EP2059938B1 - Vacuum circuit breaker - Google Patents

Abstract

The invention relates to a vacuum switch, especially a vacuum circuit breaker, for medium and high voltages, comprising a mobile switch unit arranged inside a vacuum switch compartment (1) and provided with mutually mobile elements including a contact tappet (17), an insulator (18), and a driving or switching rod (11) introduced into the vacuum switch compartment (1) by means of metal bellows. Said vacuum switch also comprises a fixed contact inserted into the housing of the vacuum switch compartment (1). The upper end of the insulator (18) is fixed to the contact tappet (17), and the lower end of the insulator (18) is fixed to the driving or switching rod (11). The contact tappet (17) is connected to a conductor (8) by a flexible, electroconductive connection (20), said conductor being electroconductively connected to at least one laterally arranged output contact (6). The aim of the invention is to enable a simplified, more economical and improved design of a flexible conductive connection to the output contact. To this end, the inner cross-sectional surface of the vacuum switch compartment (1) is covered, at the level of the at least one output contact (6), around the contact tappet (17), by film-type or plate-type electroconductive covering elements (26) which are arranged over each other in layers and at least partially cover each other.

Description

The invention is directed to a vacuum switch, in particular vacuum circuit breaker, for medium and high voltage with a movable switching unit disposed within a vacuum switching chamber, which movably comprises a contact tappet, an insulator and a driving or switching rod inserted into the vacuum interrupter chamber through a metal bellows, and a fixed contact inserted into the housing of the vacuum interrupter chamber, wherein the upper end of the insulator is fixedly connected to the contact plunger and the lower end of the insulator to the drive or shift rod, and wherein the contact plunger has a conductive connection to a conductor which is in current-conducting Connection with at least one laterally arranged outgoing contact is.

Circuit-breakers offer the possibility of dissolving existing electrical connections, whereby electrical currents of up to 160 kA can be switched. These currents occur, for example, when there is a short circuit or a ground fault in high voltage networks. Circuit-breakers can not only switch normal operating currents and low overload currents, just like switch-disconnectors, but also separate high overload currents and maximum short-circuit currents. As an overcurrent protection device with a very high switching capacity in the range of 80 kA - 160 kA, you can switch operating equipment or system components both undisturbed and for a limited time in a faulty state, eg in the event of a short circuit. Types of circuit breaker are in addition to gas pressure switches and circuit breakers vacuum switch. With vacuum switches, the contacts are under vacuum to avoid an arc.

From the DE 100 24 356 C1 a gas-insulated switchgear with vacuum switches is known in which are arranged within a filled with insulating gas vessel of the gas-insulated switchgear designed as a vacuum switch circuit breaker. A vacuum switch each comprises a vacuum switching chamber, which is designed as a vacuum space. Within the vacuum space or this vacuum interrupter chamber a fixed contact plunger and a movable contact plunger are arranged, which are led out with their respective contact rods from the vacuum space of the vacuum interrupter chamber. Here, the contact rod of the movable contact plunger is led out by a bellows from the vacuum space or the vacuum interrupter chamber. Outside the vacuum interrupter chamber, this plunger communicates with a power supply carrier and an actuator is provided for actuating the selector rod of the movable contact plunger. The insulating capacity of such vacuum switch must not only ensure the necessary insulating capacity of the switching and isolating distance, but also ensure that leakage or surface currents in the open state of the separation path does not flow from the upper port of the vacuum interrupter chamber to the lower port, the connected power supply carrier. To ensure this, it is necessary to have corresponding distances between the connections and the arrangement of the vacuum switch within a vessel filled with insulating gas. This leads to large types of vacuum switches and thus equipped switchgear.

Furthermore, it is known that the arc quenching within a vacuum interrupter chamber of a vacuum switch under vacuum requires the utilization of the magnetic field accompanying the electric current. The forced movement of the arc under the influence of the magnetic field level contact surface of the switching contact pieces of fixed contact and contact plunger, which are arranged within the vacuum interrupter chamber of the vacuum switch. Known switch contact pieces touch completely with their circular face under the action of an external force when the separation distance is closed. This contact force essentially results from the force applied by a spring assigned to the external drive. In order to influence the strength and direction of the magnetic field accompanying the current, the switching contact pieces have internal recesses which induce an axial or vertical magnetic field depending on their direction. The movable in the longitudinal direction switching contact of the contact plunger is moved at the startup at high speed and then bounces on the switching contact of the fixed contact and repeatedly hits with a frequency corresponding to the drive system and the movable mass. This impact causes during the operating times of the vacuum switch on the one hand, mechanical stress, which strain the metal bellows through which the movable contact plunger is led out of the vacuum chamber. There is a risk that after a certain number of switching cycles cracks occur, which then lead to a collapse of the vacuum in the vacuum chamber. Due to the impact of the switching contact of the movable contact plunger with repeated stop movements, however, a switch-on procedure also leads to a multiple formation of a switch-on arc. This leads to overheating of the material on the flat contact surfaces and thereby to multiple local welds of the end contacts. During a switch-off operation, the welded areas of the end contacts tear open due to the power of the switch-off drive. In this case, there is the danger that form sharp-edged tips, the homogeneity of the electric field at the contact surfaces of the end contacts and thus significantly reduce the breakdown voltage between the open end contacts.

In order to limit the use of insulating gas if necessary, it is known to arrange the outgoing contact and current terminal carrier with electrically conductive connection to the load conductor in or on the vacuum chamber or vacuum interrupter chamber and to connect via a flexible conductor with the movable in the vacuum interrupter contact pad. In this case, furthermore, the movable contact plunger arranged in the vacuum interrupter chamber is connected via an isolator to a drive or shift rod leading out of the vacuum interrupter chamber. Such, generic vacuum switch is from the DE 199 64 249 C2 known. In these switches, there is now the problem that the electrically conductive flexible connection between the movable contact plunger and the load conductor or the outgoing contact producing conductive connection must be flexible so that they can follow the longitudinal axial movement of the movable contact plunger during switching on and off. This necessary flexibility must be ensured over a long period of time and many switching cycles, so that the vacuum switch has a sufficient service life. From the DE 199 64 249 C2 the formation of a conductive connection by means of several layered superimposed thin copper film films is known. This leads in vacuum to the problem that form oxide layers that stick together and over time prevent the flexibility of the conductive connection. To solve this problem is in the DE 199 64 249 C2 proposed to construct the conductive connection by the alternating, layered construction of conductor metal layers and adhesion prevention layers or to arrange conductive connections within the vacuum interrupter chamber in a protected space, so that arcing products generated when an arc occurs can not be deposited on the flexible, conductive connection.

A disadvantage of this embodiment is that either a further housing must be provided within the vacuum interrupter chamber, in which the conductive connection is arranged protected, resulting in a significantly increased assembly costs, or it is a complex structure of the conductive connection is necessary that must be formed alternately to a conductive layer an adhesion prevention layer.

The invention has for its object to provide a solution that allows an improved switching and contact surface design.

In a vacuum switch of the type described, this object is achieved in that the fixed contact and the contact plunger each having a switching contact piece having an outer switching and contact surface and a relative thereto movable inner switching and contact surface. Refinements and developments of the invention will become apparent from the dependent claims.

The invention provides an improved switching and contact surface design of the switching contacts of a vacuum switch, which improves the durability of the switching and contact surfaces and thus the switching contact pieces having these surfaces. Due to the formation of outer and inner switching and contact surfaces and their relative mobility to each other, it is possible in a moving apart of the switching contact pieces to form a separation path, the inner switching and contact surfaces of Fixed contact and movable contact plunger as long as to keep in conductive connection to each other until the outer switching and contact surfaces of the respective switching contact pieces are far enough away from each other that an emerging and occurring arc can not skip these outer switching and contact surfaces. The arc then forms on further moving apart and the inner switching and contact surfaces only between them. These are designed accordingly high strength and burn-off and abrasion resistant, so that they are sufficiently durable. The surfaces of the outer switching and contact surfaces, however, are highly conductive, since they only have to conduct the rated current. Particularly suitable materials for the outer switching and contact surfaces are copper-silver alloys, for the inner switching and contact surfaces, these are copper-chromium alloys.

Fig. 1

schematisch in perspektivischer Darstellung eine Außenansicht des erfindungsgemäßen Vakuumschalters,

Fig. 2

den Vakuumschalter gemäß Fig. 1 nach Aufbringen einer äußeren, umhüllenden Gießharzschicht zur Ausbildung eines Gießharzgehäuses,

Fig. 3

einen Längsschnitt durch die Vakuumschaltkammer des Vakuumschalters,

Fig. 4

eine Aufsicht auf eine leitende Verbindung,

Fig.5

in schematischer Darstellung einen Schnitt längs der Achse A-A von Fig. 4,

Fig. 6

eine perspektivische Ansicht der leitenden Verbindung in Ansicht von unten,

Fig. 7

eine schematische Ansicht der leitenden Verbindung in Aufsicht von oben,

Fig. 8

eine Aufsicht eines Verbindungselementes

Fig. 9

einen Schnitt durch das Verbindungselement längs der Linie B-B von Fig. 8,

Fig. 10

das Verbindungselement gemäß Fig. 8 und 9 in perspektivischer Ansicht von oben,

Fig. 11

in perspektivischer Darstellung ein Schaltkontaktstück eines Festkontaktes und/oder eines Kontaktstößels,

Fig. 12

das Schaltkontaktstück gemäß Fig. 11 mit Durchsicht durch die innere Schalt- und Kontaktfläche,

Fig. 13

in schematischer Darstellung ein Schnitt durch das Schaltkontaktstück nach Fig. 11 und 12 bei eingefahrener, innerer Schalt- und Kontaktfläche und in Fig. 14 in schematischer Darstellung das Schaltkontaktstück nach Fig. 13 mit ausgefahrener innerer Schalt- und Kontaktfläche.

A development of the invention is to arrange electrically conductive and the inner switching and contact surface supporting support heads spirally. This embodiment allows the formation of an axial magnetic field, in which larger arc than diffuse arcs can be configured.

Fig. 1

1 is a schematic perspective view of an external view of the vacuum switch according to the invention;

Fig. 2

according to the vacuum switch Fig. 1 after application of an outer, encapsulating casting resin layer to form a casting resin housing,

Fig. 3

a longitudinal section through the vacuum interrupter chamber of the vacuum switch,

Fig. 4

a supervision of a conductive connection,

Figure 5

in a schematic representation of a section along the axis AA of Fig. 4 .

Fig. 6

a perspective view of the conductive connection in bottom view,

Fig. 7

a schematic view of the conductive connection in plan view from above,

Fig. 8

a plan view of a connecting element

Fig. 9

a section through the connecting element along the line BB of Fig. 8 .

Fig. 10

the connecting element according to 8 and 9 in a perspective view from above,

Fig. 11

in perspective view a switching contact piece of a fixed contact and / or a contact plunger,

Fig. 12

the switching contact piece according to Fig. 11 with a view through the inner switching and contact surface,

Fig. 13

in a schematic representation of a section through the switching contact piece FIGS. 11 and 12 with retracted, inner switching and contact surface and in Fig. 14 in a schematic representation of the switching contact piece Fig. 13 with extended inner switching and contact surface.

The shows in perspective view the vacuum interrupter chamber 1 of a vacuum switch. This consists of an upper gas-tight ceramic cylinder 2 and a lower gas-tight ceramic cylinder 3. The upper ceramic cylinder 2 is closed with a terminal cover 4. Between upper ceramic cylinder 2 and lower ceramic cylinder 3, a contact ring 5 is formed. The contact ring 5 has outgoing contacts 6, via which a ring 7 of a conductor 8 with a load conductor 9 is in electrically conductive connection. By means of a bellows 10 made of metal, a drive or shift rod 11 is vacuum-tight in the interior of the vacuum interrupter chamber 1 introduced. In the vacuum interrupter chamber 1, the interior thus forms a vacuum chamber 12, in which a high vacuum of 10 ^-7 to 10 ^-9 Torr or 10 ^-7 to 10 ^-9 mbar is formed. On the outside, the fully assembled vacuum interrupter chamber 1 of the vacuum interrupter is surrounded by a cast resin jacket 13 or a cast resin housing, as is known Fig. 2 is apparent.

In the Fig. 3 is a schematic sectional view of the vacuum chamber 12 of the vacuum interrupter chamber 1 in the closed position of switching contact pieces 14a, 14b, ie an electrically conductive connection from a not shown generation line conductor 15 by a fixed contact 16 and a movable contact plunger 17 and the conductor 8 and the outgoing contact 6 through the vacuum chamber 12 through to the load conductor 9. In this position, an isolating distance is not formed. By moving the movable contact plunger 17 by means of coupled via a ceramic insulator 18 drive or switching rod 11 in the direction of arrow 19, the switch contact pieces 14a, 14b move apart so far that between them a distance is formed, which then forms a separation distance.

The illustrated vacuum switch is a vacuum switch for medium and high voltage. Here, within the vacuum interrupter chamber 1 is a movable Switching unit is formed, which comprises the lower switching contact piece 14b, the contact tappet 17 fixed thereto, the insulator 18 fixed thereto and the drive or shift rod 11. At this movable switching unit, a flexible, electrically conductive connection 20 with a conductor 8 or for the formation of a conductor 8 is arranged at the level of the outgoing contacts 6 or of the contact ring 5 or current connection carrier on the contact plunger 17. About this conductive connection 20 of the electric current flow to the load conductor 9 is made, so that there is a current-conducting connection to at least one of the outgoing contacts 6.

The conductor 8 comprises a ring 7, which is arranged fixed on the inside of the contact ring 5. Furthermore, the conductor 8 comprises a plunger ring 21, which is arranged with its inner surface, preferably stationary, on the outer circumference of the contact plunger 17. The plunger ring 21 and the ring 7 are connected to each other via a plurality of connecting elements 22.

A single connecting element 22 is in FIG. 8 shown in supervision. It consists of an outer ring 23 and an inner ring 24 and four support members 25 connecting the outer ring 23 and the inner ring 24, wherein the outer ring 23, the inner ring 24 and the support members 25 of an electrically conductive, foil-like or plate-like Material exist. Like from the FIGS. 9 and 10 it can be seen, form the support members 25 from the outer ring 23 to the inner ring 24 toward rising cover 26, so that they span the interior of the outer ring 23 from one side to the diametrically opposite side arcuately with the involvement of the inner ring 24.

As seen from the supervision in Fig. 4 can be seen, which is a view in the direction of the longitudinal axis 26 of the contact plunger 17 in plan view from above, are clamped between the plunger ring 21 and the ring 7 a plurality of connecting elements 22, 22 ', 22 ", 22"' one above the other in the direction of the axis 26 arranged. In this case, each of the superimposed connection element 22, 22 ', 22 ", 22"' respectively offset in the direction of rotation about the axis 26 by 10-15 degrees to each other, so that all these connecting elements 22 in total with their respective cover elements 26, 26 ' or support elements 25, 25 'overall cover the area formed between the ring 7 and the plunger ring 21 annular surface area-covering. But this is also a total of the free inner annular cross-sectional area of the vacuum chamber 12 and the vacuum interrupter chamber 1 covered by the covering 26 of the connecting elements 22 across the board. Due to the respective layered superimposition of the cover elements offset by 10-15 degrees, they each overlap with a partial surface of their support elements 25. The connection elements 22 thus form the flexible part of the conductive connection 20 and, together with the ring 7 and the plunger ring 21, the conductor as a whole 8 off. How out Fig. 5 it can be seen, the connecting elements 22 with their outer ring 23 each fixed in the ring 7 and with its inner ring 24 fixedly arranged in the tappet ring 21, wherein between the respective superposed individual connecting elements 22, a distance in the longitudinal axial direction is present, so that through the Connecting elements 22 with their cover elements 26 and support members 25 through an air or gas space connection is continuous, on the other hand but in supervision according to Fig. 4 an opaque cover is provided by these connecting elements 22. In the assembly position, the closed position of the switching contact pieces 14a, 14b already results appropriate and in Fig. 3 illustrated positioning of the connecting elements 22 with the off Fig. 6 apparent concave underside and the out Fig. 7 apparent convex trained top. The cover elements 26 and the support elements 25 are designed so flexible that they accompany the movement of the contact plunger 17 in the individual switching operations from the closed switching position to the open disconnect position and back again.

The upper switching contact piece 14a fixedly connected to the fixed contact 16 and the lower switching contact piece 14b fixedly connected to the movable contact plunger 17 are each of identical design, so that the description below will be described solely with reference to FIG Fig. 11-14 illustrated lower switching contact piece 14b is explained. Each switch contact piece 14a, 14b has a two-part contact and button 28, which comprises an annular outer switching and contact surface 29 and a circular inner switching and contact surface 30. The outer switching and contact surface 29 is fixed in position on a carrier body 31 of the respective switching contact piece 14a, 14b arranged and the inner switching and contact surface 30 is arranged relative to the outer switching and contact surface 29 movable on support heads 32. In addition, on the inside engages the inner switching and contact surface 30 in the direction of the axis 27 of the movable contact plunger 17 by means of the force of springs 33 movable inner punch or inner plunger 34 at. In the main body or carrier body 31 springs 33 are arranged with its one end on a base surface 36, wherein abut with its other end to a stop ring 35 of the inner plunger 34. In the in Fig. 13 shown retracted position of the inner switching and contact surface 30 are the switching and contact surfaces 29, 30 of upper switching contact piece 14 a and lower switching contact piece 14b flat to each other, so that a flat contact and button 28 is formed. In this position, the springs 33 are placed over the stopper ring 35 in its compressed position. As soon as the movable contact plunger 17 is moved to the position for forming a separating gap, the outer switching and contact surfaces 29 of the upper and lower switching contact pieces 14a, 14b move away from each other. The inner switching and contact surfaces 30 of the upper and lower switching contact piece 14a, 14b remain but initially in flat succession, as long as the driving force of the now relaxing springs 33 is sufficient to push the plunger 34 into the in FIG. 14 shown extended position of the inner switching and contact surface 30 to move. If now the contact plunger 17 further away from the fixed contact 16, remove the inner switching and contact surfaces 30 of the lower and upper switching contact piece 14a, 14b from each other, so that now the separation distance is formed. In the opposite case, when the contact plunger 17 moves toward the fixed contact 16, first the inner switching and contact surfaces 30 reach into flat contact with each other, the inner switching and contact surfaces 30 against the force of the springs 33 relative to the outer switching and contact surfaces 29 moves until the in FIG. 13 shown, retracted position of the inner switching and contact surfaces and thus the in FIG. 3 shown contact position of the switching contact pieces 14a, 14b is reached.

The outer switching and contact surfaces 29 are made of an annular material which is highly conductive. This material is suitable for transferring the nominal current which is to be conducted by the vacuum switch in each case with very little resistance. The inner switching and contact surfaces 30, however, consist of a disc-shaped material, the high-strength and especially is resistant to abrasion and erosion in order to be able to endure and extinguish short-term arc currents. The underlying springs 33 are made of kurzschlusstragfähigem material, such as a copper-tungsten alloy. The material of the outer switching and contact surfaces 29 is in particular oxygen-free and consists for example of a copper-silver alloy. The material of the inner switching and contact surface 30 consists for example of a copper-chromium alloy.

When separating, i. Moving away from fixed contact 16 and contact plunger 17 by a drive mechanism acting on the drive or shift rod 11 initially move the outer switching and contact surfaces 29 away from each other, while the inner switching and contact surfaces 30 due to the springs 33 on the inner plunger 34th applied pressure from the initially uniform contact and button 28 extend and during which carry the resulting short-circuit current. In this case, the extension of the inner switching and contact surfaces 30 is adjusted so that they remain so long adjoining until such a distance is formed between the outer switching and contact surfaces 29, that skipping the resulting / occurring arc on the annulus of the outer switching - And contact surfaces 29 is prevented. Upon further moving apart of fixed contact 16 and contact plunger 17 then separate the inner switching and contact surfaces 30, so that the resulting arc is then held only between these surfaces and deleted after reaching a sufficient distance.

Furthermore, the inner switching and contact surfaces 30 are on support heads 32, which form part of a spiral arrangement of contacts for supporting the inner shift and contact surface 30 are. This makes it possible to generate an axial magnetic field with which larger and stronger arcs can be configured as diffuse arcs. In this case, the inner plunger 34 consists of a configuration of web-like segments 37 on which the support heads 32 are arranged spirally aligned with each other, wherein the support heads 32 are formed and connected electrically conductive.

The representations of the Figures 12 . 13 and 14 are in terms of the function of the springs 33 and the support heads 32 and their arrangement and training as spiral contacts, ie as a helically arranged contacts, simplified only schematically and accordingly.

The insulator 18 is one made of ceramic material. The enclosure of the vacuum interrupter chamber 1 preferably consists of a cast resin jacket or cast resin housing made of a silicone material or silicone casting resin.

Overall, the life and the life cycle of a vacuum interrupter chamber is increased by the combination of various measures, the overall insulation behavior of the vacuum chamber 12 and the vacuum interrupter 1 improved and thus achieved a compact design of the vacuum interrupter chamber 1 and thus a vacuum switch total, with the sake of completeness listed again be that the upper ceramic cylinder 2 and the lower ceramic cylinder 3 made of a gas-tight ceramic material, otherwise a vacuum in the vacuum chamber 12 would not be upright.

Even if this is due to the excellent insulating properties in the inventive Vacuum switch is not necessary, this can be arranged if desired, in a filled with insulating housing of a switchgear.

Claims (7)

1. Vacuum switch, in particular a vacuum circuit breaker, for medium and high voltages, comprising a movable switch unit arranged inside a vacuum switching chamber (1), which switch unit comprises components which move with one another including a contact tappet (17), an insulator (18) and a driving or switching rod (11) which is introduced into the vacuum switching chamber (1) by means of metal bellows (10), and comprising a stationary contact (16) which is inserted into the housing of the vacuum switching chamber (1), the upper end of the insulator (18) being rigidly connected to the contact tappet (17) and the lower end of the insulator (18) being rigidly connected to the driving or switching rod (11), and the contact tappet (17) having a flexible electrically conductive connection (20) to a conductor (8), which has an electrically conductive connection to at least one laterally arranged output contact (6),
   characterised in that
   the stationary contact (16) and the contact tappet (17) respectively comprise a switching contact part (14a, 14b) comprising an outer switching and contact surface (29) and an inner switching and contact surface (30) which can be moved in relation to the outer surface.
2. Vacuum switch according to claim 1, characterised in that the inner switching and contact surface (30) is movable by the force of at least one spring (33) so as to be driven into an extension position which is elevated relative to the outer switching and contact surface (29).
3. Vacuum switch according to either claim 1 or claim 2, characterised in that the inner switching and contact surface (30) is movable against the force of at least one spring (33) so as to be driven from the extension position into a position on a level with the outer switching or contact surface (29).
4. Vacuum switch according to any one of the preceding claims, characterised in that the extension position is calculated in such a manner that, when the extension position is reached and the inner switching and contact surfaces (30) are adjacent to one another, the outer switching and contact surfaces (29) are spaced in such a manner that any electric arc that occurs does not flash over onto the outer switching and contact surfaces (29).
5. Vacuum switch according to any one of the preceding claims, characterised in that the inner switching and contact surface (30) is arranged on electrically conductive support heads (32), preferably of the inner tappet (34), which are arranged in the manner of a mutual spiral.
6. Vacuum switch according to any one of the preceding claims, characterised in that the at least one spring (33) acts, at one end, on a stop ring or support ring (35) of the inner tappet (34) and, at the other end, on a base (36) formed in a supporting member (31) of the upper or lower switching contact part (14a, 14b).
7. Vacuum switch according to any one of the preceding claims, characterised in that the outer switching and contact surface (29) consists of a layer of highly conductive material, in particular a copper-silver alloy, and the inner switching and contact surface (30) consists of a layer of high-strength, erosion- and abrasion-resistant material, in particular a copper-chromium alloy.

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