JPH0785946A - Lightning arrester element - Google Patents

Abstract

PURPOSE:To shorten the delay time in discharging and lessen the dispersion in the operation voltage by forming an aux. electrode at the outside surface of an insulated vessel, lessening the electrode distance forming a capacitor. and enlarging the electrode area. CONSTITUTION:An aux. electrode 6 is formed at the outside surface of a cylindrical vessel 1 of a lightning arrester concerned. This aux. electrode 6 is embodied in a line form parallel with the direction of discharging and connected with one of the metal lids 3 where a discharge electrode 5 is formed in a single piece structure. The aux. electrode 6 can, for example, be made simply by printing an Ag conductor ink followed by baking. Such a configuration is also acceptable that another aux. electrode 6' in a ring form is provided-in such an arrangement as surrounding the circumferential surface of the insulative vessel 1 independently without being connected with aux. electrode 5. Because the electrode distance forming a capacitor is lessened in this aux. electrode and the electrode area is enlarged, it is practicable to make the accumulated electric charges very large. This permits shortening of the delay time in discharging to lead to lessening of dispersion in the operation voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightning protection device for protecting an electric circuit from a surge.

[0002]

2. Description of the Related Art In order to protect an electric circuit from a surge, many lightning arresters are installed at the input portion of the electric circuit.
The most common lightning protection device utilizing the discharge phenomenon is shown in the exploded perspective view of FIG.

In FIG. 3, reference numeral 1 is an insulating cylindrical container made of alumina or the like for ensuring a discharge space, and also serves as a spacer for defining an electrode interval. Reference numeral 2 is an electrode portion,
In the metallic lid 3 formed integrally with the discharge electrode 5, the cylindrical container 1 is sealed at the seal portion 4 that is in contact with the end surface of the cylindrical container 1. The lid body 3 is used as it is as an external terminal or is used by welding a lead wire. The metal lid 3
In consideration of the heat process, a metal material having a thermal expansion similar to that of alumina is selected. For example, for an alumina material, a 42 wt% Ni Fe alloy or 20 wt%
Examples include Ni and 17 wt% Co Fe alloys.

In the lightning protection device, since brazing (for example, Ag / Cu brazing) is adopted for the seal, the end surface of the alumina cylindrical container 1 is metallized. That is,
A refractory metal layer such as W or Mo is baked on the end face, for example, in an inert atmosphere. Further, this surface is plated with Ni to prevent the diffusion of the brazing material.

A brazing material is applied to the end face of the cylindrical container 1 or the sealing portion 4 of the lid 3, and brazing is performed in an inert discharge gas. This completes the gas filling and sealing and completes the lightning protection device. A rare gas is selected as the discharge gas in consideration of electrode damage and the like, but a small amount of reducing H ₂ is mixed in order to improve the flow of the wax.

[0006]

However, there are two problems to be solved in such a conventional lightning protection device. One is that the discharge delay time until a surge occurs and discharge occurs is relatively long, and the other is that the discharge delay time and the discharge generation voltage vary. These are serious drawbacks for surge protection devices.

These two problems are caused by the common cause that the generation of discharge is greatly influenced by the amount of ions in the discharge space. The amount of ions existing in the discharge space in the state where discharge does not occur is an extremely small amount of cosmic rays and the like, which is stochastic. Therefore, it takes a long time until the electron avalanche phenomenon occurs in the gas, and the discharge delay time becomes long. Further, since the amount of ions naturally existing is stochastic, the delay time and the discharge-induced voltage also vary.

The above problem can be solved by adding a radioactive element to the lightning protection element. However, in this case, it is not preferable in terms of environmental hygiene, and other circuit elements such as LSI are deteriorated.

As described above, the conventional lightning protection device is not sufficient in basic characteristics as a protection device under the present circumstances.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a lightning protection device having a short operating time and a small variation in discharge induced voltage.

[0011]

The above object of the present invention is achieved by the following lightning protection device.

That is, in a lightning protection device in which at least one pair of discharge electrodes is formed in an airtight insulating container containing a dischargeable gas, an auxiliary electrode is further formed in the insulating container. It is a characteristic lightning protection device.

The auxiliary electrode is provided outside the insulating container and / or
Alternatively, it can be formed inside. At this time, the shape of the auxiliary electrode is not particularly limited, but for example, it can be formed in a line shape in a part of the insulating container, or in the case of a cylindrical insulating container, can be provided in a ring shape so as to surround the container. .

Further, it is possible to form the auxiliary electrode by exposing it to the main discharge space inside the insulating container.

[0015]

When a voltage is applied to the discharge electrode, electric charges are induced and accumulated on the surface of the insulating container. Think of it as one type of condenser. In the conventional lightning protection device, since the cross-sectional area of the insulating container, which is the dielectric material of the capacitor, is small and the distance between the electrodes is large, the amount of accumulated charges is small. Therefore, discharge between the accumulated charge and the discharge electrode (hereinafter referred to as "preliminary charge")
Therefore, it can be said that a large applied voltage was required for the occurrence of the discharge, and the discharge between the discharge electrodes (hereinafter referred to as the main discharge) was not affected.

On the other hand, when the auxiliary electrode is formed, the electrode distance as a capacitor is made small and the electrode area is made large, so that the accumulated charge can be made very large. Therefore, it is possible to cause the preliminary discharge even at a voltage equal to or lower than the specified voltage at which the main discharge occurs. Therefore, when a surge occurs, preliminary discharge occurs at an early rise of voltage. Since this preliminary discharge is instantaneously stopped when the accumulated charges are consumed, if the surge voltage is below the specified value, continuous main discharge does not occur. However, in the preliminary discharge, many ions are generated in the discharge space, and even if the discharge is instantaneously stopped, the ions stay for a certain period of time. At this time, if the surge voltage reaches the specified value, the main discharge is instantly generated. Therefore, the statistical discharge delay becomes negligible, and the voltage at which the main discharge occurs becomes constant.

From the above actions, the shape of the auxiliary electrode,
The area and the positional relationship with the discharge electrode are appropriately determined by a simple experiment so that an appropriate amount of accumulated charge can be obtained.

[0018]

EXAMPLES The present invention will be further described based on examples.
The same components as those of the conventional example are designated by the same reference numerals to simplify the description.

FIG. 1 is a sectional view showing an embodiment of the lightning arrester of the present invention.

In this lightning protection device, the auxiliary electrode 6 is formed on the outer surface of the cylindrical container 1 of the lightning protection device having the same structure as the conventional example. The auxiliary electrode 6 is formed in a line in parallel with the discharge direction, and is connected to one of the metallic lids 3 on which the discharge electrode 5 is integrally formed.

As a method of forming the auxiliary electrode 6, a simple method of printing after printing with Ag conductive ink or the like can be adopted. If necessary, the auxiliary electrode surface may be coated with a dielectric. Therefore, it can also be formed inside the container insulating material.

FIG. 2 shows another embodiment of the lightning protection device of the present invention, in which a ring-shaped auxiliary electrode 6'is provided so as to surround the cylindrical surface of the insulating cylindrical container 1, and is different from the discharge electrode 5. It is not connected but is formed independently. As the distance between the auxiliary electrode 6'and the discharge electrode 5, it is not preferable that the distance between the auxiliary electrode 6'and the discharge electrode 5 is such that discharge occurs on the outer surface, and normally 0.5 mm or more causes no problem.

As yet another embodiment, it is possible to form an auxiliary electrode inside the cylindrical container so that the conductor surface is exposed to the main discharge space inside the insulating cylindrical container 1. However, in this case, it is a condition that the auxiliary electrode and the discharge electrode are independent. This is because if they are connected, they are no different from the discharge electrodes. However, the conductor surface exposed in the main discharge space complicates the electrode distribution, and is not a preferable design.

In these examples where the auxiliary electrode was formed,
Since the electrode distance as the capacitor is made small and the electrode area is made large, the accumulated charge can be made very large. Therefore, it is possible to cause the preliminary discharge even at a voltage equal to or lower than the specified voltage at which the main discharge occurs, and when a surge occurs, the preliminary discharge occurs at an early rise time of the voltage. Therefore, it becomes possible to shorten the discharge delay time until the surge occurs and the discharge occurs, and the dispersion of the discharge delay time and the operating voltage becomes small.

Further, since the lightning protection device of these embodiments may be the same as the conventional one except that the auxiliary electrode is formed, other known shapes, configurations, materials, forming techniques and the like are applied as they are. There is also an advantage.

When the lightning arrester of the above-mentioned embodiment was operated and compared with the conventional one, almost no variation in the operating voltage seen in the prior art was recognized and the operating time was short.

A voltage capable of preliminary discharge is applied between the discharge electrodes 5 and 5 or between the discharge electrode 5 and the auxiliary electrode 6,
By preliminarily accumulating the charges on the inner surface of the insulating cylindrical container 1, it is possible to shorten the time for accumulating the charges, albeit slightly.

[0028]

As described above, according to the lightning protection device of the present invention, the action of the auxiliary electrode makes it possible to shorten the discharge delay time until a surge occurs and a discharge occurs, and the discharge delay Variations in time and operating voltage are small.

Therefore, since the operation time is short and the variation is small without using the radioactive element, L
There is no fear of degrading circuit elements such as SI.

Further, the above effect can be easily achieved by forming the auxiliary electrode at a predetermined position of the insulating container. At this time, since it is the same as the conventional one except that the auxiliary electrode is formed, other known shapes, configurations, materials, forming techniques and the like can be applied as they are. A simple conventional method can be applied to the auxiliary electrode, and the auxiliary electrode can be easily formed.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a lightning arrester of the present invention.

FIG. 2 is a cross-sectional view showing another example of the lightning arrester of the present invention.

FIG. 3 is an exploded perspective view showing a conventional lightning protection device.

[Explanation of symbols]

 1 Cylindrical container 2 Electrode part 3 Lid body 4 Seal part 5 Discharge electrode 6 Auxiliary electrode 6'Auxiliary electrode

Claims (1)

[Claims] 1. A lightning arrester in which at least one pair of discharge electrodes is formed in an airtight insulating container containing a dischargeable gas, wherein an auxiliary electrode is further formed in the insulating container. Characteristic lightning protection element.