JPH0155756B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a discharge type lightning arrester, and more particularly to a discharge type lightning arrester such as a cold cathode discharge tube having a discharge electrode coated with a cathode material. Conventionally, for example, a discharge type lightning arrester has a pair of discharge poles that are airtightly attached to openings at both ends of a cylindrical body made of an insulating material, and are disposed facing each other so as to form a discharge gap in the cylindrical body. In order to lower the voltage and increase the operating capacity, it is known that an active material with a small work force, that is, a cathode material, is deposited on the surface of the discharge electrode to facilitate electron emission. . In this conventional discharge type lightning arrester, when an abnormal overvoltage such as a surge is applied between a pair of discharge poles, an arc discharge, which is a main discharge, is caused by electron emission from the cathode material through the discharge poles. It is designed to handle surges, etc. However, the cathode materials used in the above-mentioned conventional discharge type lightning arresters are, for example, titanium element and 1/10 of this titanium element.

The discharge of the above-mentioned conventional discharge type lightning arrester is composed of a mixture whose main component is sodium silicate in [weight ratio], and the cathode material composed of such a mixture is adhered to the discharge electrode. When an abnormal overvoltage such as a surge is applied to each pole, as shown in Figures 1 and 2, the discharge sustaining voltage and discharge starting voltage decrease as the number of surges increases. Each of these tends to be lower than the initial discharge sustaining voltage and discharge starting voltage. For example, if the above-mentioned conventional discharge-type earth arrester is subjected to repeated discharge operations by repeatedly applying a waveform of 10 x 1000 μS and a current of 100 A surge 150 times, the discharge sustaining voltage in particular decreases as the number of discharge operations increases. However, the discharge sustaining voltage after 150 repetitions decreases by around 50% compared to the initial value. Therefore, when the discharge sustaining voltage or the discharge starting voltage decreases in this manner, a follow-on current occurs, which may shorten the life of the lightning arrester, cause damage to the equipment to be protected, or reduce the protective performance of the lightning arrester. In addition, in order to eliminate these drawbacks, for example, it may be possible to set the lightning arrester in consideration of the decrease in the discharge sustaining voltage or discharge starting voltage, but setting it in this way will reduce the protection performance of the lightning arrester. There are drawbacks such as a significant loss of reliability. The present invention was made in view of the above circumstances, and
The purpose of this is to be able to maintain the discharge sustaining voltage and discharge starting voltage at approximately the same initial value regardless of the number of times surges are applied, and to effectively block follow-on current. An object of the present invention is to provide a discharge type lightning arrester that can improve reliability and extend its life. As a result of various studies on the cathode material of this type of discharge type lightning arrester, the present inventor found that the main component of the cathode material is a metal element or metal compound consisting of an alkali metal, an alkaline earth metal, or a mixture of these metals in a weight ratio. By using a mixture of 5 to 25 times as much borosilicate glass and applying it to the discharge electrodes, the discharge sustaining voltage and discharge starting voltage can be maintained approximately constant even after repeated application of surges, etc. It has been found that it is possible to obtain a discharge type surge arrester that can effectively block the following current and sufficiently satisfy various performances as a lightning arrester, such as reliability and life. The discharge type lightning arrester according to the present invention contains a metal element or metal compound consisting of an alkali metal, an alkaline earth metal, or a mixture of these metals in a weight ratio of 5 to 25.
The discharge electrode is coated with a cathode material whose main component is a mixture obtained by mixing twice as much borosilicate glass, and by using the above-mentioned specific mixture as the main component of the cathode material, the It is designed to eliminate all the drawbacks of conventional discharge type lightning arresters. An embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 3 is a characteristic diagram showing the relationship between the discharge sustaining voltage and the surge circuit of the discharge type lightning arrester according to an embodiment of the present invention, and FIG. It is a characteristic diagram showing a relationship. As an example of the present invention, metal elements or metal compounds made of alkali metals, alkaline earth metals, or mixtures of these metals are prepared, and each of these components is added at a weight ratio of 5 to 25 times. The cathode materials were prepared by mixing the borosilicate glasses with the borosilicate glasses. Each of these cathode materials is applied to the discharge electrode to make a discharge type lightning arrester, and a waveform of 10× is applied between the discharge electrodes of each of these lightning arresters.
When a surge of 1000 μS and a current of 320 A was applied 200 times, as shown in Figures 3 and 4, the discharge sustaining voltage and discharge starting voltage remained at their initial values, regardless of the number of surges. It was confirmed through experiments that substantially the same values were maintained. Further, in the above-mentioned embodiment of the present invention, the follow-on current during the discharge operation was effectively blocked, and the various performances as a lightning arrester were sufficiently satisfactory. In addition, in the present invention, the amount of borosilicate glass contained in the cathode material is selected to be 5 to 25 times the weight ratio of the metal element or metal compound consisting of an alkali metal, an alkaline earth metal, or a mixture of these metals. The reason for this is that, for example, if the amount of borosilicate glass is less than 5 times by weight, the discharge sustaining voltage and discharge starting voltage will decrease due to repeated discharge operations compared to a case in which no borosilicate glass is mixed at all. This is because although it is improved to a certain extent, sufficient characteristics are still not obtained, and if the amount of borosilicate glass exceeds 25 times the weight ratio, the discharge sustaining voltage in particular becomes higher than the initial value.

[For example, if you add and mix 30 times the amount of borosilicate glass by weight, the value will be about 150% of the initial value], so the follow-on current interruption during discharge operation will be good, but the performance as a lightning arrester, that is, the discharge starting voltage This is because the shock wave discharge characteristics and the like are not desirable characteristics. As described above, according to the present invention, by using the above-described specific cathode material as the cathode material deposited on the discharge electrode, the discharge sustaining voltage and the discharge starting voltage are always kept at their initial values, regardless of the number of times surges or the like are applied. Can be held at the same constant value. Therefore, this makes it possible to effectively block the follow-on current during the discharge operation, and has excellent effects such as improving the performance and reliability of the lightning arrester and extending its life. be. Note that the discharge type lightning arrester according to the present invention is not limited to cold cathode discharge tubes, for example, and can be applied to various discharge type lightning arresters without being limited to its shape, structure, type, etc., as long as it is a gap type discharge type lightning arrester. Of course, it is applicable.

[Brief explanation of drawings]

1 and 2 are characteristic diagrams showing the relationship between the discharge sustaining voltage and the discharge starting voltage with respect to the number of surges of a conventional discharge type arrester, respectively. FIG. 2 is a characteristic diagram showing the relationship between the discharge sustaining voltage and the discharge starting voltage with respect to the number of surges of the type lightning arrester.

Claims (1)

[Claims] 1. A cathode material whose main component is a mixture of a metal element or metal compound consisting of an alkali metal, an alkaline earth metal, or a mixture of these metals and borosilicate glass in an amount of 5 to 25 times by weight is discharged. A discharge type earth arrester characterized by being attached to a pole.