JP2000076948A - Electrical contactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit the wear of a contactor by ensuring superior breaking characteristic during the breaking of a circuit and during the opening and closing of a rated load and stably maintain contact characteristics such as temperature rise for a long period by ensuring a good fusion characteristic. SOLUTION: In an electrical contactor for use in a circuit breaker or electric switch, a contact portion where an arc is generated during the making and breaking of a circuit is used as a first contact area 7, which is composed of both a material composed chiefly of an arc-resistant component, having high melting point and being high in arc resistance and a material made of a conducting component high in electrical conductivity. The portion of the electrical contactor that normally carries current after making the circuit is used as a second contact area 8, which is composed of both a material composed chiefly of a conducting component high in electrical conductivity and a material made of an arc-resistant component which is high in arc resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact of a circuit breaker or an electric switch for performing overload interruption or overload switching and energization, and more particularly to an electric contact having an improved structure made of contact materials.

[0002]

2. Description of the Related Art In addition to breaking characteristics, electrical contacts used in circuit breakers, electric switches, and the like are regarded as important in terms of contact resistance characteristics, welding resistance, and wear resistance. Such an electric contact comprises a movable contact A and a fixed contact B as shown in FIG.
Is a base metal 1 made of copper or copper alloy having good electric conductivity.
The contacts 3 and 4 are fixed to each other by silver brazing or pressure contact with each other. In this case, the movable contact A
The contact surface of the contact 3 on the side is formed as an arc surface having a constant curvature R, and the contact surface of the contact 4 on the side of the fixed contact B is formed as a flat surface having no curvature.

The movable contact A and the fixed contact B are passed through mounting holes 5 and 6 provided in support portions of the bases 1 and 2 and are operated by bolts or the like with operating mechanisms such as a circuit breaker and an electric switch (not shown). The movable contact A is connected to the load mechanism, moves in conjunction with the movement of the operation mechanism, and performs a contacting or separating operation with the fixed contact B to perform overload interruption and load switching. .

In the electric contact having such a configuration, when the movable contact A is opened to disconnect the circuit, an arc corresponding to the load condition is generated between the contacts. The direction of movement of the arc is on the side opposite to the power supply in accordance with Fleming's left-hand rule, that is, as shown in FIG. 7, in the direction opposite to the mounting direction of the contact, and the arc 10 disappears at the tip of the contact.

[0005] By the way, the above-mentioned contact 3 of the electric contact,
As a material of No. 4, an Ag-WC alloy having a homogeneous composition as a whole, for example, containing about 60% by weight of a conductive component Ag (the rest is an arc resistant component), and about 85% by weight of a conductive component of Ag Ag-CdO containing (the rest being arc resistant components)
An Ag-In ₂ O ₃ system or an Ag-SnO ₂ system, or a Cu-W system or a Cu-WC system containing about 30% by weight of Cu as a conductive component is known. Since the Ag-based electric contactor has a low and stable contact resistance, it is used for an arc contact and a main contact of a circuit breaker or an electric switch with a medium load.

[0006]

As described above, a circuit breaker or an electric switch generally uses a contact contact having a uniform composition as a whole. However, in the case of a contact made of an Ag-based material, there is a drawback that the breaking duty (10 to 100 times the rated current) is inferior. In particular, due to arcing at the time of interruption or load switching, abnormal wear occurs partially at an initial stage, and the area of the abnormally consumed portion increases as the number of times of interruption or load switching increases. For this reason, on the contact surfaces where the contacts come into contact with each other, the arc resistance component increases, the contact resistance increases, the temperature rises remarkably, and problems such as welding may occur.

On the other hand, a Cu-based contactor is inexpensive, has a high boiling point and melting point, and has a high mechanical strength, and therefore has excellent arc resistance and welding resistance. As such, it can be used, for example, as an arcing contact for a submersible circuit breaker, and can also fulfill the required shut-down responsibilities. However, this Cu
Contact points made of a system material have a drawback in that oxidation is remarkable at a high temperature and contact resistance stability is poor.

The present invention has been made in view of the above circumstances, and has excellent breaking characteristics when breaking and when switching rated loads.
An object of the present invention is to provide an electric contact that can suppress contact wear, has good welding characteristics, and can maintain contact characteristics such as temperature rise stably for a long period of time.

[0009]

According to the present invention, an electric contact is constituted by the following means to achieve the above object. The invention emperor to claim 1 is, in an electric contact used for a circuit breaker or an electric switch, a contact portion where an arc is generated at the time of closing and breaking, as a first contact region,
The first contact region has a high melting point and is made of a material mainly composed of an arc-resistant component having a high arc resistance and a material composed of a conductive component having a high electrical conductivity. The second contact region is made of a material mainly composed of a conductive component having high electrical conductivity and a material having an arc resistant component having high arc resistance.

According to a second aspect of the present invention, there is provided the electrical contact according to the first aspect, wherein the arc-resistant material is continuously or stepwise in a direction from the first contact region to the second contact region. It is composed of a material that has been dynamically changed.

According to a third aspect of the present invention, there is provided an electric contact according to the first or second aspect, wherein
A highly conductive material is thickly plated on the contact region to form a plating layer, and the first contact region including the lower portion of the plating layer is made of a material mainly composed of a component having high arc resistance.

According to a fourth aspect of the present invention, there is provided an electric contact according to the first or second aspect, wherein
Are made of W or Mo metal or carbide, I
At least one kind of arc-resistant component selected from metals, oxides, and oxides of n, Sn, and Cd comprises 100% by weight to 60% by weight, and the material of the second contact region is a conductive component and a metal of W and Mo. Or at least one arc-resistant component selected from carbides, metals of In, Sn, and Cd, or 60% by weight.
The arc resistance component is continuously reduced from the first contact region to the second contact region, and the conductive component is continuously increased.

According to a fifth aspect of the present invention, in the electric contact according to any one of the first to third aspects, the material of the first contact region is W or Mo metal or carbide, In , Sn, Cd at least one arc-resistant component selected from metals or oxides is 80% by weight to 50% by weight.
And the material of the second contact region is 30% by weight to 60% by weight of at least one arc-resistant component selected from W or Mo metal or carbide, In, Sn, Cd metal or oxide.
% In the direction from the first contact region to the second contact region, wherein the arc resistant component is gradually reduced and the conductive component is composed of a gradually increased material.

According to a sixth aspect of the present invention, in the electric contact according to the third aspect of the present invention, the component of the highly conductive material plating in the second contact region is silver or a silver alloy containing silver as a main component. The thickness of the plating layer is 10 μm to 50 μm,
The material of the first contact region including the lower portion of the plating layer is a metal of W or Mo, which is an arc resistant component, and a total of one or more of the arc resistant components of carbide, In, Sn, and Cd. The maximum content is comprised between 80% and 50% by weight.

According to a seventh aspect of the present invention, in an electric contact used for a circuit breaker or an electric switch, a contact portion where an arc is generated at the time of closing and breaking is set as a first contact region,
The first contact region has a high melting point and is made of a material mainly composed of an arc-resistant component having a high arc resistance and a material composed of a conductive component having a high electric conductivity. The second contact region is made of a material mainly composed of a conductive component rich in electric conductivity and a material composed of an arc resistant component rich in arc resistance.
Further, a third contact area is defined between the first contact area and the second contact area, and the third contact area is shifted from the first contact area to the third contact area, and further in the direction of the second contact area. This is to reduce the material as the arc resistant component and increase the conductive component.

According to an eighth aspect of the present invention, in the electric contact according to the seventh aspect, the material of the first contact region is a metal or carbide of W or Mo, In, Sn, or C.
100% by weight to 60% by weight of at least one arc-resistant component selected from metals or oxides of d, and the material of the third contact region is a metal or carbide of W or Mo, In, Sn,
80% by weight to 50% by weight of at least one arc-resistant component selected from metals or oxides of Cd; the material of the second contact region is a conductive component and a metal or carbide of W or Mo;
At least one arc-resistant component selected from metals or oxides of In, Sn, and Cd is constituted by 60% by weight or less.

Therefore, according to the inventions corresponding to the first to eighth aspects, it is possible to suppress the wear at the time of arc generation with excellent breaking characteristics and to obtain a stable contact state with less contact surface roughness. be able to. Further, since the second contact region is made of a material mainly composed of a conductive material having a high electric conductivity, the specific resistance value is small, the contact resistance is small and stable, and the arc of this surface is small. Since there is no generation, there is almost no wear, the roughness of the contact surface is very small, the contact resistance is small and stable for a long time, and the welding characteristics due to the heat generated by the product of the contact resistance and the flowing current are improved.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are diagrams for explaining a first embodiment of an electric contact according to the present invention, wherein FIG. 1A is a configuration diagram of a fixed contact, and FIG. FIG. 4 is a view showing a general tendency of a composition component of a part. Note that the entire configuration of the electric contact is the same as that of FIG. 7, and the description thereof is omitted here.

In the first embodiment, FIG.
As shown in FIG. 2, the contact portion where an arc is generated at the time of closing and breaking is defined as a first contact region 7, and the contact portion which is always energized after the closing is defined as a second contact region 8.
Is composed of a material mainly composed of a component having a high melting point and high arc resistance, and the second contact region 8 is composed of a material mainly composed of a highly conductive component including an arc resistant material. It is.

In this case, the material of the first contact region 7 is W,
At least one arc-resistant component selected from Mo metal or carbide and In, Sn, Cd metal or carbide is 10
0 wt% to 60 wt%, and the material of the second contact region 8 is made of a conductive component and a metal or carbide of W or Mo;
At least one arc-resistant component selected from metals, carbides, and carbides of n, Sn, and Cd is 60% by weight or less (including zero). Then, as shown in FIG. 2B, the arc resistant component C is continuously reduced from the first contact region 7 to the second contact region 8, and the conductive component D is formed of a continuously increased material. ing.

In the electric contact having such a configuration, the operations at the time of closing and at the time of closing are performed in a state as shown in FIG. That is, as shown in FIG.
From the state (1), the contact point moves in the first contact area 7 (b), and as the contact force increases, the contact point moves (c), moves to the second contact area 8 and stops (d). In addition, the contact point at the time of separation moves from the second contact area 8 (d) to the first contact area 7 as the contact force decreases (b), and fires at the first contact area 7. Cut off the circuit (a).

Therefore, in the electric contact having the above-described structure, the portion where the arc is generated by contact at the initial stage of closing and the arc which is generated when the contact is separated at the time of opening is continued after the arc is released. Since the first contact region 7 where the metal disappears is composed of a material mainly composed of a material having a high melting point and a high arc resistance, it is possible to suppress the wear at the time of arc generation with excellent breaking characteristics. It is possible to obtain a stable contact state with less roughness of the contact surface.

Further, since the second contact region 8 is made of a material containing a conductive material having high electrical conductivity as a main component, the specific resistance value is small, the contact resistance is small and stable, There is almost no wear because there is no arcing at the surface, and the roughness of the contact surface is very small and the contact resistance is small and stable for a long time, and the heat (Joule heat) due to the product of the contact resistance and the conducting current is reduced. The resulting welding characteristics are improved.

FIGS. 3A and 3B are diagrams for explaining a second embodiment of the electric contact according to the present invention.
(A) is a configuration diagram on the fixed contact side, and (b) is a diagram showing a schematic tendency of the composition of the contact portion. Here, only points different from the first embodiment will be described.

In the second embodiment, FIG.
As shown in FIG. 5, as the material of the first contact region 7, a material mainly composed of a component having a high melting point and a high arc resistance, W, Mo
80% by weight to 50% by weight of at least one arc-resistant component selected from metals or carbides of In, Sn, and Cd, and a material of the second contact region 8
Materials mainly composed of a conductive component having high electrical conductivity including arc resistant materials, W or Mo metal or carbide, In, S
at least one selected from metals and carbides of n and Cd
3% to 60% by weight of the arc-resistant components,
As shown in FIG. 3B, the first contact region 7 is changed to the second contact region 8 in a stepwise manner.

Therefore, the same effect as that of the first embodiment can be obtained also in the electric contact having the above-described configuration. FIG. 4 is a configuration diagram on the fixed contact side for explaining a third embodiment of the electric contact according to the present invention.

In the third embodiment, as shown in FIG. 4, a contact portion where an arc is generated at the time of closing and breaking is defined as a first contact region 7, and a contact portion which is always energized after the closing is defined as a second contact region. As the region 8, a thick plating layer 9 made of a highly conductive material is formed in the second contact region 8, and the first contact region 7 including the lower portion of the plating layer 9 is made of a component having a high melting point and a high arc resistance. It is composed of a main material.

In this case, the plating layer 9 made of a highly conductive material formed in the second contact region 8 is made of silver or a silver alloy containing silver as a main component, and has a plating thickness of 10 μm to 50 μm.
m, and the material of the first contact region 7 including the lower portion is made of a metal or carbide of W or Mo, which is an arc resistant component, I
The maximum content of one or more of the arc-resistant components of n, Sn and Cd is 80% by weight to 50% by weight.

Therefore, the same effect as that of the first embodiment can be obtained in the electric contact having the above-described configuration. FIGS. 5A and 5B are diagrams for explaining a fourth embodiment of the electric contact according to the present invention.
(A) is a block diagram of a fixed contact side, (b) is a figure which shows the general tendency of the composition component of a contact part.

In the fourth embodiment, FIG.
Each of the above-described embodiments is characterized in that a contact portion where an arc is generated at the time of closing and breaking is defined as a first contact region 7 and a contact portion which is always energized after the closing is defined as a second contact region 8 as shown in FIG. However, the first contact area 7 and the second contact area are further divided into a portion e mainly composed of the first contact area, a part g mainly composed of the second contact area, and the first and second areas. The second contact region is divided into a third contact region f between the second contact regions, and a portion e mainly composed of the first contact region, the third contact region f, and the second contact region as shown in FIG. The main part g is made of a material that is changed continuously or stepwise.

In this case, the material of the first contact region is W, M
at least one arc-resistant component selected from metals or oxides of o, metals or oxides of In, Sn and Cd is 100
% To 60% by weight, the material of the third contact area is W,
At least one arc-resistant component selected from Mo metal or carbide, In, Sn, Cd metal or oxide is 80
% To 50% by weight, the material of the second contact region is a conductive component and a metal or carbide of W or Mo, In, Sn, Cd.
At least one kind of arc-resistant component selected from the metals or oxides described above is 60% by weight or less (including zero).

Next, a description will be given of a method of evaluating the electric contact of each embodiment configured as described above. Each electrical contact was mounted as a fixed contact and a movable contact of a no-fuse breaker, and an evaluation test was performed. In the evaluation test, first, switching is performed once under an overload condition in which a large current of 200 V-2.5 KA is applied to the circuit voltage, and then 200 V-50 A.C.
The test was performed at a rate of 2 times / minute of the resistance load switching, and the switching was performed once under the first overload condition.

Contact resistance other than the evaluation of welding characteristics, temperature rise,
The state of wear was evaluated before and after each test. The contact resistance was measured at a direct current of 6 V-1 A, and the temperature rise was measured at a value at which the temperature rise became substantially constant by applying an alternating current of 50 A.

(Comparative Example 1) As shown in FIG. 6, a 60 wt% Ag-WC contact having a uniform composition over the entire contact is abnormal on the opposite power source side (tip of the contact) in the overload switching test. Attrition is observed, and the contact resistance tends to increase. Further, after the load switching test, the increase in the contact resistance is further increased, and the temperature rise value is also increased. However, no welding occurred. In the last overload switching test, the consumption increased further, and the contact resistance and the temperature rise also increased.

(Comparative Example 2) A 30% by weight Ag-WC contact having a uniform contact composition as a whole was consumed on the non-power supply side (tip of the contact) of the contact in the overload switching test as shown in FIG. However, when the contact surface is subjected to elemental analysis using an X-ray microanalyzer, a portion of only W or WC is seen, and a tendency of increasing the contact resistance is seen. Further, after the load switching test, the increase in the contact resistance is further increased and the temperature rise value is also increased. In addition, welding has also occurred. In the last overload switching test, the consumption increased slightly, and the contact resistance and the temperature rise also tended to increase.

(Comparative Examples 3, 4, 5) 85% by weight of Ag-Cdo type contact, 85% by weight of Ag-In203 type contact, 85% by weight of Ag-Sno.
As shown in FIG. 6, in the overload switching test, abnormal wear is seen on the non-power supply side of the contact (the tip of the contact), but the contact resistance hardly increases. Even after the load switching test, there was almost no increase in the contact resistance, the temperature rise was small, and no strong welding occurred, but the slight welding (light welding that does not return naturally without applying external force) , Each occurring several times. The consumption is larger than in Comparative Examples 1 and 2. In the last overload switching test, consumption, contact resistance, and temperature rise tended to increase slightly.

Next, an embodiment will be described. (Embodiment 1) In the contact structure and composition tendencies shown in FIGS. 1 (a) and 1 (b), the component in the thickness direction is almost the same as the component on the surface. ) Is 80
Weight% WC-18% by weight Me-2% by weight Me, point b (approximately at the center and at the end of the first contact area and at the end of the second contact area) is 60% by weight WC-38% by weight Ag-2 Wt% M
e and c points (final end of the second contact area) are 40% by weight WC
A to b, b to c at -58 wt% Ag-2 wt% Me
Between are contacts that are changing smoothly. Here, Me is a metal such as Co, Ni, and Fe.

As a result of the evaluation test, as shown in FIG. 6, in the overload switching test, the first contact surface (the tip of the contact) of the contact is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase.

(Example 2) In the contact structure and composition tendencies shown in FIGS. 1 (a) and 1 (b), the component in the thickness direction is almost the same as the surface component, and the point a (the first contact region) 70% by weight WC-28% by weight Me-2% by weight M
points e and b (approximately at the center and at the end of the first contact area and at the end of the second contact area) are 50% by weight WC-48% by weight Ag
-2% by weight Me, point c (the last end of the second contact area) is 3
0% by weight WC-68% by weight Ag-2% by weight Me is a contact that smoothly changes from a to b and from b to c.

As shown in FIG. 6, the results of the evaluation test show that in the overload switching test, the first contact surface (the tip of the contact) of the contact is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase.

(Embodiment 3) In the tendencies of the contact structure and the composition components shown in FIGS. 3A and 3B, the components in the thickness direction are almost the same as the components on the surface, and the components in the first contact region are different. 8
0% by weight WC-18% by weight Ag-2% by weight Me, the component of the second contact area is 40% by weight WC-58% by weight Ag-2
It is a contact where the component rapidly changes in a stepwise manner at the d portion (approximately at the center) where the first contact region and the second contact region are joined by weight% Me.

As shown in FIG. 6, the results of the evaluation test show that in the overload switching test, the first contact surface of the contact (the tip of the contact) is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase.

(Embodiment 4) In the contact structure and composition tendencies shown in FIGS. 3A and 3B, the component in the thickness direction is almost the same as the component on the surface, and the component in the first contact region is 7
0 wt% WC-28 wt% Ag-2 wt% Me, 30 wt% WC-68 wt% Ag-2 in the second contact area
It is a contact where the component rapidly changes in a stepwise manner at the d portion (approximately at the center) where the first contact region and the second contact region are joined by weight% Me.

As a result of the evaluation test, as shown in FIG. 6, in the overload switching test, the first contact surface (the tip of the contact) of the contact is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase.

(Embodiment 5) In the contact structure shown in FIG. 4, Ag plating 9 was applied to the surface layer of the second contact area by 30 μm.
The other part of the component, including the first contact area, is a contact with a homogeneous composition of 70% by weight WC-28% by weight Ag-2% by weight Me.

As a result of the evaluation test, as shown in FIG. 6, in the overload switching test, the first contact surface (the tip of the contact) of the contact is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase.

(Embodiment 6) In the contact structure shown in FIG. 4, the surface layer of the second contact area was coated with Ag plating 9 to a thickness of 50 μm.
The other part of the composition, including the first contact area, is a contact with a homogeneous composition of 60% by weight WC-38% by weight Ag-2% by weight Me.

As a result of the evaluation test, as shown in FIG. 6, in the overload switching test, the first contact surface (the tip of the contact) of the contact is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase.

(Embodiment 7) In the contact structure and composition tendencies shown in FIGS. 5A and 5B, the component in the thickness direction is almost the same as the component on the surface, and the first contact region is the main component. 70% by weight of WC-28% by weight of Ag-2
Wt% Me, the third present between the first and second contact areas
50 wt% WC-48 wt% Ag
-2 wt% Me is a contact where the components rapidly change stepwise at the joining surface between the first and third contact regions and at the joining surface between the third and second contact regions.

As shown in FIG. 6, the result of the evaluation test shows that in the overload switching test, the first contact surface (the tip of the contact) of the contact is consumed very little and the contact resistance is hardly increased. Further, even after the load switching test, the increase in contact resistance and the rise in temperature are small, and there is no occurrence of welding. In the last overload switching test, consumption, contact resistance and temperature rise hardly increase. Its characteristics are almost the same as those of Examples 3 and 4.

[0051]

As described above, according to the present invention, the switching characteristics are excellent at the time of disconnection and at the time of rated load switching, the contact wear can be suppressed, the welding characteristics are good, and the contact characteristics such as temperature rise are prolonged. An electric contact that can be stably maintained for a period can be provided.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams for explaining a first embodiment of an electric contact according to the present invention, wherein FIG. 1A is a configuration diagram on a fixed contact side, and FIG. FIG.

FIG. 2 is a view for explaining an operation state when the electric contact is turned on and off in the embodiment.

3A and 3B are diagrams for explaining a second embodiment of the electric contact according to the present invention, wherein FIG. 3A is a configuration diagram on the fixed contact side, and FIG. FIG.

FIG. 4 is a configuration diagram on a fixed contact side for describing a third embodiment of the electric contact according to the present invention.

FIGS. 5A and 5B are diagrams for explaining a fourth embodiment of the electric contact according to the present invention, wherein FIG. 5A is a configuration diagram on the fixed contact side, and FIG. FIG.

FIG. 6 is a diagram for explaining an evaluation test result in the first to fourth embodiments of the present invention.

FIG. 7 is a view showing the movement of an arc generated when a general electric contact is opened.

FIG. 8 is a configuration diagram showing an example of a conventional electric contact.

[Explanation of symbols]

 1, 2,..., Base metal 3, 4,... Contacts 5, 6,... Mounting holes 7,. Fixed contact C: Arc resistant component D: Conductive component R: Curvature of movable contact surface

Claims (8)

[Claims] In an electric contact used for a circuit breaker or an electric switch, a contact portion where an arc is generated at the time of making and breaking is defined as a first contact region, and the first contact region has a high melting point and a high resistance. It is composed of a material mainly composed of an arc-resistant component rich in arc properties and a material composed of a conductive component rich in electric conductivity, and a constantly energized portion after being supplied is a second contact region, and the second contact region is An electric contact comprising a material mainly composed of a conductive component having high electric conductivity and a material comprising an arc-resistant component having high arc resistance. 2. The electrical contact according to claim 1, wherein the arc-resistant material is made of a material that changes continuously or stepwise from the first contact region to the second contact region. An electric contact, characterized in that: 3. The electric contact according to claim 1, wherein the second contact region is thickly plated with a highly conductive material to form a plating layer, and the first contact includes a lower portion of the plating layer. An electric contact, wherein the region is made of a material mainly composed of a component having high arc resistance. 4. The electric contact according to claim 1, wherein the material of the first contact region is selected from a metal or carbide of W and Mo, and a metal or oxide of In, Sn and Cd. 100% by weight or more of at least one arc-resistant component
60% by weight, and the material of the second contact region is made of a conductive component and a metal or carbide of W or Mo, In, Sn, Cd.
At least one arc-resistant component selected from metals or oxides of 60% by weight or less, the arc-resistant component is continuously reduced from the first contact region toward the second contact region, An electric contact, wherein the conductive component is made of a continuously increased material. 5. The electrical contact according to claim 1, wherein the material of the first contact region is W,
At least one arc-resistant component selected from Mo metal or carbide, In, Sn, Cd metal or oxide is 80
% By weight, and the material of the second contact region is 30% by weight of at least one arc-resistant component selected from W or Mo metal or carbide, In, Sn, Cd metal or oxide. % To 60% by weight, wherein the arc resistant component is gradually reduced from the first contact region to the second contact region, and the conductive component is composed of a material which is gradually increased. And electrical contacts. 6. The electrical contact according to claim 3, wherein the high-conductivity material plating component in the second contact region is silver or a silver alloy containing silver as a main component, and the thickness of the plating layer is 10 μm.
.About.50 .mu.m, and the material of the first contact region including the lower portion of the plating layer is a metal of W or Mo, which is an arc-resistant component, and one or more types of arc-resistant materials of carbide, In, Sn, and Cd. The maximum content of the total components is 80% by weight or more.
An electric contact comprising 50% by weight. 7. An electric contact used for a circuit breaker or an electric switch, wherein a contact portion where an arc is generated at the time of making and breaking is defined as a first contact region, and the first contact region has a high melting point and is resistant to heat. It is composed of a material mainly composed of an arc-resistant component rich in arc properties and a material composed of a conductive component rich in electric conductivity, and a constantly energized portion after being supplied is a second contact region, and the second contact region is A material mainly composed of a conductive component rich in electric conductivity and a material composed of an arc resistant component rich in arc resistance, and a third contact region between the first contact region and the second contact region. And the third contact region reduces the material which is the arc resistant component in the direction from the first contact region to the third contact region and further toward the second contact region, and increases the conductive component. Electrical contacts characterized. 8. The electrical contact according to claim 7, wherein the material of the first contact region is at least one selected from the group consisting of a metal or carbide of W and Mo, and a metal or oxide of In, Sn and Cd. The arc resistance component is 100% by weight to 60% by weight, and the material of the third contact region is at least one type of arc resistance component selected from W or Mo metal or carbide, In, Sn, Cd metal or oxide. 80 wt% to 50 wt%, and the material of the second contact region is a conductive component alone, or at least one kind of resistance selected from W or Mo metal or carbide, In, Sn, Cd metal or oxide. An electric contact comprising an arc component of 60% by weight or less (not including zero).