JPS595589A - Gapless arrester - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a gapless lightning arrester using a zinc oxide element (hereinafter referred to as a ZnO element).

[Technical background of the invention]

Gapless surge arrester is made of Zn, which has high nonlinear resistance characteristics.
It is made by stacking the required number of O elements. Since this may cause thermal runaway and a decrease in discharge capacity at high temperatures, it is important to pay attention to the heat dissipation structure.

FIG. 1 shows a cross-sectional configuration of this type of gapless arrester. In the figure, a required number of ZnO elements 1, which are stacked and electrically connected in series, are fixed by insulating rods 2, and housed and fixed in an insulator tube 4 as a container by connecting conductors 3.

Moreover, this insulator tube 4 has upper and lower lid bodies 5 and /? King 6
It has an airtight structure.

On the other hand, ZnO elements are a type of resistor, and have a negative resistance with respect to temperature at small currents. Therefore, when subjected to follow-on currents such as leakage currents and switching surges due to constant energization, the temperature rises. There is a concern that it may cause runaway or lack of tolerance. This tendency becomes more pronounced as lightning arresters with better protection characteristics generally generate more heat.

[Problems with background technology]

In the lightning arrester having the configuration shown in FIG. 1, the amount of heat generated in the ZnO element 1 is mainly dissipated in the vertical direction by thermal conduction 1, and the heat is not transmitted to the gas inside the insulator tube 4 to a small extent. Moreover,
Considering the phenomenon of heat conduction in the vertical direction, the elements 1 near the upper and lower ends have a large temperature gradient and are easy to cool, but near the center, the temperature difference between the elements 1 is 7 J\ and tends to become high temperature. Therefore, the thermal characteristics of a lightning arrester are often determined by the central part, and as a result, in Figure 2, which shows the heat generation and heat dissipation of the lightning arrester,
As shown in Ql, the temperature at the constant stable point At is high and the thermal runaway limit point B
It is preferable that the temperature of l is low.

[Purpose of the invention]

The present invention was made in view of the above circumstances, and its purpose is to provide a thermally stable gapless surge arrester with improved heat dissipation characteristics.

[Summary of the invention]

In order to achieve the above object, the present invention provides a gapless lightning arrester in which a predetermined number of zinc oxide elements having high non-linear resistance characteristics are housed in a stacked container, in which a metal body is provided between each of the zinc oxide elements, and The metal body is characterized in that the metal body is covered with an insulator having excellent thermal conductivity and in contact with the inner wall surface of the container.

[Embodiments of the invention]

An embodiment of the present invention shown in the drawings will be described below.

FIG. 3 shows an example of the cross-sectional configuration of a gapless surge arrester according to the present invention. The same parts as in FIG. 1 are given the same reference numerals, and the explanation thereof will be omitted, and only the different parts will be described here.

In other words, FIG. 3 shows a metal plate 7 provided between each ZnO element 1 in FIG. 8.

By the way, alternating current or direct current voltage is always applied to the lightning arrester, and a leakage current flows therefrom.

Furthermore, a large discharge current or follow-on current flows due to lightning or switching surges. If the temperature of the ZnO element becomes too high due to these currents, the following problems will occur.

(a) The life of a lightning arrester will be shortened if it is used for many years at high temperatures.

(b) Temperature runaway is likely to occur due to charging or surge.

(c) Discharge resistance against surges at high temperatures decreases.

In this respect, in the gapless lightning arrester constructed as described above, the metal plate 7 provided between each ZnO element 1 not only functions as a heat sink, but also transmits heat to the insulator tube 4 via the silicone rubber 8. Moreover, this silicone rubber 8 is a material with excellent thermal conductivity and heat resistance, and functions not only as the above-mentioned heat transfer measure but also as a cushioning material between the inside of the insulator tube 4 and internal elements. On the other hand, the thermal characteristics of such a gapless arrester are Z as shown by Qx in FIG.
The intersection with the heat generation characteristic Qo due to charging of nO element 1 is A2
+BZ, AX is always stable point, B is thermal runaway limit point, each temperature is lower than AI, and B2 is lower than B.
It is rising from l.

Therefore, in this gapless lightning arrester, the constant temperature of the ZnO element 1 can be lowered and the universal runaway limit temperature can be increased, so that the heat dissipation characteristics are improved and the service life is extended.

(b) It is difficult to cause thermal runaway due to charging or surge.

(c) Increased discharge resistance against surges even at high temperatures.

With this effect, it is possible to obtain a thermally extremely stable lightning arrester.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with various modifications within the scope of changing the gist thereof.

〔Effect of the invention〕

As explained above, according to the present invention, a metal body is provided between each zinc oxide element, and the periphery of this metal body is covered with an insulator having excellent thermal conductivity, so that heat dissipation characteristics are improved. This makes it possible to provide a highly reliable gapless surge arrester that is extremely thermally stable.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional gapless surge arrester, Figure 2
The figure shows the heat generation and heat dissipation characteristics of a lightning arrester, and FIG. 3 is a cross-sectional configuration diagram showing an embodiment of the present invention. l...ZnO element, 2... insulating rod, 3... connecting conductor, 4... insulator tube, 5... lid body, 6... backing. 7...Gold PA plate, g...Silicone rubber. Applicant's agent Patent attorney Takeshi Suzue Disciple 1 Figure 2 Figure 2 445- Figure 3

Claims (2)

[Claims] (1) In a gapless lightning arrester in which a predetermined number of zinc oxide elements having high nonlinear resistance characteristics are housed in a stacked container, a metal body is disposed between each of the zinc oxide elements,
A gapless lightning arrester characterized in that the metal body is surrounded by an insulator having excellent thermal conductivity and in contact with the inner wall surface of the container. (2) The gapless lightning arrester according to claim (1), wherein the insulator 7 is silicone rubber.