JPS6222522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear press arrester using a resistor having non-linear voltage-current characteristics.

In general, lightning arresters are connected between electrical system lines and the ground in order to suppress surge voltages caused by natural lightning and the switching of electrical systems, and to protect equipment and equipment such as transformers connected to electrical systems. Electric current constantly flows through the lines of the electrical system, and the conductors of the lines generate heat due to the current, and the temperature can reach up to 100°C for the same current.
It reaches around ℃. This heat is transferred to a lightning arrester connected to the line by a lead wire or conductor. Recently, gas-insulated switchgear, which has its live parts filled with SF ₆ gas, which has a high insulation ability, and whose volume and area have been greatly reduced, has come into widespread use. A lightning arrester forming a part of such gas-insulated switchgear has a short distance between the line bus conductor and the lightning arrester. A schematic cross-sectional view of one example is shown in FIG. In the figure, 1 is a unit element of a nonlinear resistor made of metal oxide such as zinc oxide, and a large number of these are stacked to form the main body of the lightning arrester. 2 is a conductor insulating spacer that supports the conductor 3 branched from the line side conductor and at the same time serves to separate the line side gas chamber from the lightning arrester side gas chamber. 4
5 is SF ₆ gas with excellent insulation performance, and 5 is a container for airtightly storing the gas 4, the lightning arrester element 1, and the like.
In such a lightning arrester, as described above, since the distance between the line bus conductor and the lightning arrester is short, the heat generated on the line side is transmitted to the lightning arrester through the short branch conductor 3, increasing its temperature. According to an example calculation, the temperature rise reaches 10~20℃ at the high voltage end of the arrester. On the other hand, conventional lightning arresters consist of a non-linear series resistance that limits the flow of follow-on current after activation, and a series gap that guarantees follow-on flow and disconnection, housed in an airtight container. However, recently, as explained in Figure 1, gear press arresters have been used that omit the series gap and are made of metal oxides such as zinc oxide and have excellent non-linear voltage-current characteristics (hereinafter referred to as elements). I'm getting used to it.
In such a lightning arrester, the life of the element is very sensitive to temperature, and the relationship between the two follows the Arrhenius law shown in FIG. In the figure, the horizontal axis represents the reciprocal of the temperature T, 1/T, and the vertical axis represents the life time τ. As can be seen from the figure, the life of the element rapidly shortens as the temperature rises. For this reason, the conventional structure as shown in FIG. 1 has the disadvantage that the heat generated by the bus conductor of the line shortens the life of the arrester.

Accordingly, an object of the present invention is to obtain a lightning arrester having a structure that is not affected by heat generation on the line side, and which has a long life and improved reliability.

An embodiment of the lightning arrester according to the present invention will be described below with reference to the drawings. FIG. 3 is a schematic cross-sectional view mainly depicting the connection between the line side and the lightning arrester, and in the figure, the same parts as in FIG. 6 is a metal upper support plate connected to the branch conductor 3, 7 is a lower support plate connected to the lightning arrester element, and 8 is a lightning arrester insulating spacer made of an insulator with good continuity inserted between both support plates 6 and 7. , 9 is a lightning arrester insulating spacer 8 between both support plates 6 and 7.
The reference numeral 10 is a bus conductor on the line side, which is a thin metal frame plate that surrounds the outer periphery of the line and is electrically conductive. In such a structure, the current flows through the line bus conductor 10 - branch conductor 3 - upper support plate 6 - thin frame plate 9 -
The water flows in the order of lower support plate 7 - element 1 and flows to the ground. This current is a small leakage current of about several tens to several hundred microamperes under normal conditions, and even during surge energy processing in an abnormal situation, the current peak value is as large as 10 kA, but the flow time is several ms or less. Therefore, the thin frame plate 9 may have a small cross-sectional area, and a thin plate with a relatively large surface area is used to improve the heat dissipation effect. Heat from the line bus conductor 10 is dissipated to the insulating gas 4 by the upper support plate 6, and is further efficiently dissipated to the insulating gas 4 from the wide surface area of the thin frame plate 9, so the amount of heat transferred to the element 1 is significantly small. Become. The insulating spacer 8 does not transfer this heat and firmly supports the element 1.
This support effect is even more effective when the number of stacked elements is large and the height is high, such as in lightning arresters for high voltages such as 500kV and 1000kV.

FIG. 4 shows another embodiment of the lightning arrester according to the present invention, and the same parts as those shown in FIG. 3 are given the same reference numerals and the explanation thereof will be omitted. This embodiment is characterized in that the thin frame plate is provided with heat dissipation fins to further improve the heat dissipation effect, and is illustrated in FIG. 4 as a thin frame plate 11 with heat dissipation fins. In the figure, the radiation fins are installed horizontally, but they may also be installed vertically. Although not shown, the thin frame plate may have a corrugated cross-sectional shape, that is, a pleated shape.

According to the present invention described above, the heat of the line bus conductor, which is constantly energized and generates heat, is efficiently dissipated before it reaches the lightning arrester element, so the temperature rise of the element is reduced, and the life of the element is therefore shortened. A highly reliable and economical lightning arrester can be obtained.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional diagram showing an example of a conventional lightning arrester;
Figure 2 is a characteristic diagram showing the relationship between element temperature and life of a lightning arrester element having non-linear voltage-current characteristics;
The figure is a schematic cross-sectional view showing one embodiment of the lightning arrester according to the present invention, and FIG. 4 is a schematic cross-sectional view showing another embodiment. 1... Lightning arrester element, 2... Conductor insulation spacer,
3... Branch conductor, 4... Insulating gas (SF ₆ ), 5...
...Surge arrester container, 6... Upper support plate, 7... Lower support plate, 8... Lightning arrester insulating spacer, 9... Thin frame plate, 10... Bus conductor, 11... Thin frame plate with heat radiation fins.

Claims (1)

[Claims] 1. When a lightning arrester using a nonlinear resistance element made of a metal compound such as zinc oxide is installed relatively close to the bus conductor that generates heat, such as when used in gas-insulated switchgear, the lightning arrester is installed on the bus side of the arrester. A lightning arrester insulating spacer having heat insulation properties, metal upper and lower support plates sandwiching the insulating spacer, and a thin metal frame plate connecting the support plates so as to surround the outer periphery of the insulating spacer. Characteristic lightning arrester.