JP2008262885A - Multilayer shielded wire for lightning arresting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that, since a conductor wire from a lightning rod to the ground has self inductance, if there is a lightning stroke, an abnormal high voltage is induced by the lightning surge current to cause power failure and troubles of a communication equipment. <P>SOLUTION: An insulator layer and a metal layer are coated overlapping in the order on the outer circumference of a core wire conductor for lightning arresting, alternately several times, and a core conductor with multilayer capacitors is constructed. Then, by a connecting method of each shield and electric wire, the self inductance of the core wire conductor and multilayer capacitors are connected in a parallel circuit to form an electric wire which is reduced in surge impedance and prevents an abnormal high voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lightning current path wire from a lightning rod to the ground.

  Conventionally, in order to prevent human and physical damage due to lightning, it is mandatory to install a lightning rod on high-rise structures, and the conductor that carries lightning current from the lightning rod to the ground is usually made of bare copper stranded wire. However, it is laid almost straight down and connected to a ground electrode buried deep in the ground. However, since this lightning conductor wire has a self-inductance, and the self-inductance has a characteristic of generating a high resistance in proportion to the frequency, the frequency is several tens KHz to several thousand KHz like a lightning current. When high-frequency current tries to flow, high resistance is generated, and abnormally high voltage is generated between the lightning rod on the top of the lightning conductor wire and the ground below, which causes power failure and communication equipment failure, etc. Even if lightning strikes, the function of the lightning rod is not sufficient.

  In Patent Document 1 and Patent Document 2, when lightning strikes a lightning rod, the ground potential at the grounding point increases in proportion to the lightning strike current value. In order to prevent this failure, the semiconductor layer, insulator layer, semiconductor layer, and metal shielding layer are placed on the lightning conductor wire from the lightning rod to the underground buried part. There is an electric wire obtained by insulating lightning conductors formed in order. Some of these aim to reliably discharge lightning currents into the ground and prevent recirculation to the ground.

  In Patent Document 3, there is a cable with a lightning arrester in which a varistor is built in the entire surface of an insulator of a CV cable in order to prevent a high voltage during a lightning strike from entering a CV cable that is energized.

JP 2001-023793 A JP2001-023794 JP 07-272551 A

It is impossible to increase the lightning protection effect in the present situation as long as self-inductance exists essentially to increase the lightning protection effect in current lightning conductor wires and Patent Literature 1, Patent Literature 2, and Patent Literature 3. is there.
Since these lightning conductor wires are laid in a substantially straight line, they naturally have self-inductance in terms of electromagnetic theory. Therefore, the frequency is several tens to several thousand KHz, such as a lightning current, When a large current of 1,000 amperes is about to flow, this self-inductance changes to a high surge impedance, and an abnormal high voltage is generated.
In order to suppress and reduce the abnormal high voltage, it is necessary to reduce the influence of self-inductance, which is a decisive factor for improving the lightning protection effect and is also an object of the present invention.

  In order to achieve the above object, according to the present invention, in claim 1, an insulator layer is coated on a core conductor of a lightning conductor wire, a metal layer is coated thereon, and an insulator layer is further formed thereon. The present invention provides a multi-layer shielded electric wire for lightning protection, characterized in that the coating is formed by coating the metal layer on the coating two or more times.

  In order to achieve the above object, the present invention is characterized in that, in claim 2, before the insulator layer is coated on the core conductor of claim 1, the core conductor is coated with a conductive resin. The multilayer shielded electric wire for lightning protection according to claim 1 is provided.

  As described above, the multi-layer shielded electric wire for lightning protection according to the present invention forms a plurality of capacitors in parallel with the core conductor, and forms a plurality of capacitors in parallel with the core conductor, which is a self-inductance of the core conductor. This is for reducing the size of the image.

As described above, since the multilayer shielded electric wire for lightning protection of the present invention is formed by alternately covering and covering the conductor layers with the insulator layers and the metal layers, the core conductor, the metal layer, and the metal layer of the multilayered electric shield for lightning protection Capacitors are formed between the metal layers.
By connecting multiple capacitors of this multilayer so as to form a parallel circuit with the self-inductance of the lightning conductor wire, self-inductance can be offset, surge impedance can be reduced, and abnormal high voltage can be suppressed and reduced. .
As shown in the examples of the present invention, the surge impedance was suppressed to 1.8%, and a prospect of very good results was obtained. In other words, the abnormal voltage can be suppressed to 1.8%.

  As described above, the high-frequency surge current of lightning current during lightning strikes is easily absorbed by the multi-layer capacitors, and is discharged to the ground through the shield layer, resulting in abnormal voltage. Is prevented from rising.

  As described above, the harmful abnormal high voltage that occurred during a lightning strike is eliminated, and as a result, it is possible to prevent the occurrence of failures such as power outages and semiconductor devices such as computers, and improve the lightning resistance of facilities. I can do it.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 shows a three-layer structure of a lightning protection multi-layer shielded electric wire according to the present invention, in which a first insulating layer 2 is disposed on a lightning conductor wire 1 and a first metal layer 3 is disposed thereon. The second insulating layer 4 is formed thereon, the second metal layer 5 is formed thereon, the third insulating layer 6 is formed thereon, and the third metal layer 7 is formed thereon. A front cross-sectional view and a side cross-sectional view are shown in which a coating 8 is applied and a trauma prevention coating 8 is provided thereon.

  FIG. 2 is substantially the same as the above, but before covering the first insulator layer 2 on the lightning conductor wire, the conductive resin 9 is coated with the conductive resin 9 in order to eliminate the irregularities of the stranded wire of the core conductor. The front cross-section and side cross-sectional view coated on the conductor are shown.

  The insulation material of the lightning protection multilayer shield wire is an insulating dielectric such as cross-linked polyethylene or silicon, and the shield metal is a copper plate or aluminum, and is formed by winding with a plate-like tape or by cylindrical extrusion.

As shown in FIG. 4, when the shield is a three-layer structure electric wire, the capacitor formed on the lightning protection multilayer shield electric wire is connected to the core conductor 1 and the second layer shield at the upper end on the lightning arrester side of the electric wire as shown in FIG. 5 is connected, and the core conductor 1 is connected to the first layer shield 3 and the third layer shield 7 at the lower end on the ground side.
With this connection, a circuit in which three capacitors are connected in parallel is formed on the core conductor and the ground side.

  Since the surge impedance changes proportionally to the lightning surge frequency and affects the judgment of its effect, the frequency is obtained by referring to the lightning surge waveform with a wavefront length of 10 microseconds, referring to the lightning observation records of the Central Research Institute of Electric Power Industry. The frequency was set to 25 KHz.

  The lightning conductor wire of the embodiment employs the three-layer structure shown in FIG. First, in order to eliminate the twisted wire irregularities of the core wire conductor 1, the core wire conductor is coated with the conductive resin 9, and the first layer of insulating polyethylene 2 is coated with the crosslinked polyethylene, and the copper tape 3 is coated thereon. Winding to form the first layer shield. Next, the second layer insulating dielectric 4 is coated with a crosslinked polyethylene, and a copper tape 5 is wound thereon to form a second layer shield. Furthermore, the third layer insulating dielectric 6 is coated with a crosslinked polyethylene, and a copper tape 7 is wound thereon to constitute a third layer shield. On top of that, the resin 8 is covered and protected to prevent the wire from being damaged.

The specification of the Example of the multilayer shielded electric wire for lightning protection of this invention is as follows.
[Conductor relation]
Conductor outer diameter 10.0 [mm]
Conductor cross section 60 [square millimeter]
Conductor resistance 0.301 [Ohm / Km]
Self-inductance 2.8131 × 10 [Henry / Km]
Surge impedance 441.88 [Ohm / Km]
[Insulating dielectric]
Insulator type Cross-linked polyethylene
Dielectric constant 2.3
Insulator thickness 14 [mm]
Outside diameter of conductive resin 14 [mm]
Insulator outer diameter First layer 42 [mm]
Second layer 70 [mm]
Third layer 98 [mm]
Result of calculating capacity based on the above conditions
First layer 1.1632 × 10 [F / Km]
Second layer 2.5017 × 10 [F / Km]
Third layer 3.7980 × 10 [F / Km]
Three-layer capacity total C = 7.4629 × 10 [F / Km]
The surge impedance of the 3-layer type shielded wire for lightning protection is
Z _C3 = 8.2164 [Ohm / Km]

The surge impedance of only the core conductor wire is
Z _T1 = 441.88 [Ohm / Km]
The surge impedance in the case of the three-layer shield type of the present invention is
Z _C3 = 8.2164 [Ohm / Km
The reduction rate of surge impedance is
Z _C3 / Z _T1 × 100 = 1.86%
Thus, the surge impedance of the multi-layer shielded electric wire for lightning protection according to the present invention is greatly reduced, and the occurrence of abnormal high voltage can be greatly expected.

Assuming that a lightning conductor wire is installed at a building height of 30 m, and applying the above embodiment, the induced voltage when a lightning current of 10 KA flows is calculated,
133,000V for bare copper stranded wire for normal use
In the case of the multilayer shielded wire of the present invention, 2500V
This clearly proves that the performance of the multilayer shielded electric wire for lightning protection of the present invention is good.

Industrial applicability

  Lightning strikes are at most several times a year in the same building, but some damage occurs each time a lightning strike occurs. In the current situation where an information society and semiconductor elements are used frequently, high-rise buildings are equipped with many information devices that are weak in pulse and noise, so there is a high possibility of use in office buildings and high-rise apartments. I think that the.

  When lightning strikes a special high-voltage power transmission tower, a so-called reverse flashing phenomenon may occur, in which the insulator is flashed from the tower side and discharged to the wire due to the surge impedance and grounding resistance of the tower, but the surge impedance of the tower is reduced. It may be used to prevent reverse flashover accidents.

  It can be expected to be widely used for arrester grounding wires for high-voltage overhead distribution lines and for lightning rod conductors for radio towers.

Three-layer positive cross section and side cross section of multilayer shielded wire Front and side cross-sectional views of the core conductor surface of a multilayer shielded wire with conductive resin coating Example of installing a lightning protection multi-layer shielded wire in a building Connection diagram of shield and core conductor to form capacitor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core wire conductor 2 1st layer insulator 3 1st layer metal layer 4 2nd layer insulator 5 2nd layer metal layer 6 3rd layer insulator 7 3rd layer metal layer 8 Damage protection coating material 9 Conductive resin coating 10 Lightning rod 11 Insulator 12 Lightning conductor wire 13 Ground electrode 14 Lead wire connecting the wire and shield 15 Lead wire connecting the wire and shield

Claims (2)

  In a lightning protection wire that is connected to a lightning rod and carries lightning current, cover the core conductor with an insulator layer, coat it with a metal layer, coat it with an insulator layer, and coat it with a metal layer. A multi-layer shielded electric wire for lightning protection, which is formed by covering two or more layers alternately.   The multilayer shielded electric wire for lightning protection according to claim 1, wherein the core conductor is coated with a conductive resin before the insulator layer is coated on the core conductor.

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