JPS63266720A - Contact for vacuum switch gear - Google Patents

Abstract

PURPOSE:To realize a low surge function and a large current interrupting function which are functions contrary to each other by forming a boundary region of a material, which is composed to make a height of a vapor pressure become continuously different in the radial direction, between both alloy regions which consist of materials different in the height of vapor pressure to each other, with respect to a contact. CONSTITUTION:With respect to a contact, either one of two alloy regions 21 and 23 consists of a high vapor pressure material and the other one consists of a low vapor pressure material. When the alloy region 21 consists of the high vapor pressure material, the height value of the vapor pressure of a material in an intermediate region 22 ranges in the middle of the respective height values of the alloy regions 21 and 23, and a radial distribution of the height of the vapor pressure of this material in the intermediate region becomes smaller toward the inner peripheral side from the outer peripheral side. Hence, forced transfer of an arc by the control of a vertical magnetic field is easily performed without stagnation from the alloy region, which consists of the high vapor pressure material, to the alloy region which consists of the low vapor pressure material. Accordingly, two contrary needs which are a low surge function and a large current interrupting function can be satisfied at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a contact for a vacuum valve in a vacuum switch.

(Prior Art) Vacuum switches have various superior features compared to other switches, such as being small, lightweight, maintenance-free, and environmentally friendly, so their range of application has been gradually expanded in recent years. A vacuum breaker interrupts current in a high vacuum by utilizing arc diffusivity in a vacuum, and will be explained with reference to FIG. 4, which shows a side cross section of the vacuum breaker.

The vacuum breaker has a breaker 1 kept vacuum-tight,
This includes an insulating container 2 formed of an insulating material into a substantially cylindrical shape, and sealing fittings 3a at both ends of the insulating container 2.

It is composed of metal lids 4a and 4b provided through a lid 3b.

A pair of fixed electrodes 7 and a movable electrode 8 attached to opposite ends of conductive rods 5 and 6 are disposed within the circuit breaker 1.

A bellows 9 is attached to the conductive rod 6 of the movable electrode 8, and the movable electrode 8 moves in the axial direction while maintaining vacuum tightness within the breaker 1. A metal arc shield 10 is provided above the bellows 9 to prevent the bellows 9 from being covered with arc vapor. Similarly, a metal arc shield 11 is provided in the breaker 1 to cover the fixed electrode 7 and the movable electrode 8, and prevents the insulating container 2 from being covered with arc vapor. Fixed contact 13 when energized
A movable contact 13a is in contact with b, and the current is cut off by moving the conductive rod downward to break contact between these two contacts.

Next, conductive rods 5, 6 and electrodes 7, 8, electrodes 7, 8 and contact 1
The mutual fixing structure with 3a and 13b will be explained with reference to FIG. 5, which shows details of the area around the movable electrode 8 in FIG. 4. The movable electrode 8 is fixed to the conductive rod 6 by brazing 12 or by caulking (not shown), and the movable contact 13a is fixed to the movable electrode 8 by brazing 14 or caulking (not shown). The method of fixing the fixed electrode 7 and the contact 13b on the fixed side is also the same.

(Problems to be Solved by the Invention) Requirements for contacts for vacuum switches include (1) low weldability, (2) high withstand voltage, (3) excellent wear resistance, ( 4) Low and stable contact resistance. In addition, expectations for recent vacuum switchgears have increased even further, including (5) low surge functionality;
(6) It is required to have a large current cutoff function, but
These two demands are contradictory.

First, the requirements for having a low surge function will be explained. When cutting off current in an inductive circuit such as a motor load, excessive surge voltage may be generated and the insulation of the load equipment may be destroyed.

The cause of this abnormal surge voltage is a current phenomenon that occurs on the low current side when shutting off in a vacuum (current shutoff is forcibly performed without waiting for the natural zero point of the AC current waveform). be. Abnormal surge voltage value V
are the circuit surge impedance Z and current cutoff value I
The product of OC, that is, V -22φI, is expressed as
In order to lower the 0e pressure (i.e., to have a low surge function), the current cutoff value I must be reduced. Therefore, when the contact is cut off, many ions and metal particles must be evaporated from the surfaces of the movable contact 13a and the fixed contact 13b by the arc and float between the two contacts, so that the arc can be easily connected. Therefore, the contacts 13a, 13
The material used for b is required to have a high vapor pressure property with high evaporability not only when cutting off a large current, but also when the switching current is small and the temperature rise at the contact point is small.

An Ag-WC alloy containing Ag, which is a high vapor pressure material, is known as a material that satisfies such a low surge function. Contacts made of this alloy have the following properties: (1) The presence of WC facilitates the emission of ions from the contact surface, and (2) The evaporation of metal particles from the contact surface is caused by the heating of the electrode surface due to the collision of field emission electrons. (3) The carbide in the contact material is decomposed by the arc and generates a charged body, so it has an excellent low surge function. Other materials that have this function include Cu-Cr alloy containing Cu, which is a high vapor pressure material;
U-B1 alloy etc. are known.

On the other hand, in order to have a large current interrupting function, which is the other contradictory requirement, the contacts are required to be made of a material with low vapor pressure. When cutting off a large current, the surface temperature of the contact becomes extremely high, but even in such a case, the amount of evaporation from the contact surface due to the arc is small, and almost no ions or metal particles are suspended between the two contacts. If the condition is not met, the shutoff performance will be impaired. Therefore, generally pursuing improvements in one function will result in a decline in the other function.

As a means to satisfy these two contradictory requirements, there is a method in which the contact is made of two types of materials: a high vapor pressure material and a low vapor pressure material. When the contacts that were in contact during the current flow separate in order to cut off the current, many ions and metal particles first evaporate from the part made of the high vapor pressure material and float between the contacts, leading to an arc. and connected to the high vapor pressure materials at both contacts. After the time required for the low surge function to be satisfied, the arc is transferred so that the arc that was connected to the high vapor pressure materials at both contacts is connected to the low vapor pressure materials at both contacts. This changes the distribution of ions and metal particles floating between both contacts by controlling the vertical magnetic field H using the coil electrode 44 shown in FIG. 7, the spiral electrode 45 shown in FIG. 8, etc. This can be done by forcibly moving the arc.

However, the physical properties of a high vapor pressure material that has a low surge function even when cutting off a low current are significantly different from the physical properties of a low vapor pressure material that has a large current cutting function in terms of vapor pressure properties. For this reason, even if the distribution of ions and metal particles floating between the two contacts is changed by a vertical magnetic field, the arc will remain on the boundary between the part made of high vapor pressure material and the part made of low vapor pressure material, and it will easily occur. Does not migrate. Therefore, simply constructing a contact by combining a high vapor pressure material and a low vapor pressure material cannot simultaneously satisfy the low surge function and the large current cutoff function.

In view of the above-mentioned circumstances, the transition of the arc from a high vapor pressure material to a low vapor pressure material at the time of current cutoff is carried out easily without stagnation, and it has two contradictory functions: a low surge function and a large current cutoff function. The purpose of the present invention is to provide a contact for a vacuum switch that has the following characteristics.

(Structure of the Invention) (Means for Solving the Problems) In the vacuum switch contact of the present invention, two types of alloy regions and a boundary region sandwiched therebetween are arranged concentrically, and each of the alloy regions are made of materials having different vapor pressures, and the boundary region is made of a material whose composition is such that the vapor pressures are continuously different in the radial direction.

(Function) In the vacuum switch contact of the present invention, if the alloy region located on the outer peripheral side is made of a material having a higher vapor pressure than the alloy region located on the inner peripheral side, the boundary region (B1) The vapor pressure of the material constituting the material decreases in a continuous region from the outer circumferential side to the inner circumferential side in the radial direction. Therefore, the vapor pressure of the material gradually decreases from the alloy region (A1) through the boundary region (B) to the alloy region (A2). When such vacuum switch contacts are used in a vacuum switch to cut off current, when both contacts that were in contact during energization separate, the material with the highest vapor pressure among the areas that make up the contacts Many ions and metal particles evaporate from the alloy region located on the outer circumferential side and float between the alloy regions of both contacts, and an arc is guided thereto and connected between the two.

Thereafter, by controlling the longitudinal magnetic field to change the distribution of ions and metal particles floating between both contacts, the arc moves from the alloy region located on the outer circumferential side to the boundary region.

Since the vapor pressure of the material gradually decreases from the outer alloy region through the boundary region to the inner alloy region, the arc easily moves to the boundary region without stagnation. In this way, by controlling the longitudinal magnetic field, the arc is forcibly moved toward the inner alloy region.

Then, after the time required for the low surge function to be satisfied, that is, for the arc to be connected between both contacts, the transition is made to the inner alloy region where the vapor pressure is lowest and most of the arc and metal particles do not evaporate. At this moment, the connection between the arcs is severed.

Conversely, if the inner alloy region is made of a material with a higher vapor pressure than the outer alloy region, the vapor pressure of the material in the boundary region will be higher. The height decreases continuously from the inner circumferential side toward the outer circumferential side in the radial direction. Therefore, the vapor pressure of the material gradually decreases from the inner alloy region through the boundary region to the outer alloy region. In this case, the arc is first connected between the inner alloy regions of both contacts, and by controlling the longitudinal magnetic field, the arc moves through the boundary region to the outer alloy region, and the arc connection is broken. drooping

(Example) As an example of the present invention, the contacts have two types of alloy regions (A
) and (A2) and the boundary region (B1) will be explained using FIG. 1, in which the contact point is seen from above. Compared to the conventional contact shown in Fig. 6, the alloy region (A,
) 21 and the alloy region (A2) 23 there is an intermediate region (B1
) 22 is arranged. Alloy area (A,)2
1 and alloy region (A2) 23 have different contents □
In some cases, they are made of the same alloy-based material, and in other cases, they are made of different alloy-based materials. The alloy material of the intermediate region (B1) 22 is the alloy material of the alloy region (A,) 21 and the alloy region (A2).
23, or it may be the same as at least one of the alloy materials but have a different content.

When the alloy material of the alloy region (A,) 21 and the alloy region (A2) 23 is the same, for example, in the case of an A g -WC alloy, one of the regions is made of a material having a low surge function. 40Ag-WC-10Co (values indicate weight %, the same applies hereinafter), which has a high content of Ag, a metal with high vapor pressure, was used, and the other alloy region was made of a material with a large current cutting function. 30Ag-WC-0,2Co, which has a low Ag content, can be used.

In this case, in the boundary region, there are cases where an alloy system different from the alloy system used in both alloy regions, that is, the Ag-WC system alloy, and cases where the same alloy system, the Ag-WC system alloy, is used. In either case, the composition of the material has a distribution that varies continuously in the radial direction, and as a result, the height of the vapor pressure of the material varies continuously in the radial direction.

One of the alloy region (A1) 21 and the alloy region (A2) 23 is made of a high vapor pressure material and the other is made of a low vapor pressure material, but the alloy region (A1) 21 is made of a high vapor pressure material. In this case, the range occupied by the vapor pressure height of the material in the intermediate region (B,) 22 is the alloy region (A,)
It is between the vapor pressure height value of No. 21 and the vapor pressure height value of alloy region (A2) 23, and furthermore, the distribution of the vapor pressure height of the material in the radial direction is from the outer circumferential side to the inner circumferential side. It decreases continuously towards . The opposite is true when the alloy region (A1) 21 is made of a low vapor pressure material, and the alloy region (A2)
23 is made of a high vapor pressure material, and the intermediate region (B,) 22
The range occupied by the vapor pressure height of is the alloy region (A1)
There is a value between the vapor pressure height of No. 21 and the vapor pressure height of alloy region (A2) 23, and furthermore, the distribution of the vapor pressure height of the material in the radial direction is from the outer circumference to the inner circumference. Continuously increases in height towards the sides. Any combination of these two is possible. The case where the alloy region (A2) 23 is made of a high vapor pressure material will be described below.

First, an example of a method for manufacturing a contact having such a composition will be described. As a molding die, a die 31 shown in FIG.
A first punch 32, a second punch 35, and a mold stand 37 are used.

The first punch 32 is removed from the mold 31, and the second punch 35 is installed so that its bottom 35a is in contact with the mold base 37. Mold 31 and second punch 35
The powder for forming the alloy region (A1) 21 is mixed and filled in the space between the two, and the first punch 32 presses the powder at a molding pressure P1.

Next, the second punch 35 is extracted from the mold 31, and the space 38 is filled with mixed powder for forming the alloy region (A2) 23. Apply pressure. The pressure P2 in this case is such that when the same alloy system is used for the alloy region (A1) 21 and the alloy region (A2) 23, a large amount of A
In order to infiltrate g, it is made smaller than Pl to increase the proportion occupied by pores. When using different alloy systems for the alloy region (A1) 21 and the alloy region (A2) 23, the pressure P
2 may be the same as Pl. The boundary area in this case (
B1) 22 is made by mixing and preparing the same powder as the alloy region (A1) 21, and the pressure applied by the tapered part 32b of the first punch 32 is different in the radial direction, and the alloy region (A1) It decreases as it approaches from the outer circumferential side close to Al) 21 to the inner circumferential side close to the alloy region (A2) 23, so the ratio of pores increases.

When the thus obtained product is shaped into a disk shape, a molded product 39 whose cross section in the central axis direction is shown in FIG.
get. Further, this molded body 39 is sintered in a non-oxidizing atmosphere to obtain a skeleton.

A high vapor pressure material such as Ag or Cu is brought into contact with one side of the skeleton, and the skeleton is heated at a temperature above the melting point of the material in a non-oxidizing atmosphere, thereby injecting Ag or Cu into the pores of the skeleton. Infiltrate. By this method, an alloy region (A1) 21 made of a low vapor pressure material with a constant composition, an alloy region (A2) 23 made of a high vapor pressure material with a constant composition, and Ag or Cu in the radial direction are formed. The boundary region (B, ) 22 is made of a material that has a different content distribution, and the content increases from the outer circumferential side to the inner circumferential side, that is, the vapor pressure increases as you move toward the inner circumferential side. Obtain a contact point with

The contact thus obtained has a coil electrode as shown in FIG. 7 or a spiral electrode as shown in FIG. 8, and is used as a movable contact for the vacuum switchgear shown in FIG. 4, which can control the vertical magnetic field. 13a and the fixed contact 13b to cut off current will be described. When both contacts 13a and 13b, which were in contact during energization, separate, both contacts 13a.

Among the alloy regions composing the alloy region 13b, many ions and metal particles evaporate from the alloy region (A2) 23 made of the material with the highest vapor pressure and float between both contacts, and an arc is guided by this. Connected between alloy regions (A2) 23 on both contacts.

After this, by controlling the longitudinal magnetic field, the distribution of ions and metal particles floating between both contacts changes, and the arc moves from the alloy region (A2) 23 to the boundary region (B, ) 22 adjacent to the outer circumference. . The height of the vapor pressure of the material in the boundary region (B1) 22 has a different distribution in the radial direction, and the vapor pressure in the inner circumference side is slightly higher than that of the material in the alloy region (A2) 23. The vapor pressure of the material in the alloy region (A1) 21 adjacent to the outer circumference is slightly higher than the vapor pressure in the outer circumference. Therefore, by controlling the longitudinal magnetic field, the arc from the alloy region (A2) 23 to the boundary region (Bl) 22 passes through the boundary region (B1) 22 and returns to the alloy region (A,) without being stagnant at the boundaries of each region. 21 easily.

Here, the alloy region or boundary where the vapor pressure of the material is high and many ions and metal particles are suspended between the contacts and the arc connects until the time required for the low surge function to be met. The arc is connected and transferred between the regions, and then the arc is transferred to the alloy region (A,) 21 made of a material with the lowest vapor pressure and almost no evaporation of ions and metal particles in order to satisfy the large current cutoff function. At that moment, the arc connection between both contacts is broken.

Although we have explained the case where the contact point consists of two types of alloy regions (A1) and (A2) and a boundary region (B1) between these two regions, there are three or more types of alloy regions and there are When a boundary region exists, the change in the vapor pressure height distribution in the radial direction of the contact point becomes more gradual, and the arc transition occurs more easily.
Never stagnate.

Next, the results of testing and evaluation of the low surge property and large current interrupting property of the contact according to the present invention will be explained. In order to compare and contrast the low surge function and high current cutoff function of each contact, the contact pressure when both contacts are in contact, the opening speed when they are separated from this state, and the degree of vacuum were set to the same conditions.

The superiority or inferiority of low surge properties can be evaluated by the magnitude of the current cutting value required to connect an arc between two distant contacts, and the smaller this value is, the better the low surge properties are. When an AC current of 44 A was applied through the LC circuit, the voltage drop across the coaxial shunt inserted in series with the vacuum breaker was measured with an oscilloscope, and the current cutoff value was calculated.

The superiority or inferiority of the large current interrupting property can be evaluated by the maximum value of the current when no arc that inhibits the interrupting property occurs immediately after the interrupting, and the larger this value is, the better the large current interrupting property is. After cleaning the contact surface by baking, voltage aging, etc. to keep the conditions constant, increase the current by IKA at 7.2 KV and 50 Hz, measure the maximum value of the current at the cutoff limit, and calculate the magnification to the specified standard value. was calculated as the cutoff factor.

The effects of the contact according to the present invention will be explained with reference to Table 1 showing the surge current value and cutoff magnification for each contact. In both Example 1 and Conventional Example 1, 30Ag-WC-,0,2Co, which is a low vapor pressure material, is used in the alloy region (A1), and 40Ag-WC-10, which is a high vapor pressure material, is used in the alloy region (A1).
Co is used in the alloy region (A2), and only Example 1 has a boundary region (B1). As a result, when breaking, the arc is first connected to the alloy region (A2) made of the same material in both Example 1 and Conventional Example 1, so the current cutting value is the same and the arc is low. There are no differences in gender. However, in Example 1, unlike the conventional N1, the boundary area (
B1), the alloy region (A2) to the alloy region (
The transition of the arc to At) is easily carried out without stagnation, and the cutoff factor is improved from 1.0 to 164.

This is true for Example 2 and Conventional Example 2, Example 3 and Conventional Example 3,
The same applies to both the fourth embodiment and the fourth conventional example. From the above test results, we found that not only do we have two types of alloy regions using materials with different vapor pressure heights, but also
The contact according to the present invention, which has a boundary region between each alloy region in which the vapor pressure height has a continuously different distribution in the radial direction, has not only a low surge function but also a large current interrupt function. This has been proven.

〔Effect of the invention〕

As explained above, the vacuum switch contact according to the present invention has at least two types of alloy regions: an alloy region made of a high vapor pressure material having a low surge function and an alloy region made of a low vapor pressure material having a large current cutting function. However, there exists a boundary region between each alloy region in which the radial distribution of vapor pressure height is continuously different. For this reason, the forced transition of the arc from the alloy region made of high vapor pressure material to the alloy region made of low vapor pressure material is easily performed by controlling the longitudinal magnetic field, and there is no stagnation, resulting in a low surge function and a large It is possible to simultaneously satisfy two contradictory requirements of current cutoff function.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the vacuum switch contact of the present invention, Fig. 2v4 is a diagram showing an example of a mold used when manufacturing the vacuum switch contact of the present invention, and Fig. 3 is a diagram of a molded body. 4 is a diagram showing a vacuum switch; FIG. 5 is a partially enlarged view showing details around the movable electrode 8 in FIG. 4; and FIG. 6 is a conventional vacuum switch contact. FIG. 7 is a diagram showing a coil electrode used in a vacuum switch, and FIG. 8 is a diagram showing a spiral electrode used in a vacuum switch. 1... Breaker, 2... Insulating container, 3a, 3b...
・Sealing fittings, 4a, 4b...metal lid, 5.6...
・Conductive rod, 7... Fixed electrode, 8... Movable electrode, 9.
...Bellows, 10.11...Arcshield, 12
．． 14... Brazing, 13a... Movable contact, 13b.
... Fixed contact, 14... Brazing metal part, 21... First alloy region (A1), 22... First boundary region (B,)
, 23... Second alloy region (A2), 31... Mold, 32... First punch, 32a... Bottom of first punch, 32b... Tapered part, 35... ...Second punch, 35a...Bottom of second punch, 37...Mold stand, 38...Space, 39...Molded body, 44...Coil electrode, 45... Spiral electrode, H...magnetic field. Applicant's agent Sato-O I'll Figure P) 2 Figure Island 3 Figure 7 Figure 98 Mouth

Claims (1)

[Claims] Two types of alloy regions and a boundary region sandwiched between them are arranged concentrically, and each of the alloy regions is made of a material having a different vapor pressure, and the boundary region has a different vapor pressure in the radial direction. A contact for a vacuum switch, characterized in that it is made of a material whose composition is continuously different.