JP2015226406A - Counter flow thunderbolt protection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently make a lightning surge current flow to ground at the lightning strike to a tower body and the like of user facilities to protect facility equipment and a power distribution facility in the user facilities against a counter flow thunderbolt.SOLUTION: Provided is a device that is used for a system for supplying a secondary side voltage of a pole transformer 23 to facility equipment 14 via a low-voltage lead-in line 25 as a power supply voltage, the facility equipment 14 being grounded at a user side ground 11 via an SPD 13, and that protects the facility equipment 14 and a power distribution facility 2 and the like at the lightning strike to a tower body 10. In the device, discharge gaps 31 and 32 whose operation voltage is lower than the SPD 13 are connected between a user side ground 11 connected with the tower body 10 and the facility equipment 14, and a power distribution facility side ground provided at the power distribution facility 2 (a B-type ground 26a and an overhead earth wire ground 27a). SPDs 41 and 42 are connected between a secondary side of a pole transformer 23 and a ground line 26. These discharge gaps 31 and 32 and SPDs 41 and 42 configure a counter flow thunderbolt protection device 100.

Description

  The present invention relates to a reverse lightning protection device that efficiently flows a lightning surge current to the ground during a lightning strike to a customer facility to which power is supplied from a power distribution facility, thereby protecting the customer facility and the power distribution facility.

  High structures (hereinafter simply referred to as towers) such as towers for transmitting and receiving antennas of telephone exchanges and mobile communication base stations and wind turbines of wind power plants are not only tall metal structures but also their properties. Often built on top, mountain peaks, ridges, etc. Therefore, the tower body is susceptible to lightning strikes.

  Various equipment such as communication equipment installed in telephone exchanges, mobile communication base stations, and other facilities (hereinafter referred to as customer facilities) are connected via a low-voltage service line from the pole transformer of the adjacent power distribution equipment. Power is supplied. For this reason, when lightning strikes the tower of a customer facility, surge current due to a so-called reverse current lightning flows from the low-voltage lead-in line to the distribution equipment side due to an increase in the ground potential of the customer facility. There is a risk of damage to gripping insulators, grounding wires, distribution poles, etc. Therefore, it is essential to take measures to prevent the spillover damage to the power distribution facilities during lightning strikes on the tower.

Here, the prior art will be described with reference to the drawings.
FIG. 2 is a configuration diagram of a conventional lightning surge protection system. FIG. 2 shows a case where the customer facility 1 is a telephone exchange and the tower 10 is a radio tower. Power is supplied from the power distribution facility 2 to the customer facility 1. In FIG. 2, G indicates the ground surface.

  In the customer facility 1, the lightning rod 10a of the tower body 10 is grounded at the customer side ground 11 through the ground line 10b. The equipment 14 such as communication equipment in the building 12 is also grounded at the customer side ground 11 through an SPD (surge protection element) 13 using a varistor or the like.

In the power distribution facility 2, high-voltage distribution lines 21 and overhead ground wires 22 are installed on a plurality of distribution poles 20. In addition, 20a is a reinforcing bar of the power distribution column 20.
A single-phase three-wire pole transformer 23 is mounted on the distribution pole 20 adjacent to the customer facility 1 in a state where insulation is secured by a gripping insulator 24 (lightning arrester). The high voltage distribution line 21 is connected to the primary winding 231 of the pole transformer 23, and the secondary winding 232 of the pole transformer 23 is connected to the equipment 14 in the building 12 via the low voltage lead-in wire 25. Yes. As a result, the power supply voltage is supplied to the equipment 14 from the pole transformer 23 via the low-voltage lead-in wire 25.

A neutral wire 23n on the secondary side of the pole transformer 23 is grounded together with one end of the gripping insulator 24 via a ground wire 26 at a class B ground 26a. The overhead ground wire 22 is substantially connected to the reinforcing bar 20a of each distribution column 20, and the reinforcing bar 20a is grounded by the distribution column grounding 20b. Further, the overhead ground wire 22 is grounded by the overhead ground wire ground 27 a via the ground wire 27.
It should be noted that the broken line between the reinforcing bar 20a and the overhead ground wire 22 and the broken line between the reinforcing bar 20a and the casing of the pole transformer 23 in FIG. 2 indicate that they are substantially electrically connected. . A broken line between the reinforcing bar 20a and the distribution pole grounding 20b indicates a grounding resistance due to the reinforcing bar foundation.

  On the other hand, another prior art for preventing lightning damage between a customer facility and a power distribution facility is also disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-31466. In this prior art, when a distribution line receives a lightning strike, the lightning surge current is diverted to the shield side of the communication line to prevent insulation breakdown of the distribution board relay.

Another prior art is disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2002-320319). In this prior art, the grounding of high structures such as wind power plants and wireless relay stations and the ground of the distribution line are connected by a grounding line, and the lightning surge current flowing to the high structure during a lightning strike To prevent the damage to the lightning arrester on the high structure side.
Furthermore, another prior art is disclosed in Patent Document 3 (Japanese Patent Laid-Open No. 2007-300744). In this prior art, by providing a reverse flash prevention device, lightning damage is prevented from spreading from a specific customer to the distribution facility side.

JP 2007-31466 A (paragraph [0044], FIG. 4 etc.) JP 2002-320319 A (paragraph [0024], FIG. 4 etc.) JP 2007-300744 A (paragraph [0017], FIG. 1 etc.)

  In FIG. 2 described above, when lightning strikes the lightning rod 10a of the tower body 10, a lightning surge current flows to the customer side ground 11 via the ground line 10b. However, when the ground resistance of the customer facility 1 constructed at the summit or the like is relatively high, a large potential difference is generated between the low-voltage distribution line 25 and the ground potential of the customer-side ground 11 due to lightning. For this reason, the low-pressure SPD 13 is operated by so-called backflow lightning, and a lightning surge current may flow into the distribution facility 2 via the low-voltage distribution line 25.

The lightning surge current associated with backflow lightning is extremely large, and this tendency is particularly noticeable in the case of winter lightning with a large amount of charge (high energy). Damage may not be prevented if surge current flows.
In addition, the lightning surge current caused by backflow lightning damages the equipment 14 of the customer facility 1, and further, the pole transformer 23, the grip insulator 24, the overhead ground wire 22, the ground wires 26 and 27, the reinforcing bars on the power distribution equipment 2 side. There was also a risk of damage spreading due to inflow into 20a and the like. Or the lightning surge current flowed to the ground on the power distribution equipment 2 side, causing problems such as raising the ground potential.

  It is effective to reduce the ground resistance of the customer-side ground 11 as much as possible in order to prevent damage to equipment and accidents caused by backflow lightning as described above, but the customer facility 1 including the tower body 10 is It is often built in places that are not suitable for obtaining low ground resistance, such as mountain peaks and ridges. Under such location conditions, it is not always easy to reduce the ground resistance to a desired level because of construction costs and the like.

Moreover, although the prior art described in patent document 1 makes a communication line pass as a detour of a lightning surge, since there exists a possibility that a communication apparatus may be damaged by a lightning surge, there exists room for improvement.
Furthermore, the prior art described in Patent Document 2 has a problem that the ground resistance value changes due to the ground wire between the ground of the high structure and the ground of the power distribution facility. The technology does not take into account lightning strikes, such as winter lightning.

  Therefore, the problem to be solved by the present invention is to prevent damage to equipment and power distribution equipment in the customer facility by efficiently flowing a lightning surge current to the ground when there is a lightning strike on the tower of the customer facility. An object of the present invention is to provide a reverse lightning protection device.

In order to solve the above-mentioned problems, the invention according to claim 1 includes a customer facility including a tower and equipment, a high-voltage distribution line, an overhead ground line, and a pole transformer in which the high-voltage distribution line is connected to a primary side. A secondary side voltage of the pole transformer is supplied as a power supply voltage to the equipment via a low-voltage lead-in line, and the equipment is provided via the first surge protection element. Back grounding lightning for protecting at least the equipment and the power distribution equipment when the ground potential of the customer facility rises due to a lightning strike to the tower body. In the protective device,
Operating voltage lower than that of the first surge protection element connected between the customer side ground connected to the tower body and the first surge protection element and the distribution equipment side ground provided in the power distribution equipment A discharge gap having
Second and third surge protection elements respectively connected between both ends excluding the neutral line of the secondary winding of the pole transformer and the distribution equipment side ground;
It is provided with.

  The invention according to claim 2 is the reverse current lightning protection device according to claim 1, wherein the distribution facility side ground is a class B ground connected to a neutral wire of the secondary winding of the pole transformer, An aerial ground wire connected to the aerial ground wire.

According to the present invention, when lightning strikes to the tower of a customer facility, etc., the lightning surge is efficiently flowed to the ground, so that the equipment equipment of the customer facility and the various power distribution equipment of the power distribution equipment are damaged by backflow lightning. Can be prevented.
In the present invention, since most of the existing equipment can be used as it is, it can be realized at low cost.

1 is an overall configuration diagram showing an embodiment of the present invention. It is a whole block diagram which shows a prior art.

Hereinafter, an embodiment of the present invention will be described with reference to FIG. Although there are matters in common with the prior art of FIG. 2 described above, they will be described again for clarity.
In FIG. 1, for example, a tower 10 is a radio tower if the customer facility 1 is a telephone exchange, a tower for a transmission / reception antenna if the customer facility 1 is a mobile communication base station, and a customer facility. If 1 is a wind power plant, it corresponds to a windmill, and besides these, high-structure towers in various customer facilities are targeted. In this embodiment, the case where the customer facility 1 is a telephone exchange constructed at the summit and the tower body 10 is a radio tower is illustrated.

A lightning rod 10a is installed on the top of the tower body 10, and this lightning rod 10a is grounded at the customer side ground 11 through a grounding wire 10b.
Here, in the customer facility 1, it is desirable to construct the customer-side ground 11 after performing a ground resistance reduction construction or the like. By making the ground resistance of the customer-side ground 11 as small as possible, it is possible to prevent an extreme increase in ground potential during a lightning strike to the lightning rod 10a.

  In the building 12 of the customer facility 1, equipment devices 14 such as various communication devices and a first SPD 13 for performing the function of a telephone exchange are installed. One end of the SPD 13 is grounded at the customer side ground 11.

  On the other hand, in the power distribution facility 2, a high voltage distribution line 21 and an overhead ground wire 22 are installed on the distribution pole 20. The power distribution poles 20 are concrete power poles, and a plurality of power distribution poles 20 are built at predetermined intervals (for example, 30 m intervals), and support the high-voltage distribution lines 21 and the overhead ground wires 22. A reinforcing bar 20a is provided inside the power distribution column 20, and is connected and fixed to the underground reinforcing bar foundation. This reinforcing bar foundation functions electrically as a distribution pole ground 20b.

The high-voltage distribution line 21 is installed on the distribution column 20 with a lever (not shown) and is used as a main line for power supply.
The overhead ground wire 22 is installed on the top of the power distribution column 20 and, for example, a galvanized steel stranded wire or a bare wire such as a copper single wire is used. The overhead ground wire 22 is led to a pin insulator (not shown) on the top of the distribution pole 20.

A distribution pole 20 adjacent to the customer facility 1 is provided with a single-phase three-wire pole transformer 23. The primary winding 231 (high voltage side) of the pole transformer 23 is connected to the high voltage distribution line 21, and the voltage of the secondary winding 232 (low voltage side) is supplied to the customer facility 1 via the low voltage lead-in wire 25. Is supplied to the equipment 14 in the building 12 as a power supply voltage.
Both ends of the secondary winding 232 except for the neutral wire 23n are connected to one end of each of the second and third SPDs 41 and 42 whose operating voltage is 1000 V, for example, in the reverse lightning protection device 100. The other ends of the SPDs 41 and 42 are collectively connected to the ground line 26. The ground line 26 is grounded by a B-type ground 26a.

  A gripping insulator (lightning arrester) 24 is connected between the primary side of the pole transformer 23 and the ground wire 26, and the connection point between the grip insulator 24 and the ground wire 26 is connected to the casing of the pole transformer 23. It is connected. The neutral line 23n is connected to the ground line 26 through the bypass line 28.

Further, a first discharge gap 31 and a second discharge gap 32 are connected in parallel in the backflow lightning protection device 100 between the grounding end of the SPD 13 in the building 12 and the grounding line 26. . Further, the connection point between the discharge gaps 31 and 32 on the ground wire 26 side is connected to a ground wire 27 for grounding the overhead ground wire 22, and this ground wire 27 is grounded by an overhead ground wire ground 27a. .
In the first and second discharge gaps 31 and 32, the gap length of the electrodes facing each other in the inert gas is, for example, several hundred μm to several mm, the operating voltage is, for example, 1000 V, and the first in the building 12. The SPD 13 is set to a value lower than the operating voltage.

As is well known, the electrical equipment technical standards regulate the connection between the customer-side ground 11 and the B-type ground 26a. For this reason, in the embodiment of FIG. 1, the customer side ground 11 and the B-type ground 26a are normally insulated by the discharge gaps 31 and 32. This point is the same as the customer side ground 11 and the aerial ground. The same applies to the path to the line ground 27a.
However, when the ground potential of the customer facility 1 rises due to a lightning strike to the lightning rod 10a and the voltage across the discharge gaps 31 and 32 exceeds the operating voltage, the discharge gaps 31 and 32 are discharged, and the lightning surge current is B-type grounding. 26a or an overhead ground wire ground 27a is formed.

Here, in order to prevent melting damage due to lightning surge current, ground wires 26 and 27 are thicker than usual, for example, copper wires having a cross-sectional area of 38 mm ² or more.
The distribution pole grounding 20b, the B type grounding 26a, and the overhead ground wire grounding 27a correspond to the distribution facility side grounding in the claims.

In this embodiment, by providing the reverse lightning protection device 100 having the first and second discharge gaps 31 and 32 and the second and third SPDs 41 and 42, the following operational effects can be obtained. .
That is, even if the ground potential of the customer facility 1 (the potential at the grounding end of the SPD 13) is significantly increased during a lightning strike on the tower body 10, the lightning surge current is generated in the first and second discharge gaps 31 and 32. To the B-type grounding 26a side or the overhead ground wire grounding 27a side. For this reason, the lightning surge current which flows into SPD13 in the building 12, equipment 14, the secondary side of the pole transformer 23, the holding insulator 24, etc. can be suppressed, and these damages can be prevented.

Further, since the ground lines 26 and 27 are connected to each other, a plurality of current paths to the ground side of the lightning surge current are provided, and the lightning surge flowing into the secondary side of the pole transformer 23 and the gripping insulator 24 side. It is possible to further reduce the current. At the same time, the frequency of loss of the distribution poles 20 can be reduced.
Furthermore, the lightning surge current flowing through the secondary winding 232 is reduced by connecting the second and third SPDs 41 and 42 between both ends of the secondary winding 232 of the pole transformer 23 and the ground wire 26. It is possible to suppress the lightning overvoltage generated between the lines.

As described above, according to this embodiment, even when the duration is long and the energy is large, especially in winter lightning, the lightning surge current flows into the distribution facility 2 side via the low-voltage lead-in wire 25. It is possible to prevent damage to various facilities and distribution poles.
Further, the backflow lightning protection device according to this embodiment can use the existing equipment shown in FIG. 2 as it is, and can be installed at low cost.

  The backflow lightning protection device according to the present invention can be applied to protection from backflow lightning at, for example, a telephone exchange, a mobile communication base station, a wind power plant, or the like that is constructed on the summit or ridgeline.

1: Customer facility 10: Tower 10a: Lightning rod 10b: Ground wire 11: Customer side ground 12: Building 13: First SPD
14: Facility equipment 2: Distribution facility 20: Distribution pole 20a: Reinforcing bar 20b: Distribution pole ground 21: High-voltage distribution line 22: Overhead ground wire 23: Overhead transformer 23n: Neutral wire 231: Primary winding 232: Secondary Winding 24: Grasping insulator 25: Low-voltage lead-in wire 26, 27: Grounding wire 26a: Class B grounding 27a: Aerial ground wire grounding 28, 33, 34: Bypass wire
31: First discharge gap 32: Second discharge gap 41: Second SPD
42: Third SPD
100: Backflow lightning protection device G: Ground surface

Claims (2)

A customer facility including a tower and equipment, and a power distribution facility including a high-voltage distribution line, an overhead ground line, and a pole transformer connected to the primary side of the high-voltage distribution line, and the pole transformer Targeting a system in which a secondary-side voltage is supplied as a power supply voltage to the equipment via a low-voltage lead-in line, and the equipment is grounded at a customer-side ground via a first surge protection element In the backflow lightning protection device for protecting at least the equipment and the power distribution equipment when the ground potential of the customer facility is increased by a lightning strike to the tower body,
Operating voltage lower than that of the first surge protection element connected between the customer side ground connected to the tower body and the first surge protection element and the distribution equipment side ground provided in the power distribution equipment A discharge gap having
Second and third surge protection elements respectively connected between both ends excluding the neutral line of the secondary winding of the pole transformer and the distribution equipment side ground;
A reverse lightning protection device comprising: In the backflow lightning protection device according to claim 1,
The distribution facility side ground includes a B-type ground connected to a neutral wire of the secondary winding of the pole transformer, and an overhead ground wire ground connected to the overhead ground wire. Backflow lightning protection device.

Images