JPS6034765B2 - current switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a current switch, particularly a current switch suitable for switching medium current.

In a current switch comprising opposing electrical contacts,
For example, as a current switch for switching medium current of about 20 to 100A, Ag, Ag-Cd○, Ag-ln203, A
Products equipped with electrical contacts (both poles made of the same material), such as g-S publication 02, are in practical use.

However, when using Ag contacts, the contact resistance is extremely low and the hardness is small, so while it has advantages such as less chattering during insertion, it has the disadvantage of poor wear resistance and resistance to settling. On the other hand, Ag/Cd contacts have the advantage of being applicable to current fields that cannot be covered by Ag contacts, but they are prone to welding and wear and tear and are inferior in durability. Also Ag-
Although Sn02 and Ag-ln203 contacts have excellent wear resistance, they have the disadvantage that they cannot sufficiently withstand harsh usage conditions such as increased frequency of use. Furthermore, combinations of contacts have been attempted, such as configuring one contact with a C-Cu type and the other with a Cu type as a current switch for use in elevators, car steel, etc.

In this case, the phenomenon of low wettability between C element and other metals is used to reduce or suppress the welding phenomenon, but on the other hand, it is subject to heavy wear and has a poor lifespan. Defects are recognized. Therefore, the present invention aims to provide a current switch that has low contact resistance, excellent welding resistance and wear resistance, maintains and exhibits the required performance over a long period of time, and is particularly suitable for switching medium currents. It is something.

The present invention will be described in detail below. The present invention provides a current switch equipped with opposing electrical contacts, in which at least the contact surface of one of the opposing electrical contacts is coated with 2 to 1% by weight of Sn0.
2, any one or more of ln203 (however, Sn02
In the case of mountain 03, the current switch is made of an Ag alloy containing 2 to 14% by weight), and the other electrical contact facing each other is made of an Ag alloy containing 5 to 15% by weight of Cd○. It is a vessel.

The attached figure is a sectional view showing an example of the structure of the current switch according to the present invention, in which a movable alloy 1 forming a part of the current path is connected to a movable birch 2.

Furthermore, the movable alloy 1 and the movable rod 2 are connected to a contact spring 3.
When no external force is applied, the movable alloy 1 is always biased in one direction 4 by the contact spring 3. moreover,
Fixed contacts 7a and 7b are provided at both ends of the movable alloy 1 so as to face movable contacts 6a and 6b provided at the ends of the conductive pieces 5a and 5b connected to an external electric circuit.

Then, in the movable birch 2, a current is applied to the excitation coil 11 and the iron cores 12a, 12b are attracted, thereby bringing the movable bush points 6a, 6b into contact with the fixed contacts 7a, 7b and turning on the electric contact device. It works like this. A contact leaf spring 8 is disposed on the movable contact side to absorb the dynamic movement that occurs when the movable contact 6a and the fixed contact 7a and the movable contact 6b and the fixed contact 7b come into contact with each other, and extinguish the arc that occurs between the two contacts. A grid 9 for this purpose is attached to the main body.

In the attached diagram, one of the electric contacts facing each other, for example, the movable contacts 6a and 6b, has a diameter of 5 willow and a thickness of 2 to 10% S.
Made of n02-Ag alloy or 2~10%ln203-A
It is a disc made of g-alloy. In addition, the other electrical contacts facing each other, for example, fixed contacts 7a and 7b, are made of 5.5 willow diameter and 1 rib thick.
~15%Cd○-Ag alloy disc. However, in the above, Sn02-Ag type or 1-03-Ag type S
The composition ratio of n02 or 1 payment 03 is 2 when each is used alone.
~1% by weight. The reason for this is that if it is less than 2%, the welding resistance will be impaired or the effect of improving wear resistance will be insufficient, and if it exceeds 10%, the contact resistance will increase and the desired effects will not be obtained. However, when Sn02 and Sn03 are used in combination, the total content can range from 2 to 14%, and it is sufficient that this alloy does not constitute the entire contact, but at least the contact surface. On the other hand, Cd
This is because if the composition ratio of CdO in the O-Ag system is less than 5%, welding marks tend to occur, and if it exceeds 15%, cracks may occur during contact forming, and the desired effect cannot be obtained in the end. As described above, in the current switch according to the present invention, the opposing electrical contacts are made of a combination of different types of Ag alloys, and in particular, Ag alloys containing Sn02 and ln203 are used.
Alloy contact material is installed on the polar side which shows weight loss due to current switching.

Thus, Ag-Sn02, Ag-1 uniform 03, Ag-Sn
By taking advantage of the advantages of each Ag alloy, 02-11 Yama 03 and Ag-Cd○, it has achieved excellent contact performance such as welding resistance, wear resistance, and low contact resistance characteristics, and has achieved the required properties as a current switch. It will continue to function for a long time. Next, examples of the present invention will be described.

After alloying Ag, Cd, Sn and ln in a predetermined composition ratio, it was formed and heated to 700 oo in an oxygen atmosphere of 4 atm.
for 4 days (Ag-Cd system) or 8 days (Ag-Sn,
Ag-Sn-ln system) firing, internal oxidation (Cd, Sn, l
(n is oxidation) to prepare electrical contacts having the composition ratios and shapes shown in Table 1.

Among the electrical contacts obtained in this way, the Ag-Cd○ system was used as a fixed contact, and the Ag-Sn02, Ag-ln203, and Ag
- Amount of wear and tear on each electrical contact when the Sn02-ln203 system is installed as a movable contact in an open electromagnetic switch and opened and closed 5×1 times at 200 V AC, 20 A, and a power factor of 0.8 (female ) are also shown in Table 1. Table I As is clear from Table 1, in the case of the current switch according to the present invention, the amount of wear on the contacts is small, and the amount of wear on the movable contacts and the fixed contacts is about the same, which is advantageous in terms of reliability.

On the other hand, the current switch with the above configuration was tested for welding resistance using an ASTM contact tester under the following conditions: opening force 100 mm, contact force 100 mm, and AC 200 V x 70 A. The results are shown in Table 2. .

Table 2 In the above embodiment, the fixed side contact is set to the Ag-Cd0 system, but the opposite may be used.

In other words, the Ag-Sn02 system is used on the side where the electrical contact wears out more due to operation, which is affected by the structure of the switch, heat capacity, etc.
Ag-ln203 series or Ag-Sn02-1 pay 03
Just set the system.

[Brief explanation of the drawing]

The drawing is a sectional view showing a configuration example of an electromagnetic switch according to the present invention. 1...Movable alloy, 2...Movable camphor, 3...
... Contact spring, 5a, 5b... Conductive piece, 6
a, 6b...Movable contact, 7a, 7b...
・Fixed contact, 8... Contact plate spring, 9... Arc extinguishing grid, 11... Excitation coil, 12a,
12b... Iron core.

Claims (1)

[Claims] 1 In a current switch with opposing electrical contacts,
At least 2 to 10 contact surfaces of one electrical contact facing each other
Any one or more of SnO_2, In_2O_3 in weight% (however, 2<SnO_2+In_2O_3<14% by weight)
), and the other opposing electrical contacts are each made of an Ag alloy containing 5 to 15% by weight of CdO.