JPH1042464A - Method for attaching surge protective device to steel tower supporting overhead wires in parallel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for attaching surge protective device to iron tower supporting overhead wires in parallel by which the occurring frequency of flashover accidents in the whole iron tower can be reduced, without increasing the number of surge protective devices. SOLUTION: At the time of attaching surge protective devices 1 to one-side lines of a iron tower supporting four or more lines, the devices 1 for top-side lines and devices 1 for bottom-side lines are staggeredly attached to the lines on the opposite sides of the support of the iron tower. The voltage across the insulator strings of lines having no surge protective devices can be lowered, and the occurring frequency of flashover accidents can be reduced than the conventional example where the surge protective devices are attached to lines on one side of the support.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a lightning arrester in a tower having four or more lines.

[0002]

2. Description of the Related Art As shown in FIG. 1, a parallel tower means a tower supporting four or more power lines. In general three-phase AC, one line is constituted by three-phase power lines. , 4
In the case of a line, 12-phase power lines are arranged in the case of 6 lines, and 18-phase power lines are arranged in the arms on both sides of the tower support. Each line is called an upper line and a lower line in a vertical relationship as shown in FIG. 1, and is 1 in a left and right relationship.
L, 2L.

When installing a lightning arrester on such a parallel tower, it is best to install a lightning arrester on all the lines, but it is usually expensive to install a lightning arrester on only one line because of the high cost. is there. In this case, the lightning arrester 1 is conventionally provided on the 1L or 2L side as schematically shown in FIG.
Are installed vertically. The main reason for adopting such a mounting method is to concentrate the mounting work on the same side of the steel tower, thereby reducing the number of works and the time required for power outage. As shown on the left side of FIG. 2, the lightning arrester 1 generally includes a current limiting element 2 and a series gap 3, and is attached to a tower arm 6 in parallel with an insulator string 5 supporting a power line 4. If the voltage between insulators (difference between the tower arm potential and the electric wire potential) becomes excessive due to lightning, flashing occurs at the series gap 3, the current limiting element 2 becomes a conductor, and a lightning current flows, followed by a continuous current by the constant transmission voltage. To prevent a flash accident, a ground fault, and a short circuit accident on the insulator string 5.

However, when an excessive lightning current due to a lightning strike on a tower causes the lightning arrester 1 to operate, a flashover accident may occur on a line on which the lightning arrester 1 is not installed. According to the simulation calculation, as shown in FIG. 2, the frequency of flashover accidents per power line 100 km / year in a four-station parallel tower in which the lightning arrester 1 is attached to only one line is 6.5 for one line accident. 3.5 line accidents. The one-line accident means that a flash accident has occurred in the insulator line 5 of the upper line on which the lightning arrester is not installed, and the two-line accident means that the upper and lower sides of the side on which the lightning arrester is not installed are referred to. This means that a flash accident has occurred in the insulator chain 5 of the line.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and does not break the premise that the lightning arrester is installed only on one line of the parallel tower, and on the side where the lightning arrester is not installed. It is an object of the present invention to provide a method for installing a lightning arrester in a parallel tower in which the frequency of flashover accidents on a line can be reduced more than before.

[0006]

Means for Solving the Problems To solve the above problems, the present inventor has determined what kind of voltage is applied to other lines when a lightning tower installed with a lightning arrester on only one line is subjected to lightning strike. Simulation analysis was performed to determine whether a change occurred. As a result, when the lightning arrester mounted on the 1L side of the upper line operates, the rise in the voltage between the insulators on the 2L side of the lower line is larger than the increase in the voltage between the insulators on the 1L side of the lower line, which is the lightning arrester. The cause was that the frequency of flashovers on the line on the other side where no equipment was installed was increasing. In other words, it can be said that the line protection function of the lightning arrester strongly acts on the upper and lower lines located closer to each other.

The present invention has been made on the basis of the above-described knowledge. In mounting a lightning arrester on one of four or more parallel towers, a lightning arrester for an upper line and a lightning arrester for a lower line are provided. Are mounted on opposite sides of a steel tower support.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below. FIG. 3 is a schematic view showing an example in which the present invention is applied to a four-line parallel tower, in which the lightning arrester 1 for the upper line is mounted on the 1L side and the lightning arrester 1 for the lower line is mounted on the 2L side.
The meaning of this configuration will be described below.

First, as shown in FIG. 4, the lightning arrester 1 is mounted only on the 1L side of the upper line of the four parallel towers. The result of a simulation analysis of what kind of voltage change occurs is shown. FIG. 5 is a graph showing the electric potential of the tower arm in the upper phase of the lower line when a lightning current of 50 kA flows to the top of the overhead tower, and the electric potential of the tower arm is proportional to the height from the ground. If the height is higher, the arm potentials of 1L and 2L are almost the same. FIG. 6 is a graph showing the power line potential of the lower line upper phase, and the arrow indicates the moment when the lightning arrester 1 operates. When the lightning arrester 1 operates, a large current flows from the tower to the power line on the 1L side of the upper line via the lightning arrester 1, so that the power line potential of other lines also rises sharply due to the inductive effect,
A potential change as shown in FIG. 6 occurs on the 1L side and the 2L side of the lower line. Since the inductive effect is stronger on the 1L side of the lower line, the power line potential of the lower line on the 1L side becomes higher after the lightning arrester 1 operates.

[0010] The voltage between the insulators that causes flashover is:
As described above, since the difference between the electric potential of the tower arm and the electric potential of the electric wire is obtained, subtracting the electric potential of the electric wire in FIG. 6 from the electric potential of the electric tower arm in FIG. 5 gives a graph of the voltage between the insulators as shown in FIG. As shown in FIG. 7, after the lightning arrester 1 is operated, the voltage between the insulators on the 2L side of the lower line becomes 1
It is higher than the voltage between the L-side insulators. As shown in FIG. 4, the result is 1 L of the upper line of the four towers.
If the lightning arrester 1 is installed only on the
This indicates that a flashover accident is more likely to occur on the 2L side than on the side.

As described above, the flash-prevention effect of the lightning arrester 1 acts more strongly in the vertical direction than in the horizontal direction.
When the lightning arrester 1 is further mounted on the lower line from the state of (1), the lightning arrester 1 is mounted according to the present invention (as shown in FIG. 3), rather than being vertically mounted on the same side as in the conventional case (as shown in FIG. 2). It is more reasonable to mount the lightning arrester 1 for the upper line and the lightning arrester 1 for the lower line on opposite sides of the tower support. In other words, if the lightning arrester 1 is also installed on the lower line,
When the lightning arrester 1 is attached to the 1L side of the upper line, the lightning arrester 1 is attached to the 2L side where the voltage between the insulators is higher, so that the effect of reducing the accident rate in the entire parallel tower becomes greater.

FIG. 8 shows the frequency of flashover accidents when the method of mounting the lightning arrester on the four towers is changed.
As shown in FIG. 8, a comparison between the case where the lightning arrester is mounted vertically on one line and the mounting method of the present invention shows that the frequency of two line accidents is 3.5 to 2.3 times, It can be seen that the frequency of line accidents drops by about 30% from 6.5 to 4.5.

When the lightning arresters are installed on the six towers, the lightning arrester on the upper line and the lightning arrester on the lower line are opposite to each other with the tower post interposed therebetween, as shown in FIG. It can be attached to the side.

[0014]

As described above, according to the present invention, it is possible to reduce the frequency of flashover accidents in the entire parallel tower by simply changing the mounting position of the lightning arrester without increasing the number of lightning arresters. Therefore, it is possible to greatly contribute to suppression of a power failure accident during a lightning strike.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a four-line parallel tower.

FIG. 2 is an explanatory view of a conventional method for mounting a lightning arrester.

FIG. 3 is an explanatory diagram of a method for mounting a lightning arrester of the present invention.

FIG. 4 is an explanatory view showing a state in which a lightning arrester is mounted only on the 1L side of the upper line.

FIG. 5 is a graph showing a tower arm potential when a lightning strike current of 50 kA flows through a pier.

FIG. 6 is a graph showing the electric wire potential of the lower line.

FIG. 7 is a graph showing a voltage between insulators in a lower line.

FIG. 8 is a graph showing the frequency of occurrence of flashover accidents.

FIG. 9 is an explanatory diagram in the case where the present invention is applied to a 6-line parallel tower.

[Explanation of symbols]

1 lightning arrester, 2 current limiting element, 3 series gap, 4
Power line, 5 insulators, 6 tower arm

Claims (1)

[Claims] When mounting a lightning arrester on one of four or more parallel towers, the lightning arrester on the upper line and the lightning arrester on the lower line are mounted on opposite sides of the tower support. A method for mounting a lightning arrester on a parallel tower.