JP2011014240A - Electric contact for vacuum valve, and vacuum switching device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric contact for a vacuum valve with excellent breaking performance, and a vacuum switching device for responding to enlargement of capacity.SOLUTION: The electrical contact consists of at least two layer of a contact layer and a highly-conductive layer fitted on a side connecting to a conductor against the contact layer. The contact layer consists of a sintered body containing Cr, Cu and Te, the highly-conductive layer consists of a sintered body containing Cu and carbon fiber, and Cr carbide exits between the contact layer and the highly-conductive layer. The conductivity of the highly-conductive layer is improved through the carbon fiber, and peeling between layers is prevented through existence of Cr carbide between the contact layer and the highly-conductive layer.

Description

  The present invention relates to a novel electric contact for a vacuum valve used for a vacuum circuit breaker, a vacuum switchgear and the like.

  Current switchgear using vacuum as a medium, such as a vacuum circuit breaker, has little influence on the environment, and is therefore being replaced by a gas circuit breaker. In that case, a large capacity (breaking performance of a large current) is required for a vacuum circuit breaker or the like.

  In general vacuum switchgear, Cr—Cu electric contacts are used. The electrical contact member for interrupting a large current needs to have a high density in order to increase the current carrying capacity and maintain good heat conduction. Further, it is desirable that the strength of the contact member is small in order to reduce the pulling force when the contacts are welded by the energized Joule heat. For example, in JP-A-2005-135778 (Patent Document 1), JP-A-2006-140073 (Patent Document 2), and JP-A-2009-076218 (Patent Document 3), a Cr-Cu-based high-density molded body Is sintered in an inert atmosphere and a low melting point metal such as Te is added to achieve both high density and low strength.

JP 2005-135778 A JP 2006-140073 A JP 2009-076218 A

  When a highly conductive layer containing Cu as a main component is provided on the side opposite to the contact surface of the electrical contact, high electrical conductivity can be achieved. This is effective for reducing the electrical resistance, further increasing the current carrying capacity, and suppressing the amount of generated Joule heat.

  When electrical contacts are manufactured by a sintering method, post-processing can be eliminated by near net molding, manufacturing can be facilitated, and mass production is easy. However, since the highly conductive layer manufactured by the sintering method has defects such as pores, it is difficult to obtain a conductivity equivalent to that of a Cu ingot (melted material). In addition, in order to suppress peeling at the interface between the contact layer and the highly conductive layer, a countermeasure on the shape such as providing a groove for absorbing thermal deformation is required, which may reduce productivity.

  Accordingly, an object of the present invention is to provide a high-conductivity layer that is superior in electrical and thermal conductivity compared to conventional electrical contacts consisting of two or more layers, and suppresses the separation between the two layers, and can be used for a large capacity. It is to provide a contact.

  Usually, the electrical contact has a disk shape. The electrical contact of the present invention comprises at least two layers in the thickness direction, specifically, a contact layer and a highly conductive layer provided on the side of the contact layer connected to the conductor. The contact layer includes Cr, Cu, and Te. The highly conductive layer includes Cu and carbon fiber. The highly conductive layer generates Cr carbide on the contact layer side by sintering.

  The carbon fiber preferably has an aspect ratio (fiber length / fiber diameter) of 50 to 150 and a fiber diameter of 300 nm or less. Moreover, it is preferable that the quantity of the carbon fiber contained in a highly conductive layer is 0.1 to 1.5 weight%.

  A layer (a layer containing Cr, Cu, and Te) having an intermediate composition between the contact layer and the highly conductive layer may be provided between the contact layer and the highly conductive layer. The Cr carbide is present between the contact layer and the intermediate layer.

  The above-mentioned electrical contact may be used as either a fixed side or a movable side electrode. The contact layer side is disposed close to the opposing electrode, and the highly conductive layer is connected to the conductor.

  For the above electrical contacts, the powder of the component forming the contact layer is blended into the desired composition to make the mixed powder of the contact layer. Similarly, the mixed powder of the component forming the intermediate layer and the mixed powder of the component forming the highly conductive layer are prepared. Then, these are provided in a layered form in a molding container and integrally pressure-molded, and the molded body is heated and sintered below the melting point of copper. Heat sintering is performed in a reducing atmosphere or an inert atmosphere.

  The electrode referred to in the present application is a member having an electrode bar integrally joined to the surface of the highly conductive layer of the electrical contact. The vacuum valve referred to in the present application includes a pair of electrodes (a fixed electrode and a movable electrode) in a vacuum vessel. Furthermore, the vacuum circuit breaker referred to in the present application has a vacuum valve having a pair of electrodes (a fixed side electrode and a movable side electrode) in a vacuum vessel, and is connected to each of the fixed side electrode and the movable side electrode in the vacuum valve And a conductor terminal drawn out of the bulb and an opening / closing means for driving the movable electrode. The vacuum opening / closing device referred to in the present application includes an opening / closing means for connecting a plurality of vacuum valves with a conductor and driving a movable electrode. It is preferable that at least one of the pair of electrodes is an electrode including the above-described carbon fiber.

  According to the present invention, it is possible to provide an electrical contact that can be easily and inexpensively manufactured and can have a large capacity, and can be applied to a vacuum valve, a vacuum circuit breaker, and the like.

The figure which shows the structure of an electrical contact and an electrode. The figure which shows the structure of a vacuum valve. The figure showing the structure of a vacuum circuit breaker. The figure showing the structure of the load switch for roadside installation transformers.

  Hereinafter, further details of the electrical contact of the present invention will be described. The electrical contact generally has a substantially disk shape, and the present invention assumes an electrical contact member composed of at least two layers in the thickness direction. By using a Cr—Cu alloy as the contact layer, it has excellent breaking performance and withstand voltage performance, and can satisfy the performance required as an electrical contact. By providing a highly conductive layer on the opposite side of the contact surface, the heat and electrical conductivity of the entire electrical contact is improved, the generation of Joule heat during energization is suppressed, and the electric resistance is excellent in welding resistance and energization performance. It can be a contact.

  One or a plurality of intermediate layers having an intermediate composition may be provided between the contact layer and the highly conductive layer. In this case, the electrical contact is composed of a plurality of layers in the thickness direction. By providing an intermediate layer, the stress resulting from the shrinkage difference between the contact layer and the highly conductive layer in the manufacturing process can be relaxed, the occurrence of defects such as warpage and delamination can be prevented, and the thermal expansion difference during energization can be mitigated, An increase in contact resistance due to warping can be suppressed.

  The contact layer is made of Cr, Cu and Te. On the other hand, the highly conductive layer on the side connected to the conductor is made of Cu and carbon fiber. By including Te in the contact layer, it is possible to weaken the interface bond between the Cr particles and the Cu matrix, and it is possible to reduce the welding separation force accompanying a decrease in the strength of the contact layer. In addition, in the infiltration manufacturing method described later in the examples, since the heating temperature is relatively high, the volatilization reduction of Te occurs, and the above effect cannot be expected. Therefore, the addition of Te is particularly effective in the sintering method.

  By including Cr in the contact layer (or an intermediate layer provided between the contact layer and the highly conductive layer) and carbon fiber in the highly conductive layer, the Cr of the contact layer (or intermediate layer) and the highly conductive layer Cr carbide is generated at the interface by reaction with the carbon fiber. Cr carbide strengthens the bond between the contact layer (or intermediate layer) and the highly conductive layer, and can suppress problems such as delamination.

  The carbon fiber has high electrical conductivity and thermal conductivity, and contributes to improvement of the thermal and electrical conductivity of the entire electrical contact. In particular, it is desirable that the aspect ratio represented by the fiber length / fiber diameter is 50 to 150 and the fiber diameter is 300 nm or less. When the aspect ratio is within this range, the conductivity and thermal conductivity are sufficiently improved, and fiber refraction is hardly caused. When the aspect ratio is too small, the improvement in conductivity and thermal conductivity is small. On the other hand, if the aspect ratio is too large, the effect of improving thermal and electrical conductivity may be reduced due to fiber refraction. If the carbon fibers are oriented in a specific direction (for example, the thickness direction of the electrical contact), more efficient thermal / electrical conductivity can be improved.

  The amount of carbon fiber mixed in the highly conductive layer is preferably 0.1 to 1.5% by weight of carbon fiber. By this degree of mixing, the effect of improving the thermal conductivity and electrical conductivity is fully exhibited. When the amount of carbon fiber is 0.1% by weight or less, since the amount thereof is small, the effect of improving heat and electrical conductivity is small. When added in an amount of 1.5% by weight or more, the carbon fibers may inhibit the densification of the Cu matrix, and the thermal conductivity and electrical conductivity of the entire electrical contact are lowered.

  Said electrical contact can be manufactured by the sintering method shown below. That is, a mixed powder in which the powder of the component forming the contact layer is blended in a desired composition, a mixed powder in which the powder of the component forming the intermediate layer and the carbon fiber are blended in the desired composition, the Cu powder and carbon forming the highly conductive layer The mixed powder in which the fibers are blended in a desired composition is pressure-molded integrally in a layered form, and then heated and sintered at a melting point of Cu or lower. Delamination during sintering can be prevented by forming the mixed powder constituting each layer into layers and forming them integrally. In addition, by manufacturing by the sintering method, the hardness of the contact layer is relatively low, and since there is no solid solution of Cr in the Cu matrix and high conductivity, the contact resistance with the counterpart contact is reduced, Generation of Joule heat can be suppressed. This sintering is carried out in a reducing atmosphere or in an inert atmosphere, thereby promoting the densification of the Cu matrix and obtaining an electrical contact having a sound sintered structure and excellent thermal and electrical characteristics.

  In an electrode used for a vacuum circuit breaker or the like, an electrode rod, which is a current-carrying member, is integrally joined to a surface on the high conductive layer side of an electrical contact having a substantially disk shape. By adopting such a configuration, it is possible to lead the Joule heat generated at the contact portion to the outside of the vacuum valve quickly while having good energization performance. It is desirable that the disk-shaped electrical contact has a central hole 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.

  Moreover, it is good also as an electrode of the structure where the coil electrode which makes the cup shape which consists of Cu is integrally joined to the highly conductive layer side of a disk-shaped electrical contact, and the electrode rod is integrally joined to the bottom part of the coil electrode. According to such a structure, an arc can be extinguished using a magnetic field generated at the time of current interruption, and excellent interruption performance can be obtained.

  The vacuum valve includes a pair of electrodes in a vacuum container. The disconnection / connection is switched by moving at least one of the electrodes. Generally, only one electrode is movable (movable side electrode), and the other is fixed (fixed side electrode).

  The vacuum circuit breaker includes a vacuum valve, a conductor terminal connected to an electrode in the vacuum valve, and an opening / closing means for driving the movable side electrode. The vacuum switchgear includes a plurality of vacuum valves connected in series with a conductor and provided with switchgear for driving the movable electrode. These devices suppress the Joule heat generated at the contact portion during energization by using the above-described electrical contacts, are less likely to cause welding between the electrical contacts, and are excellent in energization performance and anti-welding performance.

  Hereinafter, the best mode for carrying out the invention will be described in detail by way of examples. The present invention is not limited to these examples.

  FIGS. 1A and 1B are diagrams showing the structure of an electrode using the above-described electrical contact. FIG. 1A shows a case where the electrical contact is composed of two layers of a contact layer and a highly conductive layer, and FIG. 1B shows a case where an intermediate layer is provided. In FIG. 1, 1 is an electrical contact, 2 is a slit groove for applying a driving force to the arc, and 3 is a component for preventing the components of the electrical contact 1 melted at the time of current interruption from fouling the back surface through the slit groove 2. A stainless steel antifouling plate, 4 is an electrode rod, 5 is a brazing material, 44 is a central hole, 45 is a contact layer, 46 is a highly conductive layer, and 47 is an intermediate layer.

  An electrical contact having the composition shown in Table 1 was produced, and an electrode was produced using the electrical contact.

  The manufacturing method of the electrical contact 1 is as follows.

  The raw material powder for the contact layer is mixed with a V-type mixer at a blending ratio such that the composition of the contact layer shown in Table 1 is obtained using Cr powder and Cu powder having a particle size of 75 μm or less and Te powder having a particle size of 60 μm or less. And produced.

  In addition, the raw material powder of the highly conductive layer is composed of Cu powder having a particle size of 75 μm or less and carbon nanofibers having a diameter of 150 nm and a length of about 4.5 to 45 μm. A mortar was mixed at a blending ratio as shown in FIG. A carbon powder having a particle size of 300 nm was used as a sample material No. 8 using a carbon powder for comparison, and mixed in the same manner to obtain a powder for this highly conductive layer.

  As an example in which an intermediate layer was provided, sample material 14 (with carbon fiber) and sample material 15 (without carbon fiber) were produced. The raw material powder for the intermediate layer was prepared by mixing the above powder using a mortar and a V-type mixer at a blending ratio such that the composition of the intermediate layer shown in Table 1 was obtained.

  Next, the raw material powder was filled in layers in the order of a contact layer, an intermediate layer, and a highly conductive layer in a disc-shaped mold having a diameter of 60 mm, and was integrally pressure-formed at a pressure of 400 MPa by a hydraulic press. Under the present circumstances, the filling amount of the raw material powder was adjusted so that the thickness of each layer might become the value shown in Table 1. For comparison, for test material No. 7, each powder was separately filled in a mold and molded for each layer. The relative density of the molded body obtained by the above method 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. Under the present circumstances, about the molded object of test material No.7 shape | molded separately for every layer, it laminated | stacked in order of the contact layer, the intermediate | middle layer, and the highly conductive layer, and sintered similarly. As a result, a sintered body having a relative density of 85 to 97% was obtained.

  Furthermore, in this example, for comparison, an electrical contact 1 was also produced by an infiltration method which is one of the conventional manufacturing methods (No. 1). Using the above-mentioned Cr, Cu, Te powder and carbon nanofiber as raw materials, Cr powder is 39.9% by weight, Cu powder is 60% by weight, Te powder is 0.1% by weight with a V-type mixer. This was mixed, filled into a disk-shaped mold, and pressure-molded at a pressure of 145 MPa with a hydraulic press to produce a skeleton (low-density molded body). This skeleton was placed in a graphite crucible, and carbon nanofibers and Cu ingots were placed thereon, heated in a vacuum at 1200 ° C. for 2 hours, and the skeleton was melt-impregnated with Cu. An infiltration body having a contact layer composition and integrated with a highly conductive layer was produced.

  Table 2 shows the result of observing the sintered body and the infiltrated body obtained by the composition and method shown in Table 1.

  When carbon fiber was added to the highly conductive layer, the sintered body did not peel off. On the other hand, in the case of the test material No. 2 containing no carbon fiber, peeling occurred at the outer peripheral portion of the disc-shaped sintered body. From this, it was confirmed that the carbon fiber contained in the highly conductive layer has an effect of suppressing delamination. Peeling is due to shrinkage difference in the sintering process between the contact layer and the highly conductive layer. When the highly conductive layer does not contain carbon, Cr carbide is not generated at the interface with the contact layer, and the bonding between the layers is insufficient. it is conceivable that.

  Further, in the case of the test material No. 7, which was formed for each layer and laminated and sintered, peeling occurred between the layers. Therefore, it is not a method of mixing carbon fiber or carbon powder and molding each layer separately, but by molding and sintering together, it is possible to produce an electrical contact without causing delamination between layers. Is possible.

  The electric conductivity in the highly conductive layer of each sintered body and infiltrated body was measured. The conductivity is a value obtained by measuring the surface of the highly conductive layer by the eddy current method, and the “IACS” value is a relative value when the conductivity of annealed pure copper is 100%. In the case of the test material No. 1 obtained by the infiltration method, since the high conductive layer has a dense dissolved structure, it exhibits a relatively high conductivity, but the solid solution of Cr occurs from the contact layer. Sufficient conductivity was not obtained. In addition, carbon fibers (carbon nanofibers) were separated due to the difference in specific gravity with Cu during the infiltration process, and C was unevenly distributed in the highly conductive layer. In the case of the test material No. 2 containing no carbon fiber, it has a highly conductive layer made of copper (Cu 100%), but the conductivity was as low as 81%. This is presumably because defects such as pores exist because the manufacturing method is a sintering method. In No. 7 molded for each layer, the highly conductive layer showed sufficient conductivity, but it was not appropriate because delamination occurred as described above.

  In the test material No. 3 to which the carbon fiber was added, the conductivity was improved as compared with the test material No. 2 in which the carbon fiber was not included. In particular, in the high conductive layer of No. 9 to No. 15 to which carbon fiber of 0.1% by weight or more was added, any significant improvement in conductivity was confirmed. In addition, the sample No. 4 to which 3.0% by weight of carbon fiber was added showed high conductivity, but because of too much carbon fiber, the sinterability was lowered and the densification was insufficient. Decreased. Therefore, the amount of carbon fiber added is preferably 0.1 to 1.5% by weight.

  Next, when carbon fibers having different aspect ratios were compared, the specimen No. 5 having an aspect ratio (fiber length) of 30 and No. 6 having an aspect ratio of 300 contained only a small amount of carbon. It is presumed that No.5, which has a higher conductivity than the test material No.3 to which no fiber is added, has a small aspect ratio, has little mutual conduction, and is less likely to have an effect of improving the conductivity. No. 6 has a large aspect ratio, and the carbon fibers are refracted or aggregated, or the sinterability is lowered accordingly. Therefore, the aspect ratio of the carbon fiber is preferably about 50 to 150. For comparison, in No. 8 to which carbon powder was added, the conductivity was improved as compared to No. 2. This is presumed to be due to the getter action in which the C powder absorbs gas components such as oxygen remaining in the sintered highly conductive layer by reaction or the like. However, the addition of particulate carbon has a lower conductivity than No. 5, which has a small aspect ratio, and the effect of improving the conductivity is small, and it seems that a large effect of increasing the conductivity cannot be expected.

  The above sintered body and infiltrated body were machined to produce an electrical contact 1 having the shape shown in FIG. The diameter is 55 mm, and the thickness of each layer has the dimensions shown in Table 1. Note that No. 2 and No. 7 in which delamination occurred after sintering were not used for the production of the electrical contact 1 and the subsequent electrical performance evaluation.

  In addition to the method of processing the shape of the sintered body as described above, the electrical contact 1 is obtained also by a method of filling a raw material powder into a mold capable of forming the final shape having the slit groove 2 and sintering it. be able to. Since this method does not require post-processing such as machining, it can be easily manufactured.

Next, the electrode was produced using the electrical contact 1 as follows. The electrode rod 4 is made of oxygen-free copper, and the antifouling plate 3 is made in advance by machining with SUS304, and the brazing material 5 is placed between the electric contact 1, the antifouling plate 3, and the electrode rod 4, respectively. This was heated in a vacuum of 8.2 × 10 ⁻⁴ Pa or less at 970 ° C. for 10 minutes to produce the electrode shown in FIG. This electrode is used for a vacuum valve for a rated voltage of 24 kV, a rated current of 1250 A, and a rated breaking current of 25 kA. The anti-stain plate 3 also serves as a reinforcing plate for preventing excessive deformation of the electrical contact 1 due to the opening / closing operation. However, the anti-stain plate 3 may be omitted if the strength of the electrical contact 1 is sufficient.

  Subsequently, a vacuum valve (rated voltage 24 kV, rated current 1250 A, rated breaking current 25 kA) was produced. FIG. 2 is a diagram showing the structure of the vacuum valve. In FIG. 2, 1a and 1b are fixed-side electrical contacts and movable-side electrical contacts, 3a and 3b are antifouling plates, 4a and 4b are fixed-side electrode rods and movable-side electrode rods, respectively, and these are respectively fixed-side electrodes 6a. The movable side electrode 6b is configured. In the present embodiment, the grooves of the electric contacts on the fixed side and the movable side are installed so as to coincide with each other on the contact surface. 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. These are brazed and sealed to a high vacuum by the fixed side end plate 9a, the movable side end plate 9b, and the insulating cylinder 13, and are connected to the external conductor through the screw portions of the fixed side electrode 6a and the movable side holder 12. A shield 7 is provided on the inner surface of the insulating cylinder 13 to prevent scattering of metal vapor or the like at the time of interruption, and a guide 11 for supporting a sliding portion is provided between the movable side end plate 9b and the movable side holder 12. Provided. A bellows 10 is provided between the movable-side shield 8 and the movable-side end plate 9b, and the movable-side holder 12 is moved up and down while the vacuum valve is kept in vacuum to open and close the fixed-side electrode 6a and the movable-side electrode 6b. Can do.

  Further, a vacuum circuit breaker equipped with the above vacuum valve was produced. FIG. 3 is a block diagram of a vacuum circuit breaker showing the vacuum valve 14 and its operating mechanism of the present embodiment. The vacuum circuit breaker has a structure in which three sets of three-phase epoxy cylinders 15 are disposed on the front surface with the operation mechanism portion disposed on the front surface and supporting the vacuum valve 14 on the rear surface. The vacuum valve 14 is opened and closed by an operating mechanism via an insulating operating rod 16.

  When the circuit breaker is closed, current flows through the upper terminal 17, the electrical contact 1, the current collector 18, and the lower terminal 19. The contact force between the electrodes is maintained by a contact spring 20 attached to the insulating operation rod 16. The contact force between the electrodes and the electromagnetic force due to the short-circuit current are held by the support lever 21 and the prop 22. When the closing coil 30 is excited, the plunger 23 pushes up the roller 25 through the knocking rod 24 from the open circuit state, rotates the main lever 26 to close the space between the electrodes, and then holds it by the support lever 21.

  When the circuit breaker is free to be tripped, the tripping coil 27 is excited, the tripping lever 28 is disengaged from the prop 22, and the main lever 26 is rotated to open the electrodes. When the circuit breaker is in the open state, the link is restored by the reset spring 29 after the electrodes are opened, 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. In addition, 31 is an exhaust pipe.

  As described above, the vacuum valve 14 was manufactured by using the electrical contact 1 of this example, and a vacuum circuit breaker with a rated voltage of 24 kV, a rated current of 1250 A, and a rated breaking current of 25 kA was prepared.

  For the electrical contacts shown in Table 1, an electrical performance test was performed using the vacuum circuit breaker fabricated in Example 1. First, an increase in temperature during energization was evaluated by an energization test. Since it is difficult to directly measure the electrical contact temperature during energization, in this example, the temperature at the end of the vacuum valve after energizing 2000 A current for 10 hours was measured. The temperature at the end of the vacuum valve was measured at a room temperature of 24 ° C. Table 2 shows the results.

  All of the test materials No. 1 to No. 8 showed an end temperature of 65 ° C. or higher. On the other hand, the sample materials No. 9 to No. 15 were suppressed to 63 ° C. or lower. This is considered to depend on the electrical conductivity or thermal conductivity of the highly conductive layer. The electrical contacts No. 9 to No. 15 having high conductivity are effective in suppressing energization Joule heat. In addition, No. 14 containing carbon fibers (carbon nanofibers) in the intermediate layer showed a higher end temperature than No. 15 containing no carbon fibers in the intermediate layer. It is considered that Cr and C coexist in the intermediate layer, thereby producing Cr carbide and reducing the conductivity improving effect by the carbon nanofiber. Therefore, it is more preferable that the intermediate layer does not contain carbon fiber.

  Thereafter, the possibility of electrode separation (opening) after 25 kA current interruption test and 25 kA energization was evaluated. Table 2 also shows the results. In the case of No. 1 obtained by the infiltration method, welding after energization of 25 kA was remarkable and could not be separated. This is presumably because Te having a low melting point flows out of the contact layer during the infiltration process, and the effect of suppressing welding by Te is lowered. Therefore, the sintering method is suitable for the production method. The electrical contacts other than No. 1 were satisfactory in both breaking performance and welding resistance (electrode separation). However, No. 9 to No. 15 in which the temperature rise accompanying Joule heat is small is suitable for energization with a larger current.

  As described above, it was possible to manufacture a vacuum valve and a vacuum circuit breaker having excellent current-carrying performance, breaking performance and welding resistance while suppressing temperature rise due to Joule heat.

  The vacuum valve produced in Example 1 was mounted on a vacuum switchgear other than the vacuum circuit breaker. FIG. 4 is a view showing a load switch for a roadside installation transformer equipped with the vacuum valve 14 produced in the first embodiment.

  In this load switch, a plurality of pairs of vacuum valves 14 corresponding to main circuit switching units are 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, and the periphery (edge) of each plate member is joined to each other by welding and is installed together with the equipment main body.

  An upper through hole 36 is formed in the upper plate member 33, and an annular insulating upper base 37 is fixed to an edge of each upper through hole 36 so as to cover each upper through hole 36. A cylindrical movable electrode rod 4b is inserted into a circular space formed at the center of each upper base 37 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 is connected to an operating device (electromagnetic operating device) installed outside the outer vacuum vessel 32. Further, on the lower side of the upper plate member 33, an outer bellows 38 is disposed so as to freely reciprocate (up and down) along the edge of each upper through hole 36, and each outer bellows 38 has an axial end on the upper side. The other end side in the axial direction is fixed to the lower side of the plate member 33, and 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 vessel 32 is evacuated through the exhaust pipe.

  On the other hand, a lower through hole 39 is formed in the lower plate member 34, and an insulating bushing 40 is fixed to an edge of each lower through hole 39 so as to cover each lower through hole 39. An annular insulating lower base 41 is fixed to the bottom of each insulating bushing 40. A cylindrical fixed electrode rod 4a 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) in the axial direction of the fixed electrode rod 4a is connected to a cable (distribution line) arranged outside the outer vacuum vessel 32.

  Inside the outer vacuum vessel 32, a vacuum valve 14 corresponding to a main circuit opening / closing portion of a load switch is accommodated, and each movable side electrode bar 4b is a flexible conductor (flexible conductor) having two curved portions. ) 42 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 in the axial direction. A through hole 43 is formed in the flexible conductor 42, and each movable electrode rod 4 b is inserted into each through hole 43 and connected to each other.

  As described above, the vacuum valve manufactured in Example 1 can be applied to a load switch for a roadside installation transformer, and can also be applied to various vacuum switchgears such as a vacuum switchgear.

DESCRIPTION OF SYMBOLS 1 Electrical contact 1a Fixed side electrical contact 1b Movable side electrical contact 2 Slit groove 3, 3a, 3b Antifouling plates 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 trip coil 28 trip lever 29 reset spring 30 closing coil 31 exhaust cylinder 32 outer vacuum vessel 33 upper plate material 34 lower plate material 35 side plate material 36 upper through hole 37 upper base 38 outer bellows 39 lower through hole Hole 40 Insulating bushing 41 Lower base 2 flexible conductor 43 flexible conductor through hole 44 central hole 45 contact layer 46 high conductive layer 47 intermediate layer

Claims (7)

  An electrical contact having at least two layers of a contact layer and a highly conductive layer provided on a side connected to the conductor with respect to the contact layer, wherein the contact layer is made of a sintered body containing Cr, Cu, and Te. The electrical contact is characterized in that the highly conductive layer is made of a sintered body containing Cu and carbon fibers, and Cr carbide exists between the contact layer and the highly conductive layer. The electrical contact according to claim 1,
Having an intermediate layer between the contact layer and the highly conductive layer;
The electrical contact characterized in that the Cr carbide exists between the intermediate layer and the contact layer.   2. The electrical contact according to claim 1, wherein the carbon fiber has an aspect ratio (fiber length / fiber diameter) of 50 to 150 and a fiber diameter of 300 nm or less. The electrical contact according to claim 1,
The electrical contact according to claim 1, wherein the highly conductive layer includes 0.1 to 1.5% by weight of the carbon fiber. A method for producing an electrical contact having a contact layer and at least two layers of a highly conductive layer provided on a side connected to a conductor with respect to the contact layer,
A mixed container of Cr, Cu and Te, mixed powder of Cu powder and carbon fiber is filled in a molding container in layers, pressurized and integrally molded, and heat-sintered below the melting point of Cu. Contact manufacturing method. It is a manufacturing method of the electrical contact according to claim 5,
The method of manufacturing an electrical contact, wherein the sintering is performed in a reducing atmosphere or an inert atmosphere. A vacuum valve having a pair of fixed-side electrode and movable-side electrode in a vacuum vessel; and a conductor terminal connected to each of the fixed-side electrode and movable-side electrode in the vacuum valve and drawn out of the vacuum valve; ,
A vacuum circuit breaker comprising an opening / closing means for driving the movable electrode,
The fixed side electrode and the movable side electrode are composed of a disk-shaped member and an electrode bar integrally joined to the surface of the highly conductive layer of the disk-shaped member,
A sintered body in which at least one of the disk-like members of the fixed side electrode and the movable side electrode has a contact layer and at least two layers of a highly conductive layer provided on the side connected to the conductor with respect to the contact layer. And the contact layer includes Cr, Cu, and Te, the highly conductive layer includes Cu and carbon fiber, and Cr carbide exists between the contact layer and the highly conductive layer. .

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