JPH0134490Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a lightning arrester for a power transmission line, and in particular, to a lightning arrester for a power transmission line that has an improved structure for attaching a lightning arrester to a power transmission tower.

Overhead ground wires are generally installed on power transmission lines to prevent direct lightning strikes. However, when the lightning current becomes excessive, the potential of the power transmission tower, which is normally at ground potential, increases, and this voltage becomes higher than the system voltage of the power transmission line, resulting in what is called a reverse flash fault. Additionally, recent research on lightning phenomena shows that depending on the state of thunderclouds, overhead ground wires may not necessarily be able to prevent lightning strikes from power transmission lines, and there are many instances of lightning directly striking power transmission lines. . In such a case, a flash short circuit occurs between the ground of the suspended insulator supporting the power transmission line and the power transmission line. As a result, the power transmission line system enters a ground fault state, and ground fault current flows. Generally, in the event of such a lightning accident, a method is adopted in which the ground fault current is temporarily cut off using a circuit breaker installed in the system, and after the lightning fault has been removed, the ground fault current is turned on again. .

Recently, in the case of power transmission lines that are required to transmit high voltage and large capacity, the limit of the power transmission capacity depends on the excessive stability of the system during the above-mentioned interruptions and restarts. In order to improve this transient stability, it is necessary to prevent lightning accidents as much as possible, and the appropriate installation of lightning arresters on power transmission lines has been studied.

As is well known, conventional lightning arresters include those in which a series gap and a characteristic element made of silicon carbide are connected in series. However, the stray capacitance of a series gap is small, about 10 pF, and the discharge characteristics of the gap tend to change depending on the surrounding conditions, such as the dirtiness of the surface of the insulator that houses the lightning arrester. was necessary. Also,
When silicon carbide characteristic elements are used, a follow-on current of several hundred amperes flows at the normal ground voltage, so there is also the drawback that it is not a complete countermeasure against ground faults. Therefore, this type of lightning arrester has not been put into practical use for power transmission lines.

On the other hand, recently, zinc oxide (Zno)
A sintered element (referred to as a Zno element) whose main component is Zno element has been developed. This Zno element has extremely good non-linearity in voltage-current characteristics, and it is possible to manufacture a lightning arrester with a current flowing at a normal ground voltage of several tens of μA, which is comparable to the leakage current of an insulator. Therefore, the series gap required in the above-mentioned conventional device can be eliminated. For these reasons, the above-mentioned drawbacks of applying conventional lightning arresters to power transmission lines can be overcome by lightning arresters using Zno elements. In other words, at normal ground voltage, no follow-on current flows and there is no current, so it responds only to pulses of lightning current, and there is no disturbance to the power transmission system. Furthermore, since there is no series gap, the influence of external environmental conditions can be minimized, resulting in stable performance.

The object of this invention is to provide a lightning arrester for a power transmission line having a preferred mounting structure for applying the zinc oxide type lightning arrester to a power transmission line.

Hereinafter, this invention will be explained with reference to an embodiment shown in FIGS. 1 and 2.
The power line 3 is stretched by. 4 is a lightning arrester made of Zno elements, which connects power line 3 from transmission tower 1 to power line 3.
The upper end is connected to a support arm 5 extending in a direction parallel to , and is suspended. The lower end of the lightning arrester 4 and one power line 3 are electrically and mechanically connected by a connecting conductor 6. Both ends of the connecting conductor 6 and the upper end of the lightning arrester 4 have a pin connection structure that allows for free movement.

With the following configuration, when the power line 3 oscillates laterally due to wind pressure or the like, no bending force is applied to the lightning arrester 4 due to the flexible connection between the upper end of the lightning arrester 4 and both ends of the connecting conductor 6. 4' schematically shows the movement of the lightning arrester 4 when the power line 3 fluctuates.
The position of the support arm 5 is such that even when the power line 3 is shaken, a sufficient electrical separation distance l is maintained between the lower end of the surge arrester 4 and the power transmission line 3 on the other side to which the surge arrester 4 is not connected. stipulate.

As mentioned above, when using this invention, the lightning arrester follows the fluctuation of the power line and maintains the required separation distance from the power line on the other side, so it has sufficient mechanical and electrical stability. However, it has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is an elevational view showing the schematic structure of this invention, and FIG. 2 is a plan view. 1: Transmission tower, 2: Support insulator, 3: Transmission line,
4: Lightning arrester, 5: Support arm, 6: Connecting conductor.

Claims (1)

[Scope of utility model registration request] a support arm extending substantially parallel to the power transmission line from a power transmission tower that insulates and supports the power transmission line; a lightning arrester having one end connected to the tip of the support arm and comprising a non-linear resistor containing zinc oxide as a main component; and the lightning arrester. A lightning arrester for a power transmission line, comprising a connecting conductor that connects the other end of the lightning arrester and one of the power transmission lines, and a coupling portion between one end of the lightning arrester and both ends of the connecting conductor is freely coupled.