JPH03230487A - Discharge type surge absorbing element - Google Patents

Abstract

PURPOSE:To obtain a stable surge absorbing action by providing a fine gap generating the initial creeping discharge on a discharge type surge absorbing element between discharge electrodes and a conducting thin film. CONSTITUTION:A discharge type surge absorbing element 1 is fitted with a pair of discharge electrodes 4 formed into a cap shape with a metal with good discharge characteristic such as Ni, Fe or their alloy and connected with external terminals 3 made of a Dumet wire on both ends of a columnar insulator 2 made of ceramic such as alumina, and a discharge gap 5 with the width several mm or ten end several mm is formed between the opposite end sections 4a of the electrodes 4. A conducting thin film 6 is coated on the periphery of the insulator 2, a fine gap 7 is formed between the film 6 and the opposite end sections 4a of the electrodes 4, it is sealed in an airtight container 8 made of glass together with discharge gas of rare gas such as He, and the external terminals 3 are guided to the outside. Since the fine gap 7 generating the initial creeping discharge on the element 1 is provided between the discharge electrodes 4 and the conducting thin film 6, an unstable defective contact state is eliminated, and a stable surge absorbing action is obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a discharge-type surge absorption element that utilizes a discharge phenomenon in a discharge gap housed in an airtight container, and is capable of obtaining particularly stable surge absorption operation. , relates to a discharge type surge absorbing element with a long service life.

[Prior Art] Conventionally, it has been used as a surge absorbing element to protect electronic circuits from surges such as induced lightning that are applied to electronic circuits.

Varistors made of high-resistance elements having nonlinear voltage characteristics, arresters whose discharge gap is housed in an airtight container, and the like are widely used.

However, although the above-mentioned varistors have excellent response in surge absorption, the current withstand capacity per unit cross-sectional area is relatively small.
Therefore, it was necessary to install it internally to efficiently absorb large surge currents. In addition, the above arrester can increase the current withstand capacity by generating an arc discharge in the discharge gap, but the time required from the application of a surge to the arc discharge is slower than that of the above varistor, and its response is He had sexual problems.

Therefore, in order to improve the response of surge absorption in the arrester, as shown in FIG.
The conductive thin film 6 is divided by forming a micro gap 7 with a width of about 0.1 ma+ in a circumferential manner, and the discharge electrodes 4 are fitted on both ends of the insulator 2 with a discharge gap 5 in between. A surge absorbing element 10 has been proposed in which a conductive thin film 6.6 and discharge electrodes 4, 4 are connected, and this is sealed together with a discharge gas in an airtight container 8 to lead out an external terminal 3.3.

When a surge is applied to the surge absorbing element 10 having this minute gap 7, first the conductive thin film 6 is applied through the minute gap 7.
．． A potential difference is generated between the discharge electrodes 4 and 6, and this causes electrons to be emitted into the minute gap 7, causing a creeping discharge.2 Next, a creeping discharge occurs between the discharge electrodes 4 and 4 due to the priming effect of the electrons generated with this creeping discharge. . Then, as the surge current increases, this creeping discharge shifts to arc discharge in the discharge gap 5, and the surge is absorbed by this arc discharge. As described above, since the surge absorbing element 10 having the minute gap 7 utilizes creeping discharge which has an inherently fast response speed, it has an excellent response such as a substantially concave shape compared to the above-mentioned varistor.

The current withstand capacity is also large and excellent.

[Problems to be Solved by the Invention] However, in the conventional surge absorbing element 10 having the minute gap 7 as described above, the discharge electrode 4.4 is
When fitted to both ends of the body 2, there is a risk that a gap will be created between the discharge electrode 4.4 and the conductive thin films 6, 6, resulting in poor contact, and this will cause the surge absorption characteristics to become unstable. Ta.

Furthermore, in the conventional surge absorbing element, the conductive thin film 6
, 6 are thin and have poor physical strength, as the surge absorption is repeated, the conductive thin film 6.6 is sputtered due to the creeping discharge formed in the micro gap 7, which reduces the electrical insulation of the micro gap 7. There was a drawback that the properties of the 11fi7 were deteriorated, resulting in poor insulation and no longer functioning as a micro-interval 11fi7.

Therefore, the present invention solves the above-mentioned problems and realizes a discharge-type surge absorption element that can obtain stable surge absorption characteristics and has a long life without deteriorating its insulation properties even after repeated surge absorption. purpose.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the discharge type surge absorbing element of the present invention has a conductive thin film coated on the surface of an insulator, and discharge is applied to both ends of the insulator. Discharge electrodes are attached facing each other with a gap in between, a minute gap is formed between the discharge electrode and the conductive thin film, and the gap is housed together with the discharge gas in an airtight container.

[Function] Since the discharge type surge absorbing element of the present invention has the above-described configuration, when a surge exceeding a predetermined value is applied to the surge absorbing element, microscopic damage occurs between the discharge electrode and the conductive thin film. Since the gap is sufficiently narrower than the discharge gap between the discharge electrodes, a creeping discharge is immediately generated in the minute gap. This creeping discharge further generates electrons as it discharges, and transforms into a creeping discharge between the discharge electrodes due to the priming effect of the electrons and an increase in voltage drop due to the resistance of the conductive thin film and the surge current. Furthermore, this creeping discharge between the discharge electrodes is
The increase in surge current causes a transition to arc discharge in the discharge gap, and this arc discharge can absorb large current surges.

In the discharge type surge absorbing element of the present invention, by providing a minute gap between the discharge electrode and the conductive thin film, there is no need for electrical connection between the discharge electrode and the conductive thin film, resulting in unstable contact. This eliminates defective conditions and provides stable surge absorption operation.

In addition, in the discharge type surge absorbing element of the present invention in which a minute gap is provided between the discharge electrode and the conductive thin film, since the discharge electrode is physically difficult to sputter, the conventional surge absorbing element provided between the conductive thin film is Compared to the minute gap, there is less risk of causing insulation deterioration due to sputtering, and it is possible to extend the life of the discharge type surge absorbing element.

[Example] Hereinafter, an example of the present invention will be described based on one drawing.

FIG. 1 shows a discharge type surge absorbing element according to an embodiment of the present invention, and FIG. 1(a) is a schematic perspective view.

In FIG. 1(b), which is a sectional view of the main part, the discharge type surge absorbing element 1 has a dumet wire attached to both ends of a substantially cylindrical insulator 2 made of ceramics such as alumina, forsterite, steatite, etc. A pair of discharge electrodes 4 made of a cap-shaped metal with good discharge characteristics, such as nickel, iron, or an alloy thereof, to which external terminals 3 and 3 are connected.
, 4 by fitting or adhesion, and a width of several meters to 10 mm is formed between the opposing ends 4a and 4a of the discharge electrode 4.
A discharge gap 5 of about several meters is formed. Further, a conductive thin film 6 is deposited on the circumferential surface of the insulator 2, and this conductive thin film 6 is
and the opposing ends 4a, 4a of the discharge electrodes 4, 4, respectively, form minute gaps 7, 7, which are I-re, N
It has a structure in which it is sealed in an airtight container 8 made of glass or the like together with a discharge gas made of a rare gas such as E, Ar, etc., and the external terminals 3 are led out to the outside.

The minute gaps 7, 7 are made of carbon, conductive ceramics, etc. with a predetermined resistance value after masking in advance the portions of the peripheral surface of the insulator 2 where the discharge electrodes 4, 4 are attached and the portion where the minute gap 7 is formed. A conductive material having a conductive material is deposited by a method such as spraying, vapor deposition, or coating, and then the masking is removed and discharge electrodes 4 are attached and formed, or a conductive thin film 6 is deposited on the entire circumferential surface of the insulator 2. After.

The discharge electrodes 4, 4 can be formed by removing unnecessary conductive thin film portions by machining means such as polishing or cutting, and then attaching the discharge electrodes 4, 4.

Further, as shown in FIG. 2, the minute gaps 7, 7 are formed by depositing a conductive thin film 6 on the entire circumferential surface of the insulator 2, and then forming the minute gaps 7, 7 in this conductive thin film 6. Two grooves wider than the required width of the micro gaps 7, 7 are formed using a cutting machine or a laser processing machine at the desired positions, and the conductive thin film in these areas is cut. Alternatively, the insulator 2 may be removed, and discharge electrodes 4, 4 may be attached to both ends of the insulator 2.

In this case, both ends of the conductive thin film 6 at the center of the conductive thin film 6a, 6.6a divided into three parts by the two grooves,
Opposite ends 4a of discharge electrodes 4,4.

The attachment positions of the discharge electrodes 4, 4 to the insulator 2 are set so that the respective gap widths with respect to the discharge electrodes 4a are the widths of the minute gaps 7, 7. Note that electrical connection between the left and right conductive thin films 6a, 6a and the discharge electrodes 4, 4 is not necessary, but when these are electrically connected, the conductive thin films 6a, 6a are connected electrically.
The end portion on the micro gap 7, 7 side is the discharge electrode 4,
It is necessary to position it deeper than the opposing ends 4a, 4a of 4. This is to generate the first creeping discharge in surge absorption between the opposing ends 4a, 4a of the discharge electrodes 4, 4 and both ends of the conductive thin film 6 in the central portion.

The width of the minute gaps 7, 7 is determined based on the type of discharge gas to be filled in, taking into consideration the discharge starting voltage during surge absorption.

Set to appropriate values along with gas pressure, discharge gap width, etc. This width is preferably approximately 200 μm or less.

If this value is exceeded, depending on the conditions, the degree of electric field concentration in the minute gap 7.7 may decrease and the discharge delay may increase.

Note that the insulator 2 between the opposing ends 4a, 4a of the discharge electrodes 4, 4
Since the conductive thin film 6 deposited on the surface is electrically independent from the discharge electrodes 4, 4, when electrons come into contact with the conductive thin film 6, they are accumulated, and these electrons are used to absorb surges. Responsiveness will be improved.

[Effects of the Invention] As detailed above, according to the present invention, by providing a minute gap between the discharge electrode and the conductive thin film in which the initial creeping discharge is generated in the discharge type surge absorbing element, the discharge This eliminates the need for electrical connection between the electrode and the conductive thin film, eliminates unstable contact failure, and provides stable surge absorption operation. In addition, since the discharge electrode at one end of the Wj small gap is physically difficult to sputter, there is a risk of causing insulation deterioration due to sputtering compared to the conventional case where a small gap is provided between conductive thin films. This further extends the life of the discharge type surge absorbing element.

[Brief explanation of drawings]

FIG. 1 shows a discharge type surge absorbing element according to an embodiment of the present invention, FIG. 1(a) is a schematic perspective view, FIG. 1(b) is a sectional view of a main part, and FIG. 2 is a diagram of the present invention. FIG. 3 is a sectional view of a main part showing another embodiment, FIG. 3 shows a conventional discharge type surge absorption element, FIG. 3(a) is a schematic perspective view, and FIG. 3(b) is a sectional view of a main part. It is. 1... Discharge type surge absorption element 2... Insulator 4.
...Discharge electrode 5...Discharge gap 6...Conductive thin film 7...Minute gap 8...Airtight container Applicant: Okaya Electric Industry Co., Ltd.

Claims (1)

[Claims] A conductive thin film is deposited on the surface of the insulator, and discharge electrodes are attached to both ends of the insulator so as to face each other across a discharge gap, thereby forming a minute gap between the discharge electrode and the conductive thin film. This is a discharge-type surge absorption element in which this is housed in an airtight container together with a discharge gas.