JPS6359493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides two pot-shaped
The present invention relates to a contact device for a vacuum switchgear equipped with several contacts.

In a conventional contactor device for a vacuum switchgear, each of the pot-shaped contacts disposed coaxially and facing each other forms one rotating hollow body, and the base of the hollow body is connected to the conductive part,
The edge also forms a ring-shaped contact surface. The contact supports of both contacts have oppositely extending slanted slits which divide the contact supports into individual segments. These segments form a current loop with an arc created after the contacts open, and the Lorentz force of this current loop rotates the arc between the contacts. The inclination of the slit with respect to the axis of the pot-shaped contact is
The slits are sized so that they overlap azimuthally in the contact support. A slit can also be provided at the base of the pot-shaped contact (German Patent No. 1196751).

A known configuration example of a contact device for a vacuum switchgear has a pot-shaped contact provided with a plate-shaped contact surface. Both contacts are arranged concentrically with respect to each other, the inner contact being surrounded by a contact wall of the outer contact, the edges oriented in the same axial direction. The contact surface of the external contact is located inside the pot-like structure, and in the case of the internal contact, the conductive part is located within the pot-like structure and the base of the contact comprises the contact surface. The contact surfaces thus face each other in the central portions of both contacts. The arc that forms after the contact is released is driven away from the contact surface towards the wall of the pot-shaped contact, which serves as the reduction area of the contact. For this purpose, a flat intermediate layer made of a material with high electrical resistance is inserted between the contact surface of the contact and the conductive part, which is placed as close as possible to the conductive part at the base of the pot-shaped contact. (Federal Republic of Germany Patent Application No. 2546376).

An object of the present invention is to stabilize a foot point of a rotating arc generated between the contact surfaces between the contact surfaces in a contact device having a pot-shaped contact whose edges each form a contact surface. The object of the present invention is to control the current distribution in each of the contacts between the conductive part and the ring-shaped contact surface so as to achieve the desired effect. In this case, in particular, both radially inward and outward force components on the arc must be avoided.

According to the invention, this object is achieved by providing two pot-shaped contacts arranged coaxially with each other, and providing slits inclined in opposite directions in the contact supports of both contacts. The body comprises a closed contact ring, the end faces of which form contact contact surfaces, and the free surfaces of both contact rings are each provided with a bevel facing radially inwardly and in the direction of This is achieved by providing a zone approximately in the radial direction of the ring and/or contact support in contact with the contact ring, with a zone having a lower conductivity than the material of the contact support.

This zone of low conductivity acts to divide the conduction of current from the contact support to the contact contact surfaces of the contact ring, with the current component within the contact ring extending generally in a radial direction. The magnetic fields of these radial current components each exert a Lorentz force on the arc, which is oriented radially with respect to the center of the strip contact contact surface and stabilizes the arc discharge on the contact ring. can be made into The arc therefore neither moves into the recess of the pot-shaped contact nor toward the outer edge.

Oppositely inclined slits in the contact supports of coaxially arranged contacts cause an azimuthal component of the Lorentz force driving the arc to act on the contact ring. The arc rotates in a circular orbit between the contact surfaces.

The tilting of the contact ring prevents arcs from being ignited at locations of the contact contact surface where a stabilizing effect cannot yet occur. Furthermore, this embodiment allows high contact pressures to be achieved due to the contact contact surface which is suitably small relative to the width of the contact carrier.

In order to obtain a skin effect of the band on the current component, the electrical resistance of the band is advantageously greater than the electrical resistance of the contact carrier, at least twice, in particular at least three times. A particularly simple and effective embodiment of the contact device is obtained by forming the zone as a recess which is evacuated together with the periphery of the contact device, for example together with the interior of an arcing chamber of a vacuum switchgear. .

Zones of high electrical resistance can be obtained by inserting auxiliary materials with increased resistance, for example by diffusion or alloying. For example, tin, bismuth, phosphorus or arsenic are suitable for this purpose. For this purpose,
The surface of the contact ring facing the contact support is provided with a coating of, for example, a resistive material, which material is then melted or permeated into the contact ring. Subsequently, the coating is again removed from the surface of the contact ring.

A suitably shaped resistive material may also be inserted into the recess. This insert consists of a ferromagnetic material, for example iron, which increases the stabilizing forces acting on the arc.
The insert may also be formed from an insulating material, such as a ceramic body. Furthermore, metals with low electrical conductivity, such as chromium, chromium-copper or cobalt, may also be used as inserts. Graphite is also suitable as an insert.

The insert is advantageously designed in such a way that in the current path at least substantially perpendicular to the current direction there is a gap between the insert and the contact carrier or between the insert and the contact ring. Advantageously, the size of this gap is selected to be at least as large as the axial component of the width of the slit in the contact carrier. The gap width should generally not exceed 0.2mm.

In a special embodiment of the contact device, a recess is provided in the surface of the contact support that contacts the contact ring, and the insert consists of the material of the contact ring. In this embodiment, the contact ring can be made as a profile with a ring-shaped projection, which extends into a recess in the contact support. The height of the protrusion is preferably slightly smaller than the depth of the recess. The above-mentioned gap is formed between the end face of the protrusion and the bottom of the recess.

The contact ring is made of a material with high temperature stability, burnout resistance and mechanical strength. Such properties are, for example, possessed by sintered materials containing chromium and copper as main components. In conjunction with a contact ring consisting of a metal-impregnated metal matrix, for example a chromium-copper matrix, it is advantageous to use the impregnating metal of the contact ring, for example one containing copper, as the material of the contact carrier. The contact ring, which has at least the part that adjoins the contact carrier, can be produced by the so-called metal backing method, in which the contact ring and then the carrier are cast in a common working step. The insert can be inserted as a molded body and be surrounded by the casting material during casting, or can be subsequently removed again during appropriate shaping. In this embodiment, for example, both the contact ring and the adjacent parts of the contact carrier are provided with a common recess. This common structural part is fixed, for example soldered, to the bottom of the contact.

In a special embodiment of the contact, the electrical conductivity of the contact ring is significantly lower, in particular at most 1/3 of the electrical conductivity of the contact carrier. A higher resistance of the contact ring compared to the contact support is obtained by the use of a chromium-copper matrix. Such a high resistance can be achieved by increasing the content of suitable additives in the contact ring, e.g. up to about 15% iron, or up to about 20% cobalt, or by adding only one of iron and cobalt. obtained by.

Embodiments of the present invention will be described below with reference to the drawings. The figure shows two pot-shaped contacts disposed coaxially and opposite each other, and different examples are shown in cross section on both sides of a common rotation axis in FIGS. 1 to 4. Note that in FIG. 1, some hatchings on the cut surface are not shown for ease of viewing.

In the embodiment of the contact arrangement according to FIG. 1, a particularly flat pot-shaped contact 2 with an outer diameter of, for example, 2R = 75 mm and an inner diameter of 2r = 45 mm is provided with a contact carrier with a height H of, for example, 13 mm. 4 and a base portion 6 having a conductive portion 8. Contact support 4
has an inclined slit 10, the angle of inclination α of this slit relative to the axis of rotation 18 is chosen such that the end faces of the cement respectively occurring between the two slits do not overlap in the azimuthal direction. This means that one of the slits in the contact ring 12
This is guaranteed when starting from one edge and meeting the adjacent slit vertically upwards. Similarly, starting from the end of this slit in the contact base 6, it runs vertically downwards and hits an adjacent slit, as indicated by an arrow not shown in detail in the drawing. Due to this inclination of the slit 10, the current flowing through the resulting segment always has a directional component oblique to the axis 18, which together with the arc created between the contacts and the current in the corresponding segment of the opposing contact A current loop is formed which exerts an azimuthal Lorentz force on the arc, thus causing it to rotate between the contacts. Due to the above-mentioned inclination of the slots 10, at least one slot (not shown) in the contact carrier 4 always passes through the cutting plane.

A contact ring 12 made of a so-called contact material is provided on the end face of the contact support 4, and this material has high burnout resistance, temperature stability, and mechanical strength, such as a burnout material containing chromium and copper. It is a binding material.
The height h of the contact ring 12 is, for example, 4 mm.
The surface of the contact ring 12 facing the contact support 4 is provided with a ring-shaped recess 14, which forms a zone exhibiting a high electrical resistance to the current I, so that the current I flows across the contact support. Already in body 4 it is divided into two component partial currents I ₁ and I ₂ which are distributed in contact ring 12 at contact surface 13 .
It is oriented approximately radially with respect to the axis of rotation near the end face forming the .

The contact ring 12 has one ramp 1 on each side of the contact surface 13 in the radial direction.
It is equipped with 9 and 20. Inclined portion 19 of its outer edge
is such that the radial distance a between the outer edge of the contact surface 13 and the outer wall of the contact support 4 is larger than half the distance b between the outer edge of the recess 14 and the outer wall of the contact support 4. It is formed. Similarly, the sloped portion 20 on the inside of the contact ring 12 is formed. By configuring the inclined portion of the contact ring 12 in this way, even when an arc occurs at the edge of the contact surface when the contact is released, the radial component of the partial current I ₁ is also reduced by the partial current The radial component of I ₂ is also guaranteed.

In a special embodiment of the contact arrangement according to FIG.
Especially chosen smaller than this. This makes it possible to enhance the stabilizing effect on the arc due to the large radial current component. The edges of the contact surface also contribute to stabilization. The recess 14 is provided with a ring-shaped insert 16 made of a material that has a higher electrical resistance than the material of the contact carrier 4 . The insert may for example be made of an electrically insulating material, for example ceramic. Also suitable are ring-shaped elements made of graphite or metallic resistive materials, such as chromium or iron, for example.

Instead of the recess 14 with a suitable insert 16 of resistive material shown in FIG. It can also be produced by inserting elevated materials, for example by alloying or by diffusion. The material of the contact ring 12 in the zone of increased electrical resistance or the material of the insert in this zone is advantageously chosen such that the electrical resistance in this zone is higher than the resistance of the support 4 by a factor of at least 2. .

In the embodiment according to FIG. 3, a recess 14 containing a ring-shaped insert 16 is provided on the end face of the contact carrier 4 facing the contact ring 12. In the embodiment according to FIG. The insert 16 is secured to the contact ring 12;
Advantageously, it forms an integral part with this contact ring and is therefore made of the same material. The height of the insert 16 forming the protrusion is selected to be somewhat smaller than the depth of the recess 14, so that a gap δ is created between the end face of the insert 16 and the bottom of the recess 14, which gap is used for contact support. It is advantageous to allow small displacements of the body 4.

The contact device illustrated in the example has a voltage of 12 kV, an operating current of 1000 A, and a rated short circuit current.
Suitable for 40000A. During operation, such contacts are pressed together with a correspondingly high pressing force, for example F=4000 N, which force causes an elastic deformation of the contact support 4 and the base 6. Due to this elastic deformation, the gap δ between the insert 16 and the contact base 6 as shown in FIG. 3 becomes smaller, and the contact support 4
This gap is closed as the deformation of F increases, so that this gap sufficiently reduces further deformation of the contact due to the contact pressing force F. However, the gap width δ is
The slit 10 is limited to a selected value such that it is not completely closed due to increased deformation of the contact carrier 4.

Optionally, in the embodiment of the contact according to FIG. may occur.

Furthermore, according to FIG. 4, a recess 14 is provided which is also located in the contact carrier 4 and in which the contact ring 12 is located.
It also extends therein and is evacuated with the contact device or has an insert (not shown). This insert can be placed in the contact ring or in the contact support 4.
The size of the recess can be such that a gap as shown in FIG. 3 is created.

According to a particularly simple method for making contacts:
The contact carrier 4 is made by impregnating the matrix metal of the contact ring 12 and at the same time by so-called lining. During metal lining, the recess 14 according to FIG. 4, for example, is filled with a molded body, which is shaped in such a way that it can be removed again after the carrier 4 has been cast. The metal matrix of the contact ring 12, for example chromium-copper, and the impregnated metal of the contact support, for example copper (possibly with predetermined additives), are then firmly fused together. Subsequently, the contact carrier 4 is fixed with its end face consisting of two concentric ring surfaces to the contact base 6 and soldered, for example, with hard solder. In order to align the common element made up of the contact ring 12 and the contact support 4, the base part 6 is provided with a suitable ring-shaped projection, not shown in detail in the drawings. The radial width is equal to the radial width of the recess 14.

Optionally, it may also be expedient to use the above-mentioned molded body as an insert for the recess 14. The molded body can then be surrounded by the material of the contact carrier 4 and the contact ring 12.

The slit 10 may extend through at least a part of the base 6.

Next, the principle of operation of the present invention will be explained with reference to FIGS. 5 and 6. In the present invention, since the contact supports of both contacts have slits inclined in opposite directions, as shown in FIG. When the contacts are opened, the magnetic field RM in the gap between the contacts
have opposite polarities, and therefore their lines of magnetic force run approximately radially within the contact gap, as shown by dashed lines in the figure. The arc L is caused by the components of the current loop S formed by the arc L and the current I.
rotates on the contact ring 12. Due to the slopes provided according to the invention on the free surfaces of both contact rings 12 and the recesses 14 or inserts 16 which form zones of low conductivity compared to the material of the contact carrier, the current I is It is prevented from flowing in the direction perpendicular to the arc running surface of the contact ring 12, and is divided into two current components I ₁ and I ₂ radially and in opposite directions, as shown in FIG. Due to the Lorentz force, the foot point of the arc L is the contact ring 1
2, that is, the arc running surface of the contact ring 12, and the arc L is stably held between the contact rings 12 during its rotation.

[Brief explanation of the drawing]

1 to 4 are sectional views of different embodiments of the invention, respectively, shown on both sides of a common axis of rotation, and FIGS. 5 and 6 are illustrations of the operating principle of the invention. 2... Pot-shaped contact, 4... Contact support,
6... Contact base portion, 8... Conductive portion, 10... Slit, 12... Contact ring, 13... Contact surface, 14... Recess, 16... Insert, 19,
20... Inclined part of the contact ring.

Claims (1)

[Claims] 1. Two pot-shaped contacts arranged coaxially with each other, contact supports of both contacts are provided with slits inclined in opposite directions, and the contact supports are provided with slits inclined in opposite directions. a closed contact ring, the end face of which forms a contact contact surface, the free surfaces of both contact rings each having a radially inwardly and outwardly inclined slope; and/or for a vacuum switchgear, characterized in that the contact support has a band having a lower conductivity than the material of the contact support at approximately the center in the radial direction of the portion of the contact support that is in contact with the contact ring. Contact device. 2. A contact device for a vacuum switchgear according to claim 1, wherein the width of the band in the radial direction is larger than the width of the contact surface. 3. A contact device for a vacuum switchgear according to claim 1 or 2, wherein the zone is comprised of a recess. 4. A contact device for a vacuum switchgear according to claim 3, wherein the recess has an insert. 5. A contact device for a vacuum switchgear according to claim 4, wherein the insert is made of a ferromagnetic material. 6. A contact device for a vacuum switchgear according to claim 4, wherein the insert is made of an insulator. 7. A contact device for a vacuum switchgear according to claim 4, wherein the insert is made of a material with high electrical resistance. 8. A contact device for a vacuum switchgear according to claim 7, wherein the insert is made of chromium or chromium/copper. 9. A contact device for a vacuum switchgear according to claim 1, characterized in that the band is made of a material having at least one additive material with increased electrical resistance. 10. A contact device for a vacuum switchgear according to claim 9, wherein the additive material consists of tin, bismuth, phosphorus, or arsenic, or some of these materials. 11. The contact device according to any one of claims 3 to 8, characterized in that the contact support body has a recess, and the insert body is fixed to the contact ring. A contact device for vacuum switchgear. 12. A contact device for a vacuum switchgear according to claim 11, wherein the insert is made of the material of the contact ring. 13. A contact device according to claim 12, characterized in that the insert forms a common piece with the contact ring. 14. The contact device for a vacuum switchgear according to claim 4, wherein the recess has a gap between the insert and the contact support or the contact base. 15. The contact device according to any one of claims 1 to 12, characterized in that the contact ring is made of a chromium-copper matrix, and the contact support is made of copper. Contact device for opening/closing equipment. 16. The contact device according to any one of claims 1 to 15, for use in a vacuum switchgear, characterized in that the conductivity of the contact ring is lower than the conductivity of the contact support. Contact device. 17. In the contact device according to claim 16, the contact ring is made of up to 15% iron or 20% iron.
A contact device for a vacuum switchgear, characterized in that it contains up to % cobalt, or iron and cobalt. 18. A contact device according to any one of claims 1 to 17, characterized in that the inclined slit of the contact support extends at least partially through the contact base. A contact device for vacuum switchgear.