JPH0246679A - Discharge type surge absorption element and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a sufficient protective function to a rapidly rising surge by forming a dielectric layer having a creeping discharge characteristic between lead wires inside an airtight container while in parallel connecting a discharge gap and the dielectric layer. CONSTITUTION:A dielectric layer 5 having a good creeping discharge characteristic is formed between lead wires 3 inside an airtight container 6, while a discharge gap 4 and the dielectric layer 5 are in parallel connected. When a surge is impressed on this discharge type surge absorption element, creeping corona discharge immediately generated on the surface of the dielectric layer 5 between the lead wires acts as a trigger discharge while being translated to air discharge in the discharge gap 4 due to a priming effect of electrons and ions accompanying discharge. Consequently, arc discharge is generated in the discharge gap 4 through glow discharge so that the surge is absorbed through a large current of the arc discharge. Thereby, a sufficient protection function can be displayed to the steep surge.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a discharge-type surge absorption element that utilizes a discharge phenomenon in a discharge gap enclosed in an airtight container, and a method for manufacturing the same, and particularly relates to a The present invention relates to a discharge-type surge absorbing element whose response characteristics are improved by using creeping discharge as a trigger means for the surge absorption element, and a method of manufacturing the same.

[Prior art] Conventionally, in order to protect electronic circuit components from transient abnormal voltages and surges such as induced lightning that enter electronic equipment, varistors made of voltage nonlinear resistors and discharge gaps sealed in airtight containers have been used. Various surge absorbing elements are used, such as gas arresters that utilize this phenomenon.

Among the conventional surge absorbing elements described above, the gas arrester 1, which is a type of discharge type surge absorbing element, is as shown in FIG.
Rod-shaped discharge electrodes 2.2 having emitter layers 2a, 2a formed on their surfaces are arranged substantially parallel to each other to form a discharge gap 4 between the discharge electrodes 2.2, which is surrounded by an outer enclosure made of a glass tube. The lead wires 3, 3 are sealed together with a discharge gas in an airtight container 6 formed by sealing the body, and are connected to the discharge electrodes 2, 2.
is fixed to the airtight container 6, and has a structure in which it penetrates the container 6 and is led out to the outside.

When a surge is applied to the discharge type surge absorbing element 1,
Arc discharge is generated in the discharge gap 4 through aerial discharge, that is, glow discharge, and the surge is absorbed through the large current of the arc discharge.

In addition, when manufacturing the above-mentioned discharge type surge absorbing element l,
First, an emitter material is attached to the surface of the discharge electrode 2.2 to which the lead wire 3.3 is connected, and this is inserted into an envelope with both ends open. Arranged so as to protrude outward from one end of the outer envelope.Next, one end of the outer envelope is heated and melted, and further crushed and sealed,
Fix the lead wires 3 and 3. Thereafter, the envelope is placed inside a high-frequency coil, and high-frequency heating is performed at a temperature that thermally decomposes the emitter material while exhausting air from the other end of the envelope, decomposing the emitter material and forming the emitter layers 2a, 2a. Form. Furthermore, after exhausting the air in the envelope, the gas caused by the decomposition of the emitter material, and the gas released from each member, discharge gas is sealed inside the envelope, and the envelope is heated and melted to seal it and form an airtight container 6. form.

[Problem a to be Solved by the Invention] As described above, the discharge-type surge absorption element absorbs surges through aerial discharge, and therefore has a large current withstand capacity, but has a long discharge delay time and a steep rise. There is a problem in that a residual surge is generated in response to a surge having characteristics, and surge protection cannot be provided sufficiently.

The present invention has been devised in view of the above-mentioned points, and takes advantage of the advantages of the surge absorption element using air discharge and improves the disadvantages, thereby achieving a large current withstand capacity and a short discharge delay time. The purpose of the present invention is to realize a discharge type surge absorbing element that can provide sufficient protection against surges that suddenly rise, and furthermore, to obtain a manufacturing method that can easily manufacture the discharge type surge absorbing element. It is something to do.

[Means for Solving the Problem] As a result of various studies to achieve the above-mentioned object, we focused on the fact that the discharge delay time of creeping discharge is extremely small, and by using this as a trigger means for aerial discharge, we have achieved the present invention. It has been completed.

Therefore, in the discharge type surge absorbing element of the present invention, discharge electrodes are disposed facing each other in an airtight container filled with discharge gas, a discharge gap is formed between the discharge electrodes, and a lead wire is connected to the discharge electrodes. The lead wires are fixed to the airtight container and led out through the airtight container, and a dielectric layer having good creeping discharge characteristics is formed on the inner surface of the airtight container at least between the lead wires. The discharge gap and the dielectric layer are connected in parallel. The dielectric layer is preferably formed mainly of nickel oxide. Furthermore, it is advantageous in manufacturing that the dielectric layer is formed mainly of an oxide of the metal that constitutes the discharge electrode.

Furthermore, an auxiliary discharge electrode may be provided on at least the surface of the dielectric layer, and the auxiliary discharge gap formed between the auxiliary discharge electrode and the discharge electrode or the lead wire may be narrower than the discharge gap between the discharge electrodes. good.

The material for the auxiliary discharge electrode is not particularly limited as long as it has good discharge characteristics, but it can be manufactured using materials that are housed in an airtight container, such as lead wires or metals that make up the discharge electrode. It is advantageous.

Therefore, among the above methods for manufacturing a discharge type surge absorbing element, a method for manufacturing a discharge type surge absorbing element in which a dielectric layer is formed mainly from a metal oxide constituting the discharge electrode is such that the surface of the discharge type surge absorbing element is A manufacturing method in which an oxidized discharge electrode is heated in a reduced pressure atmosphere to melt and scatter the surface, and this is adhered to the inner surface of an airtight container to form a dielectric layer, and a discharge electrode in a reduced pressure oxidation atmosphere. There is a manufacturing method in which a dielectric layer is formed by heating the dielectric to melt and scatter the surface, oxidize the dielectric, and deposit the dielectric layer on the inner surface of the airtight container. In addition, when manufacturing the above-mentioned discharge type surge absorbing element, if there is a step of depositing an emitter material on the surface of the discharge electrode and heating and decomposing it in a reduced pressure atmosphere to form an emitter layer, this emitter layer formation By heating in a reduced pressure atmosphere during the process, the surface of the discharge electrode can be melted and scattered to form a dielectric layer.

Furthermore, as a method for manufacturing a discharge-type surge absorbing element in which an auxiliary discharge electrode is formed from metal that constitutes members such as lead wires and discharge electrodes housed in an airtight container,
There is a manufacturing method in which a member to be housed in an airtight container is heated in a reduced pressure atmosphere to melt and scatter the surface of the member, and this is adhered to at least the surface of a dielectric layer to form an auxiliary discharge electrode. In addition, when manufacturing the above-mentioned discharge type surge absorption element, an emitter material is attached to the surface of the discharge electrode,
If there is a step of heating and decomposing this in a reduced pressure atmosphere to form an emitter layer, the surfaces of the lead wires, discharge electrodes, etc. are heated in the reduced pressure atmosphere in this emitter layer forming step. An auxiliary discharge electrode can be formed by melting and scattering.

[Operation] When a surge is applied to the discharge-type surge absorbing element configured as described above, creeping corona discharge is immediately generated on the surface of the dielectric layer between the lead wires and surge absorption begins. Ru. The above creeping corona discharge acts as a trigger discharge,
Due to the priming effect of electrons and ions accompanying the discharge, the discharge shifts to an air discharge in the discharge gap. For this reason,
Arc discharge is generated in the discharge gap through glow discharge, and the surge is absorbed through the large current of the arc discharge. In this case, if the dielectric layer is formed using nickel oxide as a main component, the time required to form a creeping discharge will be extremely shortened because nickel oxide has particularly excellent creeping discharge characteristics.
A great trigger effect can be obtained. Furthermore, when the dielectric layer is formed using the oxide of the metal constituting the discharge electrode as a main component, there is no need to separately prepare a material for forming the dielectric layer.

Furthermore, when an auxiliary discharge electrode is provided on the surface of the dielectric layer to form an auxiliary discharge gap, the creeping corona discharge generated on the surface of the dielectric layer is The air discharge then transfers to the discharge gap between the discharge electrodes.

In this case, the transition time from the creeping discharge to the air discharge in the auxiliary discharge gap is narrower than the discharge gap between the discharge electrodes, so the transition time from the creeping discharge to the above discharge when the auxiliary discharge electrode is not present is narrower than the discharge gap between the discharge electrodes. This is much shorter than the transition time to air discharge in the gap.

Moreover, the transition of the air discharge from the auxiliary discharge gap to the discharge gap takes a very short time due to its priming effect, since the air discharge in the auxiliary discharge gap generates a larger amount of electrons and ions than the creeping discharge. It will be held on. Therefore, the transition time from the creeping discharge to the air discharge in the discharge gap is shortened.

In this case, if the auxiliary discharge electrode is formed from the metal that constitutes the member housed in the airtight container, there is no need to prepare a separate material for the auxiliary discharge electrode.

Among the above-mentioned manufacturing methods for the discharge type surge absorbing element, in the manufacturing method in which a dielectric layer is formed using an oxide of the metal constituting the discharge electrode, the discharge electrode whose surface has been oxidized in advance is depressurized. If the surface of the discharge electrode is heated in an atmosphere to melt and scatter, or if the discharge electrode is heated in a reduced pressure oxidizing atmosphere to melt and scatter the surface and oxidize it, the inner surface of the airtight container can be heated. Metal oxide is deposited.

Therefore, if this operation is continued until the metal oxide becomes layered, a dielectric layer is formed.

In addition, among the above-mentioned methods for manufacturing the discharge-type surge absorbing element, there is a method in which the auxiliary discharge electrode is formed from the metal that constitutes the lead wires, discharge electrodes, and other members housed in an airtight container. When the above-mentioned member is heated in a reduced pressure atmosphere, the surface of the member melts and scatters, and the metal becomes particles or a lump of particles and adheres to the dielectric layer on the inner surface of the airtight container. Therefore, if the above operation is completed with the metal particles sparsely attached to the surface of the dielectric layer, an auxiliary discharge electrode can be obtained.

Furthermore, when manufacturing the above-mentioned discharge type surge absorbing element, if there is a step of heating and decomposing the emitter material attached to the surface of the discharge electrode in a reduced pressure atmosphere to form an emitter layer, the pressure reduction rate, heating temperature, etc. By appropriately selecting the manufacturing conditions and the materials of members such as the discharge electrode and lead wire, it is possible to form the dielectric layer and the auxiliary discharge electrode described above at the same time.

[Example] Hereinafter, the present invention will be described in detail based on the drawings.

FIG. 1 is a sectional view showing a discharge type surge absorbing element according to an embodiment of the present invention. A pair of discharge electrodes 2 is formed by processing the material into a rod or plate shape, and coating the surface with emitter layers 2a, 2a made of an emitter material such as barium oxide or lanthanum hexavalent.
2, and at one end there is a lead wire 3.3 made of dumet wire (copper-coated iron-nickel alloy wire) or 42-6 alloy wire.
One end of the is connected. Further, the lead wires 3° 3 are aligned in the same direction, the discharge electrodes 2, 2 are arranged substantially parallel to each other, a discharge gap 4 is formed between the discharge electrodes 2, 2, and a creeping discharge is generated in the discharge gap 4. Dielectric layers 5 having good characteristics are connected in parallel and sealed in an airtight container 6, and the lead wires 3.3
The middle part is fixed to one end of the airtight container 6, and the other end of the lead wire 3.3 is led out to the outside by passing through one end of the airtight container 6. The airtight container 6 is formed by sealing an envelope made of a glass tube, and contains:
A discharge gas made of rare gas, nitrogen gas, sulfur hexafluoride gas, etc. is sealed.

The dielectric layer 5 is mainly composed of a dielectric material with good creeping discharge characteristics such as nickel oxide, and is formed by depositing it on the inner surface of the airtight container 6 by vapor deposition, thermal spraying, coating, etc. 3.3, the discharge mold 8i2.2 is connected to the discharge gap 4 in parallel.

Further, as shown in FIG. 2, if an auxiliary discharge electrode 7 is formed on at least the surface of the dielectric layer 5 having good creeping discharge characteristics, the trigger effect will be increased. The auxiliary discharge electrode 7 is made of a metal with good discharge characteristics, such as copper, nickel, or aluminum, and is formed between the auxiliary discharge electrode 7 and the discharge electrode 2°2 or the lead wire 3.3. It is necessary to form the auxiliary discharge gap 8 at a position where I[d is narrower than the width of the discharge gap 4 between the discharge electrodes 2.2. This is done by depositing metal materials, thermal spraying, etc.
It can be easily formed by sparsely coating the surface of the dielectric layer 5 in the form of particles or a mass of particles.

Next, an example of a method for manufacturing the above-mentioned discharge type surge absorbing element will be described.

In this manufacturing method, first, a discharge electrode 2 made of nickel is connected to a lead wire 3.3 made of a dumet wire.
．． An emitter material made of barium carbonate is deposited on the surface of the electrode 2.2 so that a part of the surface of the electrode 2.2 is exposed. Then, the lead wires 3.3 are aligned in the same direction and held by an alignment jig, the discharge electrodes 2.2 are opposed to each other at a predetermined interval, and this is inserted into an envelope made of a glass tube with both ends open. Then, the lead wire 3.3 is housed so that the end thereof protrudes from one end of the outer enclosure to the outside. Furthermore, one end of the envelope is heated with a gas flame to melt it, and the melted part is crushed inward with pinchers to seal it, and the lead wire 3.
3 is fixed to one end of the enclosure, and the lead wire 3.3 is led out of the enclosure. In this case, by heating the envelope in air, the exposed portion of the surface of the discharge electrode 2.2 is oxidized to form nickel oxide.

Next, an exhaust device is connected to the other end of the envelope, the envelope is placed inside a high-frequency coil, and the interior of the envelope is evacuated while being subjected to high-frequency heating. Barium carbonate, which is the emitter material, is thermally decomposed and discharged. Emitter layers 2a, 2a made of barium oxide are formed on the surface of the electrode 2.2, and the discharge electrode 2.2 is further formed with emitter layers 2a, 2a made of barium oxide.
The exposed portions of the two surfaces melt and begin to scatter due to the reduced pressure within the envelope due to exhaust air. At the beginning of the exhaust process,
Due to the high residual air concentration inside the envelope, the nickel constituting the discharge electrodes 2, 2 is oxidized to nickel oxide during scattering, and the nickel oxide formed on the surface of the discharge electrodes 2, 2 in the previous process is oxidized to the outside. A dielectric layer 5 is formed which adheres to the inner surface of the enclosure and has good creeping discharge characteristics.

Thereafter, as the evacuation work progresses, the concentration of residual air inside the envelope decreases, and finally the scattered nickel is no longer oxidized. Therefore, this nickel is applied to the dielectric layer 50.
If this operation is completed when the particles are sparsely adhered to the surface, the auxiliary discharge electrode 7 will be formed. The above-mentioned auxiliary discharge type @7 can also be formed by scattering copper or barium, which are metals constituting the lead wires 3.3 and the emitter layers 2a, 2a, and sparsely depositing them on the surface of the dielectric 1ij5. In addition, when forming the above-mentioned auxiliary discharge electrode 7, a certain amount of metal such as nickel, copper, or barium, which is the material of the auxiliary discharge electrode 7, is mixed into the dielectric layer 5, but the amount of mixing is such that it does not cause conductivity. If you suppress it, there will be no problem.

Finally, after removing residual air, carbon dioxide from decomposition of barium carbonate, and impurity gases released from the envelope and the members housed within the envelope through the above-mentioned exhaust operation, the interior of the envelope is brought to a high vacuum state. , the other end of the outer envelope is heated, melted, and sealed to form an airtight container 6.
Once formed, the discharge type surge absorbing element 1 is completed.

In the manufacturing method of this example, the manufacturing conditions such as heating temperature, heating time, and pumping speed, as well as the melting temperature, decomposition temperature, oxidation rate, etc. of the materials constituting each member, are appropriately selected to find the optimum conditions. Must be set.

In the case of this embodiment, there is no need to separately prepare materials and processes for forming the dielectric layer 5 and the auxiliary discharge electrode 7, and the manufacturing process can be simplified.

[Effects of the Invention] As detailed above, in the discharge type surge absorbing element of the present invention, the dielectric layer having good creeping discharge characteristics and the discharge gap are connected in parallel, so that when a surge is applied, the dielectric A creeping corona discharge occurs on the surface of the body layer, and this serves as a trigger, and the creeping discharge changes to an air discharge in the discharge gap, that is, a glow discharge, and then to an arc discharge. Therefore, the discharge-type surge absorption element of the present invention has surge absorption characteristics that combine the continuity of creeping discharge and the large current withstand capability of arc discharge, and can exhibit a sufficient protective function against steep surges. Become something. In this case, if the dielectric layer is formed using nickel oxide as a main component, the triggering effect will be particularly large because nickel oxide has excellent creeping discharge characteristics.

In addition, by providing an auxiliary discharge electrode on the surface of the dielectric layer and forming an auxiliary discharge gap narrower than the discharge gap between the discharge electrodes, creeping corona discharge can be transferred to air discharge in the auxiliary discharge gap. , and further migrates to the discharge gap between the discharge electrodes. In this case, the transition time of the discharge is shortened due to the narrow auxiliary discharge gap and the large priming effect due to the aerial discharge in the auxiliary discharge gap, so the discharge time in the dielectric layer is shortened. . Therefore, deterioration of the dielectric layer due to creeping discharge is prevented, and life characteristics are improved.

Furthermore, the dielectric layer may be formed using an oxide of the metal that constitutes the discharge electrode as a main component, and the auxiliary discharge electrode may be formed using a metal that constitutes the member housed in the airtight container. Therefore, there is no need to separately prepare materials for the dielectric layer and the auxiliary discharge electrode, and manufacturing can be simplified.

In addition, when manufacturing a discharge-type surge absorbing element, if there is a process in which the emitter material is heated and decomposed in a reduced pressure atmosphere to form an emitter layer, by appropriately selecting the process conditions, it is possible to The dielectric layer and auxiliary discharge electrode can be formed by melting and scattering the surface of the members stored in the airtight container using heating, and the materials and processes for forming the dielectric layer and auxiliary discharge electrode can be No need for separate
This makes manufacturing even easier.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is a sectional view showing an embodiment of the present invention.
FIG. 3 is a sectional view of a main part when an auxiliary discharge electrode is provided, and FIG. 3 is a sectional view of a conventional example. l...Discharge type surge absorption element, 2...Discharge electrode, 2
a... Emitter layer, 3... Lead wire, 4... Discharge gap, 5... Dielectric layer, 6... Airtight container, 7... Auxiliary discharge electrode, 8... Auxiliary discharge gap. Figure 1 Patent applicant Okaya Electric Industry Co., Ltd.

Claims (12)

[Claims] (1) Discharge electrodes are arranged facing each other in an airtight container filled with discharge gas, a discharge gap is formed between the discharge electrodes, a lead wire is connected to the discharge electrode, and the lead wire is connected to the airtight container. In a discharge type surge absorbing element fixed to a container and led out to the outside by penetrating the airtight container, a dielectric layer having good creeping discharge characteristics is formed on the inner surface of the airtight container at least between the lead wires, A discharge type surge absorbing element characterized in that the discharge gap and the dielectric layer are connected in parallel. (2) The surge absorbing element according to claim 1, wherein the dielectric layer is formed mainly of nickel oxide. (3) Claim 1 characterized in that the dielectric layer is formed mainly of an oxide of a metal constituting the discharge electrode.
Or the discharge type surge absorption element according to 2. (4) An auxiliary discharge electrode is provided on at least the surface of the dielectric layer, and an auxiliary discharge gap narrower than the discharge gap between the discharge electrodes is formed between the auxiliary discharge electrode and the discharge electrode or the lead wire. The discharge type surge absorbing element according to claim 1, 2 or 3, characterized in that: (5) The discharge type surge absorbing element according to claim 4, wherein the auxiliary discharge electrode is formed of a metal that constitutes a member housed in the airtight container. (6) The discharge type surge absorbing element according to claim 5, wherein the auxiliary discharge electrode is made of a metal that constitutes the lead wire. (7) The discharge type surge absorbing element according to claim 5, wherein the auxiliary discharge electrode is formed of a metal that constitutes the discharge electrode. (8) The surface of the discharge electrode is oxidized in advance, and the discharge electrode is heated in a reduced pressure atmosphere to melt and scatter the surface, which is then deposited on the inner surface of the airtight container to form a dielectric layer. 4. The method of manufacturing a discharge type surge absorbing element according to claim 3. (9), heating the discharge electrode in a reduced pressure oxidizing atmosphere,
4. The method of manufacturing a discharge-type surge absorbing element according to claim 3, wherein the surface of the discharge electrode is melted, scattered, and oxidized, and then deposited on the inner surface of the airtight container to form a dielectric layer. (10), attaching an emitter material to the surface of the discharge electrode so that a part of the electrode surface is exposed, and heating this in a reduced pressure atmosphere to decompose the emitter material and form an emitter layer; 10. The method of manufacturing a discharge type surge absorbing element according to claim 8, wherein the surface of the discharge electrode is melted and scattered by heating in a reduced pressure atmosphere at this time. (11) A member to be housed in an airtight container is heated in a reduced pressure atmosphere to melt the surface of the member and scatter the metal constituting the member. 6. The method of manufacturing a discharge type surge absorbing element according to claim 5, wherein the auxiliary discharge electrode is formed by adhering to the surface. (12), attaching emitter material to the surface of the discharge electrode,
By heating this in a reduced pressure atmosphere, the emitter material is decomposed to form an emitter layer, and by heating in the reduced pressure atmosphere at this time, the surface of the member to be stored in the airtight container is melted and scattered. 12. The method of manufacturing a discharge type surge absorbing element according to claim 11, further comprising the step of: