JPS62202503A - Arrestor - 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 Field of the Invention The present invention relates to a lightning arrester for protecting power equipment from abnormal voltages such as lightning surges.

BACKGROUND OF THE INVENTION In recent years, in the electric power field, the demand for a stable supply of electric power has increased more than ever before, and efforts have been made to improve the reliability of electric power equipment and the quality of electric power.

In particular, in order to improve the quality of electric power, zinc oxide-based lightning arresters without series gaps have been put into practical use in order to reliably absorb harmful abnormal voltages generated by lightning on power transmission and distribution lines. They are installed in various places. Also,
From the viewpoint of economically improving the protection characteristics of power equipment, lightning arresters built into power equipment are also being put into practical use. Surge arresters built into power equipment are represented by oil-impregnated transformers, etc.
These lightning arresters are constantly exposed to the high temperature of the transformer's insulating oil, which is considerably higher than the temperature when applied in air. , sufficient heat dissipation must be considered. Therefore, how to dissipate the heat generated from the elements that are the characteristic elements of lightning arresters has become an important issue.

Conventionally, the internal structure of this type of lightning arrester was as shown in FIG. FIG. 4 shows a cross section of the main components of the lightning arrester, with terminals at both ends serving as the terminals of the lightning arrester being omitted. In Fig. 4, 1 is a cylindrical varistor element obtained by high-temperature sintering using zinc oxide as the main raw material, adding additives such as bismuth, and the sides thereof are covered with a high-resistance layer and a glass layer. It is being said. Reference numerals 21L and 2b are metallicon end face electrodes provided on both end faces of the varistor element 1, which are formed into a disk shape by thermal spraying of aluminum. Metallicon end face electrodes 2a, 2b'ji on both end faces
As shown in FIG. 4, the required number of varistor elements 1 having seven varistor elements 1 are stacked in series according to the applicable rated voltage of the lightning arrester (3.5 varistor elements are shown in FIG. 4). 3 is an electrode plate that is pressed against one end of the stacked varistor elements 1; 4 is a spring that provides the pressure contact force necessary for pressure contact; 6 is a metal shorting bar that electrically shorts both ends of the spring 4; , 6 is an insulating case made of an inner cylindrical insulator or glass epoxy, in which the varistor element 1 and the like are housed.

7 is a space inside the varistor element 1 and the insulating case 6, and insulating oil flows through this space 7 (FIG. 4 shows a hole for oil to flow between the inside and the outside of the insulating case 6). (not shown).

The operation of the heat dissipation of the conventional lightning arrester configured as described above will be explained below.

First, when lightning surge voltage, switching surge voltage, or short-time AC overvoltage is applied across a lightning arrester, the surge current accompanying those voltages is bypassed by the arrester, and the voltage on the line to which the arrester is connected is suppressed. At this time, the surge current passes through the series-connected varistor elements 1, and the energy consumed at that time becomes Joule heat, which temporarily increases the temperature of the varistor element 1. Heat is radiated from the oil to the space 7 in the oil.

Problems to be Solved by the Invention' However, in such a conventional configuration, when the above-mentioned surge voltage or short-time AC overvoltage occurs continuously or for a long time, heat radiation from the side is not enough, and the varistor Element 1 had problems in terms of thermal stability, such as extremely high element temperature and thermal runaway at the rated AC voltage.

The present invention aims to solve these problems,
The purpose is to improve the heat dissipation characteristics from the varistor element and improve the thermal stability of the lightning arrester when processing large amounts of energy.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention aims to solve the above-mentioned problems by applying heat dissipation electrodes that are plate-shaped and have heat dissipation fins on their sides and stacked in series on the end faces or holes (between risk elements) of varistor elements. It is inserted into at least one of the following.

Function: With the above-described configuration, the present invention can dissipate heat from the varistor element not only from the side surface of the varistor element, but also from the end surface through the heat dissipation fins provided on the side surface of the heat dissipation electrode into the insulating oil. As a result, heat dissipation of the entire varistor element can be performed quickly.

Embodiment FIG. 1 shows an embodiment of the lightning arrester of the present invention, and is a sectional view of the main parts of the lightning arrester, with terminals at both ends serving as terminals of the lightning arrester being omitted. In Fig. 1, 8 is a varistor element whose main material is zinc oxide, 91L, 9b is a metallicon end face electrode, 1o is an electrode plate, 11 is a spring, 12
1 is a shorting bar, 13 is an insulating case, and 14 is a space, which respectively correspond to the conventional varistor element 1, metallicon end face electrodes 2N, 2b, electrode plate 3, spring 4, shorting bar 6,
This corresponds to the insulating case 6 and the space 7. Reference numeral 15 denotes a disc-shaped heat dissipation electrode with a diameter equivalent to that of the varistor element 8, and is made of a good heat conductor such as aluminum or copper alloy. Three parallel radiation fins are provided. These heat dissipating electrodes 15 are used by being inserted between the varistor elements.

Next, the operation of the lightning arrester configured as above will be explained. As in the conventional example, when a surge voltage or short-time AC overvoltage occurs continuously or for a long time, the element temperature of the varistor element 8 becomes extremely high due to the absorbed energy, as in the conventional example. However, the heat accumulated in the varistor element 8 is dissipated not only from the side surfaces of the varistor element 8 but also from the end face via the radiation fins of the heat radiation electrode 15 into the insulating oil that is the cooling medium. This will keep the temperature rise low. In the experimental example, it was also possible to suppress the temperature rise in the metallicon end face electrode portion of the varistor element 8 to less than half of the conventional temperature. Further, the heat dissipation characteristics of the heat dissipation electrode 15 can be controlled by the thermal conductivity of the heat dissipation electrode 16 and the shape of the heat dissipation fins.

By quickly dissipating the Joule heat of the varistor element 8 in this way, it is possible to suppress the temperature rise due to the continuous inflow of energy to a low level, and as a result, the arrester can be prevented from thermal runaway when the rated AC voltage is applied. Good thermal stability can be obtained. Further, it has the effect of reducing characteristic deterioration of the varistor element 8. Such an effect is particularly noticeable in varistor elements having a large diameter due to heat dissipation.

Next, FIG. 2a shows a second embodiment of the present invention.

This will be explained together with b. Figures 1 and 2 show a front view of the heat dissipation electrode, and Figure 2 shows a bottom view of the heat dissipation electrode. The difference from the heat dissipation electrode of the first embodiment is that the number of heat dissipation fins provided on the side surface is different. Reference numeral 16 denotes a heat dissipation electrode having six heat dissipation fins in the same shape as the heat dissipation electrode 16, and is applied in exactly the same manner as in the first embodiment. The action of the lightning arrester constructed in this way is as follows:
Although it is similar to the figure, it has the effect of further increasing heat dissipation efficiency.

Next, a third embodiment of the present invention will be described with reference to FIGS. 3a and 3b. Figure B shows a front view of the heat dissipation electrode, and Figure B shows a bottom view of the same. The difference from the heat dissipation electrode of the first embodiment is that the shape of the heat dissipation fins provided on the side surfaces is perpendicular to the end face of the varistor element and extends radially from the center.

Reference numeral 17 denotes a heat dissipation electrode provided with twelve of the above-mentioned heat dissipation fins, and is applied in exactly the same manner as in the first embodiment. The action of the lightning arrester constructed in this manner is similar to that shown in FIG. 1, but when the insulating oil flows in the axial direction, the heat dissipation effect is further enhanced.

In the embodiment of the present invention, the heat dissipation electrode 16 is entirely inserted between the varistor elements 8, but if necessary, one
You can also sandwich it in every other piece. Furthermore, it goes without saying that even if the heat dissipation electrodes 16 are sandwiched between both ends of the varistor element group stacked in series, the heat dissipation effect will be achieved.

Effects of the Invention As described above, according to the present invention, a heat dissipating electrode having a plate shape and having heat dissipating fins on its side surface is sandwiched between at least one of the end faces of columnar varistor elements stacked in series or between the varistor elements. By absorbing the Joule heat generated within the varistor element, it is quickly applied to the side surface of the varistor element, and the heat is also radiated from the end face, thereby suppressing the temperature rise of the varistor element, and as a result, the surge arrester This has the effect of ensuring good thermal stability of the varistor element and suppressing deterioration of characteristics of the varistor element.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of the lightning arrester according to the present invention, FIGS. 2 a and b are front and bottom views of a heat dissipation electrode according to a second embodiment of the present invention, and FIGS. 3 a and b are according to the present invention. A front view and a bottom view of a heat dissipation electrode according to the third embodiment, and FIG. 4 is a sectional view of the main parts of a conventional lightning arrester. 8...Varistor, 91L, 9b...Metallicon end face electrode, 13...Insulation case, 14
...Space (oil), 15, 16.17...
...Heat dissipation electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person10
-... is a stick plate! -...Spring Fig. 2 Fig. 3

Claims (1)

[Claims] A heat dissipation electrode that is plate-shaped and has heat dissipation fins on its side.
A lightning arrester characterized by being inserted into at least one of the end faces of columnar varistor elements stacked in series within an insulating case or the varistor elements.