JPS61227331A - Contact alloy for vacuum valve - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a vacuum valve (switch), and more particularly to a contact alloy for a vacuum valve with improved current carrying properties.

[Technical background of the invention]

The contacts of the vacuum valve, which cut off the current in a high vacuum by utilizing arc dispersion in a vacuum, are composed of two opposing fixed and movable contacts. In particular, when cutting off current in an inductive circuit such as a motor load, excessive surge voltage may be generated and the load equipment may be destroyed. The cause of this abnormal surge voltage is a new phenomenon in the current that occurs on the low current side when shutting off in a vacuum (current shutoff is forcibly performed without waiting for the natural zero point of the AC current waveform).
This is due to The abnormal surge voltage value ys is the product of the circuit surge impedance Z (+) and the current cutoff value ■C,
That is, it is represented by VS-220IC. Therefore, in order to lower the abnormal surge voltage vS, the current cutoff value IC
must be made smaller.

In order to meet the above requirements, a vacuum switch whose contacts are made of a composite alloy of WC and AQ has been put into practical use (patent application No. 42).
-68447). This alloy contact has the following characteristics: (1) The presence of WC facilitates electron emission, (2) The contact material accelerates evaporation due to heating of the electrode surface due to the collision of field emission electrons, and (3) Carbide in the contact material It exhibits excellent current carrying properties in that it decomposes due to the arc, generates a charged body, and connects the arc.

In addition, as another contact having the above current carrying property, Bi
A composite alloy of Cu and Qu has been produced, and this material has been put to practical use in vacuum valves (Japanese Patent Publication No. 35-14974, Japanese Patent Publication No. 12131-1972). This alloy exhibits (1) low cutting current characteristics because 3i with a weight percentage of about 10% has appropriate vapor pressure characteristics (Japanese Patent Publication No. 1494/1983).

(2) 81, which has a weight percentage of about 0.5%, segregates at grain boundaries and embrittles the alloy itself, achieving low external welding force and excellent resistance to large currents (especially Kosho 41-1
Publication No. 2131).

[Problems with background technology]

However, in recent years, the number of applications for vacuum valves in inductive circuits has increased, and high impedance loads have also appeared, so vacuum valves are desired to have even more stable current carrying properties, and to reduce costs. is desired.

In response to such demands, the contact alloy AQ-wc,
Cu-s+ had a high level of cutting current value or lacked stability. That is, in the AQ-WC contact alloy, the vapor pressure difference between AQ and WC is extremely large, leading to significant selective evaporation of AQ due to arc heat, etc., resulting in instability in current retention and fluctuations in contact resistance.

One Cu-B1 contact alloy has a 3i melting point of 271
An essential problem caused by the low temperature is that 3i aggregates during baking of vacuum valves or heating of silver soldering, leading to poor bonding.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and an object thereof is to provide a contact alloy for a vacuum valve that further improves the stability of current carrying property.

[Summary of the invention]

The present invention uses a conductive material containing copper or a refractory material such as zinc, carbide, or boride, silver, etc. in copper, and a material that is stable against heat treatment and has a vapor pressure between vacuum valve contacts that is diffused into the conductive material. Vacuum valve contact alloys consisting of simple auxiliary materials for the provision of heat conduction, such as zinc and chillite.

(Embodiment of the Invention) An embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 shows an example of the configuration of a vacuum breaker to which the contact alloy of the present invention is applied; Reference numeral 1 indicates a break-off intersection, and this break-off intersection 1 includes an insulating container 2 formed of an insulating material into a substantially cylindrical shape, and metallic lids 4a and 4b provided at both ends of the container via sealing fittings 3a and 3b. It is constructed in a vacuum-tight manner.

A pair of electrodes 7 and 8 attached to opposite ends of conductive rods 5 and 6 are arranged in the above-mentioned shank 1, with the upper electrode 7 being a fixed electrode and the lower electrode 8 being movable. It is used as an electrode. Moreover, a bellows 9 is attached to the electrode rod 6 of this movable electrode 8.
When installed, the electrode 8 can be moved in the axial direction while maintaining the inside of the new graduate 1 vacuum-tight. Further, a metal arc shield 10 is provided above the bellows 9 to prevent the bellows 9 from being covered with arc vapor.

Further, reference numeral 11 is a metallic arc shield provided in the shield 1 so as to cover the electrodes 7 and 8 to prevent the insulating container 2 from being covered with arc vapor. Furthermore, the electrode 8 is
As shown in an enlarged view in FIG. 2, the conductive rod 6 is fixed to the conductive rod 6 by means of a brazing part 12, or is crimped and connected by caulking. The contact 13a is attached to the electrode 8 by brazing 14. Note that 13b is a fixed side contact, which is attached by brazing similarly to the fixed side electrode 8.

Here, considerations for obtaining the contact alloy of the present invention will be explained. In order to improve current susceptibility, it is extremely important not only to maintain the current rupture value itself at a lower value, but also to reduce the width of its dispersion. The above-mentioned current phenomenon is said to be closely related to the amount of vapor between the contacts (vapor pressure, heat conduction), thermionic emissions from the contact material, etc., and according to the inventors' experiments, the former contributes more. It turned out to be. Therefore, it has been found that the current leakage phenomenon can be alleviated by making it easier to supply steam or by making contacts from materials that are easier to supply. Cu-B1 alloy is based on this point of view and has a low shear value, but a fatal drawback is that the Bi
Because of its low melting point (271°C), baking at around 600°C or silver brazing at 800°C, which is normally carried out with a vacuum valve, is difficult to maintain current resistance as a result of movement and aggregation due to the melting of 3i. The existence of power B1 becomes uneven. For this reason, we confirmed a phenomenon in which the width of variation in the current cutoff value increases.

On the other hand, in the Ag-refractory material alloy represented by AQ-WC, although the vapor amount of Al or Cu) is present at the boiling point of the refractory material (WC in this case), the C
Since the vapor pressure of Ag is significantly lower than the vapor pressure of Bi in the u-3i system, depending on where in the contact point (whether the refractory material is Ag or not) the arc leg is fixed, insufficient temperature, ie, insufficient steam, may occur. As a result, it was confirmed that a variation width of the current cutoff value appeared. In this way, the rapid temperature drop on the contact surface at the end of current cutoff can be prevented by using fireproof material and AQ (
It is considered that it is already possible to sustain an arc in an element using an alloy made only in combination with copper or Cu), and it has been concluded that the presence of auxiliary materials is necessary in order to further improve the performance6゛Thus, The above Cu-3i alloy and A
The results of the two considerations for the Q-WC alloy (AQ-refractory material system) indicate that a new auxiliary material is required as a stable contact point with current carrying properties, and the conditions for this are as follows: Furthermore, it is suggested that it is essential to have stability in heat treatment such as baking.

Therefore, in the present invention, as mentioned above, an auxiliary material meeting certain conditions is actively included to improve the current carrying property. Therefore, in order to obtain low shredding current characteristics, the present invention provides CU, CLJ-refractory material, Qu-Co or F
0.5 to 20% znTe is added as an auxiliary material to one of the alloys of e (in which part or all of CLI is replaced with AQ).

Te in this ZnTe is approximately 66 wt%, but Te
Alternatively, a slight deviation in zn is allowed to coexist as a CLJ-2n solid solution containing Zn and a Cu alloy containing a cu-Te compound. Under these conditions, a moderate amount of metal vapor enters the arc space by heating and vaporizing with a relatively small amount of energy - this acts to reduce the current phenomenon, and as a result, a vacuum valve contact alloy that is satisfactory for practical use is obtained. It was confirmed that

Next, an example of a method for manufacturing this contact alloy will be described. Prior to manufacturing, about 100 meshes of Te and 7-n
Pour the powder into a pot filled with argon gas for about 12 minutes.
The mixed powder mixed for a time is molded at 4 tons/r:tA, and then sintered at 900° C. for 24 hours in a hydrogen stream to obtain a ZnTe lump. This ZnTe is ground into 100 to 200 meshes and used as a raw material.

Next, the manufacturing process will be explained.

First, the production of cu-znTe contact material; the required CL
A part of the amount of I was prepared as a powder, and ZnT prepared together with this.
After mixing with E powder in a pot for about 12 hours and molding at 2 tons/c/l, the mixture is sintered in hydrogen at 900°C for 4 hours. A required amount of Cu is infiltrated into the remaining pores of the skeleton in hydrogen at 1120° C. to obtain a contact material. Or Cu powder and Zr1 corresponding to the entire amount of Cu required
The mixture is mixed with Te powder for about 12 hours, molded at 4 tons/cd, and then sintered in hydrogen at 950°C to obtain a contact material.

Second, Qu-ZrYTe-refractory material (W, MO.

Ta, Nb, Zr, Ti, Cr) and their carbides,
Production of contact material of any one of borides: approx. 10
After mixing and molding the unit material powder of 0 mesh and ZnTe powder, a skeleton is obtained by sintering. Next, the remaining pores in the skeleton are infiltrated with CU to obtain a contact material.

Thirdly, manufacture of Cu-ZnTe-Fe (Co) contact material: After about 100 meshes of powder of either Fe or CO and ZnTe powder are mixed and molded, a skeleton is obtained by sintering. Next, the remaining pores in the skeleton are infiltrated with Cu to obtain a contact material.

As described above, auxiliary materials (ZnTe: W, M
Contact alloys containing refractory materials such as O, Ta, Nb, Zr, Ti, Or, etc. are manufactured.

Next, each of the contact alloys manufactured above will be considered, and the best content ratio will be determined.

At present, AO-70%WC and Cu-15%3i, shown as comparative materials 2 and 3, are contact alloys with low current properties.
Alloys are in practical use. This is pure CLJ (comparative material-1
), the current carrying property is improved compared to Cu-3i series (
Comparative material-3) has characteristics (
(increase in cutting current value) deteriorates significantly.

On the other hand, in the Cu-2nTe system, the amount of ZnTe is 0°12% (
In comparative material-4), the current property shows a quantity characteristic, and Z
The amount of nTe is required to be at least 0.5% (Example material-1) and at most 20% (Example material-3). In this range, both the average value and the maximum value of the current cutoff value are low and stable. If the amount of ZnTe exceeds 30%, it has no effect on the current breaking property, but at a voltage of 7.2 kV, the breaking property deteriorates significantly (Comparative Example 5).

Therefore, when the ZnTe content is in the range of 0.5 to 20%,
Even when compared with the change in the properties of the Aq-70WC system, the degree of deterioration is slight, making it sufficiently practical and the best. Therefore, the amount of ZnTe is set in the range of 0.5 to 20%.

The above applies not only to the Cu-ZnTe pseudo-binary system, but also to Cu and refractory materials (W, MO, Ta).

Nb, Zr, Ti, Cr)
Similar effects were obtained even when nTe was present. This becomes clear when comparing Example Materials-5 to 19 and Comparative Materials-6 to 9.

Furthermore, since the conductive material is limited to Cu (Example material-4,
As shown in 16 and 17, even if it is AQ, Cu and AQ
Similar effects can be obtained even when coexisting with

In addition, as shown in Example Material-20, T was added to the Cu matrix.
When ZLI was present in the Cu matrix as shown in Example Material-21, the same effect was obtained. In this case, the matrix Zu or Te
(Actually, Cu2Te> exists because when ZnTe, which is the material of the present invention, slightly deviates from the ideal state containing 66% Te to Zu rich or Te rich, the remaining ZLJ or Te and Cu This phenomenon is usually recognized in industrial manufacturing considering economic efficiency, but the range should be controlled to about 2% or less for contact materials. The presence of the above is undesirable in the bonding process and should be avoided.

As mentioned above, the biggest feature of contacts containing znTe is not only that they exhibit low current breaking properties, but also that there is little variation (increase in breaking current value) after opening and closing a predetermined number of times. , this characteristic can be obtained with almost no reduction in blocking performance. The reason for this is thought to be that, as mentioned above, baking or limited brazing causes little change such as decomposition, movement, or agglomeration in response to the heat received in the process. Therefore, the aforementioned ZnTe! The remaining Zn or Te, which is about 2% deviated from (66% Te), may be consumed due to evaporation mainly due to arc heat due to current switching or current interruption. Therefore, the larger this amount is, the larger the fluctuation width of the current cutoff value or cutoff characteristics with respect to the number of openings and closings becomes, which is undesirable.
It is best to control using % as a guide.

The evaluation conditions are as follows. Cutting current: The cutting current values in the table are the voltage drop of a coaxial shunt inserted in series with the contact under test, observed using a synchroscope. In other words, an AC current of an effective value of 44 A was applied through 10 circuits, and the average value of the cutting current value and other values were determined in 500 experiments. The sample is then subjected to baking and discharge aging before being measured. If aging is insufficient, the cutoff value increases with the number of measurements, so heat and discharge are sufficient.

The sample shape is 20 m in diameter and 4 m in thickness, one side is flat, the other side is 20JIIR, and the contact pressure is 10 kg.

Shutdown evaluation: 7.2kv50Hz after being assembled into an experimental valve for shutoff testing with a diameter of 20ai and facing a cap of 2.54111, and subjected to baking, voltage aging, etc.
The cutoff limit was comparatively evaluated while increasing the current by IKA.

As described above, in the above embodiment, copper or a conductive material containing zinc or a refractory material, silver, etc. in copper, and a conductive material that is stable against heat treatment and that improves vapor pressure and heat conduction between the contacts of the vacuum valve are used. Since the contact material contains the auxiliary material zinc chillite, which is easy to supply, it has the following effects. In other words, there is little deterioration due to heat received during the manufacture of contact alloys, baking, silver brazing, etc. of vacuum valves, and stable current cutting performance can be obtained. Furthermore, the characteristics of conventional contact materials can be sufficiently maintained in terms of cut-off performance. Therefore, if the contact material of the present invention is used for a vacuum valve contact, a vacuum valve with good current cut-off properties and good cut-off properties can be obtained.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide a contact alloy for a vacuum valve that further improves the stability of current cutoff.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a vacuum valve to which an embodiment of the vacuum valve contact alloy of the present invention is applied, and FIG. 2 is an enlarged block diagram of the electrode portion of the vacuum valve shown in FIG. DESCRIPTION OF SYMBOLS 1... Yarn disconnection, 2... Insulating container, 5, 6... Conductive rod, 13a, 13b... Contact.

Claims (6)

[Claims] (1) consisting of an electrically conductive material and an auxiliary material that is diffused in this electrically conductive material in a predetermined proportion, is stable to heat treatment, and is simple for supplying vapor pressure and heat conduction between the contacts of the vacuum valve; A vacuum valve contact alloy characterized by improved breaking current characteristics. (2) The contact alloy for a vacuum valve according to claim (1), wherein the auxiliary material is zinc telluride in a weight proportion of 0.5 to 20%. (3) The auxiliary material is zinc telluride with a weight percentage of about 66%, and the conductive material is copper, a copper solid solution containing zinc with a weight percentage of less than 2%, or a copper alloy containing a copper-telluride compound with a weight percentage of less than 2%. A contact alloy for a vacuum valve according to claim (1), which is any one of these. (4) The auxiliary material is zinc telluride with a weight percentage of about 66%, and the conductive material is made of copper and one of the refractory materials selected from tungsten, molybdenum, tantalum, niubilam, zirconium, titanium, chromium carbides and borides. A contact alloy for a vacuum valve according to claim (1). (5) The auxiliary material is zinc telluride with a weight percentage of about 66%, and the conductive material is a fireproof material consisting of either iron or cobalt and copper or a copper solid solution containing zinc with a weight percentage of less than 2% or a weight percentage of 2%. A contact alloy for a vacuum valve according to claim 1, comprising any one of copper alloys containing less than or equal to 10% of a copper-terrell compound. (6) A contact alloy for a vacuum valve according to claim (1), wherein the conductive material contains copper and silver in a predetermined ratio, or is silver.