JPH07272825A - Arrester insulator device - Google Patents

Abstract

PURPOSE:To allow the device to work well with lightning in the winter period which attacks directly a power transmission cable by reducing the burden of an arresting insulator for the lightning surge current, with which it is not required to provide a plurality of arresting insulators in parallel or constructing insulator in a large size. CONSTITUTION:A power transmission cable is supported on a supporting arm 2 of a steel tower 1 through a support insulator 3. At the foremost of the supporting arm 2, an arresting insulator 8 with a buit-in current-limiting element is danglingly supported through a mounting adapter 7. A discharge electrode 6 on the electricity charging side is installed at the bottom of the support insulator 3. At the bottom of the arresting insulator 8, a discharge electrode 11 on the ground side which mates with the discharge electrode 6 while a certain aerial discharge gap G is reserved is installed. A ground electrode 16 is coupled with the bottom of the steel tower 1 through a resistor 17 consisting of zinc oxide, silicon carbide, etc., and is buried under the ground E. The ground resistance value of the steel tower 1 grounded through the ground electrode 16 is set between 30-400OMEGA through adjustment of the resistance value of the resistor 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning arrester device capable of promptly discharging a lightning surge current that has entered a power line due to a lightning stroke to the ground and interrupting a subsequent current flow thereafter.

[0002]

2. Description of the Related Art Generally, a power line is supported on a support arm of a steel tower via a support insulator, and a lightning arrester is supported on the tip of the support arm. Inside the lightning protection insulator, a current limiting element mainly made of zinc oxide having a non-linear voltage-current characteristic is housed. A discharge electrode on the charging side is provided at the lower end of the support insulator, and a discharge electrode on the ground side is provided at the lower end of the lightning arrestor, and both discharge electrodes face each other with a predetermined air discharge gap. And
When a lightning surge current due to a lightning strike enters the power line, the current is flashed from the discharge electrode on the charging side of the supporting insulator to the discharge electrode on the grounding side of the lightning insulator, and is supported through the current limiting element in the lightning insulator. It flows through the arm and the tower and is discharged to the ground. Further, the subsequent current is suppressed and cut off by the current limiting element.

By the way, when there is a direct lightning strike on a power line between adjacent towers, a lightning surge current due to the lightning flows to two adjacent tower sides via the power line. In this case, the lightning surge current is a lightning strike on the power line. The lightning insulator installed on the steel tower closer to the point is flashed over first.
Then, the lightning surge current flows concentratedly on the lightning arrester on the flashover side, and about 80% of the lightning surge current is applied to one lightning arrester. Therefore, when there is a direct lightning strike on the power line, the duty of the lightning arrestor on the lightning surge current becomes strict.

Incidentally, when there is a lightning strike on a steel tower or an overhead ground wire installed at the tip of the steel tower, the lightning surge current due to the lightning strike is larger than the lightning surge current due to the direct lightning strike on the power line. In many cases However, most of the lightning surge current flows through the steel tower and is discharged to the ground as it is, and only about 5 to 10% of the lightning surge current is applied to the lightning arrestor, so the lightning striker is less affected by the lightning strike. On the other hand, when there is a direct lightning strike on the power line, the lightning surge current due to the lightning strike is often smaller than the lightning surge current due to the lightning strike on the tower or the overhead ground wire. However, as described above, almost 80% of the lightning surge current is added to the lightning arrestor, so that the lightning striker is greatly affected by the lightning strike. For this reason,
When designing a lightning protection insulator, it is usual to determine the capacity of the current limiting element provided in the lightning protection insulator, assuming a direct lightning strike to the power line.

However, in general, lightning generated in winter (hereinafter referred to as winter lightning) has a large lightning surge current due to the lightning strike and has a long duration. Therefore, when such a winter lightning strikes the power line directly, the duty of the lightning arrestor against the lightning surge current becomes extremely strict, and the lightning insulator deteriorates at an early stage, and in some cases, the lightning insulator reaches its withstand capacity limit. It might have been destroyed.

For this reason, in the past, particularly in an area where winter lightning is likely to occur, a plurality of lightning protection insulators are installed in parallel at the installation location of the lightning protection insulator with respect to the support arm, or as an internal lightning protection insulator. The current limiting element provided in the device has a large diameter and is large in size so that it can withstand the intrusion of an excessive lightning surge current.

[0007]

However, if a plurality of lightning protection insulators are provided in parallel or the size is increased as in the conventional case, the weight of them increases. Therefore, in order to stably support such a heavy weight lightning protection insulator, it is necessary to consider the weight of the lightning protection insulator and to make the support arm and the steel tower a high-strength structure. Those structures are heavy and complicated. There was a problem of becoming. In addition, there is a problem that the installation work of the lightning protection insulator is complicated and troublesome, and the cost required for installing the lightning protection insulator increases.

The present invention has been made to solve the above problems, and an object thereof is to reduce the duty of the lightning arrester against a lightning surge current without providing a plurality of lightning arrestors in parallel or increasing the size thereof. Another object of the present invention is to provide a lightning arrester device that can handle the winter lightning that directly hits the power line.

[0009]

In order to achieve the above object, in the invention of claim 1, a steel tower is erected on the ground, a plurality of support arms are provided on the steel tower, and each support arm has a plurality of support arms. A support insulator supporting the phase power line and a lightning arrestor with a built-in current limiting element are attached respectively, and the support insulator is provided with a discharge electrode on the side of charging, and the lightning insulator has the discharge electrode on the side of charging and a predetermined air In a lightning arrester device provided with discharge electrodes on the ground side facing each other with a discharge gap, the ground resistance value of the steel tower is set to 30 to 400Ω.

According to the second aspect of the invention, a ground electrode buried in the ground is provided at the lower end of the steel tower, a resistor is interposed between the ground electrode and the steel tower, and the resistance value of the resistor is adjusted. By doing so, the ground resistance value of the steel tower is set.

Further, in the invention of claim 3, a ground electrode buried in the ground is provided at the lower end of the steel tower, and the contact area of the ground electrode with respect to the ground is adjusted to set the ground resistance value of the steel tower. It is the one.

[0012]

Therefore, according to the first aspect of the present invention, when a lightning surge current due to a lightning strike flows through the power line, the current is flashed from the discharge electrode on the charging side of the supporting insulator to the discharge electrode on the grounding side of the lightning arrester. At the same time, it flows through the support arm and the steel tower through the current limiting element in the lightning protection insulator, and is discharged to the ground. Further, the subsequent current is suppressed and cut off by the current limiting element.

At this time, the ground resistance value of the steel tower is 30 to 40.
The large value of 0Ω makes it difficult for the lightning surge current to be discharged from the tower to the ground. As a result, the lightning surge current that is flashed over from the discharge electrode on the charging side to the discharge electrode on the ground side becomes smaller, so the lightning surge current flowing through the lightning arrestor becomes smaller and the duty of the lightning insulator against the lightning surge current is reduced. To be done.

Since the lightning surge current is not easily discharged from the tower to the ground, when there is a lightning strike on the tower, a flashover occurs from the grounding side discharge electrode of the lightning arrestor to the charging side discharge electrode of the support insulator. Lightning surge current increases. As a result, the lightning surge current flowing through the lightning protection insulator increases, and the duty of the lightning protection insulator against the lightning surge current increases. However, when there is a lightning strike to the tower, the lightning surge current that flows through the lightning insulator is originally smaller than when there is a direct lightning strike to the power line. Is not so great as to impair the performance of the lightning protection insulator.

That is, when the ground resistance value of the steel tower is gradually increased, the duty for the lightning surge current of the lightning arrestor is gradually decreased in the case of direct power line lightning, and the lightning surge current of the lightning insulator is increased in the tower lightning. Responsibility for is gradually increased. It was confirmed that as the ground resistance value of the steel tower approaches 400Ω, the responsibility of the lightning arrestor against the lightning surge current becomes almost the same in the case of the direct power line strike and the tower lightning. For this reason, the ground resistance of the steel tower should be 30
Even if the duty for lightning surge current of the lightning insulator is reduced in the case of a direct power line direct lightning strike, it will not cause any trouble in the lightning strike to the steel tower.

Incidentally, the ground resistance value of the steel tower is 30 to 400.
In the case of a large Ω, it is necessary to provide lightning protection insulators corresponding to the power lines of multiple phases. That is,
When there is a lightning stroke on a steel tower with a large ground resistance value, as described above, the lightning surge current due to the lightning stroke is unlikely to be discharged from the steel tower to the ground. For this reason, if the lightning protection insulator is not provided for all power lines, the lightning surge current is not discharged promptly, and the potential on the tower side rises significantly, resulting in accidents of the support insulators and power lines. There was a problem of fear. However, in the present invention, since the lightning protection insulator is provided corresponding to each of the power lines of a plurality of phases, there is no fear of the above problems occurring.

According to the second aspect of the invention, when the resistance value of the ground at the installation location of the steel tower is relatively small, a resistance element is interposed between the ground electrode and the steel tower, and the resistance value of the resistance element is set. By adjusting the ground resistance value of the steel tower to 30 ~
It may be set to 400Ω.

Further, according to the invention of claim 3, when the resistance value of the ground at the installation location of the steel tower is originally large, the contact area of the ground electrode with respect to the ground is adjusted without providing a resistor. , The ground resistance of the tower is 30
It may be set to 400 Ω.

[0019]

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 and 2, a large number of steel towers 1 are erected on a ground E along a power line, and support arms 2 are respectively supported on the left and right sides of the towers at upper, middle, and lower stages at predetermined intervals. ing. A tension-type support insulator 3 is hung and fixed to the tip of each support arm 2, and two lines of three-phase power lines 5 are supported at the lower end of each support insulator 3 via wire gripping metal fittings 4. It extends in a direction orthogonal to 2. Further, a discharge electrode 6 on the charging side is attached to the wire gripping metal 4.

A mounting adapter 7 is attached to the tip of each of the support arms 2 so as to project in a direction orthogonal to the extending direction of the power line 5, and a lightning protection insulator 8 is attached to the tip of the mounting adapter 7. The grounding side flange fitting 9 is provided so as to be suspended and fixed. Further, a grounding-side discharge electrode 11 is attached to a charge-side electrode metal fitting 10 provided at the lower end of the lightning protection insulator 8, and the discharge electrode 11 is connected to the charge-side discharge electrode 6 in a predetermined air. The discharge gaps G are opposed to each other.

The lightning protection insulator 8 is provided inside with a current limiting element 12 mainly composed of zinc oxide (ZnO) having a non-linear voltage-current characteristic, and the current limiting element 12 is made of a tension-resistant material such as FRP. They are housed in series in a cylindrical pressure-proof insulating cylinder (not shown). The flange metal fitting 9 and the electrode-side metal fitting 10 are fitted and fixed to both ends of the pressure-proof insulating cylinder. Further, the outer circumference of the pressure-proof insulating cylinder is covered with a rubber mold 13. In addition, arc horns 14 and 15 are attached to the flange metal member 9 and the electrode metal member 10 on the power-supply side to reduce the damage of the rubber mold 13 when the surface flashes.

By the way, in this embodiment, the ground resistance value of the steel tower 1 is set to 30 to 400Ω. That is, as shown in FIG. 1, a ground electrode 16 made of a conductive metal rod is connected to the lower end of the steel tower 1 through a resistor 17, and the ground electrode 16 is buried in the earth E. The steel tower 1 is grounded to the earth E via the ground electrode 16. The resistor 17 is made of, for example, zinc oxide (ZnO) or silicon carbide (SiC), and the ground resistance value of the steel tower 1 grounded via the ground electrode 16 is 30 to 30 by adjusting the resistance value thereof. It is set to 400Ω. That is, when the resistance value of the ground E at the installation location of the steel tower 1 is relatively small, the resistor 17 is interposed between the steel tower 1 and the ground electrode 16 in order to increase the ground resistance value of the steel tower 1. .

Although not particularly shown, if the resistance value of the ground E at the installation location of the steel tower 1 is originally large, the ground electrode 16 is directly connected to the lower end of the steel tower 1 without providing the resistor 17. Then, the ground resistance value of the steel tower 1 may be set to 30 to 400 Ω by adjusting the length of the ground electrode 16 and the contact area of the electrode 16 with the ground E.

Reference numeral 18 denotes an overhead ground wire which is installed between the tops of the steel towers 1. By receiving a lightning strike from the overhead ground wire 18, a lightning strike on the power line 5 is prevented as much as possible.

Next, the operation of the lightning protection insulator device constructed as described above will be described. Now, first, the operation when there is a direct lightning strike on the power line 5 will be described with reference to the equivalent circuit shown in FIG. In FIG. 3, C is a cloud, I is a current caused by a lightning stroke, Re is an impedance of a lightning path through which lightning passes, Rp is an impedance of a power line, Ra is an impedance of a tower, and Rt is a ground resistance of the tower 1. When there is a lightning strike on the power line 5, a lightning surge current due to the lightning strike flows through the power line 5. Then, the current flows to the discharge electrode 6 on the charging side via the wire gripping metal 4, and is also flashed from the discharge electrode 6 to the discharge electrode 11 on the ground side through the air discharge gap G. Then, the lightning surge current flows through the electrode fitting 10, the current limiting element 12, the flange fitting 9, the mounting adapter 7, and the support arm 2 to the tower 1, and is further discharged through the resistor 17 to the ground E by the ground electrode 16. .
Further, the subsequent current generated thereafter is suppressed and cut off by the current limiting element 12.

At this time, in the present embodiment, the value of the ground resistance Rt of the steel tower 1 is set to a large value of 30 to 400 Ω as compared with the value of 10 Ω which is a conventionally set value. Therefore, the lightning surge current is transmitted from the tower 1 to the ground E.
It becomes difficult to be discharged. As a result, the lightning surge current flashed from the discharge electrode 6 on the charging side of the supporting insulator 3 to the discharge electrode 11 on the grounding side of the lightning protection insulator 8 becomes small.
The lightning surge current flowing through the lightning protection insulator 8 becomes small. Therefore, it is possible to reduce the duty of the lightning protection insulator 8 on the lightning surge current.

The amount of lightning surge current flashed over to the discharge electrode 11 on the ground side is reduced, so that the lightning surge current flows to the power line 5 side.
Above, the flashover is carried out from the support insulator 3 to the lightning protection insulator 11 side. Therefore, even if the lightning surge current easily flows to the power line 5 side, the current is shunted to the plurality of lightning protection insulators 8 and discharged to the ground E reliably, so that no trouble occurs. In this case, since the lightning surge current flowing through one lightning protection insulator 8 is shunted and reduced, each lightning protection insulator 8
The responsibilities for lightning surge currents in the world are not severe.

Therefore, in a region where winter lightning is likely to occur, even if the lightning protection insulator 8 equivalent to that in the region where there is no danger of winter lightning is similarly installed, there is no risk of early deterioration or destruction of the lightning protection insulator 8 and the power line. It is possible to reliably deal with winter lightning that hits directly on 5. Therefore, unlike the above-mentioned conventional, by providing a plurality of lightning protection insulators in parallel or increasing the size, the work of installing the lightning protection insulator becomes complicated and troublesome, and the structure of the support arm and the tower becomes complicated due to heavy pressure. Therefore, the cost required to install the lightning protection insulator 8 can be reduced. Further, since the duty of the lightning protection insulator 8 on the lightning surge current is reduced, the lightning protection insulator 8 can be downsized.

Next, the operation when there is a lightning strike on the tower 1 or the overhead ground wire 18 will be described with reference to the equivalent circuit shown in FIG. When there is a lightning strike on the steel tower 1 or the overhead ground wire 18, the lightning surge current due to the lightning strike is generated by the steel tower 1 and the resistor 1.
After that, it is discharged to the ground E by the ground electrode 16. At this time, as described above, in this embodiment, the value of the ground resistance Rt of the steel tower 1 is set to a large value, and the lightning surge current is unlikely to be discharged from the steel tower 1 to the ground E. Therefore, the lightning surge current flashed from the discharge electrode 11 on the ground side of the lightning protection insulator 8 to the discharge electrode 6 on the charging side of the support insulator 3 becomes large. As a result, the lightning surge current flowing through the lightning protection insulator 8 becomes large, and the duty of the lightning protection insulator 8 for the lightning surge current increases. However, when there is a lightning strike to the tower 1 or the overhead ground wire 18, the lightning surge current flowing through the lightning protection insulator 8 is originally smaller than when there is a direct lightning strike to the power line 5, Even if the duty of the lightning protection insulator 8 against the lightning surge current increases, the performance of the lightning protection insulator 8 is not hindered.

Here, the relationship between the value of the ground resistance Rt of the steel tower 1 and the duty of the lightning protection insulator 8 against the lightning surge current in the case of a direct power line lightning strike and a lightning strike to the steel tower 1 and the overhead ground wire 18 is shown. 5 shows. In the figure, when the ground resistance Rt is 10Ω, the duty of the lightning protection insulator 8 at the time of direct power line strike is 100%. As shown in the figure, when the value of the ground resistance Rt of the steel tower 1 is gradually increased, the duty for the lightning surge current of the lightning protection insulator 8 is gradually decreased in the case of a direct power line lightning strike, and the steel tower 1 and the overhead land In the lightning stroke on the line 18, the duty of the lightning protection insulator 8 for the lightning surge current gradually increases. At this time, as is clear from the figure, the value of the ground resistance Rt of the tower 1 is set to 400Ω.
It is easily confirmed that the closer to the above condition, the responsibility for the lightning surge current of the lightning protection insulator 8 becomes almost the same and averaged in the case of the direct power line lightning strike and the lightning strike to the tower 1 and the overhead ground wire 18.

Therefore, the value of the ground resistance Rt of the tower 1 is set to 3
Even if the duty for the lightning surge current of the lightning protection insulator 8 in the case of a direct power line lightning strike is reduced as a large value of 0 to 400 Ω, the duty for the lightning surge current of the lightning protection insulator 8 at the time of a lightning strike to the tower 1 or the overhead ground wire 18 However, it does not increase to such an extent that the performance of the lightning protection insulator 8 is hindered.

Incidentally, the value of the ground resistance Rt of the steel tower 1 is set to 30
In the case of a large value of ~ 400Ω, it is necessary to provide the lightning protection insulator 8 corresponding to each of the plurality of power lines 5. That is, when there is a lightning stroke on the steel tower 1 or the overhead ground wire 18 in the steel tower 1 having a large ground resistance Rt, as described above, the lightning surge current due to the lightning stroke is discharged from the steel tower 1 to the ground E. hard. Therefore, lightning protection insulator 8
If the power line 5 is not provided for all the power lines 5, the lightning surge current is not discharged promptly, and the potential on the tower 1 side increases significantly, which may cause an accident of the support insulator 3 and the power line 5. There was a problem that there is. However, in the present embodiment, since the lightning protection insulator 8 is provided corresponding to each of the plurality of power lines 5, there is no risk of the above problems occurring.

Further, conventionally, various measures had to be taken to reduce the value of the ground resistance Rt of the steel tower 1 to a small value of about 10 Ω, but in the present embodiment, it is almost necessary to take such measures. Since it is eliminated, the cost required to install the steel tower 1 can be reduced.

The present invention is not limited to the above-described embodiment, and the configuration of each part may be modified and embodied as follows. (1) The value of the ground resistance Rt of the steel tower 1 is set within the range of 200 to 400Ω. By setting it within this range, it is possible to further reduce the duty of the lightning protection insulator 8 against the lightning surge current when the power line is directly struck by lightning.

Alternatively, the value of the ground resistance Rt of the steel tower 1 is set to 30
Set within the range of 0 to 400Ω. By setting it within this range, it is possible to further reduce the duty of the lightning protection insulator 8 against the lightning surge current when the power line is directly struck by lightning. In addition, lightning protection insulator 8
Responsible for the lightning surge current of the power line direct lightning and tower 1
In the case of a lightning stroke to the ground wire or the overhead ground wire 18, it can be averaged to almost the same level.

(2) As the ground electrode, a conductive metal material formed in a mesh shape is used, and the ground electrode is spread and embedded in the ground E. At this time, when the resistance value of the ground E at the installation location of the steel tower 1 is originally large, the mesh-shaped ground electrode is directly connected to the lower end of the steel tower 1 without providing the resistor 17, as in the above embodiment. . Then, the ground resistance value of the steel tower 1 is set to 30 to 400Ω by adjusting the area of the ground electrode and the contact area of the ground electrode with the ground E.

(3) As the supporting insulator, in addition to the tension-type supporting insulator 3, for example, a suspending type supporting insulator should be used.

[0038]

As described above in detail, according to the present invention,
It is possible to reduce the responsibility of the lightning arrestor against the lightning surge current without installing multiple lightning arrestors in parallel or increasing the size, and it is possible to reliably deal with winter lightning that directly hits the power line. The excellent effect that the cost required for installing the steel tower can be reduced by almost eliminating the need to reduce the ground resistance value.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an entire steel tower in an embodiment of a lightning arrester device embodying the present invention.

FIG. 2 is a front view showing a lightning protection insulator device.

FIG. 3 is an equivalent circuit diagram for explaining the operation when there is a direct lightning strike on the power line.

FIG. 4 is an equivalent circuit diagram for explaining an operation when there is a lightning strike on a steel tower or an overhead ground wire.

FIG. 5 is a table showing the relationship between the ground resistance value and the duty of the lightning arrester against the lightning surge current in the case of direct lightning strikes on power lines and lightning strikes on steel towers and overhead ground lines.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Tower, 2 ... Support arm, 3 ... Support insulator, 5 ... Power line, 6 ... Discharge electrode on the side of charging, 8 ... Lightning arrester, 11 ... Discharge electrode on the ground side, 12 ... Current limiting element, 16 ... Ground electrode , 17
... resistor, 18 ... overhead ground wire, G ... air discharge gap, E ... ground.

Claims (3)

[Claims] 1. A steel tower is erected on the ground, a plurality of support arms are provided on the steel tower, and each support arm is provided with a support insulator for supporting a plurality of phases of power lines and a lightning protection insulator containing a current limiting element. In the lightning protection insulator device, the supporting insulator is provided with a discharge electrode on the side of charging, and the lightning arrester is provided with a discharge electrode on the ground side facing the discharge electrode on the side of charging with a predetermined air discharge gap. Ground resistance value of 30-40
Lightning arrester device set to 0Ω. 2. The grounding resistance of the steel tower is provided by providing a grounding electrode buried in the ground at the lower end of the steel tower, and by interposing a resistor between the grounding electrode and the steel tower and adjusting the resistance value of the resistor. The lightning protection insulator device according to claim 1, wherein a value is set. 3. The ground resistance value of the steel tower is set by providing a ground electrode buried in the ground at the lower end of the steel tower and adjusting the contact area of the ground electrode with respect to the ground. Lightning insulator device.