Leakage detector

Abstract

To obtain a leakage detector having a small-sized magnetic field collecting core for detecting a leaked current and capable of suppressing variations in magnetic flux density due to a positional shift of a magnetoelectric transducer in a gap part of the magnetic field collecting core.SOLUTION: A leakage detector of this invention includes: two conductors 4a, 4b; a magnetic field collecting core 1 having a through hole 7 penetrating the two conductors 4a, 4b and a gap part 2; and a magnetoelectric transducer 3 arranged in the gap part 2. The through hole 7 has a substantially rectangular shape composed of a long side and a short side. The gap part 2 is located in an almost center of the long side. The two conductors 4a, 4b are arranged at a substantially line symmetrical position in a gap width direction of the gap part 2 by setting the magnetoelectric transducer 3 as a reference point and setting a height direction of the gap part 2 as a reference line.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a leakage current detector using a magnetoelectric conversion element. [Background technology]

[0002] In conventional earth leakage detectors, two single-phase conductors (current lines) are inserted through the center of a circular magnetic collection core (detection core) with a gap in part of the circle so that currents of opposite polarity flow through it, the magnetic flux generated by the current flowing through each conductor is collected by a magnetic core, and the magnetic flux in the core gap is detected by a magnetoelectric conversion element (magnetic sensor) (see, for example, Patent Document 1).

[0003] For example, Patent Document 1 detects leakage current levels of about 10 mA to protect personnel from electric shock, while Patent Document 2 detects leakage currents of several hundred A to prevent fires caused by earth faults due to arcs. This invention describes leakage current detectors that are mainly suitable for detecting leakage currents of several hundred A.

[0004] Also, for example, Patent Document 3 shows an electrical junction box that is mounted on vehicles such as electric vehicles and hybrid vehicles and is used to distribute power from a battery to various on-board devices. In this electrical junction box, as shown in Fig. 7 of Patent Document 3, a thin plate-shaped bus bar is used for two conductors that carry current from the battery. Compared to a conductor wire with a circular cross section, a bus bar has a rectangular cross section with a large current-carrying cross section and a thin flat cross section with a large heat dissipation surface area, making it possible to carry a large current. In addition, since no insulating coating treatment is required, the bus bar has the effect of suppressing heat generation due to the passage of a large current, and is therefore widely used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2017-049182 [Patent Document 2] Patent Publication No. 2013-062955 [Patent Document 3] Patent Publication No. 2022-191739 Summary of the Invention [Problem to be solved by the invention]

[0006] When a circular magnetic collector core as described in Patent Document 1 is applied to the detection of electric leakage in a busbar (a flat rectangular conductor) that is often used for carrying large currents as described in Patent Document 3, the circular magnetic collector core requires a large space in the thickness direction of the busbar, which increases the size of the electric leakage detector and imposes many restrictions on the installation of the electric leakage detector.

[0007] Furthermore, as will be described later, when detecting leakage current with high accuracy, the magnetic flux density in the core gap of the magnetic collection core, which collects the differential magnetic flux of the magnetic flux generated by the reciprocating current, has the characteristic of fluctuating depending on the detection position of the magnetoelectric conversion element, posing the problem that the magnetic flux density fluctuates due to variations in the position of the magnetoelectric conversion element, thereby increasing the detection error.

[0008] In order to solve the above-mentioned problems, the present invention aims to obtain a leakage current detector that reduces the size of the leakage current detector by miniaturizing the magnetic collecting core through an innovative magnetic collecting core shape and conductor arrangement, and that reduces the fluctuation in magnetic flux density within the magnetic collecting core gap, thereby preventing a decrease in detection accuracy due to misalignment between the magnetic collecting core gap and the magneto-electric conversion element. [Means for solving the problem]

[0009] The leakage current detector of the present invention comprises two conductors, a magnetic core having a through hole and a gap through which the two conductors pass, and a magnetoelectric conversion element arranged in the gap of the magnetic core, wherein the through hole is a hole with an approximately rectangular cross section consisting of long sides and short sides, the gap is located approximately in the center of the long side of the through hole, the two conductors have an approximately rectangular cross section consisting of long sides and short sides, and a reference line is taken in the height direction of the gap with the position of the magnetoelectric conversion element as the reference point, and the two conductors are arranged approximately symmetrically about the reference line so that the long sides of the two conductors are approximately parallel to the gap width direction of the gap. Effect of the Invention

[0010] According to the present invention, the through hole of the magnetic collecting core is made to be approximately rectangular with long and short sides, thereby making it possible to reduce the size of the magnetic collecting core, and by arranging the two conductors in positions that are approximately linearly symmetrical with respect to a reference line in the height direction of the gap, with the magneto-electric conversion element as the reference point, it is possible to suppress magnetic flux density fluctuations due to misalignment of the magneto-electric conversion element within the gap. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view showing an earth leakage detector in accordance with a first embodiment of the present invention. [Diagram 2] FIG. 1 is a front view showing an earth leakage detector in accordance with a first embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram illustrating simulation conditions for the earth leakage detector according to the first embodiment of the present invention. [Figure 4] 13 is a table showing the results of a simulation of a leakage current of 100 A of the leakage detector in the first embodiment of the present invention. [Diagram 5] 13 is a table showing the results of a simulation of a leakage current of 100 A of the leakage detector in the first embodiment of the present invention. [Figure 6] 11 is a table showing the results of a simulation of a leakage current of 0 A for the leakage detector in the first embodiment of the present invention. [Figure 7] 11 is a table showing the results of a simulation of a leakage current of 0 A for the leakage detector in the first embodiment of the present invention. [Figure 8] FIG. 1 is a configuration diagram (front view) showing a leakage current detector having a conventional magnetic core shape. [Figure 9] FIG. 13 is a diagram illustrating the simulation conditions for a leakage current detector having a conventional magnetic core shape. [Figure 10] 13 is a table showing the results of a simulation of a leakage current of 100 A for a leakage detector having a conventional magnetic core shape. [Figure 11] 13 is a table showing the results of a simulation of a leakage current of 0 A for a leakage detector having a conventional magnetic core shape. [Figure 12] 4 is a table showing maximum outer dimensions under various simulation conditions of a conventional earth leakage detector and an earth leakage detector according to the first embodiment of the present invention. [Figure 13] FIG. 11 is a front view showing a leakage current detector in accordance with a second embodiment of the present invention. [Figure 14] 13 is a graph showing the results of a simulation of a leakage current of 100A of the leakage detector in the second embodiment of the present invention. [Figure 15] 13 is a graph showing the results of a simulation of a leakage current of 0 A for the leakage detector in the second embodiment of the present invention. [Figure 16] 13 is a graph showing the results of a simulation of a leakage current of 100A of the leakage detector in the second embodiment of the present invention. [Figure 17] 13 is a graph showing the results of a simulation of a leakage current of 0 A for the leakage detector in the second embodiment of the present invention. [Figure 18] 13 is a graph showing the results of a simulation of a leakage current of 100A of the leakage detector in the second embodiment of the present invention. [Figure 19] 13 is a graph showing the results of a simulation of a leakage current of 0 A for the leakage detector in the second embodiment of the present invention. [Figure 20] 13 is a table and a graph showing the results of a simulation of a leakage current of 100 A of the leakage detector in the second embodiment of the present invention. [Figure 21] 13 is a table and a graph showing the results of a simulation of a leakage current of 0 A for the leakage detector in the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Embodiment 1 Fig. 1 is a perspective view showing an earth leakage detector 100 according to a first embodiment of the present invention, and Fig. 2 is a front view showing the earth leakage detector 100 according to the first embodiment of the present invention. In Fig. 1, the earth leakage detector 100 includes two conductors 4a, 4b, one of which is connected to a single-phase power source (not shown) such as a DC power source and the other of which is connected to a single-phase load (not shown), a magnetic flux collecting core 1 that contains the two conductors 4a, 4b in a through hole 7, and a magnetoelectric conversion element 3.

[0013] Conductors 4a and 4b are thin bus bars made of copper, copper alloy, or aluminum, for example, and have a rectangular cross section with long and short sides that provide a large heat dissipation surface area (long perimeter of the current-carrying cross section) to suppress heat generation due to electrical resistance when electricity is passed through them, and are arranged side by side on the same plane. In the figure, only a portion of conductors 4a and 4b (the portion close to magnetic flux collecting core 1) is shown.

[0014] In Fig. 2, 1 denotes a magnetic flux collecting core, which has a through hole 7 through which conductors 4a and 4b pass. The through hole 7 has a substantially rectangular cross section consisting of long and short sides that are long horizontally. The magnetic flux collecting core 1 has a gap 2 in the center of the long side of the through hole 7.

[0015] 2, 3 is a magnetoelectric conversion element that is disposed at or around the center of the gap height direction (Y direction) of the gap 2 of the magnetic collection core 1, has a magnetic sensing axis in the gap width direction (X direction) of the gap 2, and outputs a voltage of a polarity corresponding to the direction (polarity) of the magnetic flux that is proportional to the magnetic flux density in the gap width direction (X direction) of the magnetic flux generated in the gap 2. The magnetoelectric conversion element 3 is disposed approximately at the center of the gap width direction (X direction) of the gap 2, and the two conductors 4a, 4b are disposed approximately symmetrically with respect to the reference line 2b, with the position of the magnetoelectric conversion element 3 as the reference point 2a, and the long sides of the two conductors 4a, 4b are disposed approximately parallel to the gap width direction of the gap 2.

[0016] In the present invention, unless otherwise specified, the gap width direction of gap 2 is defined as the X direction, the gap height direction as the Y direction, the direction perpendicular to these as the Z direction, and the direction of the arrow in the figure as the + direction.

[0017] Here, the magnetic flux collecting core 1 is formed of a magnetic material such as ferrite, silicon steel, or permalloy, and is processed by sintering, lamination, winding, or the like. The magnetic flux converting element 3 is, for example, a magnetic flux converting element such as a Hall element or a Hall IC. As shown in Fig. 2, the magnetic flux collecting core 1 has core protrusions 1a and 1b protruding in a direction away from the conductors 4a and 4b (+Y direction) at the end surface of the gap 2. Here, the core protrusions 1a and 1b protrude in the +Y direction, but they may also protrude in the -Y direction (direction approaching the conductors 4a and 4b), or in both the +Y and -Y directions.

[0018] The principle of earth leakage detection of earth leakage detector 100 configured in this manner will be described with reference to Figures 1 and 2. In Figure 2, reference numeral 6a denotes magnetic flux that is generated in the clockwise direction in magnetic flux collecting core 1 in accordance with Ampere's law (right-handed screw rule) when current 5a (see Figure 1) is caused to flow through conductor 4a in the direction of the arrow 5a, and reference numeral 6b denotes magnetic flux that is generated in the counterclockwise direction in accordance with Ampere's law (right-handed screw rule) when current 5b (see Figure 1) is caused to flow through conductor 4b in the direction of the arrow 5b.

[0019] In the gap 2 of the magnetic core 1, a composite magnetic flux is generated by combining the magnetic fluxes 6a and 6b in opposite directions (opposite polarity). This composite magnetic flux is applied to the magnetoelectric conversion element 3 located in the gap 2, and the magnetoelectric conversion element 3 outputs a voltage proportional to the magnetic flux density in the magnetic sensing axis direction (X direction) of the composite magnetic flux.

[0020] This composite magnetic flux is equivalent to the magnetic flux of the difference current between currents 5a and 5b, because magnetic fluxes 6a and 6b generated by currents 5a and 5b of opposite polarity flowing through conductors 4a and 4b are composited in the opposite direction (opposite polarity). In other words, the leakage current of currents 5a and 5b is detected.

[0021] Here, the resultant magnetic flux generated in the gap 2 of the magnetic collecting core 1 is calculated by simulation to obtain the amount of magnetic flux density variation due to the shift of the magnetic flux density detection point (hereinafter referred to as the magnetic sensing point) of the magnetoelectric conversion element 3. This amount of magnetic flux density variation corresponds to the measurement error of the earth leakage detector 100. This shift of the magnetic sensing point is assumed to be the variation in the relative position between the magnetoelectric conversion element 3 and the gap 2 when the earth leakage detector 100 is assembled. The simulation is also performed using finite element method electromagnetic field analysis software.

[0022] Fig. 3(a) is a diagram for explaining the simulation conditions of the earth leakage detector 100 in the first embodiment of the present invention, and shows a front view of the magnetic flux collecting core 1 and the conductors 4a, 4b. Fig. 3(b) is a diagram for explaining the simulation conditions when the protruding parts 1a, 1b of the magnetic flux collecting core 1 of the earth leakage detector 100 in the first embodiment of the present invention are protruding in the -Y direction. Figs. 4 and 5 are tables showing the results of the simulation under the condition of a leakage current of 100A, and Figs. 6 and 7 are tables showing the results of the simulation under the condition of a leakage current of 0A. In FIG. 3(a), the symbol a denotes the outer length of the magnetic core 1 in the X direction, the symbol b denotes the outer length of the magnetic core 1 in the Y direction, the symbol c denotes the X direction length of the through hole 7 of the magnetic core 1, the symbol d denotes the Y direction length of the through hole 7 of the magnetic core 1, the symbol e denotes the width of the gap 2 of the magnetic core 1, the symbol f denotes the protruding length of the core protruding parts 1a and 1b of the magnetic core 1 in the +Y direction, the symbol g denotes the Y direction length of the conductors 4a and 4b, and the symbol h denotes the outer length of the conductors 4a and 4b. 3(b), symbol i is the gap between the magnetic core 1 and the conductors 4a, 4b in the Y direction on the side approaching the gap 2, symbol j is the gap between the magnetic core 1 and the conductors 4a, 4b in the Y direction on the side moving away from the gap 2, symbol k is the gap between the magnetic core 1 and the conductors 4a, 4b in the X direction on the side moving away from the gap 2, symbol k1 is the shortest gap between the reference line 2b and the conductor 4b in the X direction, and symbol k2 is the shortest gap between the reference line 2b and the conductor 4a in the X direction. In FIG. 3(b), symbol f1 is the protruding length of the core protrusions 1a and 1b of the magnetic core 1 in the -Y direction.

[0023] In the simulation, first, calculations were performed assuming that the currents 5a, 5b flowing through conductors 4a, 4b are 5a = 200A, 5b = 100A, and the differential current equivalent to the leakage current is 100A (leakage current 100A condition), and then calculations were performed assuming that the currents 5a, 5b flowing through conductors 4a, 4b are 5a = 100A, 5b = 100A, and the differential current equivalent to the leakage current is 0A (leakage current 0A condition). Hereinafter, when simulations are performed under the same current application conditions, they will be referred to as a leakage current condition of 100 A and a leakage current condition of 0 A, respectively.

[0024] The simulation conditions for the shapes of the magnetic core 1 and the conductors 4a and 4b are explained with reference to Fig. 3(a)(b). The conductors 4a and 4b are flat-shaped to ensure a reduced size (thin) in the Y direction and a cross-sectional area for current flow, with symbols g = 2.5 mm and h = 25 mm, and the clearance between the conductors is symbol k1 = 6.25 mm and symbol k2 = 6.25 mm based on the reference line 2b. The magnetic core 1 is arranged along the periphery of the conductors 4a and 4b, with symbols a = 81.5 mm, b = 21 mm, c = 67.5 mm, d = 7.5 mm, and e = 3.8 mm, and the thickness of the magnetic core 1 (length in the Z direction, not shown) is 8 mm. The clearance between the conductors 4a and 4b and the magnetic core 1 is symbol i = 2.5 mm, j = 2.5 mm, and k = 2.5 mm, and the shape is designed to reduce the size by separating them by a certain distance.

[0025] Furthermore, to confirm the influence of core protrusions 1a and 1b, simulations were performed in which symbol f was changed from 0 mm to 10.0 mm in the Y+ direction, symbol f1 was protruding 6.5 mm in the Y- direction, and symbol f was protruding 6.5 mm in the Y- direction and 8 mm in the Y+ direction.

[0026] Furthermore, the resultant magnetic flux generated in the gap 2 of the magnetic collecting core 1 is calculated at the position of the magnetic sensitivity point of the magnetoelectric conversion element 3 and is calculated at three points: magnetic sensitivity point A at the center of the X and Y directions of the gap 2 of the magnetic collecting core 1, magnetic sensitivity point B at a point +0.5 mm away in the X direction from magnetic sensitivity point A, and magnetic sensitivity point C at a point -0.5 mm away in the X direction from magnetic sensitivity point A. This ±0.5 mm assumes a relative positional deviation between the magnetic sensitivity points of the magnetic collecting core 1 and the magnetoelectric conversion element 3 (errors due to misalignment of the magnetic electric conversion element 3 on the board, etc.).

[0027] First, the simulation results for a leakage current of 100 A will be described. Fig. 4 shows the magnetic flux density (unit: mT) at magnetic sensing points A, B, and C, and the magnetic flux density fluctuation amount (unit: %), which is the fluctuation ratio (absolute value) of magnetic sensing point B or C based on magnetic sensing point A, when the symbol f (unit: mm) is changed to 0, 3, 5, 9, and 10 in the Y+ direction. Here, the magnetic flux density fluctuation amount corresponds to the measurement error of the leakage detector 100, and taking the magnetic flux density fluctuation rate of magnetic sensing point C as an example, it becomes the absolute value of ((magnetic flux density of magnetic sensing point C - magnetic flux density of magnetic sensing point A) / magnetic flux density of magnetic sensing point A).

[0028] FIG. 5 similarly shows the simulation results when f1 is set to 6.5 mm in the Y-direction, and when f1 is set to 6.5 mm in the Y-direction and f is set to 8 mm in the Y+direction.

[0029] In the case of a leakage current of 100A, as shown in Figure 4, when there is no core protrusion, symbol f, is 0mm, the magnetic flux density at each magnetic sensitivity point is 31.77mT at magnetic sensitivity point A, 31.10mT at magnetic sensitivity point B, and 32.50mT at magnetic sensitivity point C, and the magnetic flux density fluctuation is maximum at magnetic sensitivity point C, at 2.29%.

[0030] The amount of magnetic flux density variation when symbol f is extended in the Y+ direction tends to decrease as symbol f increases, and is 1.01% at magnetic sensitivity point C when symbol f is 3.0 mm, and 0.38% at magnetic sensitivity point C when symbol f is 10.0 mm.

[0031] 5, when symbol f1 is 6.5 mm in the Y- direction, the magnetic flux density at each magnetic sensing point is 31.99 mT at magnetic sensing point A, 31.56 mT at magnetic sensing point B, and 32.44 mT at magnetic sensing point C, with the magnetic flux density variation being maximum at magnetic sensing point C, being 1.39%. When symbol f is 8.0 mm in the Y+ direction and symbol f1 is 6.5 mm in the Y- direction, the magnetic flux density at each magnetic sensing point is 31.71 mm at magnetic sensing point A, 31.58 mT at magnetic sensing point B, and 31.87 mT at magnetic sensing point C, with the magnetic flux density variation being maximum at magnetic sensing point C, being 0.48%.

[0032] Next, the simulation results for the condition of 0 A leakage current will be described. Figures 6 and 7 show the magnetic flux density (mT) of magnetic sensitivity points A, B, and C, and the magnetic flux density fluctuation amount (unit: %), which is the fluctuation ratio (absolute value) of magnetic sensitivity points B and C under the condition of 0 A leakage current, based on the magnetic flux density of magnetic sensitivity point A under the condition of 100 A leakage current in Figures 4 and 5. Here, the magnetic flux density fluctuation amount corresponds to the measurement error of the leakage detector 100, and to explain using the magnetic flux density fluctuation amount of magnetic sensitivity point C as an example, it is the absolute value of (magnetic flux density of magnetic sensitivity point C under the condition of 0 A leakage current / magnetic flux density of magnetic sensitivity point A under the condition of 100 A leakage current).

[0033] In the case of a leakage current of 0A, as shown in Figure 6, when there is no core protrusion, symbol f, is 0mm, the magnetic flux density at each magnetic sensitivity point is 0.00mT at magnetic sensitivity point A, -0.94mT at magnetic sensitivity point B, and 0.94mT at magnetic sensitivity point C, and the magnetic flux density fluctuation is greatest at magnetic sensitivity points B and C, at 2.95%.

[0034] The amount of magnetic flux density variation when symbol f is extended in the Y+ direction tends to decrease as symbol f increases; when symbol f is 3.0 mm, it is 1.31% at magnetic sensitivity points B and C, and when symbol f is 10.0 mm, it is 0.48% at magnetic sensitivity points B and C.

[0035] 7, when symbol f1 is 6.5 mm in the Y- direction, the magnetic flux density at each magnetic sensitivity point is 0.00 mT at magnetic sensitivity point A, -0.58 mT at magnetic sensitivity point B, and 0.58 mT at magnetic sensitivity point C, and the magnetic flux density fluctuation amount is maximum at magnetic sensitivity points B and C, being 1.83%. When symbol f is 8.0 mm in the Y+ direction and symbol f1 is 6.5 mm in the Y- direction, the magnetic flux density at each magnetic sensitivity point is 0.00 mT at magnetic sensitivity point A, -0.19 mT at magnetic sensitivity point B, and 0.19 mT at magnetic sensitivity point C, and the magnetic flux density fluctuation amount is maximum at magnetic sensitivity points B and C, being 0.61%.

[0036] As described above, in the leakage current detector 100 of the first embodiment of the present invention, the magnetoelectric conversion element 3 is disposed approximately at the center of the gap width direction (X direction) of the gap portion 2, and the two conductors 4a, 4b are disposed approximately symmetrically with respect to a reference line 2b in the gap height direction of the gap portion 2, with the position of the magnetoelectric conversion element 3 as the reference point 2a, and the long sides of the two conductors 4a, 4b are disposed approximately parallel to the gap width direction of the gap portion 2, making it possible to suppress fluctuations in the magnetic flux density detection value due to positional variations of the magnetoelectric conversion element 3.

[0037] When there are no core protrusions 1a, 1b in the gap 2 (f=0 and f1=0), the magnetic flux density fluctuation amount when the leakage current is 100A is suppressed to approximately 2.5%, and when the leakage current is 0A, the magnetic flux density fluctuation amount is suppressed to approximately 3%, making it possible to perform leakage detection with a measurement error of approximately 3% as a general leakage detector.

[0038] Furthermore, by adding core protrusions 1a and 1b to gap 2 and increasing the dimensions of symbols f and f1, the fluctuation in magnetic flux density to be detected can be further suppressed, enabling highly accurate leakage current detection. For example, by providing core protrusions 1a and 1b with symbol f of 3 mm, the fluctuation in magnetic flux density when detecting a leakage current of 100 A is 1.01%, enabling highly accurate leakage current detection with a measurement error of about 1%. Here, if the height of gap 2 when symbol f in Figure 3(a) is 0 mm (for example, 7 mm, which is the Y-direction length = (bd) / 2) is taken as the basic gap height and symbol f2, then symbol f of 3 mm corresponds to 0.42 times the basic gap height f2 (basic gap height ratio of 0.42 times).

[0039] Here, for comparison with the conventional technique, a magnetic flux density variation due to the shift in the magnetic sensing point of the magnetoelectric conversion element is calculated by simulation for the magnetic flux collecting core in which a gap is provided in part of the circular shape of Patent Document 1.

[0040] FIG. 8 is a front view (configuration diagram) showing a leakage current detector 101 using a magnetic core 8 with a gap in a part of a conventional circle. Here, 11a and 11b are conductors, and have the same dimensions as the conductors 4a and 4b in the first embodiment. 8 is a circular magnetic core, and 10 is a magnetoelectric conversion element, which is arranged at the center or around the gap 9 of the magnetic core 8, has a magnetic sensitivity axis in the gap width direction (X direction) of the gap 9, and outputs a voltage of a polarity corresponding to the direction (polarity) of the magnetic flux generated in the gap 9, which is proportional to the magnetic flux density in the gap width direction (X direction) of the magnetic flux generated in the gap 9. 13a is a magnetic flux generated in the magnetic core 8 in the clockwise direction in the figure according to Ampere's law (right-handed screw rule) when a current 12a is passed through the conductor 11a in the -Z direction, and 13b is a magnetic flux generated in the magnetic core 8 in the counterclockwise direction in the figure according to Ampere's law (right-handed screw rule) when a current 12b is passed through the conductor 11b in the +Z direction.

[0041] Fig. 9 is a diagram for explaining the simulation conditions and is a front view of a conventional magnetic flux collecting core 8 and conductors 11a and 11b. Fig. 10 is a table showing the results of the simulation under the condition of a leakage current of 100 A, and Fig. 11 is a table showing the results of the simulation under the condition of a leakage current of 0 A.

[0042] 9, symbol l is the maximum outer length of the magnetic core 8 in the X direction, symbol m is the maximum outer length of the magnetic core 8 in the Y direction, symbol n is the maximum outer length of the through hole 14 of the magnetic core 8 in the X direction, symbol o is the maximum outer length of the through hole 14 of the magnetic core 8 in the Y direction, symbol p is the width of the gap 9 of the magnetic core 8, symbol q is the gap between the magnetic core 8 and the conductors 11a, 11b in the X direction, symbol r is the length of the conductors 11a, 11b in the Y direction, and symbol s is the length of the conductors 11a, 11b in the X direction.

[0043] In the simulation, as in the first embodiment, first, calculations were performed under the assumption that the currents 12a, 12b flowing through the conductors 11a, 11b were 12a=200A, 12b=100A, and the differential current equivalent to the leakage current was 100A (leakage current 100A condition), and then calculations were performed under the assumption that the currents 12a, 12b flowing through the conductors 11a, 11b were 12a=100A, 12b=100A, and the differential current equivalent to the leakage current was 0A (leakage current 0A condition).

[0044] The simulation conditions for the shapes of the conductors 11a, 11b and the magnetic flux collecting core 8 will be described with reference to Fig. 9. The conductors 11a, 11b shown in Fig. 9 have the same dimensions as the conductors 4a, 4b in the present embodiment 1, with r = 2.5 mm and s = 25 mm. In contrast, the magnetic flux collecting core 8 has l = 81.5 mm, m = 81.5 mm, n = 67.5 mm, o = 67.5 mm, p = 3.8 mm, the thickness of the magnetic flux collecting core 8 (length in the Z direction, not shown) = 8 mm, the clearance between the conductors 11a, 11b and the magnetic flux collecting core 8 is q = 2.5 mm, and the length in the X direction is the same as in the present embodiment 1.

[0045] Similarly to the first embodiment, the magnetoelectric conversion element 10 has three magnetic sensitivity points: magnetic sensitivity point A at the center of the gap 9 of the magnetic collection core 8 in the X and Y directions, magnetic sensitivity point B located +0.5 mm away from magnetic sensitivity point A in the X direction, and magnetic sensitivity point C located −0.5 mm away from magnetic sensitivity point A in the X direction.

[0046] First, the simulation results for a leakage current of 100A will be described. 10 shows the magnetic flux density (mT) at magnetic sensing points A, B, and C, and the magnetic flux density fluctuation amount (unit: %), which is the fluctuation ratio (absolute value) of magnetic sensing point B or C based on magnetic sensing point A. Here, taking the magnetic flux density fluctuation amount of magnetic sensing point C as an example, the magnetic flux density fluctuation amount is the absolute value of ((magnetic flux density of magnetic sensing point C - magnetic flux density of magnetic sensing point A) / magnetic flux density of magnetic sensing point A).

[0047] As shown in FIG. 10, in the case of a leakage current of 100 A, the magnetic flux density at each magnetic sensitivity point of the conventional circular magnetic flux collecting core (magnetic flux collecting core 8) is 30.91 mT at magnetic sensitivity point A, 30.84 mT at magnetic sensitivity point B, and 31.03 mT at magnetic sensitivity point C, and the magnetic flux density fluctuation is maximum at magnetic sensitivity point C, at 0.38%.

[0048] Next, we will discuss the simulation results under the condition of 0 A leakage current. Figure 11 shows the magnetic flux density (mT) at magnetic sensitivity points A, B, and C, and the magnetic flux density fluctuation amount (unit: %), which is the fluctuation ratio (absolute value) of magnetic sensitivity points B and C under the condition of 0 A leakage current, based on the magnetic flux density at magnetic sensitivity point A under the condition of 100 A leakage current in Figure 10. Here, to explain the magnetic flux density fluctuation amount using the magnetic flux density fluctuation amount of magnetic sensitivity point C as an example, it is the absolute value of (magnetic flux density at magnetic sensitivity point C under the condition of 0 A leakage current / magnetic flux density at magnetic sensitivity point A under the condition of 100 A leakage current).

[0049] As shown in FIG. 11, when the leakage current is 0A, the magnetic flux density at each magnetic sensitivity point is 0.00mT at magnetic sensitivity point A, -0.12mT at magnetic sensitivity point B, and 0.12mT at magnetic sensitivity point C, and the magnetic flux density fluctuation is greatest at magnetic sensitivity points B and C, at 0.39%.

[0050] 12 is a table showing maximum outer dimensions under various simulation conditions for the conventional earth leakage detector and the earth leakage detector according to the first embodiment of the present invention. As shown in the figure, the maximum outer dimension in the Y direction of the earth leakage detector 101 using the conventional circular magnetic flux collecting core 8 is 81.5 mm, whereas in the earth leakage detector 100 according to the first embodiment of the present invention, it is 21 mm when the symbol f of the core protrusions 1a and 1b is 0 mm, and 31 mm when f is 10 mm.

[0051] As described above, in the leakage current detector 101 using the conventional circular magnetic flux collecting core 8, for example, when detecting a leakage current of 100 A, the magnetic flux density fluctuation is 0.38%, enabling highly accurate leakage detection of less than 1%. However, in embodiment 1 of the present invention, by providing core protrusions 1a and 1b with symbol f set to 10 mm (1.43 times the basic gap height f2), the magnetic flux density fluctuation when detecting a leakage current of 100 A is 0.38%, enabling highly accurate leakage detection equivalent to that of the conventional circular magnetic flux collecting core.

[0052] When symbol f is 10 mm, the maximum outer dimension in the Y direction of this embodiment 1 is 31 mm, which is 62% ((81.5-31) / 81.5) smaller than the maximum outer dimension of 81.5 mm when a conventional circular magnetic collecting core 8 is used, making it possible to obtain a thin earth leakage detector with a smaller physical size in the Y direction.

[0053] It is preferable to reduce the size of the magnetic flux collecting core 1 in accordance with the shape of the conductor, and it is preferable to make the length of the symbol f as long as possible in the +Y direction.

[0054] Embodiment 2 Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 13(a) is a front view showing an earth leakage detector 102 according to the second embodiment of the present invention. Fig. 13(b) is an enlarged view of part (b) in Fig. 13(a) showing the X-direction distances k1 and k2 between the reference line 2b and the conductors 4a and 4b of the electric leakage detector 102 in the second embodiment, and the Y-direction distance j between the magnetic flux collecting core 1 and the conductors 4a and 4b. Fig. 13(c) is an enlarged view of part (c) in Fig. 13(a) around the gap 2, illustrating the gap height ratio of the electric leakage detector 102 in the second embodiment.

[0055] 13(a), similarly to the first embodiment, the two conductors 4a, 4b are arranged at positions that are approximately symmetrical with respect to the reference line 2b in the gap width direction (X direction) of the gap 2, with the position of the magnetoelectric conversion element 3 as the reference point 2a. In FIG. 13(a), 4c is the Y-direction center line of the conductors 4a, 4b, and 7a is the Y-direction center line of the through hole 7 of the magnetic flux collecting core 1. As shown in Fig. 13(b), the two conductors 4a, 4b are brought closer to the reference line 2b, and are arranged so that the shortest distance (k1+k2) between the two conductors 4a, 4b is shorter than the gap width e (see Fig. 3(a)) of the gap 2. For example, the gap width (X direction) e of the gap 2 is 3.8 mm, the distances k1 and k2 are 0.25 mm, and k (see Fig. 3(a)) is 8.5 mm. Since the distance between the two conductors 4a, 4b is 0.25 mm for each of the conductors 4a, 4b with respect to the reference line 2b, (k1+k2) = 0.5 mm, which is smaller than the gap width e of 3.8 mm. Furthermore, the two conductors 4a, 4b are moved away from the gap 2 of the magnetic flux collecting core 1 in the Y-direction, and are arranged so that the Y-direction center line 4c of the conductors is below (in the Y-direction) the center line 7a of the through hole 7 of the magnetic flux collecting core 1. For example, the distance k3 from the center line 7a of the through hole of the magnetic flux collecting core 1 to the Y-direction center line 4c of the conductors 4a, 4b is 2 mm. In this case, the distance j between the conductors 4a, 4b and the magnetic flux collecting core 1 is 0.5 mm, and i (see FIG. 3(a)) is 4.5 mm. Also, as shown in FIG. 13(c), the magnetic sensing point of the magnetoelectric conversion element 3 is located at a position shifted a predetermined gap height ratio in the Y+ direction from the center 2c of the gap portion 2 of the magnetic flux collecting core 1 in the gap height direction (Y direction). The gap height ratio indicates the ratio in the height direction to the total length t of the gap 2 in the gap height direction, and when the distance from the center 2c of the gap 2 in the gap height direction to the reference point 2a, which is the magnetic sensing point position of the magneto-electric conversion element 3, is defined as distance u, the gap height ratio is calculated as follows. Gap height ratio = (distance u / total length in the gap height direction t) × 100 [%] Other configurations of the earth leakage detector 102 are similar to those in the first embodiment.

[0056] Here, the resultant magnetic flux generated in the gap 2 of the magnetic flux collecting core 1 in the second embodiment is calculated by simulation, and the amount of magnetic flux density variation due to the magnetic sensing point shift of the magnetoelectric conversion element 3 is obtained in the same manner as in the first embodiment. Moreover, the simulation is performed using finite element method electromagnetic field analysis software in the same manner as in the first embodiment. FIG. 14 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current condition of 100 A when two conductors 4a, 4b in the second embodiment of the present invention are brought closer to a reference line 2b, FIG. 15 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current condition of 0 A, FIG. 16 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current condition of 100 A when two conductors 4a, 4b are moved away from the gap portion 2 of the magnetic flux collecting core 1, FIG. 17 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current condition of 0 A, and FIG. 18 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current condition of 0 A when two conductors 4a, 4b are brought closer to a reference line 2b. FIG. 19 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current of 0 A, FIG. 20 is a simulation graph showing the amount of magnetic flux density fluctuation under a leakage current of 100 A when the position of the magneto-electric conversion element 3 is changed with two conductors 4a, 4b moved closer to reference line 2b and away from gap 2 in magnetic core 1, and FIG. 21 is a simulation graph showing the amount of magnetic flux density fluctuation under the leakage current of 0 A.

[0057] First, a simulation is performed for an arrangement in which the two conductors 4a and 4b are brought closer to each other with respect to the reference line 2b. As simulation conditions, the distances k1 and k2 of the conductors 4a and 4b with respect to the reference line 2b shown in Figures 13(a) and 13(b) are changed, and calculations are performed while changing k accordingly. In embodiment 1, the distances k1 and k2 were 6.25 mm, whereas here the distances k1 and k2 are set to 3.0 mm and 0.25 mm, respectively, so that the clearance between the conductors 4a, 4b, which are arranged approximately symmetrically with respect to the reference line 2b, is reduced, and k is changed accordingly to 5.75 mm and 8.5 mm for the calculations. In this case, the conditions for f are set to f = 5.0 mm, 10.0 mm, and 15.0 mm, and the effect of f on the results is also simulated. Other simulation conditions are the same as those in the first embodiment.

[0058] FIG. 14 shows the simulation results when the leakage current was 100A. In FIG. 14, the vertical axis indicates the larger of the magnetic flux density fluctuation amounts at magnetic sensitive points B and C described in embodiment 1, and the horizontal axis indicates the distances k1 and k2 of conductors 4a, 4b from reference line 2b. Moreover, when the symbol f is 5 mm, it is indicated by a dashed line, when the symbol f is 10 mm, it is indicated by a solid line, and when the symbol f is 15 mm, it is indicated by a dashed line. 14, for example, when the symbol f is 10 mm, the magnetic flux density fluctuation amount is 0.38% when the distances k1 and k2 are 6.25 mm, and is 0.31% when the distances k1 and k2 are 0.25 mm. In other words, the smaller the distances k1 and k2 are, the smaller the magnetic flux density fluctuation amount is, and the more the leakage detection accuracy of the leakage detector 102 is improved.

[0059] Regarding the relationship between the magnetic flux density fluctuation amount and the distances k1 and k2 when the condition of symbol f is varied, it can be confirmed that when symbol f is changed from 5.0 to 15.0 mm, the relationship in which the magnetic flux density fluctuation amount decreases as the distances k1 and k2 are reduced does not change.

[0060] FIG. 15 shows the simulation results when the leakage current was 0 A. In FIG. 15, the vertical and horizontal axes and the display line type of the symbol f are the same as those in FIG. 15, for example, when the symbol f is 10 mm, the magnetic flux density fluctuation amount is 0.38% when the distances k1 and k2 are 6.25 mm, and is 0.19% when the distances k1 and k2 are 0.25 mm. In other words, the smaller the distances k1 and k2 are, the smaller the magnetic flux density fluctuation amount is, and the electric leakage detection accuracy of the electric leakage detector 102 is improved.

[0061] Regarding the relationship between the magnetic flux density fluctuation amount and the distances k1 and k2 when the condition of symbol f is varied, it can be confirmed that when symbol f is changed from 5.0 to 15.0 mm, the relationship in which the magnetic flux density fluctuation amount decreases as the distances k1 and k2 are reduced does not change.

[0062] Next, a simulation is performed on an arrangement in which the two conductors 4a, 4b are moved away from the gap 2 of the magnetic flux collecting core 1. As a simulation condition, the distance j between the conductors 4a, 4b and the magnetic flux collecting core 1 shown in Fig. 3(a) is changed, and calculations are performed by changing i accordingly. In the first embodiment, the distance j was 2.5 mm, but here, the distance j is set to 1.5 mm and 0.5 mm so that the clearance between the conductors 4a, 4b and the magnetic flux collector 1 is small, and i is changed to 3.5 mm and 4.5 mm accordingly for calculation. At this time, the distance k3 from the center line 7a of the through hole of the magnetic flux collector 1 to the Y-direction center line 4c of the conductors 4a, 4b was 0.0 mm in the first embodiment, but here, it is 1.0 mm and 2.0 mm in the Y-direction. In this case, the condition f is also set to f = 5.0 mm, 10.0 mm, and 15.0 mm, and the effect of the code f on the results is also simulated. Other simulation conditions are the same as those in the first embodiment.

[0063] FIG. 16 shows the simulation results when the leakage current was 100A. 16, the vertical axis indicates the larger of the magnetic flux density fluctuation amounts at magnetic sensing points B and C described in embodiment 1, and the horizontal axis indicates the distance j between the conductors 4a, 4b and the magnetic flux collecting core 1. Also, when symbol f is 5 mm, it is indicated by a dashed line, when symbol f is 10 mm, it is indicated by a solid line, and when symbol f is 15 mm, it is indicated by a dashed line. 16, for example, when the symbol f is 10 mm, the magnetic flux density fluctuation amount is 0.38% when the distance j = 2.5 mm, and 0.36% when the distance j = 0.5 mm. In other words, the smaller the distance j, the smaller the magnetic flux density fluctuation amount, and the more accurately the leakage current detection by the leakage current detector 102 is improved.

[0064] Regarding the relationship between the magnetic flux density fluctuation amount and distance j when the condition of symbol f is varied, it can be confirmed that when symbol f is changed from 5.0 to 15.0 mm, the relationship in which the magnetic flux density fluctuation amount decreases as distance j is reduced remains unchanged.

[0065] FIG. 17 shows the simulation results when the leakage current was 0 A. In FIG. 17, the vertical and horizontal axes and the type of line indicated by the symbol f are the same as those in FIG. 17, for example, when the symbol f is 10 mm, the magnetic flux density fluctuation amount is 0.38% when the distance j = 2.5 mm, and is 0.22% when the distance j = 0.5 mm. In other words, the smaller the distance j, the smaller the magnetic flux density fluctuation amount, and the more accurately the leakage detection by the leakage detector 102 is improved.

[0066] Regarding the relationship between the magnetic flux density fluctuation amount and distance j when the condition of symbol f is varied, it can be confirmed that when symbol f is changed from 5.0 to 15.0 mm, the relationship in which the magnetic flux density fluctuation amount decreases as distance j is reduced remains unchanged.

[0067] Next, a simulation is performed on an arrangement in which the two conductors 4a, 4b are brought closer to each other with respect to the reference line 2b and are moved away from the gap 2 of the magnetic flux collecting core 1. As simulation conditions, the distances k1 and k2 and the distance j shown in Fig. 3(a) are changed, and k and i are changed accordingly for calculation. In the first embodiment, the distances k1 and k2 are 6.25 mm and the distance j is 2.5 mm, whereas here the distances k1 and k2 are 0.25 mm and the distance j is 0.5 mm, and accordingly the distance k is 8.5 mm and the distance i is 4.5 mm. At this time, the distance k3 from the center line 7a of the through hole of the magnetic flux collecting core 1 to the Y-direction center line 4c of the conductors 4a and 4b is 0.0 mm in the first embodiment, whereas here it is 2.0 mm in the Y-direction. In this case, the conditions for f are set to f = 5.0 mm, 10.0 mm, and 15.0 mm, and the effect of f on the results is also simulated. Other simulation conditions are the same as those in the first embodiment.

[0068] FIG. 18 shows the simulation results when the leakage current was 100A. The vertical axis indicates the larger of the magnetic flux density fluctuations at magnetic sensing points B and C described in the first embodiment, and the horizontal axis indicates the distances k1 and k2 of the conductor from the reference line 2b. Also, when symbol f is 5 mm, it is indicated by a dashed line, when symbol f is 10 mm, it is indicated by a solid line, and when symbol f is 15 mm, it is indicated by a dashed line. 18, for example, when the symbol f is 10 mm, the magnetic flux density fluctuation amount is 0.38% when the distances k1 and k2 = 6.25 mm and the distance j = 2.5 mm, and is 0.3% when the distances k1 and k2 = 0.25 mm and the distance j = 0.5 mm. In other words, the smaller the distances k1 and k2 and the distance j are, the smaller the magnetic flux density fluctuation amount is, and the electric leakage detection accuracy of the electric leakage detector 102 is improved.

[0069] Regarding the relationship between the magnetic flux density fluctuation amount and the distances k1 and k2, as well as the distance j when the condition of symbol f is varied, it can be confirmed that when symbol f is changed from 5.0 to 15.0 mm, the relationship in which the magnetic flux density fluctuation amount decreases as the distances k1 and k2, as well as the distance j, are reduced does not change.

[0070] FIG. 19 shows the simulation results when the leakage current was 0 A. In FIG. 19, the vertical and horizontal axes and the display line type of the symbol f are the same as those in FIG. 19, for example, when the symbol f is 10 mm, the magnetic flux density fluctuation amount is 0.38% when the distances k1 and k2 = 6.25 mm and the distance j = 2.5 mm, and is 0.18% when the distances k1 and k2 = 0.25 mm and the distance j = 0.5 mm. In other words, the smaller the distances k1 and k2 and the distance j are, the smaller the magnetic flux density fluctuation amount is, and the more the leakage detection accuracy of the leakage detector 102 is improved.

[0071] Regarding the relationship between the magnetic flux density fluctuation amount and the distances k1 and k2, as well as the distance j when the condition of symbol f is varied, it can be confirmed that when symbol f is changed from 5.0 to 15.0 mm, the relationship in which the magnetic flux density fluctuation amount decreases as the distances k1 and k2, as well as the distance j, are reduced does not change.

[0072] 14, 16, and 18 under the condition of a leakage current of 100A (symbol f is set to 10.0 mm, for example, to compare under the same conditions), in the arrangement in which the two conductors 4a, 4b are brought closer to each other relative to the reference line 2b in Fig. 14, the magnetic flux density variation is 0.31% when distances k1 and k2 are 0.25 mm, and in the arrangement in which the two conductors 4a, 4b are moved away from the gap 2 of the magnetic flux collecting core 1 in Fig. 16, the magnetic flux density variation is 0.36% when distance j is 0.5 mm. The arrangement in which the two conductors 4a, 4b are brought closer to each other relative to the reference line 2b in Fig. 14 has a smaller magnetic flux density variation, which can further improve the leakage current detection accuracy. 18 in which the two conductors 4a, 4b are brought closer to each other with respect to the reference line 2b and are moved away from the gap 2 of the magnetic flux collecting core 1, the variation is 0.3% when the distances k1 and k2 are 0.25 mm and the distance j is 0.5 mm. In other words, the variation in magnetic flux density is smaller in the arrangement in which the distances k1 and k2 and the distance j are reduced than in the arrangement in which only the distances k1 and k2 are reduced and the arrangement in which only the distance j is reduced, thereby enabling the leakage current detection accuracy to be improved.

[0073] When comparing the amount of magnetic flux density variation for each arrangement of conductors 4a, 4b in Figures 15, 17, and 19 under the condition of a leakage current of 0 A (symbol f is set to 10.0 mm, for example, to compare under the same conditions), in the arrangement in Figure 15 where the two conductors 4a, 4b are brought closer to each other relative to the reference line 2b, the variation is 0.19% when distances k1 and k2 = 0.25 mm, and in the arrangement in Figure 17 where the two conductors 4a, 4b are moved away from the gap 2 of the magnetic flux collecting core 1, the variation is 0.22% when distance j = 0.5 mm. Thus, the amount of magnetic flux density variation is smaller in the arrangement in Figure 15 where the two conductors 4a, 4b are brought closer to each other relative to the reference line 2b, thereby enabling greater improvement in leakage detection accuracy. 19 in which the two conductors 4a, 4b are brought closer to each other with respect to the reference line 2b and are moved away from the gap 2 of the magnetic flux collecting core 1, the magnetic flux density fluctuation is 0.18% when the distances k1 and k2 = 0.25 mm and the distance j = 0.5 mm. In other words, the magnetic flux density fluctuation is smaller in the arrangement in which the distances k1 and k2 and the distance j are reduced than in the arrangement in which only the distances k1 and k2 are reduced and the arrangement in which only the distance j is reduced, thereby enabling the leakage current detection accuracy to be further improved.

[0074] Next, a simulation is performed in which the position of the magnetic sensing point of the magnetoelectric conversion element 3 is located at a position moved in the Y+ direction from the center 2c in the gap height direction (Y direction) of the gap part 2 of the magnetic core 1. As a simulation condition, the position of the magnetoelectric conversion element 3 is moved in the Y+ direction from the center 2c in the gap height direction (Y direction) of the gap part 2 of the magnetic core 1 shown in Figure 13(c) by a gap height ratio of 0% to 50%, and calculations are performed. In this case, the conductor arrangement is calculated by changing the distances k1 and k2 and the distance j shown in FIG. 3(b) and changing k and i accordingly. In the first embodiment, the distances k1 and k2 are 6.25 mm and the distance j is 2.5 mm, whereas here the distances k1 and k2 are 0.25 mm and the distance j is 0.5 mm, and accordingly the distance k is 8.5 mm and the distance i is 4.5 mm. At this time, the distance k3 from the center line 7a of the through hole of the magnetic flux collecting core 1 to the Y-direction center line 4c of the conductors 4a and 4b is 0.0 mm in the first embodiment, whereas here it is 2.0 mm in the Y-direction. In this case, the condition f is also set to f = 5.0 mm, 10.0 mm, and 15.0 mm, and the effect of the code f on the results is also simulated. Other simulation conditions are the same as those in the first embodiment.

[0075] FIG. 20 shows the simulation results when the leakage current was 100A. In Figure 20(a), the horizontal axis indicates the gap height ratio (%) in the Y+ direction from the Y-direction center 2c of the gap portion 2 at the position of the magnetic sensing point of the magneto-electric conversion element 3, and the vertical axis indicates the larger of the magnetic flux density fluctuation amounts at the magnetic sensing points B and C described in embodiment 1. Moreover, when the symbol f is 5 mm, it is indicated by a dashed line, when the symbol f is 10 mm, it is indicated by a solid line, and when the symbol f is 15 mm, it is indicated by a dashed line. FIG. 20(b) shows the magnetic flux density fluctuation amount [%] read from the graph in FIG. 20(a), with the gap height ratio [%] shown vertically and the condition of the symbol f shown horizontally.

[0076] As shown in Figures 20(a) and (b), for example, when f = 5.0 mm, the magnetic flux density fluctuation is 0.560% when the magnetic sensing point of the magnetoelectric conversion element 3 is at the center 2c of the gap height Y direction of the core gap portion 2) on the horizontal axis of the graph, and it can be confirmed that there is a decrease in the magnetic flux density fluctuation (improved accuracy) when moving in the + direction on the horizontal axis of the graph (to the right in the figure), with the magnetic flux density fluctuation at 14.5% on the horizontal axis being 0.422%, which is the best improvement in accuracy, and then at 26.5% on the horizontal axis the magnetic flux density fluctuation is again 0.560%, after which the magnetic flux density fluctuation begins to increase rapidly (deterioration in accuracy). 20(b), based on the magnetic flux density fluctuation when the magnetic sensing point of magnetoelectric conversion element 3 is at center 2c of gap height Y direction of core gap 2, the gap height ratio range in which the magnetic flux density fluctuation is improved is 0% to 26.5% when f = 5.0 mm, 0% to 29.1% when f = 10.0 mm, and 0% to 32.5% when f = 15.0 mm. In other words, the range in which accuracy is improved changes depending on the symbol f.

[0077] Figure 20(b) also shows the gap height ratio and magnetic flux density variation when precision is most improved within the range of precision improvement. When the code f = 5.0 mm, the gap height ratio is 14.5%, when f = 10.0 mm, it is 18%, and when f = 15.0 mm, it is 21.7%. In other words, the position where precision is most improved changes depending on the code f.

[0078] The simulation results for the condition of 0 A leakage current are shown in Fig. 21(a)(b). In Figures 21(a) and (b), the vertical and horizontal axes and the type of line indicated by the symbol f are the same as those in Figures 20(a) and (b). As shown in Figures 21(a) and 21(b), for example, when f = 5.0 mm, the magnetic flux density fluctuation is 0.35% when the magnetic sensing point of the magnetoelectric conversion element 3 is at the center 2c of the gap height Y direction of the core gap portion 2) on the horizontal axis of the graph, and it can be confirmed that there is a decrease in the magnetic flux density fluctuation (improved accuracy) when moving in the + direction on the horizontal axis of the graph (to the right in the figure), with the magnetic flux density fluctuation at 17.0% on the horizontal axis being 0.255%, which is the best improvement in accuracy, and then at 31.6% on the horizontal axis the magnetic flux density fluctuation is again 0.35%, after which the magnetic flux density fluctuation begins to increase rapidly (deterioration in accuracy). 21(b), the gap height ratio range in which the magnetic flux density fluctuation is improved based on the magnetic flux density fluctuation when the magnetic sensing point of magnetoelectric conversion element 3 is at center 2c of gap height Y direction of core gap 2 is 0% to 31.6% when f = 5.0 mm, 0% to 32.2% when f = 10.0 mm, and 0% to 35.0% when f = 15.0 mm. In other words, the range in which accuracy is improved changes depending on the symbol f.

[0079] Figure 21(b) also shows the gap height ratio and magnetic flux density variation when precision is most improved within the range of precision improvement. When the code f = 5.0 mm, the gap height ratio is 17%, when f = 10.0 mm, it is 19%, and when f = 15.0 mm, it is 23%. In other words, the position where precision is most improved changes depending on the code f.

[0080] Comparing Figure 20(b) and Figure 21(b), even when f is the same value, the width of the range where accuracy improves and the position where accuracy is most improved are different between the 100 A leakage current condition and the 0 A leakage current condition. However, since the minimum magnetic flux density fluctuation in Figure 20(b) under a leakage current of 100A (for example, 0.422% when f = 5 mm) is greater than the magnetic flux density fluctuation at a gap height ratio of 0% in Figure 21(b) under a leakage current of 0A (for example, 0.35% when f = 5 mm), it is desirable to determine the position of the magnetic sensing point of the magneto-electric conversion element 3 by giving priority to the leakage current condition of 100A. In view of the above, it is preferable to change the position of the magnetic sensing point of the magnetoelectric conversion element 3 depending on the shape (f value) of the core protrusions 1a, 1b. For example, when f = 5.0 mm, the gap height ratio is 14.5%, when f = 10.0 mm, it is 18%, and when f = 15.0 mm, it is 21.7%. By moving it away from the Y-direction center 2c of the core gap 2 in the Y+ direction, the magnetic flux density fluctuation amount is reduced and the leakage current detection accuracy can be improved.

[0081] Up to this point, we have described the case where distances k1 and k2 = 0.25 mm, distance j = 0.5 mm (distance k is 8.5 mm, distance i is 4.5 mm), and f is 5 mm or more. However, when a simulation was performed under other conditions, such as distances k1 and k2 = 6.25 mm, distance j = 2.5 mm (distance k is 2.5 mm, distance i is 2.5 mm), which are the arrangement conditions of conductors 4a and 4b in embodiment 1, and f = 0 mm (when core protrusions 1a, 1b are absent), the position where accuracy was best improved was a position 14.4% away from the Y-direction center 2c of core gap 2 in the Y+ direction in terms of gap height ratio. In other words, regardless of the presence or absence of core protrusions 1a, 1b, by positioning the magnetic sensing point of the magnetoelectric conversion element 3 at a position that is 10% or more away from the Y-direction center 2c of the core gap 2 in the Y+ direction in terms of gap height ratio, the amount of magnetic flux density fluctuation is reduced and the accuracy of leakage current detection can be improved. [Explanation of symbols]

[0082] 1 Magnetic core 1a, 1b (magnetic core 1) core protrusion 2. Gap (of magnetic core 1) 2a Reference point (position of magnetoelectric conversion element) 2b Reference line 2c Center point of the entire length of the gap 2 in the gap height direction 3. Magnetoelectric conversion element 4a, 4b conductor 4c Y-direction center line of conductor 5a, 5b current 6a, 6b Magnetic flux 7 Through hole (of magnetic core 1) 7a (magnetic core 1) through hole center line in Y direction 8 (conventional circular) magnetic core 9 (of the conventional circular magnetic core 8) 10 Magnetoelectric conversion element 11a, 11b conductor 12a, 12b current 13a, 13b Magnetic flux 14 (of conventional circular magnetic core 8) through hole 100 Leakage detector in embodiment 1 101 (conventional) earth leakage detector 102 Leakage detector in embodiment 2

Claims

1. Two conductors, a magnetic flux collecting core having a through hole and a gap; a magnetoelectric conversion element disposed in the gap and configured to detect a magnetic flux density in a gap width direction of the gap and output an output signal corresponding to the magnetic flux density, The through hole is a hole having a substantially rectangular cross section consisting of long sides and short sides, The gap is located approximately at the center of a long side of the through hole, The two conductors have an approximately rectangular cross-section consisting of long and short sides, pass through the through hole, and are arranged approximately linearly symmetrically with respect to a reference line in the gap height direction of the gap portion, which has the position of the magneto-electric conversion element as the reference point, so that the long sides of the conductors are approximately parallel to the gap width direction of the gap portion.

2. 2. The earth leakage detector according to claim 1, wherein the gap has a protrusion protruding in a direction away from the two conductors.

3. 2. The earth leakage detector according to claim 1, wherein the gap has a protruding portion protruding in a direction approaching the two conductors.

4. 2. The earth leakage detector according to claim 1, wherein the gap has protrusions protruding in a direction away from and a direction toward the two conductors.

5. 3. The earth leakage detector according to claim 2, wherein the protruding portion protrudes by at least 0.42 times the length of the gap in the height direction when the protruding portion is not present.

6. 3. The earth leakage detector according to claim 2, wherein the protruding portion protrudes by 1.43 times or more compared to a length of the gap in the height direction of the gap when the protruding portion is not present.

7. 3. The earth leakage detector according to claim 2, wherein the shortest distance between the two conductors is shorter than the length of the gap in the width direction of the gap portion.

8. 3. The earth leakage detector according to claim 2, wherein a center line of the conductor in the gap height direction is located farther from the gap than a center line of the through hole in the gap height direction.

9. The leakage current detector according to any one of claims 1, 2, 5, 6, 7 and 8, characterized in that the magnetoelectric conversion element is positioned at a distance of 10% or more from the center position of the gap in the gap height direction in a direction away from the two conductors.

Images