Shunt Current Suppression Device

Abstract

To provide a shunt current suppression device which saves man-hours or cost for construction work and also reduces limitations for an installation place by using an inductance element which is easily mountable to an existing metal pipe such as a gas pipe.SOLUTION: A gas pipe 3 as a metal pipe is laid between two architectural structures 1 and 2, and equipotential bonding is performed on metallic structural materials which are constituent members of the architectural structures 1 and 2 and grounded, and the gas pipe 3. A shunt current suppression device comprises parallel connection parts of insulating joints 4a and 5a disposed in the middle of the gas pipe 3 and surge protective elements 4b and 5b such as GDT for preventing voltage resistance destruction. A magnetic substance core 8 which becomes high impedance with respect to a shunt current of a lightning current to flow, in the case of lightning in any one of the architectural structures 1 and 2, from the metallic structural material constituting the one architectural structure to the other architectural structure is mounted to the gas pipe 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a shunt current suppression device for suppressing lightning current that is diverted from a building struck by lightning to other buildings. [Background technology]

[0002] 2. Description of the Related Art A lightning protection system described in Patent Document 1 is known as a conventional technique for protecting electrical equipment installed in a building from lightning strikes. Fig. 4 is a configuration diagram showing this lightning protection system. In Fig. 4, a lightning protection transformer 103 and electrical equipment 104 connected to a power line 101 via a high-voltage transformer 102 are installed inside a building 100.

[0003] Metal pipes 105, such as gas pipes and water pipes, that communicate with the inside and outside of the building 100 are fixed to the building 100 via insulating structural parts 106, and are connected to a lightning protection ring-shaped ground wire 110. This lightning protection ring-shaped ground wire 110 is buried in the ground so as to surround the building 100, and is connected to a lightning rod 112 via an electric wire 111. Reference numeral 113 denotes a lightning arrester connected to the power line 101. Here, the lightning protection ring-shaped ground wire 110 and the electric wire 111 that surround the building 100 act as a Faraday cage.

[0004] In the above-mentioned conventional technology, the lightning current that enters from the power line 101 flows to the ground via the lightning arrester 113, and the lightning current that enters from the metal pipe 105 flows to the lightning rod 112 side via the lightning protection ring ground wire 110 and the electric wire 111, so that the electrical equipment 104 in the building 100 can be protected from lightning strikes.

[0005] Meanwhile, JIS Z9290-3:2019, which concerns lightning protection for buildings, specifies external lightning protection systems for safely passing lightning current during a lightning strike, and internal lightning protection systems for preventing dangerous spark discharges caused by voltages generated by lightning current. In gas equipment installed in buildings, it is recommended that equipotential bonding be performed immediately adjacent to the gas pipe inlet, based on the Building Standards Act. However, equipotential bonding causes lightning current to flow into the gas pipe, which can have a detrimental effect on the gas pipe.

[0006] Here, Fig. 5 is an explanatory diagram of a case where a gas pipe 3 is laid between two buildings 1 and 2, where 1a and 2a are lightning rods installed in the buildings 1 and 2, 1b and 2b are equipotential lines for connecting the metal structural materials of the buildings 1 and 2 to the gas pipe 3 to equalize the potential, 4a and 5a are insulating joints for preventing gas leakage due to electrolytic corrosion of the gas pipe 3, 4b and 5b are surge protection devices (SPDs) such as lightning arresters (GDTs), insulating spark gaps (ISGs) or metal oxide varistors (MOVs) connected in parallel to prevent the withstand voltage breakdown of the insulating joints 4a and 5a, and R1 and R2 are the ground resistances of the buildings 1 and 2. The discharge start voltage of the surge protection devices 4b and 5b is selected to a value that is in harmony with the dielectric strength of the insulating joints 4a and 5a. Moreover, the gas pipe 3 is usually formed as an insulating sheath pipe in which the periphery of a metal pipe is coated with resin.

[0007] In the above configuration, when lightning strikes the lightning rod 1a of the building 1, the ground potential of the building 1 rises due to the lightning current, and the surge protection elements 4b and 5b are activated, causing part of the lightning current to flow into the building 2. For example, if the distance between buildings 1 and 2 is 9 m, the ground resistances R1 and R2 are both 3.5 Ω, and the lightning current I T As shown in the simulation results in Figure 6, when the current I T1 ,I T2 are branched off into each other.

[0008] If a large current flows through the gas pipe 3 in this way, spark discharges may occur, which may damage the gas pipe 3 and result in adverse effects such as gas leaks and electrolytic corrosion. Therefore, in the past, although not shown, a resistor was inserted in the gas pipe 3 installed between the buildings 1 and 2, or a structure shown in Figures 7 and 8 was adopted to suppress the diversion of lightning current to the building 2. That is, FIG. 7 shows an example in which an insulating tube 6 is inserted in the middle of a buried gas pipe 3, and FIG. 8 shows an example in which a virtual electrode 7 is connected to the buried gas pipe 3 to flow the lightning current to the ground, thereby suppressing diversion to a building 2. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2002-315169 A (

[0024] ,

[0025] , FIG. 4, etc.) Summary of the Invention [Problem to be solved by the invention]

[0010] As a means for suppressing the shunting of lightning current, a resistor is inserted in the middle of the gas pipe as described above, or in the structure shown in Fig. 7, the gas pipe 3 must be cut in the middle before construction. Even in the structure shown in Fig. 8, a lot of work and expense is required for construction, and furthermore, the length of the insulating pipe 6 and the location where the fictitious electrode 7 is buried may be restricted by the site.

[0011] Therefore, the problem to be solved by the present invention is to provide a low-cost shunt current suppression device that can reduce the effort and cost of construction work by using an inductance element that can be easily attached to existing metal pipes such as gas pipes and water pipes, and that has fewer restrictions on where it can be installed. [Means for solving the problem]

[0012] In order to solve the above problems, the invention according to claim 1 provides a method for supplying gas or liquid to two buildings by laying a metal pipe between the buildings and using a metal grounded component of the buildings. A structural material and the metal pipe are bonded to each other by equipotential bonding, and an insulating joint is disposed midway along the metal pipe, and a parallel connection is provided between the insulating joint and a surge protection element for preventing a breakdown of the insulating joint. an inductance element that has high impedance with respect to a shunt current of a lightning current flowing from the metal structural material constituting one of the buildings through the metal pipe to the other building when lightning strikes the building; Near one or both of the two buildings The metal tube Above ground part It is characterized by being attached to

[0013] The invention according to claim 2 is characterized in that, in the shunt current suppression device according to claim 1, the metal pipe is a gas pipe or a water pipe.

[0014] The invention according to claim 3 is characterized in that in the shunt current suppression device according to claim 1 or 2, the inductance element is formed of a magnetic core that is detachable from the metal tube.

[0015] The invention according to claim 4 is characterized in that in the shunt current suppression device according to claim 1 or 2, the inductance element is formed of a coil member connected to the metal pipe. Effect of the Invention

[0016] According to the present invention, when lightning strikes one building, part of the lightning current is diverted from the metal structural material of the building through a metal pipe such as a gas pipe and a surge protection element to the other building. At this time, the inductance element attached midway through the metal pipe acts as a high impedance element, thereby suppressing the diverted current flowing to the ground via the other building. Furthermore, if the inductance element is made of a magnetic core that can be attached to and detached from a metal pipe, it can be easily applied to an existing metal pipe, reducing the effort and time required for installation work and reducing costs. [Brief description of the drawings]

[0017] [Figure 1] 1 is a configuration diagram of a shunt current suppression device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram of an inductance element in FIG. [Diagram 3] FIG. 4 is a current waveform diagram showing a simulation result at the time of a lightning strike in the embodiment of the present invention. [Figure 4] FIG. 1 is a configuration diagram of a lightning protection system described in Patent Document 1. [Diagram 5] FIG. 1 is an explanatory diagram showing the layout of gas pipes between two buildings. [Figure 6] 6 is a current waveform diagram showing a simulation result at the time of a lightning strike in FIG. 5. FIG. [Figure 7] FIG. 1 is a configuration diagram showing a conventional shunt current suppression device installed between two buildings. [Figure 8] FIG. 1 is a configuration diagram showing a conventional shunt current suppression device installed between two buildings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a shunt current suppression device according to this embodiment, and the same parts as those in FIG. 5 are given the same reference numerals and their explanations are omitted. The following explanation will focus on the parts that differ from FIG.

[0019] In this embodiment, a magnetic core 8 serving as an inductance element is attached to the above-ground portion of a gas pipe 3 laid between buildings 1 and 2. Here, the magnetic core 8 is desirably attached to the gas pipe 3 near a building where lightning may strike, and may be attached to the building 1 side or the building 2 side as shown in FIG. 2, the magnetic core 8 is formed into a cylindrical shape by, for example, opening a pair of magnetic pieces 8a and 8b having a semicircular cross section around a fulcrum 8c, surrounding the gas pipe 3, and then connecting them at a connecting portion 8d, so as to be attached to the gas pipe 3. Here, the shape and structure of the magnetic core are not limited to those shown in FIG. 2, and it is sufficient if it is attached to an appropriate position of the gas pipe 3 and functions as an inductance element. Instead of the magnetic core 8, a coil member electrically connected to the gas pipe 3 and wound around the gas pipe may be used as the inductance element.

[0020] FIG. 3 shows the results of a simulation of the current distribution state when the building 1 is struck by lightning using this embodiment equipped with the magnetic core 8. The simulation conditions were the same as in Figure 6. The distance between buildings 1 and 2 was 9 m, the ground resistances R1 and R2 were both 3.5 Ω, and the lightning current I T was set to 200 kA.

[0021] In this case, as is clear from Figure 3, the lightning current I T Current I T1 (=190 kA) flows on the other side of the building 2 due to the increase in impedance caused by the magnetic core 8 installed in the middle of the gas pipe 3. T Current I T2 It was confirmed that only (=10[kA]) flows. That is, by attaching the magnetic core 8 to the gas pipe 3, the lightning current I T It is now possible to significantly reduce the shunt current to building 2 due to this.

[0022] In addition to the gas pipe described as an embodiment, the present invention can also suppress shunt current flowing from one building to the other when a magnetic core or coil member is attached to a metal water pipe laid between two buildings. [Explanation of symbols]

[0023] 1,2:Buildings 1a,2a: Lightning rod 1b,2b: Equipotential lines 3: Gas pipe (metal pipe) 4a,5a: Insulating joints 4b, 5b: Surge protection element 8: Magnetic core (inductance element) 8a, 8b: Magnetic piece 8c:Fulcrum part 8d: Connecting part

Claims

1. A metal pipe for supplying gas or liquid is laid between two buildings, and a metal structural material which is a component of the building and is grounded is equipotentially bonded to the metal pipe, and an insulating joint is arranged midway along the metal pipe, and a parallel connection is provided between the insulating joint and a surge protection element for preventing a breakdown of the insulating joint; A shunt current suppression device characterized by having an inductance element that provides high impedance to the shunt current of the lightning current flowing from the metal structural material that constitutes one of the buildings through the metal pipe to the other building when lightning strikes the building, attached to the above-ground portion of the metal pipe near one or both of the two buildings.

2. 2. The shunt current suppression device according to claim 1, 13. A shunt current suppression device, wherein the metal pipe is a gas pipe or a water pipe.

3. The shunt current suppression device according to claim 1 or 2, A shunt current suppression device, characterized in that the inductance element is constituted by a magnetic core that is detachable from the metal tube.

4. The shunt current suppression device according to claim 1 or 2, A shunt current suppression device, wherein the inductance element is formed of a coil member connected to the metal pipe.

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