EP0150486B1 - Electric circuit breaker - Google Patents

Description

The invention relates to a switch, in particular load disconnector with the features specified in the preamble of claim 1.

When setting up low-voltage switchgear, predominantly in power distributors, switchgear and controls, operational switching on and off of nominal currents and overload currents, e.g. of transformers, motors, capacitors, etc., switch disconnectors are used, which are either installed in open scaffolding or encapsulated in housings. Known low-voltage switch disconnectors usually use double separating knives which are guided in parallel as a switching bridge between fixed electrical connection pieces and which are pivotably articulated on one of the electrical connection pieces. The known constructions are relatively large and consist of numerous individual parts.

The invention is based on the object of providing a switch which can be used in particular for use as a load switch in the low-voltage range and which is characterized by a small space requirement and a small number of individual parts.

This object is achieved by a switch with the features specified in claim 1.

In the switch according to the invention, the electrical connecting pieces are two rod-shaped electrodes, which lie opposite one another coaxially and are connected to one another by an insulator arranged coaxially therebetween. The two electrodes and the insulator together form a compact structural unit, which can be used as a supporting element of the switch. The insulator is bridged by at least one electrically conductive switching bridge, the two contact pieces of which are pressed against the two electrodes by the force of springs.

The springs can find their abutment on the slide, which is provided for actuating the switching bridge; however, if several switching bars are arranged around the electrodes, then the switching bars can be enclosed together by spring washers, through which the switching bars are pressed radially against the electrodes.

It contributes to the simple and compact structure of the switch if the respective switching web is not articulated to one of the electrodes, but is arranged loosely in the space between the electrodes and the slide, the necessary holding and guiding of the switching web being effected by the spatial interaction of the electrodes the slide and the springs arranged therein is effected, for which purpose the slide expediently has guide parts, between which the loosely inserted switching web is guided on both sides and is oriented parallel to the longitudinal direction of the electrodes (claim 10). These guide parts do not have to be arranged on both sides of the full length of the switching web, rather it is sufficient if the guidance takes place over part of the length of the switching web, preferably at the two ends of each switching web.

The at least one switching web is actuated by axially displacing the slide, which acts with drivers on the two ends of each switching web. The shift in the axial direction of the electrodes causes the respective switching web to slide along the electrodes, with one end of the switching web moving away from the insulator and the other end of the switching web moving towards the insulator until it detaches from the first electrode in the vicinity of the insulator and thereby interrupts the previously closed current path. By lifting the one contact piece of the switching bridge from the jacket of the first electrode, a separation distance is established between the switching poles, which makes the switch suitable for use in disconnectors. The separation distance between the switching poles is determined on the one hand by the length of the insulator and the displacement of the slide, on the other hand by a cam which is arranged under the switching bridge on the insulator and has an inclined surface which faces the one end of the switching bridge which carries out the contact separation is. On this inclined surface, the switching web runs close to its end which carries out the contact separation, as a result of which the switching web is lifted off the first electrode at this end, as a result of which contact separation is more rapid and more economical than if the switching web were only to be made with the same thickness as without a lifting movement the insulator would slide out. Of course, the cam itself must not form an electrically conductive bridge between the two electrodes. The respective switching bridge not only bridges the isolator, but also the cam and is therefore in its middle part e.g. Correspondingly curved, so that the cam can be accommodated under the switching web, or passed through a longitudinal cut in the cam.

In the simplest case, the switch according to the invention therefore only consists of the following few parts: two electrodes, an insulator inserted between them, a cam, which in the simplest case can be a piece of the insulator, and at least one switching bridge with the associated contact pieces and springs. This results in a small footprint and a simple drive for the switch. In the preferred use for switch disconnectors, the construction according to the invention allows the manufacturing costs to be drastically reduced compared to known switch disconnectors.

The slide can be moved back and forth between two switch positions. In the first switching position, the respective switching bridge lies with its two contact pieces on the outer surface of the two electrodes, so that the current path is closed between the two electrodes. In its second switching position, at least one contact piece of the respective switching web is separated from its associated electrode by pushing the switching web onto the inclined surface of the cam, thereby interrupting the current path. The second contact piece of the switching bridge can basically remain on the other electrode. In cases where a particularly high dielectric strength of the switch is important, it is also possible to provide a further cam under the switching bridge between the already mentioned cam and the second contact piece of the switching bridge, which cam also has an inclined surface which is the same end of the Switching web faces like the inclined surface of the first cam and when the slide is moved to open the switching element, the respective switching web also lifts off with its second contact piece from the second electrode, so that in the open switching position the switching web has lifted from both electrodes. Alternatively, the second electrode can be formed at a distance from its end with a reduced diameter and the arrangement made such that when the switch is closed, the switching web rests with its second contact piece of the second electrode in its thicker end section, while the switching web is opened with the switch its second contact piece is displaced into the adjacent thinner area of the second electrode, but is prevented by a projection on the slide holding it back from making contact with this thinner area of the second electrode.

Another possibility of increasing the dielectric strength of the switch is characterized in that the other electrode (also referred to here as “second electrode”) has an electrically insulating surface area at a distance from the insulator inserted between the two electrodes, on which the switching bridge with its contact piece making contact on this second electrode rests in the second switching position, namely the distance between the insulator and the insulating surface area of the second electrode is chosen so large that the switching bridge in the course of the sliding movement of the slide to open the switch with the insulating one Surface area makes contact only after the switching bridge has lifted from the first electrode (claim 2). In this way, each switching bridge in the second switching position (switch "open") is electrically insulated from both electrodes, and there is no need to lift the switching bridge from the second electrode, since it is ensured that the switching on and off process on the first electrode takes place while the second electrode is always switched only without load.

The higher dielectric strength, which is achieved in that the contact separation from the second electrode takes place later than from the first electrode, is desirable in many cases, since it may be caused by the effects of arcing in the area of the first electrode. Sooting can occur, which enables undesirable leakage currents, whereas, due to the absence of an arc, such sooting does not occur or only occurs to a lesser extent in the region of the second electrode.

An advantageous development of the invention is characterized in that sections of the first electrode consist of different, electrically conductive materials or are coated with them, specifically in a first section adjoining the insulator made of a material which is exposed to the action of an electrical switching arc behaves favorably, and in a second section adjoining the first section, on which the switching web rests in the first switching position, made of a material which behaves favorably under continuous stress, in particular security against welding. offers (claim 3). In this way it is possible on the one hand to select optimal contact materials for the continuous current load and on the other hand for the switch-off process. For the first electrode section on which the switching arc burns when the switching element is opened, materials such as Cu / W or Ag / W are advantageously selected (claim 5); Ag / WC and Ag / Ni are also suitable. For the second electrode section, materials such as Ag / C, Ag / CdO, Ag / Sn0 ₂ , Ag / Sn0 ₂ / ln ₂ 0 ₃ , Ag / Sn0 _{2 /} W0 _{3 are} advantageously chosen (claim 4). The switch is preferably switched on not on the first but on the second electrode section; this is advantageously achieved in that the length of the displacement path of the slide, the length of the first section of the first electrode adjoining the insulator and the length of the section of the switching bridge spanning the cams are matched to one another in such a way that they are lifted off the first In the first switching position (FIG. 4; switch "on"), the electrode-specific contact piece attached to one end of the switching bridge rests on the second section of the first electrode, in the second switching position (FIG. 6; switch "off") from the first Has lifted electrode, and rests in an intermediate position on the first section of the first electrode (claim 7). In this way, the first electrode section is loaded only during the switch-off process, whereas the second electrode section is loaded during the switch-on process and by continuous current.

The coaxial arrangement of the electrodes and their connection by means of the interposed insulator makes it possible to attach the slide directly to the electrodes and to guide them through the electrodes during their displacement movement (claim 11). Such an arrangement contributes significantly to the compact structure of the switch.

With the new switch, measures for arc quenching can be taken, such as under load disconnect switches that belong to the prior art, are realized in a corresponding manner; so you could provide a quenching chamber with quenching plates as required, into which the arc generated when the switch is opened is driven by a magnetic blowing field or with self-generated or externally generated compressed air. However, one preferably forms the slide itself as a switching chamber and at the same time as an arcing chamber (claim 12). This is particularly advantageous because the slide has to take up and guide the switching webs anyway, so that its further development into a closed or largely closed chamber is easily done. Particularly in view of this design of the slide as a switching and quenching chamber and in view of the fact that the electrodes themselves are expediently used for guiding the slide, it is advisable to design the slide so that it encloses the electrodes (claim 13). The chamber walls can be made from a material which releases arcing gases under the influence of an arc (claim 14), as is known, for example, from so-called hard gas switches. In order to allow the extinguishing gases to escape from the switching and extinguishing chamber, the latter is preferably perforated (claim 15).

The actuation of the switch by displacing the slide in the axial direction of the electrodes also makes it possible, through slots which are provided at that end of the slide, in particular the slide designed as a chamber, which is adjacent to the lifting end of the switching web, one or more extinguishing plates in the axial direction Introduce the direction between the one electrode and the end of the switching bridge that is lifted from it and thereby extinguish an arc that has arisen (claim 16). Another advantageous way of contributing to arc quenching is to let the driver of the slide, which acts on the lifting end of the switching bridge, strikes the insulating cam in the second (open) switching position; in this way the arc drawn between the raised end of the switching bridge and the electrode is constricted between the cam and the driver of the slide striking it. In this context too, it is advantageous if the slide is designed as a switching chamber, because then the arc is prevented from flashing again over the slide onto the electrode from which the respective switching contact has lifted.

The two switch positions of the switch are expediently defined in that the slide strikes directly or indirectly on the cam which is arranged between the electrodes. In the "open" switch position, this is expediently solved - as mentioned - in such a way that the slide strikes the cam with its driver, which takes the lifting end of the switching web with it. In the "closed" switch position, this is expediently solved by letting the switching web stop at the opposite end of the cam; this also limits the displacement of the slide, because it in turn strikes the switching bridge.

In order to bring about a certain locking of the switch in its open switching position, the cam is preferably provided with a second inclined surface, which does not face the end of the switching web which the first inclined surface also faces, but which faces the opposite end of the switching web ( Claim 17). This second inclined surface, together with the first inclined surface, forms a gable roof-shaped structure in longitudinal section, the tip of which is arranged in such a way that the switching web in the open switching position has moved over the tip with a projection on its underside and now lies on the second inclined surface. The slopes of the two inclined surfaces and the amount of curvature in the transition area between the two inclined surfaces is determined by the switch and actuating forces that can be specified. The above-mentioned projection on the underside of the switching web is preferably the part with which the switching web also slides on the first inclined surface of the cam, so that that end of the switching web which lifts off one electrode remains completely in air after lifting off.

Instead of a second inclined surface, a flat trough could also be provided at the tip of the cam, into which the switching web engages in the open switching position with a projection provided on its underside.

The switch according to the invention is also suitable for multi-pole versions and then contains a plurality of switching webs which are arranged next to one another in an axially parallel manner and which are displaced by one and the same slide (claim 18). In this case, the switching webs could in principle be arranged next to one another in one plane and two flat electrodes of corresponding width would lie on them; however, the plurality of switching webs are preferably arranged in a ring around the electrodes (claim 19), in particular in an arrangement which is symmetrical with respect to the axis of the electrodes. In this case, the slide is expediently designed as a sleeve which concentrically surrounds the electrodes and comprises all switching webs (claim 20). This sleeve can be open at its ends or closed to form a switching chamber or can be mostly closed, which leads to the advantages already mentioned above. With such a crown-like, in particular concentric arrangement of the switching webs around the electrodes, radially acting spring washers can be used to press the switching webs against the electrodes, expediently two spring washers, one of which has the switching webs with one end and the other with the switching webs their other ends against the electrodes. To the off Do not obstruct the switch too much, no metallic spring washers should be used, but those made of elastomeric material, the restoring force of which increases only moderately when the switching bars are lifted off the electrode surface. Alternatively, it is also possible to use radially arranged coil springs, which are supported at one end on the upper side of the switching webs and at the other end on the opposite wall of the slide designed as a sleeve and are guided laterally between radially extending guide walls in the sleeve. At the point of attachment of the coil springs, the switching webs expediently have radially protruding projections which dip into the coil springs and prevent them from slipping on the switching webs.

Another way of generating the necessary contact closing force is to provide a leaf spring for each switching web, which acts in the radial direction on the lifting end of the switching web (claim 21). If a ring of switching bars is provided, a ring of leaf springs is also provided accordingly. The one or more leaf springs are preferably arranged so that they cannot move by fixing them with one end to the electrode against which the other end presses the respective switching bridge: this other end of the leaf spring is expediently bent in such a way that it is inclined from of the electrode (claim 22) - in the case of a ring of leaf springs, this gives it a tulip-like shape - and the leaf spring (s) end in front of the cam in such a way that they release the respective switching web during the opening movement of the switch, before it lifts off the electrode by sliding on the cam; in this way, the lifting of the switching web is not hindered by the leaf spring, but nevertheless ensures a sufficient contact closing force. The slide can be used to guide and support the leaf spring (s), the shape of the leaf spring (s) can also be matched to the slide so that when the switch is opened, the slide lifts the leaf spring (s) and thereby the relieved of the respective switching bridge.

When using a plurality of switching webs surrounding the electrodes in a ring shape, the cams are expediently formed as a ring which surrounds the insulator or is part of the insulator (claim 23).

The arrangement of a plurality of switching bars in the switch according to the invention not only enables the currents to be switched to be divided into a plurality of parallel current paths, but also makes it possible to separate a plurality of current paths running in parallel or to carry out multiple separation in one current path. For this purpose, the electrodes are subdivided into axially running segments which are insulated from one another and which provide surface areas lying next to one another for the switching bars (claim 25). If you divide the two electrodes in the same way and orientate them so that the segments are in pairs with one another, and if you arrange at least one switching bridge on each such pair of segments that are in alignment with one another, then you have a multiphase switch, when divided into three segments, e.g. a three-phase switch. However, if you e.g. in this way, triple-subdivided electrodes are oriented so that the center lines of the segments of one electrode are aligned with the separating surfaces between the segments of the other electrode, and if on such an arrangement a total of five switching bars are arranged in such a way that two of a segment of the one Switching webs extending from the electrode end on two adjacent segments of the opposite electrode, then a current path leading back and forth between the electrodes with five interruption points lying one behind the other is obtained. The arrangement of several switching bars in the form of a ring around the electrodes has the further advantage that a bundle of parallel current paths is obtained which, if the current direction matches, leads to an increase in contact pressure as a result of the electrodynamic current forces, because parallel electrical conductors which flow through the same direction attract each other . This effect can be intensified if a ferromagnetic ring, in particular made of soft iron, is arranged under the ring of switching webs and a ferromagnetic part with a U-shaped cross section is arranged opposite each switching web, the two legs of which lie on both sides of the respective switching web against the ring are (claim 26). The resulting magnetic strengthening of the contact closing force reduces the bouncing tendency of the contacts when closing and is suitable for preventing electromagnetic lifting of the contacts in the event of short-circuit currents.

The switch according to the invention enables the arrangement of preliminary and main contacts in a simple manner, which is advantageous for its use in switch disconnectors. this is based on an arrangement with a plurality of switching webs arranged next to one another and the shape and arrangement of these are matched to the drivers on the slide and on the cams such that when the slide is moved to open the switch, at least one of the switching webs later on from one electrode takes off than the others (claim 27); when the switch is closed, this switching bridge closes in front of the other switching banks. The lifting contact piece attached to this switching bridge can be used as a pre-contact and made from a correspondingly erosion-resistant material. The lagging of a switching bridge when opening the switch can be achieved, for example, by moving the area of the switching bridge that is to slide up onto the inclined surface of the cam at a somewhat greater distance in front of the inclined surface of the Arranged cams than with the other switching webs, so that when the switch is opened it reaches the inclined surface of the cam later than the other switching webs.

The ability of the switch according to the invention for arc quenching can be further improved by producing the first electrode, from which the switching web with its one contact piece lifts when the switch is opened, in its section adjacent to the insulator from a composite material or by coating it with such a composite material which, in addition to a metal with good electrical conductivity, also contains one or more substances which, under the action of an arc, release gases which promote arc quenching.

Such composites are e.g. in US-A-4 011 426, in DE-A-26 47 822, DE-A-1665019A1 and in the older, but not previously published German patent application DE-33 12 852.

The claimed use of such a composite material with electrical conductivity and with arc-extinguishing properties in the switch according to the invention has the advantage that the arc, which is drawn between the first electrode and the lifting bar when it is lifted off, burns directly on a material with arc-extinguishing properties and is extinguished does not - as usual - have to be driven into a separate extinguishing device. In the multitude of applications in which the use of a section with arc-extinguishing properties on the first electrode is sufficient to extinguish the switching arc, this measure therefore considerably simplifies the switch and, subsequently, a very compact structure of the switch.

An electrode equipped with an arc-extinguishing material can in principle be used in all the configurations and developments of the switch described and claimed above. In particular, the arc-extinguishing effect of the composite material used can be supplemented by forming the slide or parts of the slide from materials which split off further arc-extinguishing gases under the action of the arc. If the current load is not too high, the switch can be switched on directly by contacting the composite material with the arc-extinguishing substances. However, since the current carrying capacity of such a composite material is not as high as that of classic contact materials with good electrical conductivity, the length of the sliding path of the slide, the length of the section made of or with the composite material and the length of the cam are selected in the switch according to the invention spanning section of the switching bridge preferably in such a way that the contact piece intended for lifting off the first electrode and fastened at one end of the switching bridge in the first switching position (switch “on”) rests on the second section of the first electrode containing no arc-extinguishing substances, in the second switch position (switch "off") has lifted from the first electrode and in an intermediate position lies on the section made of or with the composite material (claim 7). In this way, the composite material is not loaded with continuous current, but only during the switching operations.

In order to keep the switching webs as short as possible, the cam that lifts the switching web is preferably not fixed, but is axially displaceable on the insulator between two fixed stops (claim 8). The middle section of the switching web, which spans the cam, therefore hardly needs to be longer than the cam itself, and this favors a compact design of the switching element. The length and the displacement path of the cam and the length of the electrode section, which consists of the composite material or is coated with the composite material, are advantageously coordinated with one another in such a way that the cam in the “on” switch position is the first section of the first Electrode, which contains the composite material, covers (claim 9). As a result, the composite material is desirably prevented from releasing arc-quenching gases when the switch is closed. If, in such a further developed switch, the slide is moved for the purpose of opening the switch, then each switching web carried by the slide runs against the one inclined surface of the cam and moves the cam until it reaches the opposite stop, which limits its displacement path; during this displacement movement of the cam, that contact piece on the switching web which is to lift off from the first electrode can slide onto the section with the composite material which was exposed by the displacement of the cam. Only when the cam has reached the end of its displacement path does the switching web begin to separate from the electrode section with the composite material by sliding along the inclined surface of the cam, and any arc that is drawn burns in the desired manner on the composite material with the arc-extinguishing properties.

When the switch is switched on again, the cam is carried along by the switching web in the opposite direction to its other end position. If you want to make sure that when the switch is closed, the contact is not made on the composite material with the arc-extinguishing substances, but on the adjoining, highly conductive electrode section, which does not contain any arc-extinguishing substances, measures must be taken to prevent the respective switching bridge from being during the switch-on movement the inclined surface of the cam, which faces the lifted switching contact piece, is moved down to the first electrode before the cam has reached its end position, in which it covers the first section of the first electrode, which is made of the composite material. This can be easily achieved, for example, by designing the cam with two inclined surfaces that face the two ends of the switching web.

Such a design of the cam has already been described and claimed above. By appropriately dimensioning the cam and the displacement paths, it is ensured that the switching web with a projection with which it slides over the cam is moved over the tip of the cam when the switching position "Off" is reached and is in a detent position that it allows the cam to be moved back to its starting position with the switching web lifted off, in which it covers the section with the arc-quenching composite material.

If one selects a design of the switch with cylindrical electrodes and a slide enclosing the electrodes with guide parts for lateral guidance of the switching bridge (s), then it is possible to arrange the slide rotatable about the longitudinal axis of the electrodes. With the slide, the switching webs then also rotate accordingly around the longitudinal axis of the electrodes. This can be used to advantage in order to achieve the most uniform possible erosion of the composite material with the arc-quenching substances. Composites of this type are less resistant to erosion than pure metals and it is therefore desirable not to let the switching arcs burn continuously at the same point in the section with the arc-extinguishing composite material, but to gradually shift the base points of the arcs to other points, which is done with a rotatable slide succeed. The slider is preferably coupled to gear elements in such a way that the slider is rotated by a predetermined angle at the same time as the slider is moved axially. Gear elements with which such coupled movements can be carried out are state of the art.

• Figur 1 zeigt einen Längsschnitt durch einen Schalter in geschlossenem Zustand,
• Figur 2 zeigt denselben Schalter im Längsschnitt, jedoch in geöffneter Schaltstellung,
• Figur 3 zeigt einen Querschnitt durch den Schalter in geschlossener Schaltstellung gemäss Schnittlinie 111-111 in Fig. 1,
• Figur 4 zeigt einen Längsschnitt entsprechend Fig. 1 durch einen zweiten Schalter,
• Figur 5 zeigt einen Längsschnitt durch den Schalter aus Fig. 4, jedoch in einer Zwischenstellung des Schiebers,
• Figur 6 zeigt einen Längsschnitt entsprechend Fig. 2 durch den zweiten Schalter,
• Figur 7 zeigt einen Längsschnitt entsprechend Fig. 4 durch einen dritten Schalter entlang der Schnittlinie Vll-VII in Fig. 8,
• Figur 8 zeigt einen Querschnitt durch den dritten Schalter, und zwar entlang der Schnittlinie VIII-VIII in Fig. 7,
• Figur 9 zeigt einen Längsschnitt entsprechend Fig. 5 durch den dritten Schalter, und
• Figur 10 zeigt einen Längsschnitt entsprechend Fig. 6 durch den dritten Schalter.

Embodiments of the invention are shown schematically in the accompanying drawings and are described below.

• FIG. 1 shows a longitudinal section through a switch in the closed state,
• FIG. 2 shows the same switch in longitudinal section, but in the open switching position,
• FIG. 3 shows a cross section through the switch in the closed switching position according to section line 111-111 in FIG. 1,
• FIG. 4 shows a longitudinal section corresponding to FIG. 1 through a second switch,
• FIG. 5 shows a longitudinal section through the switch from FIG. 4, but in an intermediate position of the slide,
• FIG. 6 shows a longitudinal section corresponding to FIG. 2 through the second switch,
• FIG. 7 shows a longitudinal section corresponding to FIG. 4 through a third switch along the section line VII-VII in FIG. 8,
• FIG. 8 shows a cross section through the third switch, specifically along the section line VIII-VIII in FIG. 7,
• FIG. 9 shows a longitudinal section corresponding to FIG. 5 through the third switch, and
• FIG. 10 shows a longitudinal section corresponding to FIG. 6 through the third switch.

In the various exemplary embodiments, identical or corresponding parts are designated with the same reference numbers.

The switch shown in Fig. 1 to 3 is particularly suitable for use as a load break switch in low-voltage switchgear. It consists of two cylindrical electrodes 1 and 2 of the same diameter, which are rigidly connected to one another by a cylindrical insulator 3 of somewhat smaller diameter. Arranged on the insulator is a cam 4, hereinafter also called a ring, which has on its periphery two annular inclined surfaces 4a and 4b, one of which faces the first electrode 1 and the other inclined surface 4b of the second electrode 2. In the area of its greatest extent, the ring 4, which is also made of insulating material, has a diameter that is approximately twice as large as the diameter of the electrodes 1 and 2. The arrangement of the electrodes 1 and 2, the insulator 3 and the ring 4 is surrounded by a ring of four switching bars 5, which are identical to one another, are distributed at equal intervals around the circumference of the electrodes 1 and 2 and each carry a contact piece 6a or 6b near their two ends 5a and 5b. When the switch is closed, the contact pieces 6a and 6b rest against the lateral surfaces of both electrodes 1 and 2 (FIG. 1).

The switching webs 5 have a bulge 5c in their central area, under which the ring 4 is arranged. The contact of the switching webs 5 on the electrodes 1 and 2 is ensured by two hose rings 7 and 8 made of elastomeric material, which enclose the ring of switching webs 5 at two different locations, namely in the vicinity of the contact pieces 6a and 6b, and with radial force act on the switching bars 5. One hose ring 7 is located on axially parallel sections of the switching webs 5 and does not require any further support there, the other hose ring 8, on the other hand, is located on sections of the switching webs 5 which run obliquely to the axial direction and lie above the inclined surface 4a of the ring 4 and is therefore provided with projections 9 supported on their top, which prevent the ring 8 from sliding down over the inclined sections of the switching webs 5.

On the electrodes 1 and 2, a slide 10, hereinafter also referred to as a sleeve, is arranged to be axially displaceable. This sleeve 10 encloses the Wreath of the four switching webs 5 and distributed around the circumference, in a 90 ° position to each other according to the arrangement of the switching webs 5, axially parallel walls 11 and 12, which are arranged in pairs at a distance from each other and the individual switching webs 5 at both ends 5a and 5b with little lateral play between them and thereby guide them during the switching movement and also keep them oriented in the longitudinal direction of the electrodes 1 and 2. The transverse end surfaces of the walls 11 and 12 also serve as drivers for the hose ring 8 during the opening movement or for the hose ring 7 during the closing movement of the switch. The jacket of the sleeve 10 is expediently constructed to be rotationally symmetrical with respect to the longitudinal axis of the electrodes 1 and 2.

When the sleeve 10 is displaced, it takes the webs 5 with it. The driver for the one end 5a of the switching webs is formed by a wall 13, which is formed in the interior of the sleeve 10 and extends radially and axially near the end of the sleeve therein; the driver for the opposite end 5b of the switching webs is formed by the opposite end wall 14 of the sleeve.

To open the switch, the sleeve 10 is displaced in the direction of the arrow 15. The drivers 13 of the sleeve 10 act on the ends 5a of the switching webs and take them with them. Rounded projections 16, which are arranged on the underside of the switching webs 5 and are located close to the projections 9, hit the inclined surface 4a of the ring 4 during this displacement movement, starting from the switching position “on” shown in FIG. 1, and slide thereon Along inclined surface 4a, whereby the contact pieces 6a at the ends 5a of the switching webs are forced to lift off from the first electrode 1. The ring 4 therefore has the function of a lifting cam for the four switching webs 5. When the sleeve 10 is continuously displaced in the direction of the arrow 15, the projection 16 reaches that point 4c of the ring 4 where its diameter is greatest. The projection 16 exceeds this point 4c and slides a small distance downward on the adjoining inclined surface 4b until the movement ends when the driver 13 strikes against a collar surface 17 of the cam which faces it and which rises above the periphery of the first electrode 1 . This position is shown in Fig. 2. In it, the switching webs 5 are locked in the “open” position as a result of the point 4c of the ring 4 with the largest diameter being exceeded, and at the same time the end section of the first electrode 1 is covered by the striking of the driver 13 on the ring 4 and thus an arc which could burn between the contact piece 6a at the end 5a of each web and the first electrode 1 is cut off and forced to extinguish; The arc cannot jump onto another area of the first electrode 1 because the sleeve 10 is designed as a closed switching chamber.

To close the switch, the sleeve 10 is moved in the opposite direction of the arrow 15, the projections 16 of the switching webs 5 again moving over the point 4c of the ring 4 with the largest diameter and sliding down on its inclined surface 4a until the contact pieces 6 touch the Make ends 5a of the switching bars contact with the first electrode 1 again. The displacement movement ends when the switching webs 5 strike the second inclined surface 4b of the ring 4.

The sleeve 10 is preferably equipped in the area in which the lifting contact pieces 6a are arranged with walls made of a material which is capable of splitting off arc-extinguishing gases under the action of an arc.

Figure 3 shows that a mounting flange with holes 22 is arranged on the slide 10, with which the switch can be attached to a mounting plate.

The cross section through the switch along line 111-111 is the same for the first and second exemplary embodiments, with the exception of the position of an axial mounting hole 25 in the first electrode 1, so that FIG. 3 is valid for both.

The second exemplary embodiment differs from the first in that the ring 4 is arranged on the insulator 3 so as to be displaceable in the direction of the longitudinal axis of the electrodes 1 and 2. For this purpose, it is provided with a central bore which is in a section 21 with a larger diameter, which corresponds to the diameter of the first section 18 of the first electrode 1, which is adjacent to the insulator 3, and in a second section with a smaller diameter, with the diameter of the Isolators 3 divided diameter divided. The difference in the length of the insulator 3 and the smaller length of the narrower section of the bore in the ring 4 is its maximum displacement (FIG. 5).

The length of the section 21 of the bore of the ring 4 corresponds to the length of the first section 18 of the first electrode 1, in which there is a material which is favorable under the action of an arc, such as Ag / W or Cu / W, or a composite material which releases extinguishing gases under the action of an arc , is located.

To open the switch, the sleeve 10 is moved in the direction of the arrow 15. The drivers 13 of the sleeve act on the ends 5a of the switching webs and take them with them. Rounded projections 16, which are arranged on the underside of the switching webs 5 and are located close to the projections 9, strike the inclined surface 4a of the ring 4 during this displacement movement, starting from the switching position “on” shown in FIG. 4. However, they do not initially slide upwards on the inclined surface 4, but first move the ring 4 until it reaches a collar surface serving as a stop 19 strikes at the end of the second electrode 2. During this displacement movement, the ring 4 exposes the section 18 of the first electrode 1, which connects to the insulator 3 and consists of an electrical contact material which behaves favorably under the action of an arc or of a composite material which releases extinguishing gases under the action of an arc.

However, if the ring 4 has reached the stop 19 (FIG. 5), the projections 9 of the switching webs 5 then slide along the inclined surface 4a, as a result of which the contact pieces 6a at the ends 5a of the switching webs are forced to lift off the first electrode 1. The projection 16 crosses this point 4c and slides a small distance downward on the adjoining inclined surface 4b until the movement by striking the driver 13 on an opposing collar surface 17 of the cam 4, which rises above the periphery of the first electrode 1, ends. This position is shown in Fig. 6. In it, the switching webs 5 are locked in the “open” position as a result of the point 4c of the ring 4 with the largest diameter being exceeded, and at the same time the end section 18 of the first electrode 1 is due to the driver 13 striking the ring 4 covered and thus an arc, which could burn between the contact piece 6a at the end 5a of each web and the first electrode 1, pinched off and forced to extinguish; The arc cannot jump onto another area of the first electrode 1 because the sleeve 10 is designed as a closed switching chamber.

If the first electrode 1 contains in its section 18 a material which releases arcing gases under the influence of an arc, then an arc drawn when the contact pieces 6a are lifted off will be extinguished very quickly, because unlike known switch disconnectors, the arc does not first have to be driven into an extinguishing device, instead, the quenching device, which here is the electrode section 18, is guided to the contact pieces 6a by the displacement movement and is already at the location of the arc base points when the contact pieces 6a lift off. The arc can therefore be extinguished more quickly than with known switches, provided that the switch is opened sufficiently quickly, e.g. by means of a spring mechanism.

To close the switch, its sleeve 10 is displaced in the opposite direction of the arrow 15, the projections 16 of the switching webs 5 first taking the ring 4 in the opposite direction to the arrow 15 until it strikes the collar surface 20 of the first section 18 of the first electrode 1 , and only after that, when the ring 4 has already covered this first section 18, the projections 16 of the switching webs 5 move again over the point 4c of the ring 4 with the largest diameter and slide down on its inclined surface 4a until the contact pieces 6a at the ends 5a of the switching bars again make contact with the second section 23 of the first electrode 1 which adjoins the first section 18, the material of which is selected so that it is well suited for continuous current loading and exhibits low contact resistance and low heating.

Suitable materials are the composite materials Ag / CdO, Ag / Sn0 ₂ , Ag / Sn0 _{2 / In 2} 0 ₃ , Ag / Sn0 _{2 /} W0 ₃ and Ag / C and the like. The displacement movement ends when the switching webs 5 on the second inclined surface Strike 4b of ring 4.

The second exemplary embodiment also differs from the first exemplary embodiment in that an electrically insulating sleeve 24, which has the same outer diameter as the second electrode 2 over its remaining length, is fastened on the second electrode 2 at some distance from the insulator 3. The contact pieces 6b are pushed onto this sleeve 24 during the opening of the switching element after the opposite contact pieces 6a have lifted off the first electrode 1. The insulating sleeve 24 increases the dielectric strength of the opened switching element.

Such an insulating sleeve 24 can be arranged in the same way in the first exemplary embodiment of the switching element (FIGS. 1 and 2) on the second electrode 2 there.

The third exemplary embodiment of the switch shown in FIGS. 7 to 10, like the second, consists of two cylindrical electrodes 1 and 2, which have a matching diameter over a certain length at their two adjacent ends and are rigidly connected to one another by a cylindrical insulator 3, which has a slightly smaller diameter than this over part of its length between the two electrodes 1 and 2. Arranged on the insulator 3 is an axially displaceable ring 4 which carries four cam pairs 4 'distributed around its circumference, the cams 4' combined to form a pair running parallel to one another and one of four switching webs 5 ', 5 "between them The cams 4 'have the same design and are each delimited by an inclined surface 4a facing the first electrode 1 and an inclined surface 4b facing the second electrode 2.

The ring 4 consists entirely of insulating material and is displaceable over a predetermined length in the direction of the longitudinal axis of the electrodes. For this purpose, its central bore is divided into two outer sections 21, the diameter of which corresponds to the diameter of the adjacent electrodes 1 and 2, and a central section with a smaller diameter, which corresponds to the smaller diameter of the insulator 3. The displacement path of the ring 4 is limited on the one hand by the end of the first electrode 1 and on the other hand by the opposite collar surface 19 of the insulator 3.

The first electrode 1 has a first section 18 made of a composite material which, under the action of an arc, releases gases which have an arc-extinguishing effect. When the switch is closed (FIG. 7), this section 18 is completely covered by the ring 4.

The switch is surrounded by four switching bars 5 'and 5 ", which are distributed at equal intervals on the circumference of the electrodes 1 and 2 and, when the switch is closed, the first electrode 1 with contact pieces 6a' and 6a" and the second electrode 2 with contact pieces 6b ' and 6b ".

The essentially rectilinear switching webs 5 'and 5 "cross the ring 4, being guided in the middle region between a pair of cams 4'. The necessary contact force with which the switching webs 5 'and 5" rest on the electrodes 1 and 2 is achieved by Each produces a radially extending, approximately centrally arranged helical spring 8 ', which is supported with one end on a sleeve 10 and with its opposite end on the respective switching web 5', 5 ", which has a projection 9 for positioning the spring 8 ' Sleeve 10 is displaceably arranged on the electrodes 1 and 2, encloses the ring of the four switching webs 5 ', 5 "and has distributed around the circumference, in a 90 ° position to each other according to the arrangement of the switching webs, axially parallel walls 11, which in pairs are arranged at a distance from one another and take up the individual step webs 5 ', 5 "with little lateral play between them and thereby during the switching movement f Stir and keep oriented in the longitudinal direction of electrodes 1 and 2.

When the sleeve 10 is displaced, it takes the webs 5 ', 5 "with it. The driver for the one end 5a', 5a" of the switching webs is formed by a radially and internally formed inside the sleeve 10, which is close to the end of the sleeve axially extending wall 13; the driver for the opposite end 5b 'or 5b "of the switching webs is formed by the opposite end wall 14 of the sleeve 10.

Two opposite switching webs 5 'carry pre-contacts 6a' and 6b ', while the other two opposite switching webs 5 carry "main contacts 6a" and 6b ". The contact pieces 6a' and 6a" lying on the first electrode 1 have the same axial position, whereas the preliminary contacts 6b 'lying on the second electrode 2 are closer to the insulator 3 than the main contacts 6b ".

All switching webs 5 ', 5 "each carry on their underside a pin 16' or 16" extending transversely to the axial direction, with the switching element 5 closed on the switching webs 5 "with the main contacts 6a" and 6b "pin 16" close to the front sloping surface 4a of the cam 4 which cooperates with it, while the pin 16 'fastened to the switching web 5' with the pre-contacts 6a 'and 6b' is at a somewhat greater distance from the corresponding inclined surface 4a of the cam 4 'interacting with it.

Therefore, if the sleeve 10 is moved in the direction of the arrow 15 to open the switch, then the pin 16 ″ attached to the switching bridge with the main contact first hits the inclined surface 4a of the associated cam 4 ′, but initially does not slide upwards on it, but rather moves it the ring 4 until it strikes the collar surface 19 of the insulator 3. This ring movement exposes the section 18 of the first electrode, which consists of the composite material releasing the extinguishing gases, and only then does the pin slide 16 "along the inclined surface 4a of the associated cam 4 'and lifts the main contact 6a" from the first electrode 1. A little later, the pin 16' fastened to the switching bridge 5 'with the preliminary contacts abuts against the inclined surface 4a of the cam 4' assigned to it and slides along it, whereby the pre-contact 6a 'is also lifted off the first electrode 1. The thereby between the pre-contact 6a' and de The electrode 1 drawn arc is extinguished very quickly because the arc itself releases extinguishing gases, in particular hydrogen, from the composite material in the electrode section 18, which blow and cool the arc. The sliding movement of the sleeve 10 is continued until both pins 16 'and 16 "have passed the vertex 4c of the cams 4' (FIG. 10). A further displacement of the sleeve 10 is not possible because the sleeve 10 has one on the left in the drawing End formed socket 30, which tightly encloses the first electrode, abuts the end 17 of the ring 4. At the latest then an arc drawn between electrode 1 and the pre-contact 6a 'is forced to extinguish because the electrode 1 is covered by the socket 30.

The switching webs 5 'and 5 "each carry at their end assigned to the electrode 1 an approximately Z-shaped angled plate 31 which is as wide as the switching webs themselves and the area of the sleeve 10 with the contact pieces 6a' and 6a" from the area with the opposing contact pieces 6b 'and 6b ", so that any soot that arises as a result of arcing is restricted to the area of the sleeve 10 in which the contact pieces 6a' and 6a" lifting off from the first electrode 1 are located.

The contact pieces 6b 'and 6b "acting on the second electrode 2 also lose contact with their second electrode when the switch is opened, because this is thinner in its rear section 25 than in its front section, which adjoins the insulator 3. Die Contact pieces 6b 'and 6b''are moved into the area of this section 25, but are prevented from making contact with the electrode 2 in this area 25, since the switching webs 5' and 5 "end 5b 'and 5b" meet a projection 26 of the sleeve 10. The fact that the contact pieces 6b 'and 6b "are also separated from their electrode 2 gives a switch with improved dielectric strength; To further increase the dielectric strength, the electrode 2 is provided with an insulating coating 24 in its thinner section 25.

To close the switch, the sleeve 10 is shifted in the opposite direction of the arrow 15, the pin 16 'attached to the switching bridge 5' with the preliminary contacts initially running against the inclined surface 4b of the associated cam 4 'and taking the ring 4' with it until it comes on strikes the flange surface 20 of the section 18 of the first electrode and has completely covered this section 18. Only then does the snap pin 16 'move over the apex 4c of the cam and down on the inclined surface 4a. Since the pin 16 'attached to the switching bridge 5' with the pre-contacts leads the pin 16 "on the switching bridge 5" with the main contacts, it is the first contact with the electrode 1, after the contact pieces 6b 'and 6b "have again contact with the second Made electrode 2. For the pre-contacts 6a ', materials with low erosion are expediently chosen, whereas for the main contacts materials are selected which are particularly suitable for the continuous current flow, show low contact resistance and low heating.

The third example shown contains two switching bars with pre-contacts and two switching bars with main contacts. It is readily possible to modify the switch in such a way that it contains more switching bars with pre-contacts than with main contacts; a switch with particularly good switch-on capacity is then obtained. Conversely, if you provide more switching bars in the switch with main contacts than with pre-contacts, then you get a switch with less good switch-on capacity, but improved suitability for continuous current carrying.

Materials such as e.g. Tungsten / copper or silver / cadmium oxide. For the main contacts, e.g. silver-plated copper. In the latter case, a very inexpensive design of the switching webs is possible, as is shown in FIGS. 7 to 10, if one uses copper or a high-copper alloy for the switching webs 5, and the contact pieces 6a "and 6b" by stamping the Switching bridges 5 "trained and silvered.

Claims (27)

1. An electric switch, particularly load-isolating switch in low-voltage switchgear, which switch comprises a movable contact bridge (5, 6a, 6b) for connecting two stationary electrical terminals (1, 2) characterized in that

the terminals consist of two rod-shaped electrodes (1, 2) which are coaxial to each other and are interconnected by an insulator (3), which is coaxial to and disposed between said electrodes,

the contact bridge comprises at least one axially displaceable contact carrier (5), which carries two axially spaced apart contacts (6a, 6b), which are engageable with the two electrodes (1, 2) under the force of springs (7,8,8'),

an electrically insulating cam (4) is provided on the insulator (3) under the contact carrier (5) and has an inclined surface (4a) facing one end (5a) of the contact carrier (5),

a slider (10) is provided, which is axially displaceable along the axis of the electrodes (1, 2) and comprises coupling elements (13, 14) for acting on the two ends (5a, 5b) of the contact carrier (5), said slider being reciprocable between a first position (Figures 1 and 4), in which the contact carrier (5) lies on both electrodes (1, 2), and a second position (Figures 2 and 6), in which the contact carrier (5) is in sliding contact with the inclined surface (4a) of the cam (4) so that the one contact (6a) of the contact carrier (5) is spaced from one of the electrodes (1 ), hereinafter described as the «first electrode».

2. A switch according to claim 1, characterized in that the other electrode (2) (hereinafter described as the «second electrode») has an electrically insulating surface portion (24) spaced form the insulator (3) disposed between the two electrodes (1, 2), that contact (6b) of the contact carrier (5) which makes contact with that second electrode (2) bears on that insulating surface portion (24) in the second position of the slider (Figures 6)

and the distance between the insulator (3) and the insulating surface portion (24) of the second electrode (2) is so large that during the movement of the slider (10) in the sense to open the switch the contact carrier (5) will not contact the insulating surface portion (24) until the contact carrier (5) has been lifted from the first electrode (1).

3. A switch according to claim 1 or 2, characterized in that the first electrode (1) comprises length sections consiting of or coated with different electrically conducting materials, a first length section (18) adjoining the insulator (3) consists of a material which exhibits a favourable behavior under the action of an electric arc, and a second length section (23) which adjoins the first length section (18) and is contacted by the contact carrier (5) in its first position (Figure 4) consisting of a material which exhibits a desirable behavior upon circuit closing and when flown through by a continuous current and particularly will not be weldable under such conditions.

4. A switch according to claim 3, characterized in that the material for the second length section (23) of the first electrode (1) consists of silver- graphite (Ag/C), silver-cadmium oxide (Ag/ Cd0), silver-tin oxide (Ag/Sn0₂), silver-tin oxide-indium oxide (Ag/SnO_z/ln_z0₃) or silver-tin oxide-tungsten oxide (Ag/SnO_z/W0₃).

5. A switch element according to claim 3 or 4, characterized in that the material in the first length section (18) of the first electrode (1) consists of copper-tungsten (Cu/W), silver-tungsten (Ag/W), silver-tungsten carbide (Ag/WC) or silver-nickel (Ag/Ni).

6. A switch according to claim 3 or 4, characterized in that the material in the first length section (18) of the first electrode (1) consists of a composite material which comprises a metal having a high electrical conductivity and one or more substances which under the action of an electric arc release gases which promote the quenching of the electric arc.

7. A switch according to claim 3, characterized in that the displacement of the slider (10), the length of the first length section (18) of the first electrode (1), which first length section (18) adjoins the insulator (3), and the length (L) of that portion of the contact carrier (5) which spans the cam (4), are so selected in consideration of each other that the contact (6a) which is secured to one end (5a) of the contact carrier (5) and is to be lifted from the first electrode (1) will be in contact with the second length section (23) of the first electrode (1) in the first position of the switch (Figure 4; switch «on») and will have been lifted from the first electrode (1) in the second position of the switch (Figure 6; switch «off») and will contact the first section (18) of the first electrode (1) in an intermediate position (Figure 5).

8. A switch element according to claim 7, characterized in that the cam (4) mounted on the insulator (3) is axially slidable relative to the latter between two stationary stops (19, 20).

9. A switch according to claim 8, characterized in that the first length section (18) of the first electrode (1) is covered by the cam (4) in the closed position (Figure 4) of the switch.

10. A switch element according to any of the preceding claims, characterized in that the slider (10) comprises guiding portions (11, 12) and the contact carrier (5) is loosely inserted and between said guiding portions and is guided by them on opposite sides and is oriented to extend in parallel to the longitudinal direction of the electrodes (1, 2).

11. A switch according to any of the preceding claims, characterized in that the slider (10) is slidably mounted on and guided by the electrodes (1, 2).

12. A switch according to any of the preceding claims, characterized in that the slider (10) defines switching chamber, particularly an arc-quenching chamber.

13. A switch according to any of the preceding claims, characterized in that the slider (10) surrounds the electrodes (1,2).

14. A switch according to any of the preceding claims, characterized in that the slider (10) comprises a material which releases arc-quenching gases under the action of an electric arc.

15. A switch according to any of claims 12 to 14, characterized in that the slider (10) which defines a chamber is perforated at least in that portion which contains the liftable contact (6a) of the contact carrier (5).

16. A switching element according to any of the preceding claims, characterized in that that end of the slider (10) which is disposed adjacent to the liftable contact (6a) of the contact carrier (5) is formed with one or more slots, which are adapted to receive one or more arc-quenching sheet metal elements extending axially into the gap between the first electrode (1) and that contact (6a) of the contact carrier bridge (5) which is disengaged from the first electrode.

17. A switch according to any of the preceding claims, characterized in that the cam (4) has a second inclined surface (4b), which faces the other end (5b) of the contact carrier (5) and together with the first inclined surface (4a) has the configuration of a gable roof in longitudinal section, and the contact carrier (5) has a projection (16) bearing on the second inclined surface (4b) in the second (open) position (Figures 2 and 6).

18. A switching element according to any of the preceding claims, characterized in that a plurality of juxtaposed contact carriers (5) are provided, which are axially parallel and are displaceable by one and the same slider (10).

19. A switch according to claim 18, characterized in that the contact carriers (5) consitute an annular series around the electrodes (1,2).

20. A switch according to claim 19, characterized in that the slider (10) consists of a sleeve, which surrounds the contact carriers (5) and concentrically surrounds the electrodes (1,2).

21. A switch according to claim 1, characterized in that the spring by which the contact (6a) of the or each contact bridge (5) is urged against the first electrode (1) is a leaf spring, which extends parallel to the longitudinal axis of said electrode (1), and one end of said spring is immovably secured to said electrode (1).

22. A switch according to claim 21, characterized in that the other end of the leaf spring urges the associated contact bridge (5) towards the first electrode (1) and has been bent to extend away from the surface of said electrode (1) at an oblique angle to said surface.

23. A switch according to any of claims 19 to 22, characterized in that the cam (4) consists of a ring which surrounds the insulator (3).

24. A switching element according to claim 1, characterized in that that coupling element (13) with which the slider (10) acts on the liftable end (5a) of the contact carrier (5) engages the cam (4) when the switch is in its second (open) position (Figures 2 and 6).

25. A switching element according to any of claims 18 to 24, characterized in that the electrodes (1, 2) are divided into axially extending segments, which are insulated from each other and are acted upon by separate contact carriers.

26. A switch according to claim 19, characterized in that a ferromagnetic ring extends below the annular series of contact carriers (5) and a ferromagnetic part which is U-shaped in cross-section disposed over each contact carrier (5) and has two legs which extend on opposite sides of the contact carrier towards the ring.

27. A switching element according to claim 18, characterized in that the contact carriers (5) in consideration of the coupling elements (13, 14) of the slider (10) and the cam (4) are so designed and arranged relative to each other that a movement of the slider (10) will cause at least part of said contact carriers (5) to be lifted and closed in succession.

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