EP0800190A1 - Power switch - Google Patents

Abstract

The circuit breaker (1) has a cylindrical arc-quenching chamber extending along a central axis (2) and filled with gaseous insulation, preferably sulphur hexafluoride. Axially spaced fixed contacts in the current path are connected together by a movable bridging contact. The arc region (24) between the fixed contacts is swept by gas transferred under pressure from the injection channels. For circuit-breaking the axial pin (3) is driven at a speed between 10 and 20 m/s. It is joined by a linkage to movable contacts so that these move at a lower speed.

Description

TECHNICAL AREA

The invention is based on a circuit breaker according to the preamble of claim 1.

STATE OF THE ART

From the published patent application DE 42 00 896 A1 a circuit breaker is known which has an arcing chamber with two fixed, spaced-apart erosion contacts. The quenching chamber is filled with an insulating gas, preferably SF ₆ gas under pressure. When the arcing chamber is switched on, the two erosion contacts are connected to one another in an electrically conductive manner by means of a movable bridging contact. The bridging contact concentrically surrounds the cylindrical erosion contacts. The bridging contact and the two erosion contacts form a power current path which is only subjected to current when it is switched off. When switched off, the bypass contact slides down from a first of the erosion contacts and draws an arc, which initially burns between the first erosion contact and the end of the bypass contact facing it. As soon as this end reaches the second erosion contact, the arc base commutates from the end of the bypass contact to the second erosion contact. The arc now burns between the two erosion contacts and is blown until the arc extinguishes. The pressurized insulating gas required for the blowing is generally generated by means of a blowing piston connected to the movable bypass contact.

This circuit breaker also has a nominal current path parallel to the power current path, which carries the operating current when the circuit breaker is switched on. The nominal current path is arranged concentrically around the power current path. The bridging contact is mechanically rigidly connected to a movable nominal current contact arranged in the nominal current path. When switching off, the rated current path is first interrupted, the current to be interrupted then commutates to the power current path, where an arc is then initiated and then extinguished, as described above.

Due to its dimensions, the bridging contact has a comparatively large mass to be moved, which must first be accelerated during switching operations and then braked. The circuit breaker drive must provide the energy required for this.

Another circuit breaker is known from the published patent application DE 31 27 962 A1, which has an arcing chamber with two fixed, spaced-apart erosion contacts. The quenching chamber is filled with an insulating gas, preferably SF ₆ gas under pressure. When the arcing chamber is switched on, the two erosion contacts are connected to one another in an electrically conductive manner by means of a movable bridging contact. The bridging contact concentrically surrounds the cylindrical erosion contacts. Of the Bridging contact is also designed here as a nominal current contact. Opening this circuit breaker is similar to the circuit breaker described above.

Due to its dimensions, this bridging contact also has a comparatively large mass to be moved, which must be accelerated and braked during switching operations. The circuit breaker drive must provide the energy required for this.

From the patent specification CH 651 420 a circuit breaker is known which has a fixed blowing volume, into which insulating gas produced by a pressure source and under high pressure is fed. The high pressure is reduced when entering the blowing volume, so that only a comparatively low blowing pressure is available for blowing the arc.

A circuit breaker is known from the patent specification CH 644 969, which has two blow volumes connected in series. The clean insulating gas present in the first blowing volume is compressed by means of a piston when the movable power contact is switched off. In addition, hot gas heated by the arc in the arc zone flows into this first blowing volume, mixes with the clean insulating gas to form a gas mixture and thus increases the pressure in this first blowing volume. After a predetermined stroke of the movable power contact, a second blow volume is separated from the first blow volume, the gas mixture in the two blow volumes is then further compressed depending on the stroke. Both blowing volumes, independently of one another, interact with the pressure in the arc zone of this circuit breaker in the further course of the opening movement. However, it is expected that at the same time There are pressures of the gas mixture in approximately the same order of magnitude in each of the two blowing volumes, whereby, due to the larger cross section of the connection between the volume of the first blowing volume, which is somewhat reduced in volume, and the arc zone, somewhat higher pressures can currently occur in this than in the second blowing volume. These pressure differences are caused solely by the thermal effects of the arc. The pressure build-up in the two blowing volumes will differ from switch-off to switch-off, depending on the size of the current to be interrupted and the moment of contact separation.

PRESENTATION OF THE INVENTION

The invention, as characterized in the independent claims, solves the problem of creating a circuit breaker of the type mentioned at the outset, which has an improved breaking capacity.

The circuit breaker is equipped with a high-pressure injection, which allows a targeted increase in the blowing pressure in the arc zone. The high-pressure injection takes place directly into the arc zone, which enables particularly intense blowing of the arc. In the circuit breaker according to the invention, comparatively high blowing pressures are achieved with simple means.

The circuit breaker has fixed erosion contact arrangements connected to a bypass contact. Since the bridging contact is arranged in the interior of the erosion contact arrangements, it can be designed with an advantageously small diameter and thus with a particularly small mass. The bypass contact is here as a simple switching pin formed, which has no resilient contact elements, it is therefore relatively simple and inexpensive to manufacture.

This circuit breaker is operated at a comparatively high opening speed, since the comparatively small mass of the bridging contact can be accelerated effectively even with a comparatively small and advantageously inexpensive drive and can also be braked reliably at the end of the opening movement.

The movable nominal current contact is moved much more slowly than the switching pin connected to it via a speed-reducing lever linkage. The service life of the rated current contacts is advantageously increased due to the lower mechanical stress, which significantly improves the availability of the circuit breaker. The movable nominal current contact is also housed in a volume that is completely separate from the area of the circuit breaker in which hot gases and combustion particles generated by the arc occur. These hot gases and combustion particles can therefore not negatively influence the nominal current contacts, which advantageously increases their stability and thus their service life.

A further advantageous reduction in the cost of the circuit breaker according to the invention results from the fact that the erosion contact arrangements and in some cases also the housing parts are constructed from identical parts in mirror image to a plane of symmetry.

As a means for increasing the blowing pressure, the circuit breaker has at least one compression unit with at least one first piston-cylinder arrangement, which has at least two pistons connected in series , of which a first compression piston pre-compresses the insulating medium in a first compression volume, and a second compression piston further compresses the pre-compressed insulating medium in a second compression volume separated from the first compression volume. This further compressed insulating medium is introduced directly into the center of the arcing zone through at least one injection channel. This compression in two successive stages results in a particularly high blowing pressure, which allows particularly intense blowing of the arc.

The further developments of the invention are the subject of the dependent claims.

The invention, its further development and the advantages which can be achieved therewith are explained in more detail below with reference to the drawing, which represents only one possible embodiment.

BRIEF DESCRIPTION OF THE DRAWING

• Fig.1 einen Schnitt durch die schematisch dargestellte Kontaktzone einer ersten Ausführungsform eines erfindungsgemässen Leistungsschalters im eingeschalteten Zustand,
• Fig.2 einen Schnitt durch die schematisch dargestellte Kontaktzone einer ersten Ausführungsform eines erfindungsgemässen Leistungsschalters während des Ausschaltens,
• Fig.3 einen Teilschnitt durch die schematisch dargestellte Kontaktzone einer zweiten Ausführungsform eines erfindungsgemässen Leistungsschalters,
• Fig.4 einen stark vereinfachten Schnitt durch einen erfindungsgemässen Leistungsschalter, in der rechten Hälfte der Figur ist der Leistungsschalter im eingeschalteten Zustand dargestellt, in der linken Hälfte der Figur ist der Leistungsschalter im ausgeschalteten Zustand dargestellt,
• Fig.5 einen ersten stark vereinfachten Teilschnitt durch eine erste Ausführungsform eines erfindungsgemässen Leistungsschalters, wobei diese Schnittfläche gegenüber den in den Fig.1 bis 4 dargestellten Schnittflächen um 90° um die zentrale Achse gedreht ist, in der linken Hälfte der Figur ist der Leistungsschalter im eingeschalteten Zustand dargestellt, in der rechten Hälfte der Figur ist der Leistungsschalter nach der Zurücklegung von etwa einem Drittel des Ausschalthubes dargestellt,
• Fig.6 einen zweiten stark vereinfachten Teilschnitt durch die erste Ausführungsform eines erfindungsgemässen Leistungsschalters, wobei diese Schnittfläche derjenigen von Fig.5 entspricht, in der linken Hälfte der Figur ist der Leistungsschalter nach der Zurücklegung von etwa zwei Dritteln des Ausschalthubes dargestellt, in der rechten Hälfte der Figur ist der Leistungsschalter im ausgeschalteten Zustand dargestellt,
• Fig.7 einen dritten stark vereinfachten Teilschnitt durch eine dritte Ausführungsform eines erfindungsgemässen Leistungsschalters, diese Anordnung basiert auf der in Fig.5 auf der rechten Seite gezeigten Anordnung,
• Fig.8 einen vierten stark vereinfachten Teilschnitt durch eine vierte Ausführungsform eines erfindungsgemässen Leistungsschalters, und
• Fig.9 einen fünften stark vereinfachten Teilschnitt durch eine fünfte Ausführungsform eines erfindungsgemässen Leistungsschalters.

Show it:

• 1 shows a section through the schematically illustrated contact zone of a first embodiment of a circuit breaker according to the invention in the switched-on state,
• 2 shows a section through the schematically illustrated contact zone of a first embodiment of a circuit breaker according to the invention during the opening,
• 3 shows a partial section through the schematically illustrated contact zone of a second embodiment of a circuit breaker according to the invention,
• 4 shows a greatly simplified section through a circuit breaker according to the invention, in the right half of the figure the circuit breaker is shown in the switched on state, in the left half of the figure the circuit breaker is shown in the switched off state,
• 5 shows a first, greatly simplified partial section through a first embodiment of a circuit breaker according to the invention, this cutting surface being rotated by 90 ° about the central axis in relation to the cutting surfaces shown in FIGS. 1 to 4, in the left half of the figure the circuit breaker is in switched on state shown, in the right half of the figure, the circuit breaker is shown after covering about a third of the opening stroke,
• 6 shows a second, greatly simplified partial section through the first embodiment of a circuit breaker according to the invention, this sectional area corresponding to that of FIG. 5; in the left half of the figure, the circuit breaker is shown after covering approximately two thirds of the opening stroke, in the right half the figure shows the circuit breaker in the switched-off state,
• 7 shows a third, greatly simplified partial section through a third embodiment of a circuit breaker according to the invention, this arrangement is based on the arrangement shown on the right in FIG. 5,
• 8 shows a fourth, greatly simplified partial section through a fourth embodiment of a circuit breaker according to the invention, and
• 9 shows a fifth, greatly simplified partial section through a fifth embodiment of a circuit breaker according to the invention.

Elements with the same effect are provided with the same reference symbols in all the figures. All elements not necessary for the immediate understanding of the invention are not shown.

WAYS OF CARRYING OUT THE INVENTION

1 shows a schematically represented section through the contact zone 1 of the arcing chamber of an embodiment of a circuit breaker according to the invention in the switched-on state. The quenching chamber is arranged centrally symmetrically about a central axis 2. A cylindrical, metallic switching pin 3 extends along this central axis 2 and can be moved along the central axis 2 by means of a drive (not shown). The switching pin 3 has a dielectrically favorably shaped tip 4, which can be provided with an electrically conductive, erosion-resistant material if required. In the switched-on state, the switching pin 3 electrically bridges a distance a between two erosion contact arrangements 5, 6.

The erosion contact arrangement 5 has a schematically illustrated contact basket 7, which is electrically conductively connected to a shoulder of a plate-shaped carrier 8 made of metal. The contact basket 7 has contact fingers made of metal, which resiliently on the surface of the Put switch pin 3 on. On the side of the carrier 8 facing the erosion contact arrangement 6, an erosion plate 9 has been connected to this carrier 8 using one of the known methods, in such a way that the ends 10 of the contact fingers are protected against erosion. The erosion plate 9 is preferably made of graphite, but it can also consist of other electrically conductive, erosion-resistant materials such as sintered tungsten copper connections. The surface of the erosion plate 9 facing away from the carrier 8 is protected against arcing by means of an annular cover 36 made of an erosion-resistant insulating material. In addition, the cover 36 prevents the arc base from moving too far into the storage volume 17.

The structure of the erosion contact arrangement 6 corresponds to that of the erosion contact arrangement 5, but it is arranged as a mirror image of the latter. A dash-dotted line 11 indicates the level of reflection. The erosion contact arrangement 6 has a schematically illustrated contact basket 12, which is connected in an electrically conductive manner to a shoulder of a plate-shaped carrier 13 made of metal. The contact basket 12 has contact fingers made of metal, which resiliently rest on the surface of the switching pin 3. On the side of the carrier 13 facing the erosion contact arrangement 5, an erosion plate 14 has been connected to this carrier 13 using one of the known methods, in such a way that the ends 15 of the contact fingers are protected against erosion. The erosion plate 14 is preferably made of graphite, but it can also consist of other electrically conductive, erosion-resistant materials such as, for example, sintered tungsten copper connections. The surface of the erosion plate 14 facing away from the carrier 13 is formed by means of a ring Cover 41 made of a fire-resistant insulating material protected against arcing. In addition, the cover 41 prevents the arc base from migrating too far into the storage volume 17. In this embodiment variant, the two covers 36 and 41 form an annular nozzle duct, the throat of which is at a distance a.

An annular partition wall 16 made of insulating material, which is arranged concentrically to the central axis 2, is clamped between the supports 8 and 13. The carriers 8 and 13 and the partition 16 enclose an annular storage volume 17, which is designed for storing the pressurized insulating gas provided for blowing the arc. The carrier 8 represents an end face of a cylinder-shaped exhaust volume 18 completely enclosed by metallic walls. The carrier 13 represents an end face of a cylinder-shaped exhaust volume 19 completely enclosed by metallic walls. If a nominal current path is provided, this represents the switched-on state of the circuit breaker represents the electrically conductive connection between the metallic walls of the two exhaust volumes 18 and 19.

The carrier 13 is provided with a bore 20, which is closed with a check valve 21 shown schematically. A line 22 is connected to the bore 20, which leads the insulating gas compressed by a piston-cylinder arrangement that is operatively connected to the switching pin 3 to the storage volume 17 during a switch-off process. However, an inflow of the pressurized insulating gas into the storage volume 17 is only possible if there is a lower pressure in the storage volume 17 than in the line 22.

2 shows a schematically illustrated section through the contact zone 1 of an embodiment of the arcing chamber of a circuit breaker according to the invention during the opening. The switching pin 3 has drawn an arc 23 between the erosion plates 9 and 14 in the course of its opening movement in the direction of arrow 27. The arc 23 thermally acts on the insulating gas surrounding it and thereby briefly increases the pressure in this area of the arcing chamber located between the erosion contact arrangements 5 and 6 and referred to as the arc zone 24. The pressurized insulating gas is briefly stored in the storage volume 17. However, part of the pressurized insulating gas flows through an opening 25 into the adjacent exhaust volume 18 and through an opening 26 into the adjacent exhaust volume 19.

The switching pin 3 is connected to a piston-cylinder arrangement, in which insulating gas is compressed during a switch-off process. This compressed insulating gas, as indicated by an arrow 28, is introduced into the storage volume 17 through the line 22 if the pressure in the storage volume 17 is lower than in the line 22. This is the case, for example, when the arc 23 is so low in current, that it cannot heat the arc zone 24 intensely enough. However, if a high-current arc 23 heats the arc zone 24 very strongly, so that a high pressure of the insulating gas occurs in the storage volume 17, an excess pressure valve 29 opens after a predetermined limit value is exceeded and the excess pressure is released into the exhaust volume 18. However, it is also possible to dispense with the pressure relief valve 29 if the openings 25 and 26 are dimensioned accordingly.

If the arc 23 is set in rotation about the central axis 2, the heating of the arc zone 24 is known to be significantly increased as a result. 3 shows a partial section through a contact zone, provided with blowing coils 30 and 31, of a circuit breaker according to the invention in the switched-off state. The magnetic field of the blow coils 30 and 31 sets the arc 23 in rotation in a known manner when it is switched off. The blow coil 30 is embedded in a recess in the carrier 8, the one winding end 32 having a bare metal contact surface which is pressed by means of a screw 33 against the bare metal surface of the carrier 8. The winding end 32 is thus electrically conductively connected to the carrier 8. Electrical insulation 34 is provided between the remaining surface of the blow coil 30 facing the carrier 8 and the carrier 8. This insulation 34 also distances the windings of the blow coil 30 from one another. The other winding end 35 of the blow coil 30 is electrically conductively connected to the erosion plate 9. The surface of the blow coil 30 facing away from the carrier 8 and part of the surface of the erosion plate 9 is protected against arcing by means of a cover 36 made of an erosion-resistant insulating material.

The blow coil 31 is embedded in a recess in the carrier 13, the one winding end 37 having a bare metal contact surface which is pressed by means of a screw 38 against the bare metal surface of the carrier 13. The winding end 37 is thus connected to the carrier 13 in an electrically conductive manner. Electrical insulation 39 is provided between the remaining surface of the blow coil 31 facing the carrier 13 and the carrier 13. This insulation 39 also distances the windings of the blow coil 31 from one another. The other winding end 40 of the blow coil 31 is electrically conductive with the erosion plate 14 connected. The surface of the blow coil 31 facing away from the carrier 13 and part of the surface of the erosion plate 14 is protected against arcing by a cover 41 made of an erosion-resistant insulating material.

The two blow coils 30 and 31 are arranged in such a way that the magnetic fields generated by these blow coils 30 and 31 reinforce one another. The blow coils 30 and 31 can be used in any of the variants of the present circuit breaker. In this embodiment variant, the two covers 36 and 41 form an annular nozzle channel, the throat of which is at a distance a, and which widens in the radial direction until it merges into the storage volume 17.

4 shows a greatly simplified section through a circuit breaker according to the invention, shown schematically, in the right half of the figure the circuit breaker is shown in the switched-on state, in the left half of the figure the circuit breaker is shown in the switched-off state. The circuit breaker is constructed concentrically around the central axis 2. The exhaust volume 18 filled with insulating gas under pressure, preferably SF ₆ gas, is enclosed by the carrier 8, a cylindrical housing wall 42 connected to it and a sealing cover 43 opposite the carrier 8 and screwed tightly to the housing wall 42. The closure cover 43 is provided in the center with a cylindrical flow deflection 44 extending in the direction of the opening 25. The housing wall 42 and the closure cover 43, like the carrier 8, are generally made of an electrically highly conductive metal.

The housing wall 42 is pressure-tightly connected to a cylindrical insulating tube 45. On the side opposite the housing wall 42, the insulating tube 45 is pressure-tightly connected to a further cylindrical housing wall 46. The housing wall 46 is of exactly the same design as the housing wall 42, but is arranged in mirror image to it, the dash-dotted line 11 indicating the plane of reflection. The insulating tube 45 is arranged concentrically with the insulating partition 16. This housing wall 46 is connected to the carrier 13. The exhaust volume 19 filled with insulating gas under pressure, preferably SF ₆ gas, is enclosed by the carrier 13, the housing wall 46 connected to it and a cover 47 opposite the carrier 13 and screwed to the housing wall 46 in a pressure-tight manner. The cover 47 is provided with a cylinder 48 in the center. The housing wall 46 and the cover 47, like the carrier 13, are generally made of an electrically highly conductive metal. A distance b is provided between the two housing walls 42 and 46. The housing wall 42 is provided on the outside with attachment options for power connections 49. The housing wall 46 is also provided on the outside with attachment options for power connections 50. The insulating tube 45 is arranged in an annular recess formed by the two housing walls 42 and 46, as a result of which the tensile forces caused by the pressure in the exhaust volumes 18 and 19 and which stress the insulating tube 45 in the axial direction are minimized. As a result of this recessed arrangement, the outer surface of the insulating tube 45 is particularly well protected against damage in transit.

A compression piston 51, which is connected to the switching pin 3, slides in the cylinder 48. The compression piston 51 is designed and provided with piston rings made of insulating material that no stray currents from the Switch pin 3 can flow into the wall of the cylinder 48. The compression piston 51 compresses the insulating gas located in the cylinder 48 when the switching pin 3 is switched off. The compressed insulating gas flows through the schematically illustrated lines 22 and 22a into the storage volume 17 if the pressure conditions in this volume allow this. If an excessive compression pressure should occur in this cylinder 48, it can be reduced into the exhaust volume 19 by a pressure relief valve, not shown.

The compression piston 51, the lines 22 and 22a and the check valve 21 can also be omitted in the case of other possible design variants of this circuit breaker.

The switching pin 3 is moved by a drive, not shown. At least one lever 52 is articulated to the switching pin 3. One end of the lever 52 is rotatably held in a bearing 52a connected to the switching pin 3. The other end of the lever 52 is rotatably and slidably mounted in the housing wall 46 here. A rocker arm 53 is rotatably connected to the lever 52 and transmits the force exerted by the lever 52 to an articulated rod 54. The rod 54 moves parallel to the direction of the central axis 2, it is guided here with little friction in the housing wall 46 and in the carrier 13. The other end of the rod 54 is connected to a finger basket 55, shown schematically as a triangle. The finger basket 55 serves as a holder for a plurality of resiliently suspended contact fingers 56. In order to avoid tilting, at least two such lever linkages are provided for the actuation of the finger basket 55, as is shown in FIG. The contact fingers 56 form the movable part of the rated current path of the circuit breaker when switched on. In the right part of the 4 shows the finger basket 55 when the circuit breaker is switched on, the contact fingers 56 bridge the distance b in an electrically conductive manner in this position. The current through the circuit breaker then flows, for example, from the current connections 49 through the housing wall 42, through the contact fingers 56 and the housing wall 46 to the current connections 50.

The space 57, in which this movable part of the rated current path is accommodated, is very advantageously completely separated from the arc zone 24 by the insulating partition 16 and the supports 8 and 13, so that no burn-up particles generated in the arc zone 24 reach the area of the rated current contacts and can negatively influence them. The service life of the rated current contacts, in particular the abrasion resistance of the contact surfaces, is thereby increased very advantageously, which results in an advantageously increased availability of the circuit breaker.

The lever linkages, which each consist of a lever 52, a rocker 53 and a rod 54 are designed so that the comparatively high switch-off speed of the switching pin 3 generated by the drive, not shown, which is in the range from 10 m / sec to 20 m / sec is, is implemented in an approximately ten times lower turn-off speed of the finger basket 55 from about 1 m / sec to 2 m / sec. As a result of this slower movement of the finger basket 55, the mechanical stress on the finger basket 55 and also on the contact fingers 56 are advantageously small, so that these components can be designed to be comparatively light and low-mass, since they do not have to withstand great mechanical stresses. Because of the comparatively low speed, no large mechanical reaction forces act on the contact fingers 56, so that the springs which press the contact fingers 56 against the contact surfaces provided on the housing walls 42 and 46 can be interpreted comparatively weak. The wear of the contact points of the contact fingers 56 and of the contact surfaces on which the contact fingers 56 will slide, as a result of the comparatively low spring forces, is substantially reduced.

The switching pin 3 is guided on the one hand with the aid of the compression piston 51 sliding in the cylinder 48 and on the other hand in a guide part 58. The guide part 58 is connected to the carrier 13 by means of ribs arranged in a star shape. Here, too, it is structurally ensured that no stray currents can flow from the switching pin 3 into the guide part 58.

In the described designs of the power contacts of the circuit breaker, the contact elements are each designed as identical parts, which are arranged in mirror image. The use of the same parts advantageously reduces the manufacturing costs of the circuit breaker and also simplifies the storage of its spare parts.

5 shows a first, greatly simplified partial section through a first embodiment of a circuit breaker according to the invention, this cutting surface being rotated by 90 ° about the central axis 2 in relation to the cutting surfaces shown in FIGS. 1 to 4. The circuit breaker is shown in the switched-on state in the left half of FIG. 5, and the circuit breaker is shown in the right half of FIG. 5 after covering approximately a third of the opening stroke. The circuit breaker is provided with two compression units 60 and 61 of identical construction for the compression of the insulating gas, which are rigidly connected to the carrier 13. It is also possible to provide only one compression unit 60 or a large number from them. The compression units 60 and 61 are embedded in the carrier 13 such that the injection channels 62 and 63 emerging from them, which open into the arcing zone 24, are designed to be as short as possible, so that they have a small dead volume. The injection channel 62 is assigned to the compression unit 60, the injection channel 63 is assigned to the compression unit 61. The axis of the injection channels 62 and 63 generally penetrates the center of the arc zone 24, because with this orientation of the injection channels 62 and 63 the insulating gas can blow the arc 23 most effectively under pressure. However, it is also conceivable that these axes do not meet in the center of the arc zone 24.

By changing the entry angle of the injection channels 62 and 63, it is possible to optimize the blowing of the arc 23 and to effectively increase the pressure generation due to the thermal effects of the arc 23 on the injected insulating gas under pressure. The pressurized insulating gas can also be passed into an annular channel which concentrically surrounds the arc zone 24. A plurality of injection channels distributed around the circumference then lead from this ring channel into the arc zone 24.

The compression unit 60 is constructed cylindrically, it has an axis 64 running parallel to the central axis 2 and a first compression volume 65 which, when the circuit breaker is switched on, is larger than a downstream second compression volume 66. The first compression volume 65 is provided by a first compression piston 67 acted upon. The second compression volume 66 is acted upon by a second compression piston 68. The two compression pistons 67 and 68 are in the usual way with piston and sealing rings, not shown fitted. The second compression piston 68 slides through and seals the first compression piston 67 in the center thereof. The side of the second compression piston 68 facing the second compression volume 66, as can be seen more clearly from FIG. 7, is provided on the surface with longitudinally extending grooves 69. The dimensions of the first compression volume 65 are matched to the dimensions of the second compression volume 66 in such a way that a sufficiently high blowing pressure is generated for blowing the arc 23.

The first compression piston 67 is moved by means of an articulated rod 70. The rod 70 is articulated at the other end to a bearing point 72 fastened on a gear 71. The second compression piston 68 is moved by means of an articulated rod 73. The rod 73 is articulated at the other end to a bearing point 74 fastened on the gear 71. The gear wheel 71 has a center 75 which is rotatably mounted in the housing wall 46. The ring gear of the gear 71 engages in a rack 76 embedded in the surface of the switching pin 3. When the switching pin 3 moves in the switch-off direction, that is to say in the direction of the arrow 27, the gearwheel 71 driven by it rotates in the direction of the arrow 77 and the compression unit 60 is thereby driven.

The compression unit 61 is cylindrical, it has an axis 78 running parallel to the central axis 2 and a first compression volume 79. The two axes 64 and 78 lie in one plane with the central axis 2. When the circuit breaker is switched on, the first compression volume 79 is larger than a second compression volume 80 connected downstream. The first compression volume 79 is acted upon by a first compression piston 81. The second compression volume 80 is replaced by a second Compression piston 82 acted upon. The two compression pistons 81 and 82 are equipped in the usual way with piston and sealing rings, not shown. The second compression piston 82 slides through and seals the first compression piston 81 in the center thereof. The side of the second compression piston 82 facing the second compression volume 80 is, as can be seen more clearly from FIG. 7, provided on the surface with longitudinally extending grooves 69. The dimensions of the first compression volume 79 are matched to the dimensions of the second compression volume 80 in such a way that a sufficiently high blowing pressure is generated for blowing the arc 23.

The first compression piston 81 is moved by means of an articulated rod 83. The rod 83 is articulated at the other end to a bearing point 85 fastened on a gear 84. The second compression piston 82 is moved by means of an articulated rod 86. The rod 86 is articulated at the other end to a bearing point 87 fixed on the gear 84. The gear wheel 84 has a center 88 which is rotatably mounted in the housing wall 46. The ring gear of the gear wheel 84 engages in a toothed rack 89 embedded in the surface of the switching pin 3. When the switching pin 3 moves in the switch-off direction, that is to say in the direction of the arrow 27, the gearwheel 84 driven thereby rotates in the direction of the arrow 90 and the compression unit 61 is thereby driven.

7 shows a third, greatly simplified partial section through a third embodiment of a circuit breaker according to the invention, this arrangement is based on the arrangement shown on the right in FIG. It also shows some structural details of the compression units 60 and 61, which are more difficult for FIGS. 5 and 6 because of the comparatively small scale there are removed. The compression units 60 and 61 each have a housing 91 into which cylinders for the respective first 67 and 81 and second compression pistons 68 and 82 are incorporated. The cylinder delimiting the first compression volume 65 or 79 each has a wall through which bores 92 pass. The bores 92 are positioned in such a way that, when the circuit breaker is switched on, they connect the first compression volume 65 or 79 to the exhaust volume 19, so that the insulating gas can fill up this volume, this corresponds to the position shown on the left in FIG. As soon as the switch-off movement of the switching pin 3 begins in the direction of the arrow 27, the respective first compression piston 67 or 81 closes these bores 92 and the first compression volume 65 or 79 is closed.

7 also shows, in the course of the injection channel 63, a schematically indicated pressure relief valve 93, which only allows the discharge of this high-pressure insulating gas through the injection channel 63 into the arc zone 24 after a predetermined threshold value of the pressure of the insulating gas in the second compression volume 80 has been exceeded. These threshold values can be in the range around 100 bar. Care is taken that both the injection channel 63 and the pressure relief valve 93 have the smallest possible dead volume in order to avoid a reduction in the pressure of the flowing high-pressure insulating gas, so that the entire pressure generated in the compression unit 61 is used to blow the arc 23 Available. It is now entirely possible to equip only one of the two compression units 60 and 61 with the pressure relief valve 93, which has the advantage that during the blowing of the arc 23 by the compressed gas generated in the first compression unit 60 there is a sudden increase in the The intensity of the blowing occurs when the pressure relief valve 93 additionally opens the injection channel 63 for the injection of insulating gas which occurs at a higher pressure from the compression unit 61. If multiple compression units are provided, the installation of a number of pressure relief valves 93 and their response pressures can be optimized according to the operating requirements.

The separate compression units 60 and 61, as are shown, for example, in FIGS. 5 to 7, could also be designed as a single, coherent compression unit. This compression unit would then be constructed in a ring around the central axis 2. The first compression piston would be designed as a closed ring, which would work in an annular first compression volume. The second compression piston could also be designed as an annular piston, which would work in a correspondingly designed second compression volume. However, it is also conceivable that the first compression piston is designed as a closed ring, while the second compression piston is constructed from a multiplicity of individual individual pistons distributed on this ring, which slide in a corresponding number of cylindrically designed second compression volumes.

The above-described drive of the compression units 60 and 61, by means of the toothed racks 76 and 89 incorporated into the shift pin 3, engage in which toothed wheels 71 and 84, which, with a rotation of 180 °, bring about the entire stop stroke of the compression units 60 and 61, only one the drive options. By means of a further lever linkage, which has toggle levers which are articulated on the switching pin 3, the Move compression units 60 and 61 directly and effectively.

It is also possible to install one or more high-pressure containers 94, which are generally filled with liquid insulating gas, at the location of the compression units 60 and 61, as can be seen in FIG. 8, which is a fourth, greatly simplified partial section through a fourth embodiment of an inventive one Circuit breaker shows. In the high-pressure container 94 shown there, a solenoid valve 95 is provided upstream of the injection channel 63 leading away. This solenoid valve 95 is actuated electromagnetically by the higher-level protection of the system in the event of an impending fault current shutdown, in particular in the event of a short-circuit shutdown, so that the pressurized insulating gas is injected directly into the arc zone 24 through the injection channel 63 at the right moment. The solenoid valve 95 is closed again after a predetermined opening time in order to keep the consumption of the high-pressure insulating gas low. However, there is also the possibility of opening this solenoid valve 95 with each switch-off, regardless of the size of the switch-off current. This high pressure container 94 is provided with a pressure monitor, not shown. An eye 96 is incorporated into the high-pressure container 94, to which a pressure line 97 is connected, through which fresh SF ₆ gas is fed under high pressure into the high-pressure container 94, which in each case replaces the used SF ₆ gas. The insulating gas additionally fed into the circuit breaker when switching must be removed and processed again from the exhaust volumes 18 and 19 after switching in order to avoid overloading the pressurized housing parts. The removed insulating gas is cleaned in a processing device 98, then pressurized again and through the pressure line 97 is fed back into the high-pressure container 94. Processing device 98 will generally work at earth potential in addition to the circuit breaker, so that its supply line (not shown) and pressure line 97 must be made at least partially of insulating material in order to be able to bridge the potential difference.

The embodiment of the circuit breaker shown in FIG. 8 can be simplified by omitting the cylinder 48 and the compression piston 51. The guide function that the compression piston 51 has for the switching pin 3 would then have to be performed by another component. The pressure generation in the arcing zone 24 can advantageously be improved with the aid of blowing coils, as shown in FIG. 3, in particular also in the time range of the shutdown, where the pressure injection is not yet fully effective. The design variants shown here can be combined with one another in any way, adapted to the respective operating requirements.

In the embodiment of the circuit breaker, in which the pressure injection is not triggered during normal operational shutdowns, it makes sense to specifically increase the blowing pressure generation caused by the thermal effect of the arc 23. If the arc 23 is set in rotation about the central axis 2, the heating of the arc zone 24 is known to be significantly increased as a result. This rotation is generally achieved by installing one or more blow coils in a known manner in the area of the contact zone of a circuit breaker. The magnetic field of the blow coils causes the arc 23 to rotate. In the present circuit breaker, the blow coils could each be embedded in a recess in the carrier 8 or 13 as shown in Fig.3. With this comparatively simple and effective measure, the consumption of the insulating gas stored in the high-pressure containers 94 can be substantially reduced, since the high-current short-circuits, for whose switching off this additional high-pressure injection of insulating gas is really necessary, occur comparatively very rarely.

9 shows a fifth, greatly simplified partial section through a fifth embodiment of a circuit breaker according to the invention. The high-pressure container 94 is closed here by an injection valve 99, which is controlled directly and depending on the stroke of the switching pin 3. A dashed line of action 100, which connects the switching pin 3 to the injection valve 99, indicates this interaction. This injection valve 99 is actuated each time it is switched off so that it opens at the right moment and closes again after a predetermined opening time. The insulating gas that is additionally fed into the circuit breaker when it is switched off must also be removed and processed from the exhaust volumes 18 and 19 after switching in order to avoid overloading the pressurized housing parts. The removed insulating gas is cleaned in a treatment device 98, then pressurized again and fed back through the pressure line 97 into the high-pressure container 94. This embodiment variant is particularly suitable for circuit breakers used as generator switches, which as a rule only carry out a comparatively small number of switching operations.

The use of high-pressure containers 94 is also conceivable for generator switches, the insulating gas filling of which is dimensioned such that they are necessary anyway for all possible short-circuit shutdowns until the next one Contact revision is sufficient. It would then not be necessary to reprocess the insulating gas and feed it back. During the contact revision, the injected insulating gas could then be extracted and the empty high-pressure container 94 replaced with a full one. In this embodiment of the circuit breaker, a solenoid valve 95 triggered by the higher-level system protection would have to be used as the valve, as a result of which the gas consumption could be kept low. This solenoid valve 95 also closes after a predetermined opening time. Exhaust volumes 18 and 19 would then have to be dimensioned such that the injected insulating gas, which initially remains in them, cannot cause a pressure overload of the housing enclosing them.

To explain the mode of operation, the figures are now considered in more detail. When switching off, the switching pin 3 draws an arc 23 in the course of its switching-off movement between the erosion plates 9 and 14. The switching pin 3 moves at a comparatively very high switch-off speed, so that the arc 23 burns only briefly on the tip 4 of the switching pin 3 and immediately on the Burning plate 14 commutates. The tip 4 therefore shows hardly any signs of erosion. The erosion plates 9 and 14 are made of a particularly erosion-resistant material, and therefore they have a comparatively long service life. The burnout contacts of the circuit breaker therefore only have to be revised comparatively rarely, which means that it has a comparatively high availability.

The arc 23 will reach its full length comparatively quickly due to the very rapid switch-off movement of the switching pin 3, so that the full arc energy is available shortly after the contact separation for the pressurization of the insulating gas in the arc zone 24. The arc 23 acts on it surrounding insulating gas thermally and thereby briefly increases the pressure in the arc zone 24 of the arcing chamber. The pressurized insulating gas is briefly stored in the storage volume 17. However, part of the pressurized insulating gas flows through an opening 25 into the exhaust volume 18 and through an opening 26 into the exhaust volume 19. However, the switching pin 3 is generally connected to a single-stage piston-cylinder arrangement in which insulating gas is compressed during a switch-off process. This compressed insulating gas is introduced into the storage volume 17 through the line 22 in addition to the thermally generated pressurized insulating gas.

However, this inflow takes place only if there is a lower pressure in the storage volume 17 than in the line 22 or 22a. This is the case, for example, before the contact is separated or when the arc 23 is so low in current that it cannot heat the arc zone 24 intensely enough. However, if a high-current arc 23 heats the arc zone 24 very strongly, so that a comparatively high pressure of the insulating gas occurs in the storage volume 17, at this high pressure there is initially no inflow of the compressed gas generated in the piston-cylinder arrangement. If a predetermined limit value of the stored pressure is exceeded in the storage volume 17, an excess pressure valve 29 opens after this predetermined limit value is exceeded and the excess pressure is reduced into the exhaust volume 18. In this way, it is prevented with great certainty that an inadmissible exceeding of the mechanical strength of the components can occur in this area.

As long as there is overpressure in the arc zone 24, very hot ionized gas also flows through the openings 25 and 26 into the exhaust volumes 18 and 19. When constructing these two flow areas, care was taken to ensure that they were geometrically similar in order to achieve the same outflow conditions in both exhaust volumes 18 and 19. The tip 4 of the switching pin 3 is arranged in the center of the exhaust volume 19 opposite the opening 26 and, together with the ribs of the guide part 57, influences the gas flow in this area. The flow deflection 44 is arranged in the exhaust volume 18 at the point corresponding to the tip 4 opposite the opening 25 and influences the gas flow there in a similar manner. The two gas flows are similar because of the very similarly designed flow areas, so that the pressure built up in the arc zone 24 flows approximately evenly and in a controlled manner to both sides, as a result of which the insulating gas present in the storage volume 17 for quenching the arc 23 is stored under pressure for so long until the arc 23 can be blown.

In this embodiment of the circuit breaker, the blowing pressure effective in the arc zone 24 is additionally significantly increased by the high-pressure injection, which takes place directly into the arc zone 24. The blowing of the arc 23 is particularly effective here.

5 and 6 show how the compression units 60 and 61 work. In the switched-on state, that is to say as shown in the left half of FIG. 5, the bores 92 are open and the insulating gas, here for example SF ₆ gas, which is generally pressurized to about 6 bar, fills the first compression volume 65 or 79 with this pressure. As soon as the switching pin 3 begins its switch-off movement in the direction of arrow 27, it drives the gearwheels 71 and 84, respectively. The Gears 71 and 84 each rotate in the direction of the associated arrows 77 and 90. At the same time, the lever linkage is actuated via the bearing 52a, which moves the contact fingers 56 of the rated current path in the switch-off direction. Furthermore, only the one of the two compression units 60 and 61 considered in each case is described here. The rod 70 fastened to the bearing point 72 now moves the first compression piston 67 in the opposite direction to the direction indicated by the arrow 27, the rotary movement is thereby converted into a linear movement. The second compression piston 68 is simultaneously moved slightly downward, so that the SF ₆ gas compressed in the first compression volume 65 can flow through the grooves 69 into the second compression volume 66. In this compression phase, the SF ₆ gas is compressed in the two volumes simultaneously.

The right half of FIG. 5 shows how the bearing point 87, in which the rod 86 moving the second compression piston 82 is mounted, runs through a dead center. The second compression piston 82 reverses its direction of movement here, it now moves upwards. The first compression piston 81 still maintains its direction of movement and thereby further increases the pressure in the first compression volume 79. The grooves 69 still connect the first compression volume 79 to the second compression volume 80. The switching time is shown in the left half of FIG. 6, where the second compression piston 68 has slid so far into the second compression volume 66 that the grooves 69 are just closed so that pressure equalization between the two volumes is no longer possible. The intermediate pressure in the first 65 and in the second compression volume 66 has now risen by ten to fifteen times the initial pressure. The bearing point 72 of the rod 70 is now also in a dead center position, and the first compression piston 67 reverses its direction of movement. As shown in FIG. 6 on the right side, the second compression piston 82 compresses the intermediate pressure in the second compression volume 80 by a factor of ten to fifteen until it reaches its end position. The first compression piston 67 has moved downward, the pressure in the first compression volume 65 in the end position shown corresponds approximately to the initial pressure of 6 bar.

The information regarding the compression values was created on the assumption that no pressure flows through the injection channels 62 and 63 during the compression process. However, this assumption is only more accurate if pressure relief valves 93, as shown in FIG. 7, prevent the outflow until their response pressure is reached. For special operating conditions, it makes sense to design the blowing of the arc 23 in such a way that it commences comparatively late, but instead acts all the more powerfully, as is achieved by the design with the pressure relief valve 93 according to FIG. 7.

However, it can also make sense if already partially compressed SF ₆ gas is derived from the first compression volume 65 or 79 and is used for blowing the arc 23 before the actual high-pressure injection begins. This blowing also advantageously takes place through the injection channels 62 and 63 directly into the arc zone 24. In this blowing variant, a flow channel is provided which connects the first compression volume 65 or 79 past the second compression volume 66 or 80 to the injection channel 62 or 63. This can be particularly advantageous, for example, when small inductive currents have to be switched off. The arc 23 then becomes early and comparatively less intense blow so that it does not tear off and has already gone out when the high-pressure injection takes effect. In this way, high switching overvoltages can be avoided in a simple manner.

The blowing of the arc 23 can be varied in different ways. As already stated, it can be supported by blow coils 30 and 31 and also by SF ₆ gas which is additionally compressed in a one-stage piston-cylinder arrangement and which is introduced into the storage volume 17. In addition, the high-pressure injection can be graded as desired and optimally adapted to the respective operating conditions of the circuit breaker.

Insulating liquids can also be used as the compressed insulating medium in the present circuit breaker. It may prove useful not to inject them directly into the arc zone 24. In particular in the case of liquefied gases, it may be more favorable under certain circumstances to inject them first into the storage volume 17.

The circuit breaker designs with high-pressure containers 94 can also be modified by blow coils 30 and 31 and also by SF ₆ gas compressed in a single-stage piston-cylinder arrangement, which is introduced into the storage volume 17, so that these circuit breakers also optimally meet the respective operating requirements can be customized.

The circuit breaker according to the invention is particularly well suited for switchgear in the medium-voltage range. The compact cylindrical design of the circuit breaker is particularly suitable for installation in metal-enclosed systems, in particular also for installation in metal-enclosed generator leads. In addition, the Circuit breaker very well suited for the replacement of obsolete circuit breakers, since it, with the same or better breaking capacity, requires much less space than this, usually no complex structural changes are necessary with such a retrofitting. If the circuit breaker is to be used for operating voltages above approximately 24 kV to 30 kV, the distances a and b must be increased and the required voltage must be adjusted; if necessary, the opening speed of the switching pin 3 must also be adjusted accordingly, ie increased.

The switch-on speed of the switching pin 3 is in this circuit breaker in the range 5 m / sec to 10 m / sec, while the contact fingers 56 of the movable nominal current contact with a switch-on speed, in accordance with the values specified by the speed-reducing lever linkage, in the range of 0.5 m / sec move to their switch-on position up to 1 m / sec.

LIST OF DESIGNATIONS

1

Contact zone

2nd

central axis

3rd

Switching pin

4th

top

5.6

Burning contact arrangement

7

Contact basket

8th

carrier

9

Burning plate

10th

end up

11

dash-dotted line

12th

Contact basket

13

carrier

14

Burning plate

15

end up

16

partition wall

17th

Storage volume

18.19

Exhaust volume

20th

drilling

21

check valve

22.22a

management

23

Electric arc

24th

Arc zone

25.26

opening

27.28

arrow

29

Pressure relief valve

30.31

Blow coil

32

Winding end

33

screw

34

isolation

35

Winding end

36

cover

37

Winding end

38

screw

39

isolation

40

Winding end

41

cover

42

Housing wall

43

Sealing cover

44

Flow deflection

45

Insulating tube

46

Housing wall

47

cover

48

cylinder

49.50

Power connections

51

Compression piston

52

lever

52a

storage

53

Swingarm

54

pole

55

Finger basket

56

Contact finger

57

room

58

Guide part

60.61

Compression unit

62.63

Injection channels

64

axis

65

first compression volume

66

second volume of compression

67

first compression piston

68

second compression piston

69

Grooves

70

pole

71

gear

72

Bearing point

73

pole

74

Bearing point

75

center

76

Rack

77

arrow

78

axis

79

first compression volume

80

second volume of compression

81

first compression piston

82

second compression piston

83

pole

84

gear

85

Bearing point

86

pole

87

Bearing point

88

center

89

Rack

90

arrow

91

casing

92

Holes

93

Pressure relief valve

94

High pressure tank

95

magnetic valve

96

eye

97

Pressure line

98

Processing facility

99

Injector

100

Line of action

from

distance

Claims (15)

Circuit breaker with at least one cylindrical chamber-shaped quenching chamber filled with an insulating medium and extending along a central axis (2) and having a power current path, with two fixed, arranged on the central axis (2), spaced apart from one another in the axial direction, arranged in the power current path Burn-up contact arrangements (5, 6), with a movable bridging contact which electrically connects the burn-off contact arrangements (5, 6) in the switched-on state, with an arcing zone (24) provided between the fixed burn-off contact arrangements (5, 6), and with a parallel to the power current path , provided with movable nominal current contacts nominal current path, characterized, - that at least one source for high-pressure insulating medium is provided, and - That this at least one source is connected directly to the arcing zone (24) by means of at least one injection channel (62, 63). Circuit breaker according to claim 1, characterized in - The bridging contact is designed as a switching pin (3) which is arranged in the interior of the erosion contact arrangements (5, 6) and extends along the central axis (2), - The switching pin (3) is driven with a switch-off speed in the range from 10 m / sec to 20 m / sec, - That the switching pin (3) is connected to the movable nominal current contacts via at least one lever linkage, and - That the lever linkage is designed so that the rated current contacts are always movable at a lower speed than the switching pin (3). Circuit breaker according to claim 1 or 2, characterized in - That the source of high-pressure insulating medium has at least one compression unit (60, 61) with at least one first piston-cylinder arrangement, which has at least two pistons connected in series, of which a first compression piston (67, 81) the insulating medium in one first compression volume (65.79), of which a second compression piston (68.82) further compresses the pre-compressed insulating medium in a second compression volume (66.79) separated from the first compression volume (65.79) to form a high-pressure insulating medium . Circuit breaker according to claim 3, characterized in - That the second compression piston (68,82) is provided on a part of the surface in the second compression volume (66,80) sliding with axially extending grooves (69). Circuit breaker according to one of claims 1 to 4, characterized in that - That a pressure relief valve (93) is provided in the at least one injection channel (62, 63). Circuit breaker according to one of claims 3 to 5, characterized in that - That the first compression piston (67.81) and the second compression piston (68.82) are movable depending on the movement of the switching pin (3). Circuit breaker according to claim 1 or 2, characterized in - The at least one source has at least one high-pressure container (94) filled with high-pressure insulating medium, and - That a valve connected to the high-pressure container (94) specifically releases and controls the entry of the insulating medium under high pressure into the injection channel (62, 63). Circuit breaker according to claim 7, characterized in - That as a valve, a solenoid valve (95) or a mechanically, depending on the movement of the bridging contact, on and off injection valve (99) is provided. Circuit breaker according to one of claims 1 to 8, characterized in that - That the movable nominal current contacts of the nominal current path are arranged in a space (57) completely separated from the arcing zone (24). Circuit breaker according to one of claims 1 to 9, characterized in that - That between the fixed erosion contact arrangements (5, 6) an annular nozzle zone is arranged, which is in an annular, from an insulating Partition (16) limited storage volume (17) opens. Circuit breaker according to one of claims 1 to 10, characterized in that - That the erosion contact arrangements (5, 6) each have openings (25, 26) on the side facing away from the arc zone (24) for a controlled outflow of ionized gases from the arc zone (24) into adjacent exhaust volumes (18, 19) . Circuit breaker according to one of claims 3 to 11, characterized in that - That, in addition to the source of high-pressure insulating medium, either a second piston-cylinder arrangement for the generation of pressurized insulating gas is installed, or that the erosion contact arrangements (5,6) are provided with at least one blow coil (30, 31), or that the second piston-cylinder arrangement is additionally installed combined with at least one blowing coil (30, 31). Circuit breaker according to one of claims 1 to 12, characterized in - That the components of the erosion contact arrangements (5, 6) are designed as identical parts, which are arranged in mirror image to a plane of symmetry arranged perpendicular to the central axis (2). Circuit breaker according to claim 11, characterized in - That the exhaust volumes (18, 19) are each delimited by walls, the first exhaust volume (18) is enclosed by a first housing wall (42), a first carrier (8) connected to the latter and a closure cover (43), and the second exhaust volume (19) by a second housing wall (46), a carrier (13) connected to this and a lid (47) is enclosed, - that the first housing wall (42) is connected to the second housing wall (46) by means of at least one insulating tube (45), an electrically insulating distance (b) remaining between the two housing walls (42, 46), and, - That contact fingers (56) bridge the electrically insulating distance (b) between the first (42) and the second housing wall (46) in an electrically conductive manner in the switched-on state. Circuit breaker according to claim 14, characterized in - That the first housing wall (42) and the second housing wall (46) are designed as identical parts, which are arranged in mirror image to a plane of symmetry arranged perpendicular to the central axis (2).

Images