embodiment. Furthermore, the measurement unit using the individual current transformers 21 and 22 in the first embodiment may be replaced with the measurement unit using the zero-phase-sequence current transformer 23, or the measurement unit using the zero-phase-sequence current transformer 23 in the first embodiment may be replaced with the measurement unit using the individual current transformers 21 and 22.

[0167] Furthermore, the measurement unit using the ground-side current transformer 94 in the third embodiment may be provided in the earth leakage measuring devices 20, 50, and 100 of the first, second, and fourth embodiments. Furthermore, one or more of the measurement units in each embodiment may be omitted, or the number of measurement units may be increased. Furthermore, the set of power lines 82-84 in the third and fourth embodiments may be branched into multiple sets on the downstream side as in the second embodiment, and the measurement unit may be provided on at least one of the upstream and downstream sides of the branch.

[0168] In the first, third and fourth embodiments, the earth leakage measuring instruments 20, 90 and 100 are earth leakage monitoring devices, and in the second embodiment, an earth leakage monitoring device is configured by the earth leakage measuring instrument 50 and the control device 60. However, this is not limited to this, and an earth leakage monitoring device may be configured by combining some or all of the earth leakage measuring instruments 20, 50, 90 and 100, or by further combining these with the control device 60, external control device 40, etc.

[0169] In the third embodiment, the leakage current of the measurement object 80 equipped with the AC power supply 81 that outputs three-phase AC power is monitored by the leakage current meter 90, but this is not limiting. The AC power supply 81 may be replaced with a power supply that outputs single-phase AC power. In this case, the power supply line 84 and the individual current transformer 93 may be omitted, and the sum of the currents measured by the two individual current transformers 91 and 92 may be used as the value of the leakage current.

[0170] Furthermore, in a three-phase, four-wire system, single-phase AC power may be supplied to a single-phase AC device from, for example, power line 82 and neutral line 81a. In this case, the leakage current value can be calculated by summing the currents of individual current transformer 91 of power line 82 and the individual current transformer through which neutral line 81a passes. Also, neutral line 81a may be omitted, and AC power supply 81 may be a three-phase, three-wire power supply. In this case, it is preferable to ground any one of power lines 82 to 84 upstream of individual current transformers 91 to 93.

[0171] In the third and fourth embodiments, the earth leakage measuring instruments 90, 100 are described as not having the reference detection unit 24 that measures the voltage V1, but this is not limited to this. For example, the earth leakage measuring instruments 90, 100 may be provided with a reference detection unit that detects voltage cross points between the phases of the power lines 82 to 84 through which three-phase AC flows, and the leakage current may be corrected based on the measurement results of the reference detection unit.

[0172] Specifically, in the leakage current measuring instrument 90, the leakage current Igr may be calculated as the corrected leakage current from the sum of the currents from the individual current transformers 91-93 and the cross point of the voltages detected by the reference detection unit. A known method may be used to calculate the leakage current Igr, such as the method disclosed in Japanese Patent No. 4945727. The leakage current generated in the measurement object 80 through which AC flows includes the leakage current Igc due to capacitance to the ground and the leakage current Igr due to insulation resistance to the ground.

[0173] The reference detection unit 24 of the earth leakage measuring instruments 20, 50 in the first and second embodiments may be omitted, and the sum of the currents A1, A2 may be used as the earth leakage value L1. In addition, when the reference detection unit 24 is provided, it is not limited to being built into the earth leakage measuring instruments 20, 50. If a voltmeter for measuring the voltage of the battery 11 or the like is mounted on the measurement object 10 or the like, the voltmeter may be used as the reference detection unit 24.

[0174] In the above embodiment, the earth leakage measuring instruments 20, 50, 90 calculate the earth leakage values ​​L1 to L4 by summing the currents A1, A2, etc. measured by the individual current transformers 21, 22, 51 to 56, 91 to 93, but this is not limiting. For example, the earth leakage measuring instruments 20, 50, 90 may not calculate the earth leakage values ​​L1 to L4, but the external control device 40 or the control device 60 may calculate the earth leakage values ​​L1 to L4. That is, the earth leakage measuring instruments 20, 50, 90 may be configured to transmit the measurement results of the individual current transformers 21, 22, 51 to 56, 91 to 93, the zero-phase current transformer 23, the ground-side current transformer 94, and the reference detection unit 24 directly to the external control device 40 or the control device 60. Analysis using the earth leakage values ​​L1 to L4 and the voltage V1 may be performed by the earth leakage measuring instruments 20, 50, 90 instead of the external control device 40, etc.

[0175] Furthermore, the leakage data memory 62b and the operating state memory 62c may be provided in the leakage measuring instrument 50, and the processes of S81 to S87 of the main process of the control device 60 shown in Fig. 11 may be executed by the leakage measuring instrument 50. In this case, the leakage data memory 62b may be omitted, and the data capacities of the peak detection memory 26c, the short-term change detection memory 26d, the long-term change detection memory 26e, and the cycle collection memory 26f may be increased. Furthermore, these memories 26c to 26f may be combined into a single memory.

[0176] Furthermore, the data stored in the leakage data memory 62b and the operating status memory 62c may be transmitted from the control device 60 of the vehicle 19, which is the object to be measured, to an external control device provided outside the vehicle 19, and the processes of S83 to S87 may be executed by the external control device. In this case, instead of lighting up the forecast lamp 72 and the alarm lamp 73, a message may be displayed on the display device of the external control device, advising that maintenance of the vehicle 19 be performed.

[0177] Furthermore, in the first, third, and fourth embodiments, operating status data similar to that of the second embodiment may be acquired by leakage current measuring instruments 20, 90, 100 or external control devices 40, etc., and the operating status data may be used to analyze the cause of leakage current in the measurement object 10, 80.

[0178] In the above embodiment, the memories 26c to 26f that store data permitted to be transmitted to the external control device 40 store the leakage current values ​​L1 and L2 themselves as data related to the leakage current values ​​L1 and L2 (the sum of the currents A1 and A2, the total current A3), or store average values ​​M1 and M2 obtained by averaging a plurality of leakage current values ​​L1 and L2, respectively. However, the present invention is not limited to this. The currents A1 and A2 and the total current A3 may be stored in the memories 26c to 26f as data related to the leakage current values ​​L1 and L2, and the currents A1 and A2 and the total current A3 selected based on the leakage current values ​​L1 and L2 may be transmitted to the external control device 40.

[0179] In the above embodiment, the case where data permitted to be transmitted to the external control device 40 is temporarily stored in each of the memories 26c to 26f has been described, but this is not limiting. Data permitted to be transmitted may be transmitted directly to the external control device 40 without being stored in each of the memories 26c to 26f. This can be done when the earth leakage measuring instrument 20 and the external control device 40 are capable of communicating with each other; when communication between them is not possible, temporary storage in each of the memories 26c to 26f is required.

[0180] In the above embodiment, the currents A1, A2, etc. measured by the individual current transformers 21, 22 are digitized and acquired by the CPU 25 of the earth leakage measuring instrument 20, but this is not limited to this. For example, the measured currents A1, A2 may be summed as analog signals, and the sum may be digitized and acquired by the CPU 25. When the measurement results of the individual current transformers 21, 22, 51 to 56, 91 to 93, the zero-phase current transformer 23, the ground-side current transformer 94, and the reference detection unit 24 are digitized, the digitizing converters may communicate wirelessly with the input / output port 29.

[0181] In the above embodiment, the case where the earth leakage measuring instrument 20 executes the peak detection process S20, the average detection process S21, and the cycle collection process S22 has been described, but this is not limiting. For example, it is possible to execute at least one of the peak detection process S20, the average detection process S21, and the cycle collection process S22, without executing the other processes.

[0182] In the above embodiment, the case where the leakage current value L1 from the start position S to the end position E is stored in the peak detection memory 26c in the peak detection process S20 has been described, but this is not limited to this. For example, when the leakage current value L1 at the latest position of the upstream ring buffer 27a changes from below the threshold to equal to or greater than the threshold, the leakage current value L1 from 15 seconds before to the latest position may be stored in the peak detection memory 26c, and a newly calculated leakage current value L1 at the latest position may be stored in the peak detection memory 26c in each peak detection process S20 until 15 seconds have elapsed since the leakage current value L1 changed from equal to or greater than the threshold to less than the threshold.

[0183] In the above embodiment, the leakage value L2 is stored in the peak detection memory 26c along with the leakage value L1 in the processes of S48 and S51 of the peak detection process S20, but this is not limited to this. The leakage value L2 may not be stored in the processes of S48 and S51. In this case, the peak detection process for the leakage value L2 is performed separately from the peak detection process S20 for the leakage value L1. In the peak detection process for the leakage value L2, the leakage value L1 in the processes of S41 to S51 is replaced with the leakage value L2, and the upstream ring buffer 27a is replaced with the downstream ring buffer 27b. The same applies to the average detection process S21. In the average detection process S21 for the leakage value L2, the average value M1 in the processes of S64 to S69 is replaced with the average value M2.

[0184] In the first embodiment, a leakage current detection method has been described that includes individual measurement steps (processing of S11 and S12) in which currents A1 and A2 are measured individually by individual current transformers 21 and 22, a summing step (part of the processing of S16) in which the multiple currents A1 and A2 measured in the individual measurement steps are summed, and a detection step (e.g., part of the processing of S16) in which leakage current L1 of measurement object 10 is detected based on the current "A1+A2" summed in the summing step. This method is also applicable to the second and third embodiments as described above.

[0185] In the individual measurement step, for example, individual current transformer 22 may be omitted, and after measuring current A1 of positive electrode line 12 with individual current transformer 21, negative electrode line 13 may be passed through individual current transformer 21, which has been disconnected from positive electrode line 12, and current A2 of negative electrode line 13 may be measured with individual current transformer 21. Similarly, individual current transformer 21 may be omitted, and currents A1 and A2 may be measured individually with individual current transformer 22. Furthermore, the measurement points by individual current transformers 51 to 56 and 91 to 93 may each be measured in sequence with one individual current transformer. In addition, in the detection step, for example, the sum of currents "A1 + A2" may be detected as leakage current L1.

[0186] In contrast to the leakage current detection methods of the first to third embodiments, the fourth embodiment described above is a leakage current detection method that includes a measurement step in which the upstream current transformer 101 and the downstream current transformer 102 individually measure the currents flowing at two locations on the power line 82, a difference step in which the difference between the currents at the two locations measured in the measurement step is calculated, and a detection step in which the leakage current of the object to be measured 80 is detected based on the difference in current calculated in the difference step.

[0187] In this measurement step, for example, the downstream current transformer 102 may be omitted, and after measuring the current on the upstream side of the power line 82 with the upstream current transformer 101, the moved upstream current transformer 101 may measure the current on the downstream side of the power line 82. Similarly, the upstream current transformer 101 may be omitted, and the downstream current transformer 102 may measure the currents at two locations on the power line 82 individually. In addition, in the detection step in the fourth embodiment, the difference in current calculated in the difference step is detected as the leakage current as is, but the current difference may be corrected by the voltage of the power line 82 or the like to detect the leakage current value.

[0188] In the above embodiment, the individual current transformers 21, 22, 51-56, 91-93, the zero-phase current transformer 23, the grounding-side current transformer 94, the upstream current transformer 101, and the downstream current transformer 102 are each configured as annular current transformers through which the electric wire to be measured passes, and are used as measuring instruments to measure the value of the current flowing through the passed-through portion. However, these current transformers may be replaced with other measuring instruments capable of measuring the value of the current flowing through the electric wire to be measured. An example of such other measuring instruments is a non-annular measuring instrument that measures the magnetic field generated in the electric wire when current is passed through it and measures the value of the current based on that magnetic field. Another example of such other measuring instruments is limited to those that individually measure the current in a single electric wire, but may be one that uses a shunt resistor. <Other> <Means> The leakage current monitoring device of technical idea 1 monitors the leakage current of a measurement object that includes a set of multiple power lines that supplies load power from upstream to downstream and a load device that operates using the load power supplied from the set of power lines, and is equipped with one or more measuring units that can monitor the leakage current that occurs within a specified range of the measurement object, and one of the measuring units is formed by a set of multiple individual measuring instruments that individually measure the current flowing through each of the set of multiple power lines. The leakage current monitoring device of technical idea 2 is the leakage current monitoring device of technical idea 1, and is equipped with a reference detection unit that measures the voltage occurring between a set of the power supply lines at the measurement position of a set of the individual measuring instruments, and a reference correlation means that correlates the voltage measured by the reference detection unit with the current measured by the individual measuring instruments at the time of measurement. The leakage current monitoring device of technical idea 3 is the leakage current monitoring device of technical idea 1, and is equipped with an acquisition means for acquiring the operating state of the load equipment, and a state association means for associating the operating state acquired by the acquisition means with the current measured by the individual measuring instrument at the time of acquisition. The leakage current monitoring device of Technical Idea 4 is the leakage current monitoring device of Technical Idea 1, and is equipped with a memory unit capable of storing data relating to the total current measured by a set of individual measuring instruments, a sum calculation means for calculating the total current, a memory judgment means for determining whether to store the data relating to the total in the memory unit based on the total calculated by the sum calculation means, and a memory execution means for storing the data in the memory unit when the memory judgment means determines that the data should be stored. The leakage current monitoring device of technical idea 5 is the leakage current monitoring device of technical idea 1, in which two or more measuring units are provided separately on the upstream and downstream sides of a set of power lines, and each unit monitors the leakage current generated in the measurement object downstream of the position where it is placed. The leakage current monitoring device of Technical Idea 6 is the leakage current monitoring device of Technical Idea 5, in which one of the measuring units is formed by a zero-phase measuring instrument that collectively measures the magnetic fields generated in each of multiple power lines of a set when current is passed through them, and measures the total current flowing through those power lines based on the magnetic fields. The leakage current monitoring device of Technical Idea 7 is a leakage current monitoring device of Technical Idea 5 or 6, in which the set of power lines comprises a main electric wire set on the upstream side and multiple sets of branch electric wires branching off from the main electric wire set, and multiple load devices are provided, each connected to one set of the branch electric wires, and the measuring unit is arranged in one set of the main electric wires upstream of the multiple sets of branch electric wires, and a different measuring unit is arranged in one set of the branch electric wires. The leakage current monitoring device of Technical Idea 8 is the leakage current monitoring device of Technical Idea 1, in which the object to be measured comprises a housing in which the load equipment is housed and a grounding wire that grounds the housing, and two or more measuring units are provided, one of which is formed by a grounding side measuring instrument that measures the current flowing through the grounding wire. The leakage current monitoring device of Technical Idea 9 monitors the leakage current of a measurement object that includes a set of multiple power lines that supply load power from upstream to downstream and a load device that operates using the load power supplied from the set of power lines, and includes an upstream measuring instrument that measures the current flowing through one of the power lines, and a downstream measuring instrument that measures the current flowing through the power line whose current is measured by the upstream measuring instrument, downstream of the measurement position of the upstream measuring instrument. The leakage current detection method of technical idea 10 is a method for detecting leakage current in a measurement object that includes a set of multiple power lines that supply load power from upstream to downstream and a load device that operates using the load power supplied from the set of power lines, and includes an individual measurement step in which the current flowing through each of the set of multiple power lines is measured individually using a measuring instrument, a summation step in which the multiple currents measured individually in the individual measurement step are summed, and a detection step in which the leakage current in the measurement object is detected based on the current summed in the summation step. The leakage current detection method of technical idea 11 is a method for detecting leakage current in a measurement object that includes a set of multiple power lines that supply load power from upstream to downstream and a load device that operates using the load power supplied from the set of power lines, and includes a measurement step in which the currents flowing at two different points on one of the power lines are measured individually using a measuring instrument, a difference step in which the difference between the currents at the two points measured in the measurement step is calculated, and a detection step in which the leakage current in the measurement object is detected based on the difference in current calculated in the difference step. <Effects> The leakage current monitoring device of Technical Idea 1 uses one or more measuring units to monitor leakage current occurring within a predetermined range of a measurement object that operates a load device using load power supplied from a set of multiple power lines. One of the measuring units is formed by a set of multiple individual measuring instruments. This set of individual measuring instruments individually measures the current flowing through each of the set of multiple power lines of the measurement object. For example, if there is no leakage current in the object being measured, basically all of the current that passes through one part of a set of power lines toward the load equipment will return upstream from the load equipment through another part of the set of power lines, so the total current measured by one set of individual measuring instruments (the total current flowing through one set of power lines) will be approximately 0 A. Note that the "total current measured by one set of individual measuring instruments" is the sum of the current flowing upstream, which is a positive value, and the current flowing downstream, which is a negative value. On the other hand, as with conventional technology, if a leakage current occurs downstream of the measurement position of an individual meter (the position where the current is measured by the individual meter), the sum of the currents measured by a set of individual metering devices indicates the value of that leakage current. In this way, the leakage current monitoring device can monitor leakage currents occurring downstream of the measurement position of the individual metering devices using a set of individual metering devices (measurement unit). In particular, with the leakage current monitoring device of the present invention, the current flowing through each of a pair of power lines is measured individually by individual measuring instruments, so that even if the power lines are separated from each other, the total current flowing through the pair of power lines can be calculated and leakage current can be monitored. As a result, the leakage current monitoring target can be expanded. The leakage current monitoring device of Technical Idea 2 achieves the following effect in addition to the effect achieved by the leakage current monitoring device of Technical Idea 1. When the sum of the currents measured by a set of individual measuring instruments is calculated as the leakage current, this sum is affected by the voltage occurring between the set of power lines at the measurement positions of the individual measuring instruments. Therefore, this voltage is measured by a reference detection unit. Furthermore, this measured voltage is related to the current measured by the individual measuring instruments at the time of measurement by a reference correlation means. This makes it possible to calculate the value of the leakage current by correcting the sum of the currents measured by the set of individual measuring instruments based on the voltage, thereby widening the range in which leakage current detection accuracy can be ensured. Note that associating "A" (e.g., the total current measured by a set of individual measuring devices) with "B" (e.g., the voltage measured by a reference detection unit) means, for example, storing "A" and "B" in the same memory in a mutually associated state, or storing "A" and "B" in separate memories and associating them based on the measurement dates and times of "A" and "B." Furthermore, calculating a specific value using "A" and "B" may also be referred to as associating "B" with "A." Furthermore, "B" is not limited to associating "A" itself, but may also be associated with a value calculated using "A." The leakage current monitoring device of Technical Idea 3 achieves the following effect in addition to the effect achieved by the leakage current monitoring device of Technical Idea 1. The operating state of the load equipment (such as the control state of the load equipment, the time, the outside temperature, and humidity) is acquired by an acquisition means. Furthermore, this acquired operating state is associated by a state association means with the current measured by the individual measuring instruments at the time of acquisition. As a result, for example, if the value of the leakage current calculated from the sum of the currents measured by a set of individual measuring instruments becomes large only in a specific operating state, it can be assumed that a leakage current is occurring in the part through which current flows in that specific operating state. This makes it easier to analyze the cause of the leakage current. The earth leakage monitoring device of Technical Idea 4 achieves the following effect in addition to the effect achieved by the earth leakage monitoring device of Technical Idea 1. The total calculation means calculates the total of the currents measured by a set of individual meters. The memory determination means determines whether to store data related to the total in the memory unit based on the total calculated by the total calculation means. If the memory determination means determines to store the data, the memory execution means stores the data related to the total in the memory unit. This makes it possible, for example, to select data from the data related to the total that is effective for analyzing leakage current and store it in the memory unit, thereby reducing the amount of data stored in the memory unit per given time, making it easier to make the earth leakage monitoring device smaller and reduce costs. Note that data relating to "X" (e.g., the total current measured by a set of individual measuring devices) may be the data for "X" itself, data for calculating "X" (e.g., the current measured by each individual measuring device), or data for a value calculated using "X" (e.g., the average value obtained by averaging multiple totals). The leakage current monitoring device of Technical Idea 5 achieves the following effect in addition to the effect achieved by the leakage current monitoring device of Technical Idea 1. Two or more measurement units are provided at a distance from each other on the upstream and downstream sides of a pair of power lines, and each monitors the leakage current occurring in the measurement object downstream of its location. This makes it possible to measure the leakage current occurring between the upstream measurement unit and the downstream measurement unit, for example, from the difference in measurement results between the upstream measurement unit and the downstream measurement unit. This makes it easier to analyze the cause of the leakage current. The leakage current monitoring device of Technical Idea 6 achieves the following effect in addition to the effect achieved by the leakage current monitoring device of Technical Idea 5. One of the measurement units is formed by a zero-phase meter that collectively measures the magnetic fields generated in each of multiple power lines in a set when current is passed through them, and measures the total current flowing through those power lines based on that magnetic field. This makes it possible to measure the total current at a location where, for example, each of a set of power lines is bundled together, making it difficult to measure the current using individual meters, using the zero-phase meter. As a result, the degree of freedom in arranging the measurement unit can be improved, making it easier to analyze the cause of leakage current. The leakage current monitoring device of Technical Idea 7 achieves the following effects in addition to the effects achieved by the leakage current monitoring device of Technical Ideas 5 or 6. A set of power lines includes an upstream main line and multiple sets of branch lines branching off from the main line. Multiple load devices are connected to each set of branch lines. A measurement unit located on the main line upstream of the multiple sets of branch lines can easily monitor (measure or calculate) the total leakage current of the load devices connected to the multiple sets of branch lines. Furthermore, because a separate measurement unit is located on a set of branch lines, the leakage current of the load devices connected to that set of branch lines can be monitored without being affected by the leakage current of the load devices connected to the other branch lines. Furthermore, by comparing the measurement results of the measurement unit on the main line side and the measurement unit on the branch lines side, it becomes easier to analyze the cause of the leakage current. The leakage current monitoring device of Technical Idea 8 achieves the following effects in addition to the effects achieved by the leakage current monitoring device of Technical Idea 1. The object to be measured comprises a housing that houses a load device and a ground wire that grounds the housing. One of the two or more measurement units is formed by a ground-side measuring instrument that measures the current flowing through the ground wire. This ground-side measuring instrument can measure the leakage current that occurs between the load device and the housing. By comparing this measurement result with the measurement result from a set of individual measuring instruments (leakage current that occurs downstream from the measurement position of the individual measuring instruments), it becomes easier to analyze the cause of the leakage current. The leakage current monitoring device of Technical Idea 9 monitors the leakage current of a measurement object that operates a load device using load power supplied from a set of multiple power lines. An upstream measuring instrument measures the current flowing through one of the set of multiple power lines. Furthermore, a downstream measuring instrument measures the current flowing through the power line downstream of the upstream measuring instrument's measurement position. If there is a difference between the measurement results of the upstream measuring instrument and the downstream measuring instrument, it can be determined that a leakage current has occurred between them. In this way, the leakage current monitoring device can monitor leakage current without measuring the current of each of the set of multiple power lines, thereby broadening the scope of objects that can be monitored for leakage current. According to the leakage current detection method of Technical Idea 10, similar to the effect achieved by the leakage current monitoring device of Technical Idea 1, by individually measuring the current flowing through a set of multiple power lines, the leakage current of the object being measured can be detected based on the sum of those currents, thereby expanding the range of objects that can be monitored for leakage current. According to the leakage current detection method of technical idea 11, similar to the effect achieved by the leakage current monitoring device of technical idea 9, it is possible to detect the leakage current of the object to be measured without measuring the current of each of a set of multiple power lines, thereby expanding the range of objects that can be monitored for leakage current. [Explanation of symbols]

[0189] 10,80 Measurement object 12 Positive wire (power wire) 12a,13a Main power line 12b~12d, 13b~13d Branch wires 13 Negative wire (power line) 14~17,85 Load equipment 14a~17a,85a enclosure 18 Ground wire 19 Vehicle (measurement object) 20, 90, 100 Leakage current measuring instrument (leakage current monitoring device) 21, 22, 51-56, 91-93 Individual current transformers (measuring section, individual measuring instrument) 23 Zero-phase current transformer (measurement section, zero-phase measuring instrument)) 50 Leakage current measuring instrument (part of leakage current monitoring device) 60 Control device (part of earth leakage monitoring device) 82~84 Power line 94 Ground side current transformer (measurement section, ground side measuring instrument) 101 Upstream current transformer (upstream measuring instrument) 102 Downstream current transformer (downstream measuring instrument )

Claims

1. A leakage current monitoring device for monitoring a leakage current of a measurement object, the measurement object including a set of power lines that supplies load power from upstream to downstream, and a load device that operates using the load power supplied from the set of power lines, two or more measuring units provided separately on the upstream side and downstream side of one set of the power supply lines, respectively, and capable of monitoring leakage current occurring in the measurement object downstream of the respective positions where the measuring units are provided; A leakage current monitoring device characterized in that one of the measuring units is formed by a set of multiple individual measuring instruments that individually measure the current flowing through each of the set of multiple power lines.

2. 2. The leakage current monitoring device according to claim 1, wherein one of the measuring units is formed by a zero-phase measuring instrument that collectively measures the magnetic fields generated in each of a set of power lines when current is passed through them, and measures the total current flowing through those power lines based on the magnetic fields.

3. The set of power lines includes: One upstream pair of main conductors; a plurality of sets of branch electric wires each branching off from the one set of trunk electric wires; a plurality of the load devices are provided, each connected to one of the sets of branch electric wires; The leakage current monitoring device according to claim 1 or 2, characterized in that the measuring unit is arranged in one set of the main electric wire upstream of the plurality of sets of the branch electric wires, and another measuring unit is arranged in one set of the branch electric wires.

4. A leakage current monitoring device for monitoring leakage current of a measurement object, the device comprising: a set of power lines for supplying load power from upstream to downstream; a load device that operates with the load power supplied from the set of power lines; a housing that houses the load device; and a grounding wire that grounds the housing, two or more measuring units capable of monitoring leakage current occurring within a predetermined range of the measurement object; One of the measuring units is formed by a set of a plurality of individual measuring devices that individually measure the current flowing through each of the set of a plurality of power supply lines, A leakage current monitoring device characterized in that one of the measuring units is formed by a ground side measuring instrument that measures the current flowing through the ground wire.

5. A leakage current monitoring device for monitoring a leakage current of a measurement object, the measurement object including a set of power lines that supplies load power from upstream to downstream, and a load device that operates using the load power supplied from the set of power lines, an upstream measuring instrument that measures a current flowing through one of the power supply lines; A leakage current monitoring device characterized by comprising: a downstream meter that measures the current flowing through the power line downstream of the measurement position of the upstream meter on the power line whose current is measured by the upstream meter.

6. A leakage current detection method for detecting a leakage current in a measurement object that includes a set of multiple power lines that supplies load power from upstream to downstream, and a load device that operates using the load power supplied from the set of power lines, comprising: an individual measuring step of measuring the current flowing through each of the plurality of power supply lines in the set by an individual measuring device; a summing step of summing the multiple currents individually measured in the individual measurement steps; a first detection step of detecting a leakage current occurring in the measurement object downstream of the position where the individual measuring device is disposed, based on the current summed in the summing step; a second detection step of detecting a leakage current occurring in the object to be measured downstream of a measurement unit provided on one set of the power lines at a position upstream or downstream of the position where the individual measuring devices are arranged; A leakage current detection method comprising:

7. A leakage current detection method for detecting a leakage current in a measurement object comprising a set of multiple power lines that supply load power from upstream to downstream, a load device that operates with the load power supplied from the set of power lines, a housing that houses the load device, and a ground wire that grounds the housing, comprising: an individual measuring step of measuring the current flowing through each of the plurality of power supply lines in the set by an individual measuring device; a summing step of summing the multiple currents individually measured in the individual measurement steps; a detection step of detecting a leakage current of the measurement object based on the current summed in the summing step; a ground-side measuring step of measuring the current flowing through the ground wire by a ground-side measuring instrument; A leakage current detection method comprising:

8. A leakage current detection method for detecting a leakage current in a measurement object that includes a set of multiple power lines that supplies load power from upstream to downstream, and a load device that operates using the load power supplied from the set of power lines, comprising: a measuring step of measuring currents flowing through two different points of one power line by a measuring instrument; a difference step for calculating the difference between the currents measured at the two points in the measurement step; a detection step of detecting a leakage current of the measurement object based on the difference in current calculated in the difference step; A leakage current detection method comprising:

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