JPH0119205B2 - - 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, etc. become smaller and their switching capacity increases, wear and welding of contacts increases. In order to counter this, it is necessary to increase the volume of the contact point or increase the separation force. However, this would make the equipment too large and would no longer meet its initial purpose. 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 has been satisfactory. Conventionally, contacts made of silver-oxide, in which metal oxide is dispersed in silver, have been used for combination electrical contacts, and among these, combination electrical contacts, in which contacts made of silver-tin oxide-indium oxide are placed facing each other, are highly concentrated. It has superior wear resistance compared to a combination electrical contact made of silver and nickel, which has contacts facing each other, but tin oxide and indium oxide in silver-tin oxide-indium oxide are deposited on the contact surface each time the contact is closed. As it aggregates, the welding resistance becomes unstable and the welding force increases when welded. In addition, in the case of a combination electrical contact in which contacts made of high concentration silver and nickel face each other, they have some degree of adhesion resistance due to the thermally stable effect of nickel, but since the nickel oxidizes during opening and closing, the contact resistance becomes higher, and the welding force when welding increases. As described above, in the conventional combination electric contact, the same electric contact material was used for the opposing fixed contact and movable contact, which caused problems such as increased welding force when welded. Therefore, as a result of intensive research to develop a combination electrical contact with excellent welding resistance even in miniaturized breakers, magnetic switches, etc., the inventors of the present invention have found that a fixed contact and a movable contact facing each other have a fixed contact and a movable contact. It has been found that welding resistance can be improved by using different contact materials. The present invention has been made with attention to this point, and uses a silver-tin oxide-indium oxide type contact as a combination electrical contact that can reliably improve welding resistance even if it sacrifices wear resistance to some extent. It is an object of the present invention to provide a combination electrical contact formed by opposing highly concentrated silver-nickel contacts. The combination electrical contact according to the present invention has a tin content of 2% by weight (hereinafter referred to as "w/o") in opposing contacts.
A silver-tin oxide-indium oxide system contact consisting of 15 w/o, indium 1 w/o to 7 w/o and the balance silver, and a high concentration silver-nickel system consisting of nickel exceeding 20 w/o and 50 w/o or less and the balance silver. This is characterized by the use of contacts. In the combination electrical contact of the present invention, the reason why the materials for the opposing contacts are limited as described above is that by taking advantage of the ease of wear of the high-concentration silver-nickel system, even when a large current is applied to the small contact, This is to obtain a combination electrical contact that requires fewer welding times and has a lower welding force. In addition, the reason why the content of tin in the silver-tin oxide-indium oxide system was limited to 2w/o to 15w/o is that if it is less than 2w/o, the wear resistance when combined with a high concentration silver-nickel electrical contact is This is insufficient, and if it exceeds 15 w/o, the amount of tin oxide that aggregates on the contact surface will increase, resulting in increased contact resistance and increased welding force when welded. The reason why the indium content is limited to 1 w/o to 7 w/o is that if it is less than 1 w/o, internal oxidation of tin is difficult, and if it exceeds 7 w/o, tin oxide tends to aggregate. The content of nickel in the silver-nickel system is 20w/o.
The reason for setting it above 50w/o is that below 20w/o, it is not possible to compensate for the adhesion resistance of the silver-tin oxide-indium oxide system, and when it exceeds 50w/o, a thick film of nickel oxide forms on the surface. This is because contact resistance becomes extremely poor. Next, in order to clarify the effects of the combined electrical contact according to the present invention, specific examples and conventional examples thereof will be described. Example 1 5 mm diameter made of silver-tin oxide-indium oxide with 8 w/o tin, 3 w/o indium and the balance silver
Fixed contacts, nickel 40w/o and balance silver -
A movable contact made of nickel and having a diameter of 5 mm was placed facing each other to form a combination electric contact. Example 2 A fixed contact with a diameter of 5 mm made of silver-tin oxide-idium oxide with 6 w/o tin, 2 w/o indium and the balance silver, and a fixed contact with a diameter of 5 mm made of nickel 25 w/o and the balance silver.
A movable contact made of nickel and having a diameter of 5 mm was placed facing each other to form a combination electric contact. Conventional example 1 5 mm diameter made of silver-tin oxide-indium oxide with 8 w/o tin, 3 w/o indium, and the balance silver.
A fixed contact and a movable contact with a diameter of 5 mm were made to face each other to form a combination electric contact. Conventional Example 2 A fixed contact of 5 φ mm and a movable contact of 5 φ mm made of nickel 10 w/o and silver-nickel with the balance being silver were made to face each other to form a combination electric contact. Comparative Example 1 5 mm diameter made of silver-tin oxide-indium oxide with 8 w/o tin, 3 w/o indium and the balance silver
A fixed contact and a flexible contact of 5 mm in diameter made of nickel 10 w/o and silver-nickel with the balance being silver were placed opposite each other to form a combination electrical contact. However, when each of these combinations of electrical contacts was subjected to a welding resistance test under the following test conditions, the results shown in the right column of the table below were obtained. Welding resistance test conditions A C 100V 50Hz Current 2230A Number of openings and closings 20 times Open-close-close repetitions Opening and closing frequency 1 time/2 minutes Contact force 500g Breaking force 150g

[Table] As is clear from the table above, the combination electrical contact of the present invention, in which a silver-tin oxide-indium oxide contact and a highly concentrated silver-nickel contact are placed opposite each other, is said to have good welding resistance. It has better welding resistance than the conventional combination electrical contacts in which silver-nickel contacts are opposed to each other, and the welding force when welded is also lower. Furthermore, compared to the electrical contact combination of Comparative Example 1, in which a similar combination of low-concentration silver-nickel-based contacts and silver-tin oxide-indium oxide contacts were made to face each other,
Welding force is low when welding in high current no fuse breaker test. The silver-tin oxide-indium oxide used in the present invention is produced by an internal oxidation method, a powder metallurgy method, a combination of an internal oxidation method and a powder metallurgy method, etc., and the metal oxide is finely dispersed in silver. It is good as long as it is true. As detailed above, the combination electrical contact of the present invention is
It has exceptional adhesion resistance, so even when used in miniaturized breakers, magnetic switches, etc., and the amount of current flowing per unit area increases,
It has the effect of suppressing the occurrence of welding, requiring only a low welding force, and improving the reliability and life of equipment.

Claims (1)

[Claims] 1 Silver - tin oxide - consisting of 2% to 15% by weight of tin, 1% to 7% by weight of indium, and the balance silver
A combination electrical contact consisting of an indium oxide-based contact and a silver-nickel-based contact consisting of more than 20% by weight but not more than 50% by weight of nickel, and the balance being silver, facing each other.