TWI395252B - Gas discharge tube - Google Patents

Description

Gas discharge tube

The invention relates to the field of gas discharge tubes, which comprise a surge arrester, a gas discharger, a high-intensity discharge tube, an electric flower gap, a switched electric flower gap and a triggered electric flower gap, which are used in various applications, such as Surge voltage protector for controlled switching of communication network voltages for capacitive discharge circuits, and in particular a new type of such devices, which exhibits higher selectivity, better performance and more Environmental protection. The invention relates in particular to the design of an insulating portion of such a gas discharge tube.

When an electronic device is connected to a long signal or power line, antenna, etc., it is exposed to a transient phenomenon caused by an inductance that occurs by lightning or electromagnetic pulses (EMP). A surge arrester protects the device from damage by absorbing energy in the transient or connecting the device to ground. Surge arresters must be self-healing, can handle repeated transients and can be made into automatic defenses. An important characteristic is the ignition speed and selectivity. In other words, the surge arrester must be active without delay and not so sensitive that it is triggered by a standard communication signal. These characteristics should not change over time and are independent of the firing interval. In addition, a surge arrester should be suitable for mass production with high and uniform quality.

Inflatable discharge tubes are used to protect electronic equipment but are also commonly used as switching devices in power switching circuits, such as in reel machines and automotive products such as gas discharge headlamps. Other application areas are telecommunications and data communication, audio/visual Frequency equipment, power supplies, welding equipment, electronic ignition devices for gas heating and gas household appliances such as cookware, industrial medical devices, architectural safety and military applications.

Early surge arresters included two solid graphite electrodes separated by an air gap or a mica layer. However, these dimensions, reliability, performance and production techniques cannot be compared to modern surge arresters.

A modern conventional surge arrester is an inflator discharge tube that can have one or several discharge paths or discharge gaps, and typically includes two terminal electrodes, optionally with an additional electrode, which is attached to a central electrode. Or in the form of two hollow cylindrical insulators made of an electrically insulating material such as ceramic, a suitable polymer, glass or the like. Typically, the insulation system in a two-electrode surge arrester is soldered to both sides of the terminal electrode to connect them in a closed manner.

For example, one method of producing a conventional surge arrester is described in US-A-4,437,845. According to US-A-4,437,845, the process consists of sealing a component in a tube in a light gas mixed with another gas at a suitable temperature and a substantially atmospheric pressure, in view of the desired effect of the tube. Ideally and heavier than the gas described above; and reducing the pressure outside the tube to atmospheric pressure while lowering the temperature to such an extent that the heavy gas can only be diffused and/or to a negligible extent Or oozing out through the wall of the tube, and the enclosed light gas can diffuse and/or bleed out of the tube wall such that it will exit the tube wall due to the pressure differential, thereby causing a decrease in the total gas pressure within the tube.

In addition, an external coating of one of the surge arrester assemblies has been disclosed In US-A-5,103,135, a tin coating is applied to the electrodes and an annular protective coating is applied to the ceramic insulator having a thickness of at least 1 mm. The protective coating is formed from an acid resistant heat resistant colorant or varnish that is continuous in the axial direction of the surge arrester. The protective coating forms part of the identification of the surge arrester. For example, the identification can be in the form of an imprint of one of the protective coatings. Additionally, tin coated wires can be coupled to the electrodes.

US-A-4,672,259 discloses a power electric flower gap for protecting an electronic device against ultra-high voltage and having a high current capacity, the electric flower gap comprising two carbon electrodes, each having a half-spherical configuration and a carbon electrode The ceramic casing is insulated, whereby the carbon electrodes contain venting openings to the interior thereof to provide arc transfer to an internal durable electrode material. The electric flower gap is desirably used for a high voltage line in which the length of the electric flower is expected to be about 2.5 cm (1 inch) and transmitted at about 140 kV. The electric flower gap is not isolated and sealed, but is freely connected to air. The resulting arc begins at the respective lower electrodes and passes through the vents. Thus, to a large extent, the formation of the electric flower is based on the underlying material that is not necessarily inert, but is caused by oxidation in the existing environment, which means that the electric flower voltage cannot be measured and regenerated.

US-A-4,407,849 discloses an electrical flower gap device and in particular a coating on the electrode of the electric flower gap in order to minimize the filament configuration. The coating is applied to a lower electrode whereby the coating can be composed of carbon in the form of graphite. The surge limiter is an inflated surge limiter. This reference does not address the problem with or without an inert surface on the electrode, or any other related problem.

US-A-2,103,159 discloses a discharge device having a long distance for any creeping current which has been produced by extending the height of the device between the electrodes comprising a waveform envelope. Such devices do not meet the requirements of modern discharge devices.

Another discharge device is disclosed in US-A-2,050,397 which shows an extreme distance between the electrodes to provide a shield for either pair of creep currents. The device exhibits a narrow tubular structure of one of the insulating materials.

The previously mentioned problems with sensitivity and defense have been solved by using electron donors on or elsewhere on the electrode surface. This electron donor may include a radioactive element such as ruthenium and/or a toxic alkaline earth metal such as ruthenium. Obviously, this solution additionally has specific drawbacks associated with the radioactivity and/or toxicity of the components.

The object of the present invention is to make available gas discharge tubes for all relevant fields of application, which show a particularly small size compared to other gas discharge tubes, which exhibit the same efficiency and have a smaller volume and more Light weight and / or less raw material consumption.

This goal is achieved by providing a new insulating ring design or any hollow shape while maintaining the electrode gap distance.

In particular, the present invention relates to an insulating ring having an extended width compared to its height thereby providing a long distance for any possible creep current. The gas discharge tube includes at least two electrodes and at least one hollow insulating ring, the at least one hollow insulating ring being fastened to at least one of the electrodes, whereby the insulating ring has a Inwardly And/or an extension of a creep current on at least one of the outward insulator surfaces, thereby providing a long distance for any possible creep current.

In a preferred embodiment, the insulator has a total height h of the insulator and a total length L of a creeping current for at least one of the inward and/or outward surfaces. The ratio of less than 1:1.3, the ratio of h to L is preferably 1:1.5, preferably 1:2, more preferably 1:2.5, still more preferably 1:3, and further more 1:5. .

At a particular voltage during operation, the desired length for avoiding a creeping current on the outer and inner surfaces may vary depending on various conditions such as the gas and pressure inside and outside the sealed seal assembly.

The term "ring" as used herein means any hollow structure that is limited by a raised peripheral boundary. Thus the ring may take the form of a circle, an ellipse, or a polygon (e.g., a triangle, a square, a pentagon, a hexagon, a heptagon, an octagon, etc.).

The term "insulator" or "insulating member" as used herein means a body that is non-conductive with respect to the current system. These components are typically made of alumina, other porcelain, glass, plastic, composite or other insulating materials. High voltage insulation systems for high voltage power transmission are made of glass, porcelain, or synthetic polymeric materials. The porcelain insulation system is made of clay, quartz or alumina and feldspar and is covered by a smooth glaze to mask the dirt. Insulators made of alumina-rich porcelain are used for high mechanical stress as a standard. Glass insulators have been used (and in some areas still used) for hanging transmission lines. Some insulator manufacturers stopped manufacturing glass insulators in the late 1960s, switched to various ceramics, and recently switched to composites.

In some electrical installations, polymeric composite materials have been used in certain types of insulators consisting of a central rod made of fiber-reinforced plastic and an outer sheath made of silicone rubber or EPDM. Composite insulators are less expensive, lighter, and have excellent hydrophobic properties. This combination makes it ideal for use in contaminated areas. However, these materials do not have the long-term proven service life of glass and porcelain.

The invention will be described in more detail hereinafter with reference to the accompanying drawings.

A general purpose gas discharge tube includes at least two electrodes that are joined to a hollow insulator body. As illustrated in Figure 8, a frequently encountered type of gas discharge tube includes two terminal electrodes 1 and 2, each electrode comprising a type of flange base and at least one hollow cylindrical insulator 3 that is welded or adhered to The base of the terminal electrodes. One of the coatings or elements forming the resist layer is illustrated as a shielded region 4 on the two electrodes. Regardless of the type of gas discharge tube, it is important that at least the cathode has this coating or is made of the materials or structures described below. However, it is preferred that all of the electrodes have this layer or structure because the polarity of the transient phenomenon can vary. A standard size for a gas discharge tube, for example for igniting a high pressure xenon lamp, is axially extending about 6.2 mm and extending radially 8 mm (diameter). This tube has a 4.4 mm height insulator ring and can withstand a few thousand volts of discharge using a 0.6 mm electrode gap.

Figure 1 shows a first embodiment of the invention in which insulator 11 represents a ceramic ring of any of the shapes defined above and is known to have electrically insulating properties. The insulator 11 includes a cylindrical structure 12, a radially extending flange 13 and 14 extends inward and outward from it. The two electrodes 15 and 16 are attached to the end surface of the cylindrical structure 12 of the ring by welding. The electrodes 15 and 16 are typically made of copper, silver or gold, an iron/nickel alloy, or have one or more of these metals on their surface.

As noted above, the insulator 11 includes a cylindrical structure 12 having two flat, oppositely facing surfaces 17, which are typically intended to receive a weld metal such as a tin and tin alloy or a hard solder alloy. In addition, the insulator 11 includes an outwardly, radially extending flange 14 having two radially extending surfaces 18 and 19 that form an angle with the cylindrical structure 12 and an edge axially oriented Surface 20. On the inwardly facing side of the cylindrical structure 12 of the insulator 11, there is a second radially extending flange 13 having two radially extending surfaces that form an angle with the cylindrical structure 12. 21 and 22, and an edge axial guiding surface 23.

The radially extending surface 18, 19, 21 or 22 may be perpendicular to the insulator 11 or may additionally form a blunt pointed corner. However, it is obvious that this non-vertical angle is only slightly blunt or micro-tip. Thus the angle a can be any angle between 75 and 105 degrees.

Referring to the definition of Fig. 1, the total height h of the insulator 11 is 0.6 mm, and the total height of the discharge tube including the electrodes is 1.0 mm, which uses an electrode gap of 0.6 mm. Referring to the definition of Figure 5, the total length L of the surfaces 21, 22 and 23 (L is the sum of the bold mark lengths of the inwardly facing cross section) is 2.7 mm and or the surfaces 18, 19 and 20 The total length is 2.7 mm for a creeping current on at least one of the inner and/or outer surfaces. The ratio h:L is less than 1:1 and is actually 1:4.7. h is smaller than L At 1:1.3, which is the ratio between the total height h of the insulator and the total length L of a creeping current used on at least one of the inner and/or outer surfaces, the ratio of h to L It is preferably 1:1.5, preferably 1:2, more preferably 1:2.5, still more preferably 1:3, and further more 1:5.

Another method of defining the invention utilizes the width w of the ring (which is defined as the distance between the outer edges of the radially extending flanges 13 and 14) and the height h. The ratio between h and w is at least 1:2, preferably 1:3 to 5, preferably 1:3 to 10, more preferably at least 1:4, still more preferably at least 1:5.

Figure 2 shows a multi-electrode embodiment of the invention in which a third electrode 25 is shown. There is an assembly of an electrode and an insulator 11, whereby the central electrode is annular and shared by the other two electrodes, that is, the third electrode 25 is fixed to the two insulators 11.

Figure 3 shows a further embodiment of the invention wherein the radially extending surfaces of the radially extending flanges have been modified to have a wave shape or have any shape or ditch to allow for any potential creep current Growth path.

The radially extending flanges 13, 14 extend the path through which any of the creeping current must flow from one electrode to the other, and will more or less correspond in this respect to a regular insulator present (presented in The path of the gas discharge tube known to date.

Figure 4 shows a gas discharge tube similar to that shown in Figure 1, however, wherein the gap between the electrodes is reduced by pressing the center of the electrode below the normal plane of the electrode.

Figure 5 shows a further embodiment of the invention in which the path has been completed inside and outside of a component for any possible creeping current increase unit. Thereafter, the overall final form of the gas discharge tube will be more similar to today's gas discharge tubes. The same definition appears here as above, whereby L inside the gas discharge tube will be of the desired length.

Figure 6 shows a further embodiment of the invention in which the path has been completed inside and outside of a component for any potential creeping current that may occur. Thereafter, the overall final form of the gas discharge tube will be more similar to today's gas discharge tubes. The same definition appears here as above, whereby L inside the gas discharge tube will be of the desired length.

Figure 7 shows a further embodiment of the invention in which the path has been completed within a component for any potential creeping current that may have occurred. Thereafter, the overall final form of the gas discharge tube will be more similar to today's gas discharge tubes. The same definition appears here as above, whereby L inside the gas discharge tube will be of the desired length.

However, in addition to this feature, the inwardly extending flange will also provide a weakly conductive inner surface. Thereby, sputtering of a metal such as copper (if a copper electrode is used) may occur during gas discharge, and the sputtered metal will condense on the tube wall. However, the inwardly extending flange, which is shown at an angle to the electrode surface, will also create a mask for the sputter material that will be difficult to reach the radially extending surfaces 21 and 22. Thus, the possibility of forming a conductive layer on the inner wall of the tube between the electrodes is small, which further increases the operational life of such a discharge tube.

Preferably, at least a portion of the opposing surfaces of the terminal electrodes are covered by a layer or coating of a compound or element that resists the formation of a layer such as an oxide layer. Other undesired layers are, for example, hydrides, the concept of the present invention is to prevent Stop its formation. In general, the phrase "unwanted layer" includes any layer formed on the electrodes and affecting the effectiveness of the tube by interaction with surrounding compounds, such as gases contained in the gas discharge tube.

The compound that forms the inventive layer and resists the formation of undesirable layers can be a highly stable metal alloy, a metal such as titanium, or an element that is nearly inert, such as gold. The compound may be a carbon-containing compound, preferably a carbon to which a metal such as chromium or titanium is added.

As used herein, carbon is defined as an allotrope of any carbon, such as diamond, diamond-like carbon or graphite. The carbon may also contain other elements, such as one or more metals, the total amount depending on the application, for example up to about 15%.

Preferably, the opposite surfaces of the isoprene electrodes are covered by a coating or graphite layer comprising an additive metal such as chromium or titanium.

According to one embodiment, the inert surface or oxidation resistant coating or layer is applied to the electrodes by electroless plating, sputtering, or the like. Preferably, the anti-oxidation layer is applied by conventional sputtering or plasma deposition techniques, which are well known to those skilled in the art.

In the case where a coating is applied to a substrate, suitable procedures include chemical vapor deposition (CVD), physical vapor deposition (PVD). Sputtering, which is a physical deposition method, is currently considered to be the most suitable method.

In the case of a metal coating, it is also possible to use an electroplating procedure or so-called electroless plating. These procedures are particularly suitable for coating coatings composed of precious metals such as gold or platinum.

According to an embodiment, the surfaces of the electrodes may be only partially coated, such as on a small area in the direction of the opposing electrode.

As an alternative embodiment, one of the electrodes is partially made of an inert material, such as a carbon-containing body that is fastened (e.g., pinched or sintered) to one of the metal bases of the electrode. It is contemplated that the electrode can be formed as a metal base, such as a copper or aluminum base, which is shielded or nested within a graphite body that exhibits at least one surface in the direction of the at least one opposing electrode.

In accordance with the present invention, a surge arrester having an electrode surface exhibits a lower arc voltage and a narrower distribution of static ignition voltage than the present device.

Furthermore, the present invention provides a solution that is easy to implement in existing surge arrester designs and that is suitable for mass production. Furthermore, according to the invention, the solution does not have any negative impact on the environment and does not require special waste handling procedures, which are in connection with currently used surge arresters (which contain radioactive gases such as helium and/or toxic compounds such as barium salts). ) form a control.

The gas used for the charge surge arrester is nitrogen, helium, argon, methane, hydrogen, and the like or mixtures thereof.

The invention will be illustrated by a non-limiting example of a product which describes the manufacture of a surge arrester in accordance with an embodiment of the invention.

Product example

A surge arrester is produced by subjecting a batch of copper electrodes to the following processing steps: First, the electrodes are rinsed in a solution to remove dispersed stains and traces of grease or fat. The electrodes and the insulating ring are placed in a vacuum which is filled into a gas or gas mixture to reach a certain gas pressure and welded to a given gas discharge tube.

If the electrodes are to have a coating, the electrodes are placed in a mask to expose the area to be coated. a set of electrodes that are cleaned up and Placed in a mask and then introduced into an evacuated sputtering chamber. The electrodes are then cleaned by removing the impurities from the electrodes by inverting the sputtering. This current is then reversed and methane is introduced into the chamber. A reactive sputtering process is performed by providing chromium in the form of a chromium cathode. The electrodes receive a graphite layer with chromium atoms added to lock the graphite layers. Eventually, the sputtering process is terminated and the coated electrodes are removed from the chamber and subjected to standard quality control.

These coated electrodes exhibit improved quality, such as higher heat resistance. Surge arresters made with these coated electrodes exhibit improved quality, such as lower arc voltage, narrower ignition voltage distribution, improved speed and selectivity, and longer life cycle times.

Although the present invention has been described in terms of its preferred embodiments, which constitute the best mode known to the present invention, it should be understood that various changes and modifications as would be apparent to those of ordinary skill in the art The scope of the invention is set forth in the appended claims.

1‧‧‧ terminal electrode

2‧‧‧ terminal electrode

3‧‧‧ hollow cylindrical insulator

4‧‧‧Shielded area

11‧‧‧Insulator

12‧‧‧Cylindrical structure

13‧‧‧radially extending flange

14‧‧‧ Radially extending flange

15‧‧‧Electrode

16‧‧‧Electrode

17‧‧‧ Flat, opposite surface

18‧‧‧radial extension surface

19‧‧‧ Radially extending surface

20‧‧‧Axial guiding surface

21‧‧‧radially extended surface

22‧‧‧ Radially extending surface

23‧‧‧Axial guiding surface

25‧‧‧ third electrode

1 shows a cross section of a first embodiment of a gas discharge tube having two electrodes in accordance with the present invention; and FIG. 2 shows a cross section of a second embodiment of a gas discharge tube in accordance with the present invention. The gas discharge tube has three electrodes; FIG. 3 shows a cross section of a third embodiment of a gas discharge tube having two electrodes according to the present invention; and FIG. 4 shows a gas discharge according to the present invention. a cross section of a fourth embodiment of the tube, the gas discharge tube having two electrodes; Figure 5 is a cross section showing a fifth embodiment of a gas discharge tube having two electrodes in accordance with the present invention; and Figure 6 is a cross section showing a sixth embodiment of a gas discharge tube in accordance with the present invention. The gas discharge tube has two electrodes; FIG. 7 shows a cross section of a seventh embodiment of a gas discharge tube having two electrodes in accordance with the present invention; and FIG. 8 shows a prior art of the present invention. A cross section of a gas discharge tube.

11‧‧‧Insulator

12‧‧‧Cylindrical structure

13‧‧‧radially extending flange

14‧‧‧ Radially extending flange

15‧‧‧Electrode

16‧‧‧Electrode

17‧‧‧ Flat, opposite surface

18‧‧‧radial extension surface

19‧‧‧ Radially extending surface

20‧‧‧Axial guiding surface

21‧‧‧radially extended surface

22‧‧‧ Radially extending surface

23‧‧‧Axial guiding surface

Claims (23)

A gas discharge tube comprising at least two electrodes (15, 16) and at least one hollow insulator (11), the insulator (11) being fastened to at least one of the electrodes (15, 16), characterized by The insulator (11) includes an insulating ring, and at least one radially extending flange 13 or 14 extends inwardly and/or outwardly from the insulating ring such that the insulator (11) has a height relative to the insulating ring An extension length for snagging current on at least one of an inwardly facing and/or outwardly facing surface of the at least one radially extending flange, thereby providing for any creep current a long distance whereby the insulator has a total height h of the insulating ring and a creeping current for at least one of the inward and/or outward surfaces of the at least one radially extending flange A ratio between the total lengths L is less than 1:1.3, and thus the ratio between h and w is at least 1:2, where w is the width of the insulator, which is defined as the radially extending flange 13 and 14 The distance between the outer edges. The gas discharge tube of claim 1, wherein the ratio between the total height h and the total length L is 1:1.5. The gas discharge tube of claim 1, wherein the ratio between the total height h and the total length L is 1:2. The gas discharge tube of claim 1, wherein the ratio between the total height h and the total length L is 1:2.5. The gas discharge tube of claim 1, wherein the ratio between the total height h and the total length L is 1:3. The gas discharge tube of claim 1, wherein the total height h is between the total length L The ratio is 1:5. The gas discharge tube of claim 1, wherein h:w is 1:3 to 1:10. The gas discharge tube of claim 7, wherein h:w is 1:3 to 1:5. A gas discharge tube according to claim 1, wherein h:w is at least 1 to 4. A gas discharge tube according to claim 1, wherein h:w is at least 1 to 5. A gas discharge tube according to any one of claims 1 to 4, characterized in that the insulator (11) comprises a cylindrical structure (12) having two flat, facing surfaces (17), in addition to the insulator (11) includes an outwardly, radially extending flange (13) having two radially extending surfaces (18) and (at an angle to the cylindrical structure (12) And an edge axial guiding surface (20) further comprising a second radially extending flange (14) on the inwardly facing side of the cylindrical portion of the insulator (11) Having two radially extending surfaces (21) and (22) forming an angle with the cylindrical structure (12) and an edge axial guiding surface (23) forming an angle with the cylindrical structure (12) Two radially extending surfaces (21) and (22) and an edge axial guiding surface (23). A gas discharge tube according to claim 11 which is characterized in that it consists of two or more electrode assemblies, each electrode assembly comprising an insulator (11). A gas discharge tube according to claim 12, characterized in that the one or more electrodes (15, 16, 25) assembly has an axial extension. A gas discharge tube according to claim 11, characterized in that one or two radially extending flanges (13, 14) are formed in a wave shape. A gas discharge tube according to claim 11, characterized in that one or both of the radially extending flanges (13, 14) have a ditch. A gas discharge tube according to any one of claims 1 to 4, wherein the at least two electrodes have a chemically inert surface. A gas discharge tube according to any one of the preceding claims, wherein the inert surface is formed on the electrodes without affecting interaction with a surrounding compound such as a gas contained in the gas discharge tube Any layer of performance. A gas discharge tube according to claim 17 which is characterized in that the inert surface resists the formation of any oxide or hydride layer. A gas discharge tube according to any one of claims 1 to 4, characterized in that at least one of the surfaces of the electrodes is covered with a coating of a compound which resists the formation of a layer such as an oxide layer. A gas discharge tube according to claim 19, characterized in that the coating comprises carbon. A gas discharge tube according to claim 20, characterized in that the coating comprises graphite. A gas discharge tube according to any one of claims 1 to 4, wherein the at least one electrode further comprises one element of chromium or titanium. A gas discharge tube according to any one of claims 1 to 4, characterized in that at least one of the electrodes is made of a material resistant to the formation of a layer such as an oxide and a hydride layer.