JP5211246B2 - Electrical contact for vacuum valve and vacuum circuit breaker and vacuum switchgear using the electrical contact - Google Patents

Description

  The present invention relates to an electrical contact for a vacuum valve and a vacuum circuit breaker and a vacuum switchgear using the electrical contact.

  Vacuum switchgear using vacuum as a medium, such as a vacuum circuit breaker, has a small impact on the environment, and therefore, replacement of a gas circuit breaker or the like is being promoted, and a large capacity is required. The electrical contact member for cutting off a large current made of a refractory metal and a conductive metal used in this vacuum switchgear needs to have a high density in order to increase current carrying capacity and maintain good heat conduction. It is.

  For this reason, for example, Cr—Cu-based electrical contacts used in general vacuum switching devices are manufactured by an infiltration method or a sintering method capable of increasing the density.

  For example, in the technique disclosed in Japanese Patent No. 2874522, an electrical contact of a current switching device is manufactured by melting and impregnating a Cr-Cu low-density molded body with Cu.

  In the technique disclosed in Japanese Patent Application Laid-Open No. 2005-135778, a high-density electrical contact for use in a current switching device is obtained by sintering a Cr-Cu-based high-density molded body in an inert atmosphere. ing.

Japanese Patent No. 2874522 JP, 2005-135778, A On the other hand, when electrical contacts are welded by Joule heat at the time of energization, it is necessary to be able to separate the electrical contacts without any trouble at the time of current interruption. Is required.

  Therefore, in the technology disclosed in Japanese Patent No. 2874522, the electric contact member in which the electric contacts are welded to each other is destroyed by uniformly dispersing the hard and high melting point metal.

  In the technique disclosed in Japanese Patent Application Laid-Open No. 2005-135778, a small amount of a low melting point metal is added to reduce the interface bonding force between Cr and Cu, thereby reducing the strength of the electrical contact member.

  The refractory metal dispersion intended to reduce the strength of the electrical contact member used in the current switching device not only becomes unstable depending on the dispersion state, but also the workability is lowered because the refractory metal is hard. In addition, if the addition amount of the low melting point metal is not appropriate, it melts and volatilizes in the brazing process to the current-carrying member, causing problems such as poor brazing, and the arc continues due to volatilization during current interruption and cannot be interrupted. Induces or withstand voltage performance degradation.

  An object of the present invention is to provide an electrical contact for a vacuum valve that maintains electrical conductivity and thermal conductivity, and has a strength of the electrical contact member set to a desired value such that the electrical contact can be separated without any trouble when the current is interrupted. The object is to provide a vacuum switching device using contacts.

The electrical contact for a vacuum valve of the present invention comprises a base material made of a conductive metal, and a refractory metal and a conductive metal formed on the upper surface side of the base material, and the base material and the contact layer are integrally bonded. The refractory metal and the conductive metal in the contact layer are formed so that the crystal grain size is in the range of 5 to 20 μm. In the contact layer, the diffusion phase between the refractory metal and the conductive metal or The reaction phase is formed such that the range is 50 nm or less .

The vacuum valve of the present invention is a vacuum valve comprising a pair of fixed side electrodes and a movable side electrode disposed facing the fixed side electrode in a vacuum vessel, wherein at least the fixed side electrode and the movable side electrode One of the disk-shaped contact layer and the disk-shaped member constituting the base material, the anti-stain plate installed on the back side of the disk-shaped member, and the base material and anti-stain plate of the disk-shaped member It is an electric contact used for the electrode rod joined together, and the electric contact used for the electrode rod consists of a base material made of a conductive metal and a refractory metal and a conductive metal on the upper surface side of the base material. A contact layer is formed, and the base material and the contact layer are integrally bonded to each other, and the refractory metal and the conductive metal in the contact layer have a crystal grain size in the range of 5 to 20 μm. In the contact layer, fire resistance Range of the diffusion phase, or reaction phase between genera and conductive metal, characterized in that it is formed such that the range of 50nm.

The vacuum circuit breaker of the present invention includes a vacuum valve provided with a pair of fixed-side electrodes and a movable-side electrode disposed opposite to the fixed-side electrodes in the vacuum vessel, the fixed-side electrodes in the vacuum valve, A vacuum circuit breaker having a conductor terminal connected to the outside of the vacuum valve and an opening / closing means for driving the movable side electrode to each of the movable side electrodes, wherein the vacuum valve includes at least the fixed side electrode and the movable side electrode. One of the disk-shaped contact layer and the disk-shaped member constituting the base material, the anti-stain plate installed on the back side of the disk-shaped member, and the base material and anti-stain plate of the disk-shaped member An electrode for a vacuum valve having an electrode rod integrally joined thereto, and an electrical contact used for the electrode rod includes a base material made of a conductive metal, and a refractory metal and a conductive material on the upper surface side of the base material. Contact layer made of conductive metal Formed to constitute bonded integrally with the contact layer and the base material, crystal grain size of the refractory metal and the conductive metal in said contact layer is formed to be in the range of 5 to 20 [mu] m, the contact The layer is formed such that the range of the diffusion phase or reaction phase between the refractory metal and the conductive metal is 50 nm or less .

The vacuum switchgear according to the present invention comprises a plurality of vacuum valves each having a pair of fixed-side electrodes and a movable-side electrode disposed opposite to the fixed-side electrodes in a vacuum container, and the movable-side electrodes are connected to each other by a conductor. In the vacuum opening / closing device provided with the opening / closing means to be driven, the vacuum valve is configured such that at least one of the fixed side electrode and the movable side electrode is a disk-shaped member constituting the disk-shaped contact layer and the base material, and the disk-shaped member. A vacuum valve electrode having a fouling prevention plate installed on the back side of the member, and an electrode rod integrally joined to the base material and the fouling prevention plate of the disk-shaped member, and used for the electrode rod The electrical contact is formed by forming a base material made of a conductive metal and a contact layer made of a refractory metal and a conductive metal on the upper surface side of the base material, and integrally bonding the base material and the contact layer. Configured in the contact layer Crystal grain size of the refractory metal and the conductive metal is formed to be in the range of 5 to 20 [mu] m, in the contact layer, the diffusion phase or reaction phase between the refractory metal and the conductive metal range below 50nm It is formed so that it may become a range .

  According to the present invention, an electrical contact for a vacuum valve that maintains electrical conductivity and thermal conductivity, and has the electrical contact member strength set to a desired value such that the electrical contact can be separated without any trouble when the current is interrupted. Vacuum switchgear using contacts can be realized.

The top view which shows the structure of the electrical contact which is 1st Example of this invention, and an electrode. Sectional drawing which shows the electrical contact and electrode for vacuum valves which are 1st Example of this invention shown in FIG. The analysis result of the element distribution of the interface of Cr and Cu in the contact layer about the electrical contact of a comparative example product. The analysis result of the element distribution of the interface of Cr and Cu in the contact layer about the electrical contact of the Example article of the present invention. Sectional drawing which shows the structure of the vacuum valve which is the 2nd Example of this invention which attached the electrical contact and electrode for vacuum valves of 1st Example of this invention. The figure showing the structure of the vacuum circuit breaker which is the 3rd Example of this invention provided with the vacuum valve of 2nd Example of this invention shown in FIG. Sectional drawing which shows the structure of the load switch for the roadside installation transformer which is the 4th Example of this invention provided with the vacuum valve of 2nd Example of this invention shown in FIG.

  An electrical contact for a vacuum valve according to an embodiment of the present invention has a base material made of a conductive metal, and a contact layer made of a refractory metal and a conductive metal on the upper surface side of the base material. And the contact layer are integrally bonded, and the crystal grain size of the refractory metal and the conductive metal in the contact layer is in the range of 5 to 20 μm. Thus, an electrical contact having excellent electrical conductivity can be obtained.

  Further, the refractory metal and the conductive metal in the contact layer have a fine structure in which the refractory metal is uniformly dispersed when the crystal grain size is in the range of 5 to 20 μm. Voltage performance is obtained.

  Regarding the interruption | blocking performance, a heat conductive and electroconductivity become high and stabilized because the parent phase which consists of electroconductive metals, such as Cu, forms a continuous network, for example. At this time, it is important to eliminate as much as possible solute atoms, precipitates, segregation, crystal grain boundaries and the like that inhibit or scatter the heat flow or current of the matrix.

  Solute atoms, precipitates, segregation, and the like may be achieved by reducing the impurities mixed in the raw materials and manufacturing. It is difficult to eliminate the crystal grain boundary, that is, to make a single crystal, because it is a composite material composed of a refractory metal and a conductive metal. If it is a crystal grain diameter, the influence which the crystal grain boundary has on conductivity is negligible.

  On the other hand, the withstand voltage performance is stabilized by making the crystal grains of the refractory metal and the conductive metal uniform and fine. That is, the arc generated between the electrodes moves on the electrode surface from moment to moment. At this time, since the electrode surface is a composite material composed of a refractory metal and a conductive metal, the two phases are uniformly and finely dispersed, so that the refractory metal exists uniformly on the arc orbit, The sustainability of the arc is reduced.

  In an electrical contact for a vacuum circuit breaker, a uniform distribution of the refractory metal with respect to the arc diameter can be realized if the crystal grain size is approximately 20 μm or less. However, the electrical contact for the vacuum circuit breaker needs to be designed in case the contacts are welded together.

  In order to easily separate the welded contacts, it is a useful means to reduce the strength of the contacts. However, the uniform and refinement for decreasing the arc sustainability rather increases the strength. Therefore, in order to satisfy these two required characteristics, it is necessary to control the bonding force between the refractory metal and the conductive metal.

  In order to control the bonding force, it is important to prevent diffusion or reaction between the refractory metal and the conductive metal. In the electrical contact for a vacuum circuit breaker, the thickness of the diffusion phase or reaction phase between the refractory metal and the conductive metal in the contact layer is approximately 50 nm or less, and the crystal grain sizes of the refractory metal and the conductive metal are If it is approximately 20 μm or less, the force to peel one uniformly dispersed refractory metal from the conductive metal is small, so the influence on the separation performance can be ignored.

  In general, electrical contacts are assembled in a vacuum valve, and then the electrical contacts are opened and discharged in a state of providing a gap, and the contact surface layer structure is refined to improve performance stability. If the structure is uniformly refined within a crystal grain size range of 5 to 20 μm, the treatment is unnecessary.

  Since both the diffusion phase and the reaction phase grow as the temperature rises, they are not exposed to high temperatures during the manufacturing process. Based on thermodynamic reaction kinetics, the reaction rate increases by an order of magnitude or more as the temperature increases by several hundred degrees Celsius. For example, when Cr is used as the refractory metal and Cu is used as the conductive metal, the conventional sintering method is exposed to 1000 ° C. or more for several hours, and thus the diffusion phase or the reaction phase tends to grow.

  In order for the thickness of the diffusion phase or reaction phase to be approximately 50 nm or less, it is necessary to lower the process temperature during production to about 800 ° C. That is, the melting point of Cu is about 1080 ° C., and the melting point of Cr is much higher than that, so that a manufacturing process in a solid phase state without necessarily melting the material is good.

  The electrical contacts having the structure and structure as described above can be realized by using a friction stir process. In general, in the Cu friction stirring process, the process temperature is about 700 to 800 ° C., and the crystal grain size of Cu obtained is in the range of 10 to 20 μm.

  In the friction stir process, it is possible to disperse the powder in the mother phase by simultaneously using a material powder having a melting point higher than that of the material to be the mother phase. For example, when Cr powder is used, the melting point of Cr is higher than that of Cu by 800 ° C. or more, and therefore, the friction stirring process temperature is about 700 to 800 ° C. and is very stable thermodynamically.

  For this reason, even if it is stirred with Cu, since it exists stably as Cr, a diffusion phase or a reaction phase is not generated at the Cu / Cr interface. Further, due to the high strain rate peculiar to the friction stir process, the hard and brittle Cr powder is pulverized and uniformly finely dispersed in the Cu matrix.

  In the friction stir process, recesses such as grooves and indentations are formed by machining on the surface of the conductive metal disk that forms the base material, and a refractory metal powder is filled therein. In addition, the formation method of a recessed part may be a general metal processing method such as forging.

  Next, a rotary tool called a tool is inserted into the surface at a depth corresponding to the thickness of the contact layer, and after softening due to frictional heat, the tool is scanned over the entire surface to form a refractory metal. Stir the conductive metal.

  At this time, the surface of the groove or indentation filled with the refractory metal powder is closed with a conductive metal plate-like member, and when the tool is scanned from above, the refractory metal powder is scanned by the rotating tool. Scattering can be prevented, and a desired contact layer composition can be easily obtained.

  Further, by providing a protrusion having a smaller diameter than a tool called a pin at the tip of the tool, it becomes easy to bite the tool to a depth of several millimeters. Furthermore, by using an alloy composed of a refractory metal and a conductive metal as the material of the tool, a contact layer having a desired composition can be obtained even if the tool is worn or mixed.

  According to this friction stir process, unlike the infiltration method and the sintering method, the contact layer components can be combined at a relatively low temperature of 800 ° C. or lower, so that the crystal of the conductive metal itself can be produced without causing crystal coarsening. The particle size is refined to about 10 μm, and the refractory metal powder itself is ground and refined to the same extent and uniformly dispersed. Further, there is very little diffusion / reaction between the refractory metal and the conductive metal, and both are only physically and mechanically bonded, and the strength is lower than that of the conventional manufacturing method.

  In the case of the conventional sintering method, the range of diffusion or reaction between the refractory metal and the conductive metal varies depending on the components and sintering conditions, but at least 100 nm exists. On the other hand, when the friction stirring process is used, the range is 50 nm or less.

  Further, according to this friction stir process, only the contact layer exposed to the arc in the electrical contact is a composite structure of a refractory metal and a conductive metal, and the base material that is not in direct contact with the arc is composed of the conductive metal, Therefore, compared with the electrical contact which consists only of the contact layer by the conventional infiltration method or a sintering method, it is excellent in electricity_supply performance, can suppress generated Joule heat, and does not produce welding of electrical contacts easily.

  In the electrical contact for a vacuum valve which is an embodiment of the present invention, the refractory metal in the contact layer is one or a mixture or a compound of two or more of Cr, W, Mo and Nb. By making the conductive metal Cu or a Cu alloy containing Cu as a main component, it is possible to obtain a breaking performance, a withstand voltage performance, an energization performance and the like necessary for an electrical contact for a vacuum valve.

  The composition of the contact layer is preferably 15 to 40% by weight for the refractory metal and 60 to 85% by weight for the conductive metal.

  When the refractory metal is less than 15% by weight, the withstand voltage performance becomes insufficient. When the refractory metal exceeds 40% by weight, the electrical resistance increases and the current-carrying performance decreases, and sufficient interruption performance cannot be obtained.

  In addition, the oxygen content of the contact layer is preferably 0.4% by weight or less, and if it is contained more than this, oxygen gas released at the time of current interruption increases, and the arc is sustained to make interruption impossible, and the withstand voltage performance is remarkably high. descend.

  The shape of the electrical contact for a vacuum valve according to an embodiment of the present invention is such that the contact layer and the base material, which are integrally joined, are each formed in a disc shape, and the contact layer and the base in the disc shape are formed. A center hole is formed at the center of the circle of the material, and a plurality of slit grooves penetrating from the center of the circle toward the outer periphery are formed without contact with the center hole. It is desirable to form a separated blade-shaped planar shape portion.

  The center hole is for preventing an arc generated when the current is interrupted from starting at the center of the electrical contact, and avoiding the inability to interrupt due to the stagnation of the arc. The slit groove has an effect of driving the arc to the outer peripheral side by electromagnetic force and promoting current interruption.

  An electrode using an electrical contact according to an embodiment of the present invention has good current-carrying performance by integrally joining an electrode rod as a current-carrying member to the surface of a contact layer of a disk-shaped electrical contact. At the same time, the Joule heat generated at the contact portion can be quickly led out of the vacuum valve.

  It is desirable that the disk-shaped electrical contact has a shape in which a central hole is provided at the center of the circle and is separated into a blade shape by a spiral slit groove having a curved shape. By providing the central hole, it is possible to prevent the arc generated when the current is interrupted from occurring at the center of the contact surface and stagnating.

  Further, by providing the slit groove, the generated arc can be moved to the outer peripheral side of the electrical contact, and the current can be cut off quickly.

  An electrode using an electrical contact according to an embodiment of the present invention is formed by integrally joining a cup-shaped coil electrode made of Cu to the contact layer side of a disk-shaped electrical contact, and at the bottom of the coil electrode. A structure in which the electrode rods are integrally joined may be used. Thereby, the arc is extinguished using the magnetic field generated at the time of current interruption, and an excellent interruption performance can be obtained.

  A vacuum valve according to an embodiment of the present invention is a vacuum valve comprising a pair of fixed side electrodes and a movable side electrode disposed opposite to the fixed side electrodes in a vacuum vessel. At least one of the movable side electrodes is an electrode using the electrical contact for a vacuum valve of the present invention.

  In addition, a vacuum circuit breaker according to an embodiment of the present invention includes a pair of fixed-side electrodes using the electric contacts of the present invention at least one of them and a movable-side electrode disposed to face the fixed-side electrodes in a vacuum container. A vacuum valve provided inside, a conductor terminal connected to each of the fixed side electrode and the movable side electrode in the vacuum valve, and an opening / closing means for driving the movable side electrode. .

  Furthermore, a vacuum switching device according to an embodiment of the present invention includes a vacuum container in which at least one of the pair of fixed side electrodes using the electrical contact of the present invention and a movable side electrode disposed to face the fixed side electrode A plurality of vacuum valves provided inside are connected by a conductor and provided with opening / closing means for driving the movable side electrode.

  According to these embodiments of the present invention, the Joule heat generated at the contact portion during energization is suppressed, the welding between the electrical contacts is difficult to occur, and the vacuum circuit breaker excellent in energization performance and anti-welding performance, and various vacuums A switchgear is obtained.

  Each embodiment of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited to these embodiments.

  As an example of the electrical contact of the present invention, the contact layer 45 is made of a metal having the composition shown in Table 1, and the base 46 is made of Cu which is a conductive metal. Using the material 46, the vacuum valve electrode 1 shown in FIG.

  As the conductive metal forming the base material 46, Cu or a Cu alloy containing Cu as a main component was used.

  FIG. 1 shows the No. of each example described in Table 1. 9 to No. 14 shows an electrode structure in which an electrical contact 1 made of a contact layer 45 made by a contact layer composition made of a refractory metal and a conductive metal shown in FIG. 14 is placed on the surface side of a base material 46 made of a conductive metal. FIG. 2 is a vertical cross-sectional view of the electrode of FIG.

  The refractory metal forming the contact layer 45 is one or a mixture or compound of any of Cr, W, Mo, and Nb, and the conductive metal forming the contact layer 45 is Cu or Cu. Cu alloy as the main component.

  1 and 2, a slit groove 2 for applying a driving force to an arc is provided on an electrical contact 1 constituting a vacuum valve electrode composed of a contact layer 45 and a base 46 formed in a disk shape. The layer 45 and the base material 46 on which the contact layer 45 is placed are penetrated together.

  And in order to prevent the component of the electrical contact 1 melted at the time of current interruption from fouling the back surface through the slit groove 2, a stainless antifouling plate 3 is installed on the back surface side of the base material 46.

  A base material 46 and an antifouling plate 3 are joined to the electrode rod 4 by a brazing material 5, respectively. In addition, a center hole 44 is formed through the contact layer 45 and the base material 46 at the center of the disk-shaped contact layer 45, and the shaft tip of the electrode rod 4 is fitted into the center hole 44 from below. Match.

  A method for producing the electrical contact 1 shown in FIGS. 1 and 2 is as follows. First, a plurality of grooves each having a depth of 4 mm and a width of 3 mm are provided at an arbitrary interval on a flat surface on one side of an oxygen-free copper disk (diameter 60 mm, thickness about 11 mm) constituting the base 46. Is filled with a refractory metal powder having a particle size of 75 μm or less.

  At this time, the groove is not limited to a straight line, but may have any shape, and the groove interval and the amount of the refractory metal powder are adjusted so that the refractory metal and the Cu of the base material 46 have the desired composition of the contact layer. To do.

  Cover the surface of this oxygen-free copper disk with a lid-like plate made of oxygen-free copper with a thickness of 0.5 mm, and bite it to a depth of about 4 mm while rotating the tool (rotary tool) from above. After the temperature was raised by frictional heat, the tool was moved across the entire surface of the disk provided with grooves, and a friction stirring process was performed in which the components of the base material 46 and the refractory metal powder were mixed.

  By applying this friction stirring process, a portion corresponding to a lid-like plate made of oxygen-free copper is integrated with the contact layer 45.

  At this time, an argon gas as an inert gas was blown around the tool so as not to oxidize the layer to be mixed. The rotation speed of the tool is 1200 rpm, and the moving speed is 400 mm / min.

  In this embodiment, the tool is moved over the entire surface spirally from the center of the processing surface of the disk to the outer periphery. However, for example, a method of scanning the entire surface linearly may be used. By the above method, a member of the electrical contact 1 having a diameter of 60 mm, an overall thickness of about 10 mm, and a contact layer 45 of about 4 mm formed on one surface was produced.

  The outer peripheral surface of the member of the electrical contact 1 and the surface of the contact layer 45 manufactured in this way are cut so as to have predetermined dimensions, and the slit groove 2 and the central hole 44 are formed by machining to have a diameter of 55 mm and an overall thickness. The electrical contact 1 shown in FIG. 1 having a thickness of 9 mm and a contact layer 45 thickness of 3 mm was obtained.

  Note that the groove for filling the refractory metal powder has a cross-sectional shape that becomes narrower in the depth direction, so that the composition can be inclined from the contact layer 45 to the base material 46, and the electrical contact 1. The thermal deformation can be suppressed by relieving the interlayer thermal expansion difference due to Joule heat during energization.

  In order to compare with the electrical contact 1 of this example, an electrical contact 1 by a sintering method and an infiltration method, which are conventional manufacturing methods, was also produced. The manufacturing method by the sintering method of the conventional manufacturing method is as follows. A refractory metal powder having a particle size of 75 μm or less and a Cu powder having a particle size of 60 μm or less are No. The contact layer composition shown in 1, 2, 4, and 5 was mixed by a V-type mixer to obtain a contact layer material.

  The mixed powder was filled into a disk-shaped mold, and further filled with the Cu powder, and was integrally pressure-formed at a pressure of 400 MPa by a hydraulic press. At this time, the filling amount of the raw material powder was adjusted so as to ensure a desired thickness of each layer. The relative density of the molded body thus obtained was approximately 68 to 73%.

  These were heated and sintered in vacuum at 1060 ° C. for 2 hours to produce a sintered body that was a material for the electrical contact 1. The relative density of this sintered body is approximately 93 to 97%. In addition, in the comparative example product of Table 1, No. 2 and no. In the sintered body of No. 5, peeling occurred at the outer peripheral end due to a difference in thermal expansion at the layer interface between the contact layer 45 and the base material 46.

  On the other hand, the manufacturing method by the infiltration method of the conventional manufacturing method is as follows. The above-mentioned refractory metal powder and Cu powder are used as raw materials, Cr powder is mixed by 55% by weight, Cu powder by 38% by weight, and Nb powder by 7% by weight. A skeleton (low-density molded body) was produced by filling the metal mold and press-molding with a hydraulic press at a pressure of 145 MPa.

  This skeleton was placed in a graphite crucible, and a Cu ingot was placed thereon, heated in a vacuum at 1200 ° C. for 2 hours, and the skeleton was melted and impregnated with Cu. An infiltration body having a contact layer composition of 3 and integrated with a base material made of Cu was produced. The sintered body and the infiltrated body obtained above are machined, and the comparison is made with a diameter of 55 mm, an overall thickness of 9 mm, and a contact layer 45 thickness of 3 mm, which have the same shape as the electrical contact 1 shown in FIG. An example electrical contact 1 was made.

Next, the electrode for vacuum valves provided with the above-mentioned electrical contact 1 was produced. The method for producing the electrode is as follows. The electrode rod 4 is made of oxygen-free copper, and the antifouling plate 3 is made by machining in advance with SUS304, and the electric contact 1, the antifouling plate 3 and the electrode rod 4 obtained above are brazed. The material 5 was placed and heated in a vacuum of 8.2 × 10 ⁻⁴ Pa or less at 970 ° C. × 10 minutes to produce an electrode having the configuration shown in FIG.

  No. 1 shown in Table 1, which is an example product of the present invention described above. 9-No. As shown in the column of the oxygen amount (ppm) of the contact layer in Table 1 and the column of the maximum crystal grain size (μm) of the highly conductive metal in the contact layer, respectively, The oxygen amount is 4000 ppm (0.4% by weight) or less, the crystal grain size is in the range of 5 to 20 μm, and the barrier performance and the welding resistance are satisfied.

  This electrode is used for a vacuum valve 100 for a rated voltage of 24 kV, a rated current of 1250 A, and a rated breaking current of 25 kA, which will be described later. The electrode antifouling plate 3 also serves as a reinforcing plate for preventing excessive deformation of the electric contact 1 due to the opening / closing operation. However, if the electric contact 1 has sufficient strength, the antifouling plate 3 may be omitted. Good.

  The crystal grain size of the refractory metal and the conductive metal in the contact layer in the contact of this example is set in the range of 5 to 20 μm, and the diffusion range between the refractory metal and the conductive metal in the contact layer is 50 nm or less. Refer to the description of the vacuum valve 100 of the second embodiment, which will be described later, with reference to Table 1, for the operational effects of being set in the range.

  According to the present embodiment, the electrical contact for vacuum valve that maintains electrical conductivity and thermal conductivity, and has the electrical contact member strength set to a desired value such that the electrical contact can be separated without any trouble when the current is interrupted, and Vacuum switchgear using electrical contacts can be realized.

  Next, the vacuum valve 100 which is one Example of this invention is demonstrated.

  A vacuum valve 100 having a rated voltage of 24 kV, a rated current of 1250 A, and a rated breaking current of 25 kA was produced.

  FIG. 5 is a cross-sectional view showing an embodiment of a vacuum valve 100 including an electrode having the electrical contact 1 of the embodiment shown in FIGS. 1 and 2.

  The vacuum valve 100 shown in FIG. 5 includes a fixed side electrode 6a and a movable side electrode 6b that serve as electrodes. The fixed-side electrode 6a includes a fixed-side electrical contact 1a, a fixed-side electrode rod 4a provided with the fixed-side electrical contact 1a, and an antifouling plate 3a installed between the fixed-side electrical contact 1a and the fixed-side electrode rod 4a. It consists of and.

  The movable side electrode 6b includes a movable side electrical contact 1b that is separated from and in contact with the fixed side electrical contact 1a of the fixed side electrode 6a, a movable side electrode bar 4b that includes the movable side electrical contact 1b, and a movable side electrical contact 1b that is movable. The anti-stain plate 3b is disposed between the side electrode rod 4b.

  In the vacuum valve 100 of the present embodiment, the fixed-side electrical contact 1a and the movable-side electrical contact 1b have the same structure as the electrical contact 1 of the embodiment shown in FIGS. And the slit groove | channel 2 each formed in the fixed side electrical contact 1a and the movable side electrical contact 1b is installed so that it may correspond in both contact surface.

  The vacuum valve 100 is surrounded by an insulating cylinder 13 around its side surface, and a fixed-side electrode 6a and a movable-side electrode 6b facing the fixed-side electrode 6a are disposed inside the insulating cylinder 13. ing. A fixed-side end plate 9a and a movable-side end plate 9b that connect the insulating tube 13, the fixed-side electrode 6a, and the movable-side electrode 6b are provided on the upper and lower portions of the insulating tube 13, respectively.

  On the outer peripheral side of the fixed-side electrical contact 1a provided at the distal end of the fixed-side electrode 6a and the movable-side electrical contact 1b provided at the distal end of the movable-side electrode 6b respectively disposed inside the insulating cylinder 13, the electrical contact is cut off A movable shield 7 is provided to prevent scattering of metal vapor or the like at the time.

  The movable side electrode 6b is brazed and joined to the movable side holder 12 via a movable side shield 8 that prevents scattering of metal vapor or the like at the time of interruption.

  The fixed side end plate 9a, the movable side end plate 9b, and the insulating cylinder 13 are sealed to each other in a high vacuum by brazing, and have an external conductor (see FIG. 5) having screw portions provided on the fixed side electrode 6a and the movable side holder 12. (Not shown). Between the movable side end plate 9b and the movable side holder 12, a guide 11 for supporting the sliding portion of the movable side holder 12 is provided on the movable side end plate 9b.

  A bellows 10 is provided between the movable shield 8 inside the insulating cylinder 13 and the movable end plate 9b, and the movable holder 12 is placed in the insulating cylinder 13 while the vacuum valve 100 is kept in vacuum. The fixed side electrode 6a and the movable side electrode 6b can be opened and closed by moving up and down.

  Regarding the electrical contacts of the example products shown in Table 1, a breaking test was performed using the vacuum circuit breaker 200 provided with the vacuum valve 100 having the electrical contacts produced in Example 1, and after the interruption of the current 25 kA and the energization of 25 kA The possibility of electrode separation (opening) was evaluated. At this time, in order to verify the influence of the amount of oxygen contained in the contact layer of the electrical contact and the crystal grain size, the surface layer was not subjected to the surface layer refinement treatment by discharge, and was subjected to a blocking test.

  The right column of Table 1 shows the oxygen amount of the contact layer in the electrical contact, the crystal grain size, and the result of the interruption test. 1-No. No. 8 is a comparative product, no. 9-No. 14 is an example product of the present invention.

  No. produced by the sintering method and the infiltration method. The electrical contacts of Comparative Examples 1 to 5 have a lower oxygen content in the contact layer than the electrical contacts of Examples of the present invention produced by the friction stir process, and all of them can cut off a current of 25 kA.

  However, the electrical contact of the comparative product has a crystal grain size of the contact layer of several 10 to 10 as shown in the column of the maximum crystal grain size (μm) of the conductive metal in the contact layer in Table 1. Since it is as large as several hundred μm, the conductive metal component of the contact layer is likely to melt after a large current is applied, and welding is likely to occur. As described above, it was impossible to separate (separate) the electrodes.

  No. produced by the friction stirring process of the comparative example product. The electrical contact of No. 6 has a refractory metal of less than 15% by weight in the contact layer, and the contact layer has a relatively small electric resistance and can be separated without welding even after passing a large current. Due to the shortage, the blocking performance was insufficient.

  In addition, the comparative example product No. In No. 7, the refractory metal exceeds 40% by weight, which is satisfactory in the breaking performance but has a large electric resistance of the contact layer, resulting in welding and cannot be separated.

  Furthermore, No. of the comparative example product. No. 8 was prepared by the friction stir process, and it was processed without blowing argon gas. The contact layer contained 4000 ppm (0.4 wt%) or more of oxygen, and the arc was generated by releasing oxygen when the current was interrupted. Persistence and inability to shut off occurred.

  As described above, the electrical contact of the comparative product obtained by the sintering method and the infiltration method has a large crystal of the contact layer and is inferior in welding resistance, and the electrical contact by the friction stir process has a fire resistance of the contact layer. When the amount of the conductive metal and the oxygen content were outside the desired ranges of the present invention, it was confirmed that the barrier performance and the welding resistance were insufficient.

  On the other hand, No. which is an example product of the present invention. 9-No. As shown in the column of the oxygen amount (ppm) of the contact layer in Table 1 and the column of the maximum crystal grain size (μm) of the highly conductive metal in the contact layer, each of the 14 electrical contacts is the contact layer. The oxygen content was 4000 ppm (0.4% by weight) or less, and the crystal grain size was in the range of 5 to 20 μm, thereby satisfying the shielding performance and the welding resistance.

  Further, as shown in the column of the contact layer structure in Table 1, the refractory metal component in the contact layer is refractory regardless of whether it is Cr alone or a mixture of Cr and other W, Mo, Nb. It was confirmed that the performance could be satisfied if the functional metal (wt%) was in the range of 15 to 40 wt%.

  Here, No. of the comparative product manufactured by the sintering method. 1 and No. 1 which is an example product of the present invention. 3 and 4 show the results of analyzing the element distribution of the Cr / Cu interface in the contact layer using an energy dispersive X-ray analyzer with respect to 9 electrical contacts.

  In the analysis results of the element distribution at the Cr / Cu interface in the contact layer shown in FIGS. 3 and 4, FIG. FIG. 4 shows the result of analysis of the element distribution at the Cr / Cu interface in the contact layer for the electrical contact No. 1 and No. 1 which is an example product of the present invention. It is an analysis result of element distribution of the Cr / Cu interface in the contact layer for 9 electrical contacts.

  The comparative product No. In the electric contact 1, the diffusion range of Cr indicated by a solid line and Cu indicated by a broken line is approximately 180 nm. This is thought to be because Cr is diffused into Cu by sintering at high temperature, and thereby the interface strength between Cr and Cu is large, and when the contacts are welded together, the interface does not easily break, The separation after the current application is impossible.

  On the other hand, No. which is an example product of the present invention. In No. 9, the diffusion range of Cr indicated by a solid line and Cu indicated by a broken line is as extremely small as about 30 nm. This is presumably because no diffusion occurs at the interface between Cr and Cu due to the friction stir process at a relatively low temperature, and the two are mechanically or physically bonded. Thereby, since the interface strength is small, the separation after welding is facilitated.

  Therefore, the electrical contact of the embodiment product of the present invention has a thickness of the diffusion phase or reaction phase between the refractory metal and the conductive metal in the contact layer of 50 nm or less, so that no low melting point metal is added. It was confirmed to have excellent welding resistance.

  The thickness of the diffusion phase or reaction phase between the refractory metal and the conductive metal in the contact layer should be 50 nm or less. Preferably, the thickness of this diffusion phase or reaction phase is infinitely zero. It is desirable that the value be close to or zero.

  According to the present embodiment, the electrical contact for vacuum valve that maintains electrical conductivity and thermal conductivity, and has the electrical contact member strength set to a desired value such that the electrical contact can be separated without any trouble when the current is interrupted, and Vacuum switchgear using electrical contacts can be realized.

  Next, the vacuum circuit breaker 200 which is one Example of this invention is demonstrated using FIG.

  A vacuum circuit breaker 200 according to an embodiment of the present invention equipped with the vacuum valve 100 having the configuration shown in FIG. 5 was produced.

  FIG. 6 is a configuration diagram showing a configuration of a vacuum circuit breaker 200 which is an embodiment of the present invention provided with the vacuum valve 100 of the embodiment shown in FIG. 5 and its operation mechanism.

  In FIG. 6, the vacuum circuit breaker 200 has an operation mechanism portion disposed on the front surface (right side in FIG. 6) and three sets of three-phase epoxy cylinders 15 supporting the vacuum valve 100 on the rear surface (left side in FIG. 6). It is the structure which arranged. The vacuum valve 100 is operated to open and close the fixed-side electric contact 1a of the fixed-side electrode rod 4a and the movable-side electric contact 1b of the movable-side electrode rod 4b through the insulating operation rod 16 by an operation mechanism.

  When the vacuum valve 100 of the vacuum circuit breaker 200 is in a closed state, current flows to the lower terminal 19 via the upper terminal 17, the fixed contact 1 a constituting the electric contact, the movable contact 1 b, and the current collector 18 in this order.

  The contact force between the fixed side electrode bar 4a and the movable side electrode bar 4b each having the fixed contact point 1a and the movable contact point 1b is such that the movable side electrode bar 4b and the insulating operation rod 16 for operating the movable side electrode bar 4b And is maintained by the spring force of the contact spring 20 attached to the insulating operation rod 16.

  The contact force between the electrodes of the fixed electrode rod 4a and the movable electrode rod 4b and the electromagnetic force due to the short-circuit current are held by the support lever 21 and the prop 22 which are connected to the insulating operation rod 16 via the main lever 26. ing.

  An operation mechanism unit that operates the vacuum valve 100 is provided with a closing coil 30, a plunger 23 that is driven by excitation of the closing coil 30, and a roller 25 that is pushed up via the knocking rod 24. ing.

  The operating mechanism for operating the vacuum valve 100 is driven by a tripping coil 27 and excitation of the tripping coil 27, and the main lever 26 is driven by the fixed-side electric contact 1a of the fixed-side electrode rod 4a and the movable-side electrode. A tripping lever 28 is installed that rotates in the direction in which the electrode between the rod 4b and the movable electrical contact 1b is closed to disengage from the prop 22.

  When the closing coil 30 of the operation mechanism is excited, the vacuum valve 100 of the vacuum circuit breaker 200 pushes up the roller 25 through the knocking rod 24 by driving the plunger 23 from the open circuit state, and the fixed side electric contact 1a of the fixed side electrode rod 4a After the main lever 26 is rotated in a direction in which the gap between the movable side electrode bar 4b and the movable side electrical contact 1b is closed, the movement of the main lever 26 is supported by the support lever 21.

  Further, when the vacuum valve 100 of the vacuum circuit breaker 200 is in a free-release state, the trip coil 27 is excited, the trip lever 28 disengages the prop 22 and the fixed-side electrical contact 1a of the fixed-side electrode rod 4a. By rotating the main lever 26 in the direction in which the electrode between the movable electrode bar 4b and the movable electric contact 1b of the movable electrode 4b opens, the electrode is opened.

  In the open circuit state of the vacuum valve 100 of the vacuum circuit breaker 200, after the electrodes are opened, the link is restored by the reset spring 29 provided on the roller 25, and the prop 22 is engaged at the same time. When the closing coil 30 is excited in this state, a closed state is obtained. The exhaust cylinder 31 is disposed in the vacuum valve 100.

  As described above, the vacuum valve 100 of the embodiment shown in FIG. 5 is manufactured by using the electrical contact 1 of the embodiment shown in FIG. 1, and the vacuum circuit breaker 200 including the vacuum valve 100 and its operation mechanism is prepared. Configured. The vacuum circuit breaker 200 is a vacuum circuit breaker having a rated voltage of 24 kV, a rated current of 1250 A, and a rated breaking current of 25 kA.

  The crystal grain size of the refractory metal and conductive metal of the contact layer at the contact of the vacuum valve 100 provided in the vacuum circuit breaker 200 of the present embodiment is set in the range of 5 to 20 μm, and the refractory metal and the conductive layer of the contact layer are electrically conductive. Refer to the description of the vacuum valve 100 of the second embodiment described above with reference to Table 1 for the effect of setting the diffusion range between the conductive metals to a range of 50 nm or less.

  As described above, a vacuum valve and a vacuum circuit breaker having excellent breaking performance and welding resistance can be obtained by the electrical contact which is an embodiment of the present invention.

  According to the present embodiment, the electrical contact for vacuum valve that maintains electrical conductivity and thermal conductivity, and has the electrical contact member strength set to a desired value such that the electrical contact can be separated without any trouble when the current is interrupted, and Vacuum switchgear using electrical contacts can be realized.

  Next, the load switch 300 which is one Example of this invention is demonstrated.

  A load switch 300 according to an embodiment of the present invention in which the vacuum valve 100 of the first embodiment shown in FIG. 5 is mounted on a vacuum switch device other than a vacuum circuit breaker will be described.

  FIG. 7 shows a load switch 300 for a roadside installation transformer, which is an embodiment of the present invention equipped with the vacuum valve 100 of the embodiment shown in FIG.

  In FIG. 7, a load switch 300 has a plurality of (three in this embodiment) vacuum valves 100 corresponding to main circuit switching units housed in a vacuum-sealed outer vacuum container 32. . The outer vacuum container 32 includes an upper plate member 33, a lower plate member 34, and a side plate member 35 between the upper plate member 33 and the lower plate member 34, and the peripheries (edges) of the plate members are joined together by welding. And installed in the main body of the load switch 300.

  A plurality of upper through holes 36 are formed in the upper plate member 33 constituting the outer vacuum vessel 32, and an annular insulating upper base 37 covers each upper through hole 36 at the edge of each upper through hole 36. It is fixed to.

  In the circular space formed in the center of each upper base 37, a cylindrical movable electrode bar 4b constituting one of the electrodes of each vacuum valve 100 is inserted so as to freely reciprocate (up and down). . That is, each upper through hole 36 is closed by the upper base 37 and the movable electrode rod 4b.

  The axial end (upper side) of the movable electrode rod 4b constituting the vacuum valve 100 is connected to an operating device (electromagnetic operating device) (not shown) installed outside the outer vacuum vessel 32. It is like that.

  Further, on the lower side of the upper plate member 33 that is inside the outer vacuum vessel 32, the outer bellows 38 reciprocates (vertically moves) along the axial direction of the movable electrode rod 4b along the edge of each upper through hole 36. The outer bellows 38 are arranged freely, and one end side in the axial direction is fixed to the lower side of the upper plate member 33, and the other end side in the axial direction is attached to the outer peripheral surface of each movable electrode rod 4b.

  That is, in order to make the outer vacuum container 32 have a hermetically sealed structure, outer bellows 38 are arranged at the edge of each upper through hole 36 along the axial direction of each movable electrode rod 4b. In addition, an exhaust pipe (not shown) is connected to the upper plate member 33, and the inside of the outer vacuum container 32 is evacuated and held in a vacuum state via the exhaust pipe.

  On the other hand, a plurality of lower through holes 39 are formed in the lower plate member 34 constituting the outer vacuum vessel 32, and an insulating bushing 40 is fixed to the edge of each lower through hole 39 so as to cover each lower through hole 39. Has been. An annular insulating lower base 41 is fixed to the bottom of each insulating bushing 40.

  A cylindrical fixed-side electrode rod 4 a that constitutes the other of the electrodes of each vacuum valve 100 is inserted into the circular space at the center of each lower base 41.

  That is, the lower through holes 39 formed in the lower plate member 34 are closed by the insulating bushing 40, the lower base 41, and the fixed electrode rod 4a, respectively. One end side (lower side) of the fixed-side electrode rod 4a in the axial direction is connected to a cable (distribution line) (not shown) arranged outside the outer vacuum vessel 32.

  A plurality of vacuum valves 100 corresponding to the main circuit opening / closing portion of the load switch 300 are housed inside the outer vacuum vessel 32, and each movable side electrode bar 4b constituting these vacuum valves 100 includes two movable electrode bars 4b. The flexible conductors (flexible conductors) 42 having curved portions are connected to each other.

  The flexible conductor 42 is configured by alternately laminating a plurality of copper plates and stainless steel plates as conductive plate members having two curved portions.

  A through hole 43 is formed in the flexible conductor 42, and each movable side electrode bar 4b is inserted into each through hole 43 to connect the flexible conductor 42 and the movable side electrode bar 4b to each other.

  In the above description, the vacuum valve 100 of the embodiment shown in FIG. 5 is manufactured, and the vacuum valve 100 is applied to a load switch 300 for a roadside installation transformer that is a vacuum switching device other than a vacuum circuit breaker. explained.

  In addition, this invention is applicable also to various vacuum switchgears, such as a vacuum insulation switchgear other than the above-mentioned load switch.

  According to the present embodiment, the electrical contact for vacuum valve that maintains electrical conductivity and thermal conductivity, and has the electrical contact member strength set to a desired value such that the electrical contact can be separated without any trouble when the current is interrupted, and Vacuum switchgear using electrical contacts can be realized.

  The present invention is applicable to a vacuum valve electrical contact and a vacuum switchgear using the electrical contact.

  1: Electrical contact, 1a: Fixed side electrical contact, 1b: Movable side electrical contact, 2: Slit groove, 3, 3a, 3b: Antifouling plate, 4, 4a, 4b: Electrode rod, 5: Brazing material, 6a: Fixed side electrode, 6b: movable side electrode, 7: shield, 8: movable side shield, 9a: fixed side end plate, 9b: movable side end plate, 10: bellows, 11: guide, 12: movable side holder, 13: Insulating cylinder, 14: Vacuum valve, 15: Epoxy cylinder, 16: Insulating operation rod, 17: Upper terminal, 18: Current collector, 19: Lower terminal, 20: Contact spring, 21: Support lever, 22: Prop, 23: Plunger, 24: knocking rod, 25: roller, 26: main lever, 27: tripping coil, 28: tripping lever, 29: reset spring, 30: closing coil, 31: exhaust pipe, 32: outer vacuum vessel, 33 : Upper plate 34: Lower plate material, 35: Side plate material, 36: Upper through hole, 37: Upper base, 38: Outer bellows, 39: Lower through hole, 40: Insulating bushing, 41: Lower base, 42: Flexible conductor, 43 : Flexible conductor through hole, 44: center hole, 45: contact layer, 46: base material, 100: vacuum valve, 200: vacuum circuit breaker, 300: load switch.

Claims (10)

A base material made of a conductive metal, and a contact layer made of a refractory metal and a conductive metal is formed on the upper surface side of the base material, and the base material and the contact layer are integrally bonded, and the contact Forming the crystal grain size of the refractory metal and conductive metal in the layer to be in the range of 5 to 20 μm ;
An electrical contact for a vacuum valve , wherein the contact layer is formed such that a range of a diffusion phase or a reaction phase between a refractory metal and a conductive metal is 50 nm or less . The electrical contact for a vacuum valve according to claim 1,
The refractory metal in the contact layer is one or a mixture or compound of Cr, W, Mo, or Nb, and the conductive metal in the contact layer is Cu or a Cu alloy containing Cu as a main component. An electrical contact for a vacuum valve, characterized by being . In the electrical contact for a vacuum valve according to claim 1 or claim 2,
An electrical contact for a vacuum valve, wherein the conductive metal in the substrate is Cu or a Cu alloy containing Cu as a main component . The electrical contact for a vacuum valve according to claim 1,
The electrical contact for a vacuum valve, wherein the contact layer is composed of 15 to 40% by weight of a refractory metal and 60 to 85% by weight of a conductive metal . The electrical contact for a vacuum valve according to any one of claims 1 to 4,
An electrical contact for a vacuum valve, wherein the contact layer has an oxygen content of 0.4 wt% or less . The electrical contact for a vacuum valve according to any one of claims 1 to 5,
The contact layer and the base material constituted by being integrally joined are each formed in a disk shape,
A center hole is formed at the center of the circle of the disk-shaped contact layer and the base material, and a plurality of slit grooves penetrating from the center of the circle toward the outer periphery are formed in a non-contact manner with respect to the center hole, An electrical contact for a vacuum valve, wherein a plurality of planar shapes separated from each other are formed in the contact layer by slit grooves . The electrical contact for a vacuum valve according to any one of claims 1 to 6,
The contact layer and the base material provided in the electric contact for the vacuum valve constitute a disc-like member integrally joined, and a fouling prevention plate is installed on the back side of the disc-like member, and the disc-like member An electrode for a vacuum valve, comprising an electrode rod integrally joined to both the base material and the antifouling plate . In a vacuum valve provided with a pair of fixed-side electrodes and a movable-side electrode disposed opposite to the fixed-side electrodes in the vacuum vessel,
At least one of the fixed side electrode and the movable side electrode is a disk-shaped contact layer and a disk-shaped member constituting the base material, a fouling prevention plate installed on the back side of the disk-shaped member, and the disk-shaped It is an electrical contact used for the electrode rod integrally joined to the base material and antifouling plate of the member,
The electrical contact used for the electrode rod is formed by forming a base material made of a conductive metal, a contact layer made of a refractory metal and a conductive metal on the upper surface side of the base material, and the base material and the contact layer. It is configured to be integrally bonded, and is formed such that the crystal grain size of the refractory metal and the conductive metal in the contact layer is in the range of 5 to 20 μm,
The vacuum valve, wherein the contact layer is formed such that a diffusion phase or a reaction phase between the refractory metal and the conductive metal has a range of 50 nm or less. A vacuum valve provided with a pair of fixed side electrodes in the vacuum container and a movable side electrode disposed opposite to the fixed side electrode, and the vacuum on each of the fixed side electrode and the movable side electrode in the vacuum valve In a vacuum circuit breaker comprising a conductor terminal connected to the outside of the valve and an opening / closing means for driving the movable electrode,
In the vacuum valve, at least one of the fixed side electrode and the movable side electrode is a disk-shaped contact layer and a disk-shaped member constituting the base material, and an antifouling plate installed on the back surface side of the disk-shaped member, And an electrode for a vacuum valve having an electrode rod integrally joined to the base material and the antifouling plate of the disk-shaped member,
The electrical contact used for the electrode rod is formed by forming a base material made of a conductive metal, a contact layer made of a refractory metal and a conductive metal on the upper surface side of the base material, and the base material and the contact layer. It is configured to be integrally bonded, and is formed such that the crystal grain size of the refractory metal and the conductive metal in the contact layer is in the range of 5 to 20 μm,
A vacuum circuit breaker characterized in that the contact layer is formed such that a range of a diffusion phase or a reaction phase between the refractory metal and the conductive metal is 50 nm or less . A vacuum comprising a pair of fixed-side electrodes in a vacuum vessel and a plurality of vacuum valves each having a movable-side electrode disposed opposite to the fixed-side electrodes by a conductor, and an opening / closing means for driving the movable-side electrode. In switchgear,
In the vacuum valve, at least one of the fixed side electrode and the movable side electrode is a disk-shaped contact layer and a disk-shaped member constituting the base material, and an antifouling plate installed on the back surface side of the disk-shaped member, And an electrode for a vacuum valve having an electrode rod integrally joined to the base material and the antifouling plate of the disk-shaped member,
The electrical contact used for the electrode rod is formed by forming a base material made of a conductive metal, a contact layer made of a refractory metal and a conductive metal on the upper surface side of the base material, and the base material and the contact layer. It is configured to be integrally bonded, and is formed such that the crystal grain size of the refractory metal and the conductive metal in the contact layer is in the range of 5 to 20 μm,
A vacuum switchgear characterized in that the contact layer is formed so that the range of the diffusion phase or reaction phase between the refractory metal and the conductive metal is 50 nm or less .

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