JPH0119608B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to improvements in combination electrical contacts. Recently, with the development of electrical and electronic technology, various electrical
As electronic devices have become smaller, breakers, magnetic switches, etc. have also become smaller. However, as breakers, magnetic switches, and the like become smaller, it becomes difficult to maintain creepage distances and insulation distances for the devices. In other words, a problem arises in that the insulation resistance and withstand voltage decrease due to wear and tear of the contacts.
In addition, the contact force and opening force of electrical contacts are reduced,
There is a problem that welding easily occurs. For this reason, there is a demand for a combination electrical contact that has good wear resistance and excellent welding resistance, and various combination electrical contacts have been developed, but so far none have been satisfactory. Conventionally, combined electrical contacts have used contacts made of silver-metal oxide, in which metal oxides are dispersed in silver, and among these, combined electrical contacts in which contacts made of silver-antimony oxide are placed facing each other have excellent welding resistance. It has been frequently used for. However, it requires a lot of wear and tear, resulting in insulation deterioration, so it has not been applied particularly to small relays. On the other hand, silver - nickel -
Although tungsten carbide contacts wear uniformly and have little wear and tear resistance, they suffer from variations in welding resistance that are typical of silver-nickel contacts, making them unsuitable for small relays that cannot handle large opening forces. In this way, conventional combination electrical contacts use electrical contact materials with the same properties for the opposing fixed and movable contacts, so they have good welding resistance but poor abrasion resistance, or conversely, Although the properties were good, there were problems such as poor welding resistance. Therefore, the inventors of the present invention have conducted intensive research in order to develop a combination electrical contact that has good wear resistance, does not deteriorate insulation resistance, and has excellent welding resistance even in miniaturized breakers, magnetic switches, etc. As a result, it has been found that welding resistance and wear resistance can be improved by using contact materials with different wear resistance for the fixed contact and movable contact that face each other. The present invention has been made with attention to this point, and uses a silver-antimony contact and a silver-nickel-tungsten carbide or tungsten contact as a combination electrical contact that can reliably improve welding resistance and wear resistance. It is an object of the present invention to provide a combination electrical contact that is opposed to each other. The combined electrical contact according to the present invention has a silver-antimony oxide contact consisting of 5 to 12 weight % antimony and the balance silver, and one or two of 10 to 60 weight % nickel, tungsten, or tungsten carbide, as an alloy composition ratio before oxidation. It is made by facing a silver-nickel type contact consisting of a total of 0.5 to 5% by weight of seeds and the balance being silver. The reason for limiting the materials of the opposing contacts as described above in the combination electrical contact of the present invention is that
In order to take advantage of the excellent welding resistance of antimony oxide, tungsten or tungsten carbide is added to the silver-nickel alloy to create a combination electrical contact in which contacts made of the same or similar materials are placed opposite each other. This is to eliminate poor insulation resistance characteristics that depend on poor welding resistance or wear resistance. In addition, the content of antimony in the silver-antimony oxide system was set to 5 to 12% by weight (hereinafter abbreviated as "w/o") because less than 5w/o would result in insufficient adhesion resistance. This is because if it exceeds this, there will be no problem with welding resistance, but the amount of wear will be extremely large. The content of silver-nickel based nickel is 10~
The reason why it is limited to 60 w/o is that if it is less than 10 w/o, the wear resistance is insufficient, and if it exceeds 60 w/o, the contact resistance becomes extremely unstable. In addition, one or both of tungsten and tungsten carbide can be used in total.
The addition of 0.5 to 5 w/o is not only to prevent the agglomeration of nickel particles in the silver-nickel alloy, but also to prevent tungsten carbide and tungsten from being oxidized and become tungsten oxide during wear due to the arc during contact opening/closing operations. This is because surface wettability with antimony oxide contacts is improved, and welding resistance is improved. Next, in order to clarify the effects of the combined electrical contact according to the present invention, specific embodiments and conventional examples thereof will be described. Example 1 Diameter 5mm made of silver-antimony oxide 12w/o
An electric contact was constructed by combining a fixed contact with a movable contact having a diameter of 4 mm made of silver-nickel-tungsten carbide containing 25 w/o of nickel and 2.5 w/o of tungsten carbide and facing each other. Example 2 Silver-antimony oxide 11w/o-bismuth oxide
A fixed contact with a diameter of 5 mm made of 0.5 w/o and a movable contact with a diameter of 4 mm made of nickel 15 w/o - tungsten carbide 1 w/o, silver containing tungsten 0.5 w/o, nickel - tungsten carbide - tungsten are placed opposite each other. A combined electrical contact was constructed. Conventional example 1 Diameter 5mm made of silver-antimony oxide 12w/o
An electric contact was constructed by combining a fixed contact with a diameter of 4 mm and a movable contact with a diameter of 4 mm facing each other. Conventional example 2 Nickel 15w/o, tungsten carbide 1.5w/o
An electric contact was constructed by combining a fixed contact with a diameter of 5 mm and a movable contact with a diameter of 4 mm, which were made of silver-nickel-tungsten carbide containing 100% nickel and tungsten carbide, facing each other. When nine sets of each of these combinations of electrical contacts were measured for welding frequency, insulation resistance, and amount of wear under the following test conditions, the results shown in the table below were obtained. Welding resistance test conditions ΓAC100V 50Hz ΓCurrent: Closing current 40A Breaking current 10A ΓSwitching frequency: 20 times/min ΓContact force: 40g Breaking force: 40g Insulation resistance measurement ΓDC500V by megger.

[Table] As is clear from the table above, the combined electrical contacts of the present invention, in which a silver-antimony oxide contact and a silver-nickel-tungsten carbide (tungsten) contact are opposed to each other, are used in combination with each other. It is an electrical contact that has an excellent combination of welding resistance and abrasion resistance, which complement each other's shortcomings and enhance its strengths. By using the combination contact of the present invention, it is possible to fully cope with the severe usage conditions of miniaturized breakers, magnetic switches, relays, etc.

Claims (1)

[Claims] 1 As the alloy composition ratio before oxidation, antimony 5~
A silver-antimony oxide contact consisting of 12% by weight and the balance being silver, 10 to 60% by weight of nickel, and one or two of tungsten or tungsten carbide for a total of 0.5%.
A combination electrical contact consisting of a silver-nickel type contact consisting of ~5% by weight and the balance being silver, facing each other.