JPH0612649B2 - Contact material for vacuum circuit breaker - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a contact material for a vacuum circuit breaker, which has excellent large-current breaking performance and good withstand voltage performance.

The vacuum circuit breaker has advantages such as no maintenance, no pollution, and excellent breaking performance, so that its application range is rapidly expanding. Along with this, larger breaking capacity and higher withstand voltage are required. On the other hand, the performance of the vacuum circuit breaker is extremely dependent on the contact material in the vacuum container.

As the satisfactory characteristics of contact materials for vacuum circuit breakers, (1)
Large breaking capacity, (2) High withstand voltage, (3) Small contact resistance, (4) Small welding force, (5) Small contact consumption, (6) Breaking current value Is small,
(7) Good workability, (8) sufficient mechanical strength, etc.

In an actual contact material, it is quite difficult to satisfy all of these properties, and in general, it is necessary to use a material in which the other properties are sacrificed to some extent while satisfying particularly important properties depending on the application. It is the actual situation.

Conventionally, copper-bismuth (hereinafter Cu-
Display as Bi. Materials that consist of other elements and combinations of elements are also indicated by the element symbol), Cu-Cr-B
i, Cu-Co-Bi, Cu-Cr, etc. were used. But C
In an alloy contact containing a low melting point metal such as u-Bi, part of it diffuses and evaporates from the contact due to high temperature heating during the exhaust process, and adheres to the metal shield or insulating container in the vacuum container.
This is one of the major factors that deteriorate the withstand voltage of the vacuum circuit breaker. Also, when the load is opened or closed or a large current is cut off, the low-melting-point metal is vaporized and scattered to deteriorate the withstand voltage and the cut-off performance is deteriorated. Even in Cu-Cr-Bi, etc. added with Cr, Co, etc., which has excellent vacuum withstand voltage to eliminate the above-mentioned drawbacks, the above-mentioned drawbacks due to the low melting point metal are not fundamentally solved, and high voltage, large current I can not cope. On the other hand, Cu-Cr
Materials such as the combination of metals with excellent vacuum withstand voltage (Cr, Co, etc.) and Cu with excellent electrical conductivity are superior to the contact materials containing low melting point metal in terms of welding resistance. Although somewhat inferior, it is often used in high voltage and high current regions because of its excellent cutoff performance and withstand voltage performance. Furthermore, even with Cu-Cr alloys, since the breaking performance is limited, the contact shape is devised and the current path of the contact is manipulated to generate a magnetic field, forcing a large current arc. There was an effort to drive and improve the cutting performance.

However, demands for higher current and higher voltage are more severe, and it is difficult for conventional contact materials to sufficiently satisfy the required performance. Further, as for the downsizing of the vacuum breaker, similarly, the conventional contact performance is not sufficient, and a contact material having higher performance has been demanded.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional ones, and provides a contact material for a vacuum breaker which is excellent in large-current interruption performance, and has good withstand voltage, welding resistance and workability. Is intended.

We prototyped contact materials in which various metals, alloys, and intermetallic compounds were added to Cu, and incorporated them in a vacuum switch tube for various experiments. As a result, contact materials in which Cu, Cr, and Al are distributed as elemental metals, tripartite or bipartite alloys, tripartite or bipartite intermetallic compounds, or composites thereof have very good blocking performance. It was found that the withstand voltage performance was good. The contact material for a vacuum circuit breaker of the present invention contains Cu as a main component and Cr as another component of 20 to 30% by weight.
And Al is contained in a range of 3% by weight or less.

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 is a structural diagram of the vacuum switch tube, vacuum insulation container (1)
And the electrodes (4) and (5) inside the container formed by the end plates (2) and (3) closing both ends of the vacuum insulation container (1).
Are arranged at one end of each of the electromagnetic rods (6) and (7) so as to face each other. The electromagnetic (7) is a bellows.
It is joined to the end plate (3) via the (8) so that the end plate (3) can move in the axial direction without impairing the airtightness. The shields (9) and (10) respectively cover the inner surface of the vacuum insulating container (1) and the bellows (8) so that they are not contaminated by vapor generated by the arc. The electromagnetic field (5) is brazed on its rear surface by inserting a brazing material (51) on the electromagnetic bar (7).
The electrodes (4) and (5) are made of the Cu-Cr-Al-based contact material of the present invention.

Fig. 3 shows the relationship between the amount of Al added to the alloy with Cr content of 15, 20, 25, 30 and 35 wt% and the breaking capacity, and the range of Al content of 3 wt% or less. When the Cr content is 30% by weight or less, the cutting performance is close to that of the conventional product or higher than that of the conventional product, and the Al content is 1.
It can be seen that when the Cr content is 3% by weight and the Cr content is 30% or less, the breaking performance is remarkably increased as compared with the conventional product (Cu-25% by weight Cr alloy).

The amount of Al added shows a peak in the range of 1% by weight or less, and when the amount of Al added is further increased, the blocking capacity decreases again. If the Al content exceeds 3% by weight,
The cutting performance is lower than that of the conventional product (Cu-25 wt% Cr product).

That is, Cr and Al coexist in Cu, and only a small amount of Cu, Cr, Al
2) or 3) alloys and intermetallic compounds are formed and distributed in Cu, the blocking performance is increased due to their interaction, and when Al is increased beyond a certain level, the compound of Cu and Al The electrical conductivity and thermal conductivity of the Cu matrix are significantly reduced due to such a large amount of heat generation, making it difficult to quickly dissipate the heat input by the arc, and local melting tends to occur and the arc is sustained. It seems that this is because the cutting performance is deteriorated.

When a large current is used or gas is used for downsizing of equipment, the cutting capacity is more than 1.3 times that of the conventional product (Cu-25 wt% Cr alloy), Cr 25% and Al 1.3 wt% or less. Is most preferable, but the Cr content is 30% by weight or less, Al
Those having a content of 3% by weight or less are sufficiently usable in terms of blocking capacity. The Cu-Cr-Al alloy used in this experiment is
It is obtained by molding and sintering a mixed powder in which Cu powder, Cr powder and Al powder are mixed in necessary amounts. The vertical axis of FIG. 3 represents the ratio with the value of the breaking capacity of the conventional Cu-25 wt% Cr alloy being 1, and the horizontal axis represents the amount of Al added.

Similarly, FIG. 4 shows the relationship between the amount of Al added and the electrical conductivity. As is clear from the figure, the electrical conductivity decreases as the Al content increases, and when the Al content is 1% by weight or more, the electrical conductivity becomes half that of the conventional product. This is due to the increase in compounds formed by Cu and Al. Further, the contact resistance increases as the electric conductivity decreases, which may adversely affect the energization and temperature rise after the switching of the load. Therefore, the amount of Al is 1.
A range of 3% by weight or less is more desirable. The vertical axis of FIG. 4 shows the ratio with the electric conductivity of the conventional product (Cu-25 wt% Cr alloy) as 1, and the horizontal axis shows the amount of Al added.

Similarly, FIG. 5 shows the relationship between the Al addition amount (A) and the withstand voltage (B) performance. As is clear from the figure, when the Cr content is 25% by weight, the hardness of Al is increased to 0.5% by weight, and the hardness is increased abruptly.
This is because the compound consisting of Al and Cu consists of an intermetallic compound having a very high hardness. On the other hand, the withstand voltage performance is superior to the conventional product when the Cr content is 25% by weight and the Al content is in the range of 3% by weight or less, and is inferior to the conventional product when it exceeds 3% by weight. After that, the withstand voltage tends to increase as the Al content increases. Thus, the relationship between hardness and withstand voltage
When the amount of Al is 3% by weight or less, it is non-linear, and when the amount of Al is 3% by weight or more, there seems to be a correlation between pressure resistance and hardness. From the viewpoint of hardness (A), withstand voltage (B) performance, etc. as described above, it is recognized that the Al content is 3% by weight or less in terms of electrical characteristics and workability, and is suitable as a contact material for circuit breakers. It was The vertical axis of FIG. 5 shows the ratio of the hardness and withstand voltage of the conventional product (Cu-25 wt% Cr alloy) to 1, and the horizontal axis shows the amount of Al added.

The inventors have also conducted experiments on alloys in which the amount of added Al and the withstand voltage are variously changed, as shown in FIG. 5, but when the amount of Cr is less than 20% by weight, the withstand voltage is unsatisfactory. Was enough. Further, although not shown, the welding resistance was also insufficient. Therefore, from the results of the breaking performance shown in FIG. 3 and the results of the withstand voltage shown in FIG. 5, it is appropriate that the Cr content be in the range of 20 to 30% by weight.

In addition, although not shown, Bi, Te, Sb, Tl, Pb,
At least one of low melting point metals such as Se, Ce and Ca, alloys thereof, intermetallic compounds thereof, and oxides thereof.
It has been confirmed that even in the case of a low breaking vacuum contactor for a vacuum breaker containing 20% by weight or less of a seed, there is an effect of increasing the breaking performance and the withstanding voltage performance as in the above-mentioned embodiment.

When 20% by weight or more of at least one of low melting point metals, their alloys, their intermetallic compounds, and their oxides was added, the breaking performance was remarkably reduced. Further, when the low melting point metal is Ce or Ca, the characteristics are slightly inferior.

As described above, according to the present invention, copper is contained as a main component, and chromium as another component is contained in a range of 20 to 30% by weight and aluminum in a range of 3% by weight or less. In addition, there is an effect that a contact material for a vacuum circuit breaker which is excellent in breaking performance and excellent in withstand voltage, welding resistance and workability can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a general vacuum switch tube,
FIG. 2 is an enlarged sectional view of the electrode portion of FIG. FIG. 3 shows the amount of Cr in the contact material of the present invention of 15,2.
Fig. 4 is a characteristic diagram showing the change in the breaking capacity when changing the amount of Al added to the alloys of 0, 25, 30 and 35% by weight. Fig. 4 shows that the Cr content in the contact material of the present invention is fixed at 25% by weight. Fig. 5 is a characteristic diagram showing the change in electrical conductivity when changing the amount of Al added to the alloys shown in Fig. 5. Fig. 5 shows the amount of Al added to the alloy in which the Cr amount in the contact material of the present invention is fixed at 25% The hardness and the amount of Cr when changing
It is a characteristic view which shows change of withstand voltage performance when changing the amount of Al additions with respect to 5, 30 and 35 weight% alloy. (1) ... vacuum insulation container, (2), (3) ... end plate, (4), (5) ... electrode, (6), (7) ... electrode rod, (8) ... bellows, (9), (10) ... shield, (51) ... brazing material

Claims (3)

[Claims] 1. A main component is copper, and chromium is another component.
A contact material for a vacuum circuit breaker, which contains 20 to 30% by weight of aluminum and 3% by weight or less of aluminum. 2. A contact material for a vacuum circuit breaker according to claim 1, wherein the aluminum content is 1.3 wt% or less. 3. A patent characterized in that copper, chromium, and aluminum are distributed as a single metal, a tripartite or bipartite alloy, a tripartite or bipartite intermetallic compound, or a complex thereof. The contact material for a vacuum breaker according to claim 1 or 2.