JP2014220186A - Arc contact and process of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arc contact excellent in anti-arc erosion properties that suppresses erosion caused by HF of a side surface of the arc contact.SOLUTION: The arc contact for a gas-blast load-break switch is composed of a conductive component material containing copper as a main body and tungsten. A weight ratio of tungsten in a portion from a surface of a side surface to a depth of 20 μm is 98 wt.% or more.

Description

  The present invention relates to an arc contact for a gas switch and a manufacturing method thereof.

Arc contacts used in gas switches such as gas circuit breakers and gas disconnectors have heat resistance to withstand the high-temperature arc generated when the current is interrupted, and in addition to a certain level to commutate the arc current. Conductivity is also required. Therefore, an alloy in which a material having a high melting point and excellent arc resistance is combined with a material having excellent conductivity is used. Specifically, an alloy composed of copper and tungsten (Cu-W alloy) is widely used. Has been applied. In addition, SF ₆ gas is most used as an arc extinguishing gas for interrupting current.

  Conventionally, an arc contact for a gas switch is manufactured by an infiltration method, a sintering method, an electric heating sintering method, a discharge plasma sintering method, a hot press sintering method, a metal powder injection molding method, etc. It has been manufactured by infiltrating a conductive component material (such as Cu) into a gap between arc-resistant component materials (such as W) made of wound thin wires or thin plates (see, for example, Patent Document 1).

In such a gas switch arc contact, when the current is interrupted, the SF ₆ gas is decomposed by a high-temperature arc and reacts with hydrogen in the tank to generate HF, so that the surface of the arc contact is caused by HF. Corrosion occurred, and there was no possibility of melting or evaporation due to arc when the current was interrupted on the side surface, so that corrosion progressed and arc erosion resistance could be deteriorated.

Japanese Patent Laid-Open No. 10-216877

  The present invention has been made to solve the above-described problems, and has an object to obtain an arc contact having excellent arc erosion resistance by suppressing corrosion due to HF on the side surface of the arc contact. Yes.

The present invention is composed of a conductive component material mainly composed of copper and tungsten,
An arc contact for a gas switch, characterized in that a weight ratio of tungsten in a portion from a side surface to a depth of 20 μm is 98% by weight or more.

The present invention is also a method for manufacturing the arc contact,
A sintering process for producing a porous body by sintering tungsten powder;
An extrusion molding step of producing a molded body in which the vicinity of the side surface is compressed by extruding the porous body;
The present invention also relates to a manufacturing method including an infiltration step of infiltrating copper into the molded body.

  In the arc contact of the present invention, the weight ratio of tungsten in the portion from the surface of the side surface to a depth of 20 μm is 98% by weight or more, so that the progress of corrosion due to HF on the side surface can be suppressed, and the erosion resistance performance is improved. An arc contact for an excellent gas switch can be obtained.

  Moreover, since the manufacturing method of this invention includes the process of producing the molded object by extruding the porous body which consists of tungsten, the arc contactor in which the weight ratio of tungsten in the side surface vicinity improved can be obtained.

It is a cross-sectional schematic diagram which shows an example of the gas circuit breaker to which the arc contact of Embodiment 1 is applied. It is a cross-sectional schematic diagram of the arc-extinguishing chamber of the gas circuit breaker shown in FIG. It is a flowchart which shows the manufacturing method of an arc contactor. It is a longitudinal cross-sectional schematic diagram which shows the extrusion molding process in the case of manufacturing a rod-shaped stationary arc contact. It is a longitudinal cross-sectional schematic diagram which shows the infiltration process in the case of manufacturing a rod-shaped stationary arc contactor. It is a cross-sectional schematic diagram of a rod-shaped fixed arc contactor. It is a longitudinal cross-sectional schematic diagram which shows the extrusion molding process in the case of manufacturing a cylindrical movable arc contactor. It is a cross-sectional schematic diagram of a cylindrical movable arc contactor.

  Hereinafter, an example of an embodiment of an arc contact for a gas switch according to the present invention will be described. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts. In addition, dimensional relationships such as length, width, thickness, and depth are changed as appropriate for clarity and simplification of the drawings, and do not represent actual dimensional relationships.

<Embodiment 1>
FIG. 1 is a schematic cross-sectional view showing an example of a gas circuit breaker to which the arc contact of Embodiment 1 is applied. In FIG. 1, a gas circuit breaker 1 includes an arc extinguishing chamber 5 having a fixed electrode portion 2, a movable electrode portion 3, and an insulating cylinder 4, an insulating operation rod 6 interlocked with the movable electrode portion 3, and a supporting insulating cylinder. 7, a cooling tower 8 coupled to the fixed electrode portion 2, a conductor 9a, a bushing 10a and a terminal 11a for deriving the solid electrode portion 2, a conductor 9b, a bushing 10b for deriving the movable electrode portion 3, and It is comprised by the terminal 11b and the container 12 which accommodated the arc-extinguishing gas and the above-mentioned structural member inside. One end of the insulating operation rod 6 is led out from the container 12 and connected to an operation device 14 inside the control box 13 installed in close contact with the container 12.

  FIG. 2 is a schematic cross-sectional view for explaining the internal configuration of the arc extinguishing chamber 5 of the gas circuit breaker shown in FIG. In FIG. 2, the fixed electrode portion 2 and the movable electrode portion 3 are electrically insulated and fixed by an insulating cylinder 4.

  The movable electrode unit 3 includes a movable arc contact 15, a nozzle 16, a drive rod 17, a movable main contact 18, a shield 21, and a puffer cylinder 23. Among these, the movable arc contact 15, the nozzle 16, the drive rod 17, and the movable main contact 18 are integrally moved by the operating device. A cylindrical movable arc contact 15 is disposed inside the nozzle 16 at the tip of the movable electrode 3. The other end of the movable arc contact 15 is connected to the insulating operation rod 6 via a drive rod 17. A movable main contact 18 is fixed to the drive rod 17 outside the movable arc contact 15. The movable main contact 18 is partially covered with a shield 21. When the current is interrupted, the driving rod 17 moves to compress the puffer cylinder 23 so that the arc extinguishing gas flows inside the nozzle 16.

  The fixed electrode unit 2 includes a fixed main contact 19, a fixed arc contact 20, and a shield 22. In the fixed electrode portion 2, a rod-shaped fixed arc contact 20 is fixed inside the fixed main contact 19. The fixed main contact 19 is partially covered with a shield 22.

  Next, the current interruption operation in the arc extinguishing chamber 5 will be described. When the current is interrupted, the movable arc contact 15 on the movable electrode 3 side slides away from the fixed arc contact 20 that has been in a contact state until then, and an arc A1 is generated between these arc contacts. (This arc is shown as A1 in FIG. 2). At that time, the movable main contact 18 and the fixed main contact 19 are also separated at the same time.

  On the other hand, the arc extinguishing gas compressed in the puffer cylinder 23 is blown to the arc A1 and flows into the nozzle 16 to extinguish the arc A1. While the arc is generated and the arc is extinguished with the arc-extinguishing gas, the fixed arc contact 20 and the movable arc contact 15 are exposed to a very high temperature (about 20000 K) by the hot arc A1.

  In the gas circuit breaker operating in this way, at least one of the fixed arc contact 20 and the movable arc contact 15 is constituted by the arc contact of the present invention.

[Arc contactor]
Next, the structure of the arc contact according to the first embodiment will be described. FIG. 6 shows a schematic diagram of a cross section (AA ′ cross section in FIG. 2) of an arc contact used as the rod-shaped fixed arc contact 20. FIG. 8 shows a schematic diagram of a cross section (BB ′ cross section in FIG. 2) of an arc contact used as the cylindrical movable arc contact 15. 6 and 8, the fixed arc contact is composed of a conductive component material 26 (white background portion) mainly composed of Cu and tungsten 27 (black background portion).

In the gas circuit breaker, SF ₆ gas, which is the extinguishing gas, is decomposed by a high-temperature arc generated when the current is interrupted, and reacts with hydrogen in the tank to generate HF. Therefore, the surface of the arc contact is corroded by HF. However, on the contact surface (tip portion) of the arc contact, since the material is melted and evaporated by the arc every time the current is interrupted, the corrosion does not proceed. On the other hand, on the side surfaces (surfaces that are in contact with the arc-extinguishing gas other than the contact surface, including the outer and inner surfaces), there is no melting or evaporation by the arc when the current is interrupted, so corrosion progresses and the material falls off And wear out. As a result, the arc erosion resistance performance of the arc contact decreases.

  Note that the conductive component material mainly composed of copper may contain a small amount of inevitable impurities (Ag, Al, Fe, Si, P, O, N, H, etc.) contained in the raw material.

  The weight ratio (content) of tungsten (W) with respect to the total amount of the arc contact is preferably 50% by weight to 90% by weight, and more preferably 60% by weight to 80% by weight. If the weight ratio of W is less than 50% by weight, the heat resistance against arc heat is impaired and wear increases, and if it exceeds 90% by weight, the thermal conductivity is deteriorated and evaporation wear is promoted.

  The arc contact according to the first embodiment is characterized in that the weight ratio of tungsten in the portion from the side surface to a depth of 20 μm is 98 wt% or more, preferably 99 wt% or more. The weight ratio of tungsten can be measured by surface analysis of a cross section from the surface to a depth of 20 μm using, for example, EPMA. In the arc contact according to the present embodiment, since the weight ratio of W in the portion from the side surface to a depth of 20 μm is 98% by weight or more, corrosion due to HF is suppressed, and material dropout and wear are reduced. It is an arc contact for gas switches with excellent erosion resistance.

[Method of manufacturing arc contact]
Next, a method for manufacturing the arc contact according to the first embodiment will be described. FIG. 3 is a schematic diagram illustrating a manufacturing process of the arc contact according to the first embodiment. As shown in FIG. 3, a step of sintering a tungsten (W) powder to produce a porous body made of W (sintering step) and a step of extruding the porous body made of W to make a molded body An arc contactor is manufactured through (extrusion molding process) and a process (infiltration process) of infiltrating copper (Cu) into the compact.

(Sintering process)
A porous body made of W can be obtained by filling W powder in a predetermined mold and then sintering by various known methods. The average particle diameter (median diameter) of the W powder is preferably 1 μm or more and 20 μm or less, more preferably 5 μm or more and 15 μm or less. By using the W powder in this range, the porosity of the porous body becomes a desirable range, and the weight ratio of W in the finally produced arc contact is within a desired range (preferably 50 wt% or more and 90 wt%). % Or less). The average particle diameter (median diameter) is a value measured by a laser diffraction method or the like.

  Examples of the shape of the porous body include a columnar shape (bar shape) and a cylindrical shape having a bottom surface with a predetermined shape. Examples of the rod shape include a columnar shape, and examples of the cylindrical shape include a cylindrical shape. As the predetermined mold, those corresponding to these shapes are used.

(Extrusion process)
As an example, the extrusion process in the case of manufacturing the rod-shaped fixed arc contact 20 is demonstrated using FIG. Referring to FIG. 4, a porous body 24 obtained by sintering W powder is a mold 25 having an opening diameter on the downstream side (lower side in FIG. 4) smaller than the opening diameter on the upstream side in the extrusion direction. By pushing through the inside of the porous body, the W in the vicinity of the side surface 241 of the porous body is pushed into the inside of the porous body while being rubbed by the mold 25 in contact with the side surface, and the pores in the vicinity of the side surface 241 are crushed. Thus, the W density in the vicinity 241 of the porous body is increased. In this way, a molded body in which the weight ratio of W in the vicinity of the side surface of the arc contactor is increased can be obtained.

  The compression ratio of the diameter of the porous body in the extrusion process (ratio of the size of the downstream side to the size of the upstream side) is suitably from 98% to 99%. That is, the ratio of the downstream opening diameter to the upstream opening diameter of the mold is preferably 98% or more and 99% or less. If it is less than 98%, the side surface of the porous body collapses and the shape cannot be maintained, which is not preferable. If it exceeds 99%, the weight ratio of W on the side surface of the porous body is not sufficiently improved, which is not preferable.

  Next, the extrusion process in the case of manufacturing the cylindrical movable arc contact 15 will be described with reference to FIG. The cylindrical movable arc contact can also be manufactured basically in the same manner as the rod-shaped fixed arc contact, and therefore, duplicate description is omitted. Referring to FIG. 7, a cylindrical porous body 24 obtained by sintering W powder is extruded through the inside of a mold 25 having a cylindrical opening, so that the vicinity of the side surface 241 of the porous body. W is pushed into the porous body while being rubbed by the mold 25 in contact with the side surfaces (outer side surface and inner side surface), and the voids in the vicinity of the side surface 241 are crushed. Thereby, the W density in the vicinity 241 of the porous body is increased.

  Also in this case, the compression ratio of the diameter of the porous body in the extrusion process is suitably 98% or more and 99% or less, that is, the ratio of the opening diameter on the downstream side to the opening diameter on the upstream side of the mold is 98% or more. It is preferably 99% or less. In this case, the diameter of the porous body means a length obtained by subtracting the diameter of the inner hole from the outer diameter of the porous body, and the opening diameter of the mold is determined from the outer diameter of the opening. It means the length obtained by subtracting the diameter of the inner mold part.

  The porosity of the entire porous body after extrusion molding is preferably 15% by volume or less, more preferably 5% by volume or less.

(Infiltration process)
FIG. 5 is a schematic longitudinal sectional view showing an infiltration process in the case of manufacturing a rod-shaped fixed arc contactor. For example, Cu infiltration is performed by placing a conductive component material 26 mainly composed of Cu on the upstream surface (for example, the upper side) of the molded body 27 obtained in the extrusion molding process and heating it in a hydrogen furnace. It is carried out by allowing molten Cu to permeate in the downstream direction (for example, downward) of the molded body 27 by the weight of the active ingredient material 26 or the pressure reduction on the downstream side. The infiltration temperature (heating temperature in a hydrogen furnace or the like) may be not lower than the melting point of Cu (1085 ° C.) and lower than the melting point of W (3380 ° C.), preferably 1085 to 1200 ° C., more preferably 1086. ~ 1100 ° C. As an example, 1090 ° C. is appropriate.

  By these steps, an infiltrated body (arc contact) in which the weight ratio of W in the portion from the side surface to the depth of 20 μm is 98% by weight or more can be obtained.

  In addition, although the arc contact of this Embodiment was demonstrated as what is used for the gas circuit breaker which is one of the gas switches, it is used for the gas disconnector etc. which are other gas switches, Also good.

  DESCRIPTION OF SYMBOLS 1 Gas circuit breaker, 2 Fixed electrode part, 3 Movable electrode part, 4 Insulation cylinder, 5 Arc extinguishing chamber, 6 Insulation operation rod, 7 Support insulation cylinder, 8 Cooling tower, 9a, 9b Conductor, 10a, 10b bushing, 11a, 11b terminal, 12 container, 13 control box, 14 operation device, 15 movable arc contact, 16 nozzle, 17 drive rod, 18 movable main contact, 19 fixed main contact, 20 fixed arc contact, 21, 22 shield, 23 Puffer cylinder, 24 W porous body, 25 mold, 26 conductive component material, 27 tungsten.

Claims (6)

Consists of conductive component material mainly composed of copper and tungsten,
An arc contact for a gas switch, wherein a weight ratio of tungsten in a portion from a side surface to a depth of 20 μm is 98% by weight or more.   The arc contact according to claim 1, wherein the weight ratio of tungsten to the total amount is 50 wt% or more and 90 wt% or less. It is a manufacturing method of the arc contact according to claim 1,
A sintering process for producing a porous body by sintering tungsten powder;
An extrusion molding step of producing a molded body in which the vicinity of the side surface is compressed by extruding the porous body;
An infiltration step of infiltrating copper into the molded body.   The manufacturing method according to claim 3, wherein, in the extrusion step, the porous body is extruded through the inside of a mold in which an opening diameter on the downstream side in the extrusion direction is smaller than an opening diameter on the upstream side.   The manufacturing method according to claim 4, wherein a ratio of the downstream opening diameter to the upstream opening diameter in the mold is 98% or more and 99% or less.   The average particle diameter (median diameter) of the said tungsten powder is a manufacturing method in any one of Claims 3-5 which are 1 micrometer or more and 20 micrometers or less.

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