Load break switch

Abstract

Load break switch (1) for use in medium-voltage networks up to 24 kV, comprising a main contact point (2) designed as a sliding contact, which carries the rated and load current, with an upper main contact piece (4) and a lower main contact piece (5) mounted in a contact tube (10) so as to be linearly displaceable, and b. a secondary contact arrangement arranged electrically parallel to the main contact point (2) for taking over the rated and load current during a switching-off process, wherein the secondary contact arrangement has a second contact point (3) designed as an arc-extinguishing device (8) with a fixed contact (6) and a movable contact (7) and a third contact point (16) arranged electrically in series with the second contact point, characterized in that the fixed contact (6) of the arc-extinguishing device (8) is firmly connected to the upper main contact piece (4).

Description

The invention relates to a load interrupter having an arc extinguishing device, which is suitable in particular for safe and efficient disconnection and switching of electrical loads in medium-voltage and high-voltage networks, in particular for use up to 24 kV. In particular, the present disclosure relates to a load interrupter having a main contact point designed as a sliding contact and a secondary contact arrangement which comprises an arc extinguishing device. The load disconnect switch is advantageously robust and requires little maintenance.Load disconnect switches are essential components in electrical distribution networks because they provide the ability to disconnect and close circuits under load conditions without causing dangerous arcs. In such load interrupters, a main contact point which conducts the rated and load current is connected to an arc extinguishing device. Such an arc extinguishing device serves to reliably and efficiently extinguish the electric arc which is produced when the circuit is disconnected. When a load disconnect switch is actuated, the current flow cannot be immediately interrupted, but an arc occurs between the disconnecting contacts. This arc is extremely hot and can damage both the switching contacts and surrounding components if it is not quenched in a controlled manner.Known systems typically include a main contact pad that conducts current during normal operation and a subcontact arrangement that accepts current during the turn-off operation. These auxiliary contact arrangements are often equipped with arc extinguishing devices in order to quickly and reliably extinguish the arc which occurs during the switching off. Arc quenching is of central importance in this case in order to prevent damage to the switching contacts and other components, to extend the service life of the load interrupter and to ensure the safety of the switching operation. Effective arc extinguishing also reduces the risk of fires and other safety-relevant incidents, which is of great importance especially in medium-voltage and high-voltage applications.It is known from the prior art that different arc quenching devices are used based on the hard gas quenching principle. Other load interrupters also use vacuum switching chambers as the arc extinguishing device, since the vacuum provides a very effective environment for arc extinguishing. In vacuum, the arc can be extinguished quickly and without residues, which further enhances the mentioned advantages.This is especially important in order to extend the service life of the load circuit breaker and to ensure the safety of the switching operation.In addition, the effective extinguishing of the arc can reduce the risk of fires and other safety-relevant incidents. This is especially important in medium and high voltage applications.The switching unit represents a core component of the load interrupter since efficient and reliable arc extinction is essential when switching off load and operating currents. The arc extinguishing device protects the switching contacts from wear and damage due to the arc, which lengthens the maintenance intervals and reduces the operating costs.DE 197 51 648 A1 discloses a load circuit breaker which has a movable vacuum chamber between two fixed contact pieces. This vacuum chamber is pivoted after the arc has been extinguished, in order to realize a separating path necessary for the secure separation of the stationary contact pieces.Furthermore, DE 19859007 A discloses a load circuit breaker which combines a main contact which provides a separating section with a vacuum switching chamber. A movable vacuum chamber is formed in a push tube. The main contact is thereby opened by moving a switching tube in such a way that the main contact opens. The vacuum switching chamber arranged in the contact tube then acts and extinguishes the arc which is produced.Despite the considerable advances in the art of load interrupters, there remains a need for improved solutions that further increase arc extinguishing efficiency and reduce mechanical complexity. The object of the invention is thus to provide a device which overcomes the disadvantages of the prior art, in particular to provide a reliable, less maintenance-intensive load disconnect switch which can be produced cost-effectively.The object is achieved by a device having the features of the independent claim. Further developments are specified in the dependent claims.A first aspect of the invention relates to a load circuit breaker which has been developed specifically for use in medium-voltage networks with voltages of up to 24 kV. This load circuit breaker comprises a main contact point which is designed as a normally open contact and carries the rated and load current. The main contact point consists of a stationary upper main contact piece and a linearly displaceable lower main contact piece, which together ensure the electrical contact. The electrical contact of the main contact point is thus ensured by the upper main contact piece and the lower main contact piece. The lower main contact piece is arranged in a contact tube. In addition, the load disconnect switch has a secondary contact arrangement which is arranged electrically in parallel with the main contact point and takes over the rated and load current during a switch-off operation.This auxiliary contact arrangement includes a second contact point, which is designed as an arc extinguishing device having a fixed contact and a movable contact, and a third contact point, which is arranged electrically in series with the second contact point. It is characteristic here that the fixed contact of the arc extinguishing device is firmly connected to the upper main contact piece. The arc extinguishing device is thus arranged stationary, i.e. stationary. The arc extinguishing device is also not positioned in the movable contact tube. An advantage of this arrangement is that the unit for moving the contact tube can be dimensioned smaller, since the arc extinguishing device does not have to be moved. This contributes to a reduction in the mechanical load and the dimensions of the load interrupter and improves sustainability by reducing the materials used.A sliding contact is, in the sense of the invention, a contact point in which a first contact piece of the contact point is formed fixed and a second contact piece of the contact point is formed linearly displaceable. In the main contact point designed as a sliding contact, the upper main contact piece is fixed and the lower main contact piece is designed to be linearly displaceable.In the context of the invention, the fixed contact of the arc extinguishing device and the upper main contact piece are fixedly connected to one another means that the connection between the upper main contact piece and the fixed contact of the arc extinguishing device is formed in such a way that the fixed contact and the main contact piece are not displaceable relative to one another. The fixed contact of the arc extinguishing device is then fixed stationary on the upper main contact piece.Advantageously, the load disconnect switch can be designed such that it can be easily replaced with existing load disconnect switches already installed at the customer, in particular the model C3. For this purpose, identical fastening elements can be arranged on the load interrupter, for example, an equally spatial arrangement of the primary connections, such as the center pole spacing, can be provided, and an equal or more compact installation space can be realized, for example. This retrofit capability allows customers to upgrade their existing systems cost effectively without having to make extensive changes to the existing infrastructure. This not only contributes to reduction of the running cost, but also supports the decarbonization targets by modernizing and improving the energy efficiency of the switchgear.According to one possible embodiment, the load disconnect switch according to the invention is of compact design, which results in new possible applications. In particular in modern space-saving switching installations, the load interrupter can be used effectively, as a result of which the flexibility and versatility of the installations is increased. These characteristics make the load disconnect switch a future safe solution for a variety of applications in power distribution and control.According to a preferred embodiment of the load interrupter, the load interrupter is designed as an interior load interrupter which has insulators. The configuration meets at least the requirements, in particular with regard to the dimensions, which are defined in DIN VDE 0101. Advantageously, the load disconnect switch can be made very compact, whereby the dimensions can be selected to be significantly smaller than prescribed or defined in this standard. This advantageously enables a compact configuration of the load interrupter or of the interior load interrupter.According to a possible embodiment, the load disconnect switch is designed in such a way that the stroke width in air is advantageously less than 80 mm.The load interrupter or the interior load interrupter preferably has a plurality of poles. The center-to-center distance of the pole is preferably 150 mm, particularly preferably a maximum of 125 mm. This design is suitable for operating voltages of 12 kV and advantageously enables a compact and resource-saving design of the load interrupter or of the interior load interrupter.According to one embodiment, the load interrupter comprises an arc extinguishing device which is designed as a vacuum switching chamber. This vacuum chamber serves to effectively quench the arc which occurs when the circuit is disconnected. Arc quenching in a vacuum chamber is advantageously a common and also safe option, in particular in comparison with other quenching principles, such as the hard gas quenching principle or switching into insulating oil.The vacuum switching chamber is comprised of a fixed contact and a movable contact disposed within a hermetically sealed chamber. The fixed contact of the vacuum switching chamber is fixedly connected to the upper main contact piece, whereby the vacuum switching chamber is fixedly arranged. Thus, the vacuum switching chamber is advantageously not subjected to any mechanical stress by the movement of the contact tube, which increases the service life of the vacuum switching chamber and improves the reliability of the load disconnect switch. Due to the stationary arrangement of the vacuum switching chamber, the unit for moving the contact tube can be dimensioned smaller, since the mass of the vacuum switching chamber does not have to be moved. This leads to a more compact and lighter construction of the load interrupter. The vacuum switching chamber takes over the function of arc quenching by quenching the arc which arises during the disconnection of the main contact within the vacuum switching chamber. This is accomplished by moving the contact pieces of the vacuum switching chamber apart, whereby a switching path is formed and the arc is extinguished. The hermetically sealed vacuum switching chamber prevents the ingress of air and other gases, which increases the efficiency of arc quenching and reduces the formation of pollutants. The use of a vacuum switching chamber also offers the advantage that it has a high electrical insulation capacity and thus increases the safety of the load circuit breaker. The combination of the vacuum switching chamber with the main contact point and the auxiliary contact arrangement creates a reliable and efficient switching device which meets the requirements of modern medium-voltage networks.The stationary arrangement of a vacuum switching chamber minimizes the load on the vacuum switching chamber, since the vacuum switching chamber is no longer subjected to the mechanical loads due to the movement in the switching process. This leads to a reduction of the mechanical loads and potential damage to the vacuum switching chamber and the mechanical parts connected thereto.A decisive advance of the described load interrupter with a vacuum switching chamber lies in arc quenching in vacuum instead of alternative quenching in ambient air. This method offers considerable advantages with regard to efficiency and safety, since arc extinguishing in vacuum takes place much more quickly and reliably, which extends the service life of the switching contacts and reduces the maintenance requirements. Due to the stationary arrangement of the vacuum switching chamber, the large mass of the vacuum switching chamber advantageously does not have to be moved in the contact tube.The invention has the advantage that little material is required for the load interrupter, since on the one hand the arc extinguishing device, preferably the vacuum switching chamber, can be dimensioned much smaller, since it is arranged in the circuit for the arc extinguishing. In addition, the arc extinguishing device, preferably the vacuum chamber, is not moved, so that the movement of the contact tube, which can also be referred to as a contact tube, can be realized by means of a smaller amount of energy. Preferably, the arc quenching device or the vacuum chamber is arranged in a pole head.According to one embodiment, the load disconnect switch comprises a commutator arrangement which serves for the mechanical commutation of the rated or load current from the main contact point to the auxiliary contact arrangement. This commutator arrangement enables efficient switching of the current flow. The commutator arrangement ensures that the current is diverted from the main contact point to the auxiliary contact arrangement during the switch-off operation, which enables a controlled and reliable disconnection of the circuit. This contributes to increasing the operating reliability and the service life of the load circuit breaker. The integration of the commutator arrangement makes it possible to use the auxiliary contact arrangement, in particular the arc extinguishing device, only during the switch-off process. This leads to an advantageous reduction in the dimensions of the auxiliary contact arrangement, since it is active only for short periods of time and can therefore be made smaller and more compact. The arc quenching device, for example the vacuum chamber, is used only for a few milliseconds during the quenching of the arc, which makes it possible to dimension it very small for powers which are required for a current of 630 A and a voltage of 12 V. This compact construction contributes to reducing the overall dimensions of the load interrupter and assists in satisfying the requirements for a space-saving and resource-saving construction.Since the fixed contact of the vacuum switching chamber according to the embodiment of the invention is fixedly connected to the upper main contact piece and the vacuum chamber therefore does not have to be moved, the vacuum chamber can also be designed as a larger-dimensioned vacuum chamber, as is offered by various manufacturers as standard.According to one embodiment, the load disconnect switch has an actuating slide which is movably mounted in the contact tube. In addition, the actuating slide is coupled to a contact pressure spring and a switch-off spring for switching the arc extinguishing device. The actuating slide is designed and arranged in such a way that it is mechanically actuated during the opening or switching-off movement of the contact tube. As a result, the arc extinguishing device, for example the vacuum switching chamber, is activated and electrically contacted. This arrangement offers the advantage that the auxiliary contact arrangement conducts the current for a short time during the switch-off process before the arc extinguishing device is opened and the arc is extinguished. The mechanical coupling of the actuating slide to the contact pressure and switch-off springs ensures that the contacts of the arc extinguishing device are actuated precisely and reliably.The actuating slide and the contact pressure spring and the switch-off spring are in this case, according to a possible configuration, a component of the commutator arrangement. According to this embodiment, the commutator arrangement has an actuating slide arranged in the contact tube, which is coupled to a contact pressure spring and a switch-off spring in order to switch the arc extinguishing device efficiently. According to an advantageous embodiment, the actuating slide is movably mounted in the contact tube, wherein it is preferably limited in its movement. The arrangement enables precise control of the switching operations by mechanically actuating the actuating slide during the opening or switching-off movement of the contact tube. This mechanical coupling ensures that the arc extinguishing device is reliably activated and electrically contacted, which leads to a safe and controlled disconnection of the circuit. The integration of the actuating slide contributes to improving the operating reliability and to increasing the service life of the load interrupter by minimizing the mechanical stress on the arc extinguishing device.The contact tube is preferably designed and arranged in such a way that a displacement of the contact tube occurring during the switch-off process results in a mechanical actuation and electrical contacting of the arc extinguishing device.Overall, the commutator arrangement offers improved functionality and efficiency of the load disconnect switch by enabling a precise and reliable switching of the current flow.According to one configuration of the load disconnect switch, the main contact point in the closed state has a main resistor and the auxiliary contact arrangement has an auxiliary resistor when the second contact point is closed and the third contact point is closed. The shunt resistance is at least 5 times, preferably at least 8 times, the main resistance. According to an advantageous embodiment, the shunt resistor is larger than the main resistor by a resistance factor. The resistance factor is preferably in a range from 5 to 50, preferably in a range from 8 to 20, particularly preferably in a range from 9 to 12.According to one embodiment, the load disconnect switch is designed such that the contact tube is arranged and formed such that the second contact point opens shortly after the main contact point opens. This means that the arc extinguishing device, which forms the second contact point, opens only when the main contact point is already open. This timing of the opening operations is decisive for the effective interruption of the load current. The main contact pad carrying the rated and load current initially opens and transfers the current to the paralleled subcontact assembly that includes the arc extinguishing device. The arc extinguishing device is designed in such a way that it reliably and rapidly extinguishes the arc which is produced, which enables a reliable disconnection of the circuit. According to this advantageous embodiment, the configuration and arrangement of the contact tube ensures that the second contact point, i.e. the arc extinguishing device, which is preferably designed as a vacuum switching chamber, opens only after the opening of the main contact point. This has the advantage that the load current initially flows via the main contact point and is only transmitted to the arc extinguishing device after it has been opened. As a result, the mechanical stress on the arc quenching device is reduced since it conducts the load of the current only briefly. This results in an extended life of the arc extinguishing device and an improved reliability of the load circuit breaker.According to one embodiment of the invention, the load disconnect switch comprises a contact tube which contains a movably mounted contact pin. This contact pin is designed and positioned in such a way that it allows the connection or disconnection of the auxiliary contact arrangement by means of a latching contact and a sliding contact, as a result of which the second contact point is therefore incorporated into the current path or disconnected from the current path. The third contact point is formed by the interaction between the contact pin and the latching contact, as a result of which precise control of the electrical connection is ensured.The auxiliary contact arrangement is arranged parallel to the main contact point and takes over the rated and load current during the switch-off process. The movably mounted contact pin within the contact tube plays a decisive role in controlling the electrical connection to the auxiliary contact arrangement. The latching contact serves to maintain the contact pin in a particular position, while the sliding contact allows low friction movement of the contact pin to control the connection or disconnection of the auxiliary contact assembly.In this case, the contact pin is preferably mounted in the contact tube in a movable manner, that is to say in a linearly displaceable manner. The movement of the contact pin is limited in this case, so that a movement of the contact tube initially does not cause a movement of the contact pin, since the contact pin at the beginning of the movement of the contact tube moves relative to the contact tube and remains in its position on the latching contact. Starting from a certain length of the displacement of the contact tube, however, the contact pin is then pulled out of the latching contact.This arrangement offers several advantages. First, it allows precise control of the connection and disconnection of the auxiliary contact arrangement, which is decisive for the reliable functioning of the load disconnect switch. Secondly, the use of a latching and sliding contact reduces the mechanical load on the components, since the contact pin does not have to be kept constantly under tension, but is held in position by the latching mechanism. This reduces wear and extends the service life of the components, since here only mechanical wear and not electrical wear occur. In addition, the integration of the contact pin into the contact tube contributes to a more compact design of the load interrupter, which reduces the space requirement and facilitates installation in confined environments. Moreover, the arrangement enables a faster and more efficient switching operation, since the contact pin can change rapidly between the positions by the sliding contact without requiring considerable forces. These features help to increase the reliability and efficiency of the load disconnect switch, particularly in applications where fast switching operations and high switching frequencies are required.According to one embodiment, the load disconnect switch comprises a main contact point and a second contact point which are designed and arranged such that during the switch-off process the main contact point first opens and then the second contact point opens. Upon switching on, the second contact point closes after the closing of the first contact point. The main contact point provides a separating path. This arrangement allows a controlled and stepwise disconnection of the circuit, thereby reducing the mechanical stress on the components. During the switch-off process, the operating or load current is initially transmitted from the main contact point to the second contact point, which is designed as an arc extinguishing device, in particular as a vacuum switching chamber. This arc extinguishing device is fixedly connected to the upper main contact piece and is mechanically operated by the movement of the contact tube. With this construction, the vacuum arc chamber is not moved directly, which reduces the mechanical load and increases the life of the arc extinguishing device, in particular the vacuum arc chamberWhen the load disconnect switch is turned on, the main contact point closes first, followed by the arc extinguishing device. This sequence of switching operations ensures reliable and reliable disconnection and restoration of the circuit by the creation and extinguishing of the arc in the arc extinguishing device being controlled. An advantage of this arrangement is the reduction of the mechanical load on the arc extinguishing device, for example the vacuum switching chamber, and the associated increase of the operating reliability and service life of the load interrupter. A further advantage is the compact construction which is made possible by the stationary arrangement of the arc extinguishing device, which leads to a saving in space and simpler integration into existing systems. The arrangement of the contact points also ensures a clear and visible separation path in the switched-off state, which ensures the safety and the checkability of the switching state.According to one embodiment of the load interrupter, the third contact point is designed and arranged in such a way that, during the switch-off process, the main contact point first opens and then the second contact point opens, wherein the third contact point opens after arc extinction in the arc extinguishing device, and that, during a switch-on process, the main contact point closes and then the second contact point closes. This arrangement and configuration of the third contact point enables a sequential opening and closing sequence of the contact points, which ensures a controlled and reliable separation and restoration of the current flow. During the turn-off operation, the main contact point first opens, as a result of which the current flow is diverted to the secondary contact arrangement. The secondary contact arrangement has the second contact point, which is designed as an arc extinguishing device. This enables a controlled arcing and extinguishing within the arc extinguishing device, which is preferably designed as a vacuum switching chamber. This advantageously extends the service life of the contacts and increases the operational reliability. After the arc is extinguished, the third contact point opens, thereby establishing a visible gap.The third contact point is formed and arranged in such a way that the contact pieces of the third contact point are at a distance of at least 8 cm in the open state.This sequential opening order ensures that the arc is extinguished in a controlled environment before the third contact point opens, which prevents the generation of arcs outside the arc extinguishing device and thus enhances the safety and reliability of the circuit breaker. During the turn-on process, the main contact point and the third contact point first close, restoring the main current path, but the second contact point is still open. The second contact point then closes, whereby the bypass flow path is closed. This sequential closing sequence ensures that the main current path is first closed, whereby the load on the arc quenching device, in particular the vacuum switching chamber, is reduced and a reliable and reliable restoration of the current flow is ensured.One embodiment of the load disconnect switch provides that the load disconnect switch has a lower stationary contact which does not move with respect to the upper main contact piece and which realizes a mechanical guidance and an electrical contacting of the contact tube. An important advantage of this embodiment of the load interrupter lies in the increased stability and reliability of the contacting. The lower stationary contact, which does not move with respect to the upper main contact piece, ensures constant mechanical guidance. This minimizes the risk of misalignment or mechanical failure during the shift. In addition, the fixed position of the lower contact ensures reliable electrical contacting of the contact tube, which increases the efficiency and safety of the switching operation. This construction thus contributes to the lengthening of the service life of the load circuit breaker and to the reduction of maintenance requirements.An advantageous embodiment provides that the upper main contact piece has contact fingers and the lower main contact piece is designed as a contact blade. An important advantage of this embodiment lies in the improved contact quality and the increased reliability of the electrical connection. By using contact fingers on the upper main contact piece and a lower main contact piece designed as a contact blade, an optimum fit and contact surface is ensured. The contact blade is preferably designed in such a way that it has a shape corresponding to the contact fingers, i.e. matching for electrical contacting, which leads to stable and efficient electrical contacting. This precise adjustment reduces the contact resistance and minimizes the generation of heat at the contact points, which increases the overall performance and service life of the load circuit breaker. Moreover, this construction improves the mechanical guidance, which leads to uniform wear and a lower maintenance requirement.The invention advantageously makes it possible to provide a load circuit breaker which is suitable in particular for interior applications and which has particularly small dimensions. The load interrupter is preferably designed as an interior load interrupter. The construction according to the invention makes it possible for forces acting on the arc extinguishing device, in particular on the vacuum switching chamber, to be reduced or avoided. The selected construction also makes possible a reduction of the materials used due to the fact that the vacuum switching chamber is used only briefly for current conduction.According to the design, the load disconnect switch has a main contact point designed as a sliding contact with a contact tube, via which the operating or load current is conducted. The main contact point is formed by an upper main contact piece and a lower main contact piece arranged in the contact tube. In addition, the load disconnect switch has a secondary contact arrangement with a second and a third contact point. The second contact point is designed as an arc extinguishing device, preferably as a vacuum switching chamber, which can extinguish an arc that occurs during the switch-off process in a controlled manner. Since the arc extinguishing device is arranged in the stationary part of the load interrupter, the arc extinguishing device advantageously does not have to be moved with the contact tube. It is thus less susceptible to wear and maintenance. In order to realize the stationary arrangement of the arc extinguishing device, the arc extinguishing device, preferably the vacuum switching chamber, is connected with its fixed contact firmly, i.e. not displaceable relative to one another, to the upper main contact piece.Preferably, the switch-off movement of the contact tube, which has the lower main contact piece, results in a mechanical actuation and electrical contacting of the arc extinguishing device. Advantageously, the operating or load current is thereby commutated, after the disconnection of the first contact point, to the auxiliary contact arrangement which has the arc quenching device preferably embodied as a vacuum switching chamber. In the further course of the switch-off movement of the contact tube, arc extinguishing takes place in the arc extinguishing device, after which the third contact point is separated by a movement of the contact pin. The opened main contact point and the opened third contact point then form the visible isolation section. Preferably, the main contact point forms the minimum visible separation path. During the switch-on process, after closing the main contact point by means of an actuating slide, the second contact point and the third contact point are closed. The short-circuit current turn-on resistance of the load interrupter takes over the main contact point.The switched-off load disconnect switch has an open main contact point, wherein the minimum visible separation distance between the upper main contact piece and the lower main contact piece, according to a possible embodiment between the contact finger and the lower main contact piece designed as a contact blade. This minimum isolation distance is decisive for the dielectric strength of the load circuit breaker. A characteristic of the load interrupter disclosed herein is that the additional opened second contact point and the opened third contact point do not influence the dielectric strength of the isolation gap, since this region is at free potential in the open state due to the opened contacts of the arc quenching device.For the realization of the invention, it is also expedient to combine the above-described embodiments, embodiments and features of the claims with one another in a suitable arrangement.Exemplary EmbodimentsFurther details, features and advantages of embodiments of the invention are evident from the following description of exemplary embodiments with reference to the associated drawings. The exemplary embodiments are intended to describe the invention without limiting it. In particular, elements of exemplary embodiments described below can be combined with elements of other exemplary embodiments disclosed herein. The following are shown: FIG. 1 : a load interrupter in which the arc quenching device is designed as a vacuum switching chamber, with closed contact points, FIG. 2 : a load disconnect switch at the beginning of the switch-off process, FIG. 3 : a load disconnect switch in which the main contact point is opened, FIG. 4 shows a load disconnect switch in which the contacts of the vacuum switching chamber begin to open, FIG. 5 shows a load disconnect switch in which the contacts of the vacuum chamber are opened, FIG. 6 : a load disconnect switch in which the third contact point begins to open, FIG. 7 shows a fully open load disconnect switch, FIG. 8 : shows a load isolating switch during the switch-on process with the main contact already closed, FIG. 9 shows a load disconnect switch at the moment of contact contact contact of the contacts within the vacuum switching chamber, FIG. 10 shows a schematic illustration of a switch-off operation in four circuit diagrams, and FIG. 11 is a schematic illustration of a switch-on process in three circuit diagrams.FIG. 1 shows a load circuit breaker 1, preferably an interior load circuit breaker, in which the main contact point 2 and the second contact point 3 are closed. The load isolating switch 1 is thus in the switched-on position. The main contact point 2 is formed by the upper main contact piece 4 and the lower main contact piece 5. As shown in this exemplary embodiment, the upper main contact piece 4 can have a stationary main contact piece 4A and contact fingers 4B. In this embodiment, the main contact point 2 is formed between the contact fingers 4B and the lower main contact piece 5.The second contact point 3, which is formed here by the fixed contact 6 and the movable contact 7, is arranged in an arc extinguishing device 8 designed as a vacuum switching chamber 8A. The fixed contact 6 is electrically conductively connected to the upper main contact piece 4. This connection is preferably rigid.In addition, the load disconnect switch 1 has a lower lower stationary contact 9. This lower stationary contact 9 is arranged in a fixed manner and, in addition to the electrical contacting of a contact tube 10, also takes over the linear guidance of this contact tube 10; in this case, the lower stationary contact 9 can be electrically conductively connected to the contact tube 10 via a sliding contact point 11. The lower main contact piece 5 is designed here as a contact blade and is arranged on the contact tube 10. The lower main contact piece 5 is connected rigidly and electrically conductively to the contact tube 10.The vacuum switching chamber 8A shown here can be controlled mechanically. For this purpose, an actuating slide 12 is arranged on the contact tube 10. This actuating slide 12 can actuate a toggle lever 13 which is connected to a contact pressure spring 14 and to a switch-off spring 15. The actuating slide 12 actuates the toggle lever 13, which stresses the contact pressure spring 14 and the switch-off spring 15.Furthermore, the load disconnect switch 1 has a third contact point 16. At the third contact point 16, a contact pin 17 arranged in the contact tube 10 can ensure the electrical contact between the movable contact 7 and the lower main contact piece 5 or the lower stationary contact 9. For this purpose, a contact pin sliding contact point 18 can be arranged in the contact tube 10. In addition, the contact pin 17 can establish the electrical contact with the movable contact 7 of the vacuum switching chamber 8A by means of a latching contact 19.The arrangement in FIG. 1 shows that the main current path and the secondary current path are now closed and electrically connected in parallel. This means that the operating or load current can flow via both paths. The main current path formed by the main contact point 2 has a significantly lower electrical resistance than the secondary current path which is guided through the vacuum switching chamber 8A and the third contact point 16. Due to this resistance ratio of about 1:10, only one tenth of the operating, load or short circuit current flows via the bypass current path. This dimensioning of the electrical conductivity of the components in the bypass flow path is decisive in order to minimize the load on the vacuum switching chamber 8A and to lengthen its service life.In FIG. 2, a load disconnect switch 1 is shown in which the main contact point 2 opens by moving the lower main contact piece 5 away from the upper main contact piece 4. This can be realized by moving the contact tube 10, which is rigidly connected to the lower main contact piece 5, in the illustrated opening direction R 1, as in this exemplary embodiment. In particular, the lower main contact piece 5 is moved away from the stationary main contact piece 4A, wherein the lower main contact piece 5 is then also separated from the contact fingers 4B. At the same time, the operating or load current is commutated to the auxiliary contact arrangement, which here has the vacuum switching chamber 8A and the third contact point 16 with the contact pin 17.The actuating slide 12, which is arranged on the contact tube 10, holds the toggle lever 13 pressed via a latching nose 20, so that the vacuum switching chamber 8A remains closed. The contact pin 17, which is arranged in the contact tube 10, ensures the electrical contact between the movable contact 7 and the lower main contact piece 5 or the lower stationary contact 9, respectively. the third contact point 16 remains closed via the latching contact 19, as a result of which the bypass current path continues to be guided.The illustration in FIG. 2 shows the point in time during the switch-off process, starting from which the operating or load current is commutated from the main contact point 2 to the auxiliary contact arrangement. From this moment on, the operating or load current is thus only conducted via the bypass current path.FIG. 3 shows the moment in the disconnection process of the load interrupter 1, at which the linear stroke of the actuating slide 12 in the contact tube 10 is mechanically limited. This limitation has the effect that the actuating slide 12 is moved along with the further movement of the contact tube 10 in the opening direction R 1. This movement leads to the latching nose 20 releasing the toggle lever 13. The toggle lever 13 is connected to the contact pressure spring 14 and the switch-off spring 15, both of which are responsible for the mechanical actuation of the vacuum switching chamber 8A.At this time, the linear movement of the contact pin 17 in the contact tube 10 is not yet limited, which means that the bypass current path via the latching contact 19 remains closed. During this phase, the third contact point 16, which is formed by the contact pin 17 and the latching contact 19, remains closed, so that the operating or load current is conducted via the auxiliary contact arrangement. The contact pin 17 is supported within the contact tube 10 so as to be linearly movable and provides the electrical connection between the movable contact 7 of the vacuum switching chamber 8A and the lower main contact piece 5.It is shown in FIG. 3 how the mechanical limitation and movement of the actuator slide 12 within the contact tube 10 enables precise control of the switching operations to ensure safe and efficient disconnection of the circuit. The arrangement of the components and the sequential release of the mechanical elements contribute to the reliability and longevity of the load disconnect switch 1.FIG. 4 shows the moment of switch-off, at which the latching nose 20 on the actuating slide 12 has released the toggle lever 13. This causes the contact pressure spring 14 to depressurize and the switch-off spring 15 starts to open the contacts of the vacuum switching chamber 8A. The contact pin 17 keeps the bypass current path closed, which leads to an arc igniting in the vacuum switching chamber 8A between the fixed contact 6 and the movable contact 7.The illustration shows that the arc is generated in the vacuum switching chamber 8A as soon as the contacts of the vacuum switching chamber 8A begin to open. This is a critical moment in the switch-off process, since the arc has to be quenched reliably and efficiently in order to avoid damage to the switching contacts and other components.In FIG. 5, the vacuum switching chamber 8A is fully opened, thereby forming the switching path between the fixed contact 6 and the movable contact 7 of the vacuum switching chamber 8A. The arc which arises between the contacts of the vacuum switching chamber 8A is extinguished at the next zero crossing of the current. The actuating slide 12 is moved back into its starting position in the contact tube 10 by a tension spring 21. The bypass current path continues to remain contacted since the contact pin 17 is still held in its position and the third contact point 16 is thus still closed.FIG. 6 shows the further moment of switching off the load interrupter 1 after the arc in the vacuum switching chamber 8A has been extinguished and thus the bypass current path has been opened or interrupted. The contact pin 17 has covered its maximum linear movement in the contact tube 10, wherein it is limited in its movement in the contact tube 10 by a limiting element 23. In this state, the contact pin 17 begins to be pulled out of the latching contact 19 and is moved back into the contact tube 10 by a compression spring 22. The third contact point 16, which is formed by the contact pin 17 and the latching contact 19, is now open, as a result of which the electrical connection of the auxiliary contact arrangement is interrupted.The vacuum switching chamber 8A is fully opened, thereby forming the switching distance between the fixed contact 6 and the movable contact 7 of the vacuum switching chamber 8A.The mechanical movement of the contact tube 10 in the opening direction R 1 has thus led to complete separation of the current path. The main contact point 2, consisting of the upper main contact piece 4 and the lower main contact piece 5, is already open, and the vacuum switching chamber 8A has extinguished the arc before the third contact point 16 has been opened.This arrangement ensures that the current flow is interrupted in a controlled manner by extinguishing the arc in the vacuum switching chamber 8A before the third contact point 16 is opened. This increases the reliability and safety of the load circuit breaker 1 by minimizing the mechanical stress on the components and extending the life of the vacuum switching chamber 8A.FIG. 7 shows the load disconnect switch 1 completely switched off, the main contact point 2 is open, and the minimum visible isolation distance 24 is now located between the contact finger 4B and the lower main contact piece 5, which is designed as a contact blade. This minimum isolation distance 24 is decisive for the dielectric strength of the load disconnect switch 1. the third contact point 16 does not influence the dielectric strength of the isolation distance, since this region is at free potential due to the open contacts of the vacuum switching chamber 8A.The actuating slide 12 has completed its movement and the toggle lever 13 is in its end position. The contact pressure spring 14 and the switch-off spring 15 are relaxed. The contact pin 17 has been completely released from the latching contact 19 and is located in its rest position within the contact tube 10. The vacuum switching chamber 8A remains in the open position, with the arc extinguishing being complete and no further electrical connections existing.In summary, FIG. 7 shows the state of the load circuit breaker 1 after the complete disconnection process, wherein all relevant contact points are opened and the main contact point 2 and the third contact point 16 ensure a safe disconnection path.FIG. 8 shows the load disconnect switch 1, wherein the contact tube 10 has moved counter to the switch-on direction R 2 and has just reached the moment of contact contact at the main contact point 2. The main current path is thus closed and the operating or load current can flow. At this time, the contact of the vacuum switching chamber 8A is still open, and the latch contact 19 has not yet been latched, thereby keeping the bypass flow path open.The actuating slide 12 starts to actuate the toggle lever 13 from this moment in order to close the contacts of the vacuum switching chamber 8A. That is, the mechanical operation of the toggle lever 13 is initiated by the operation slider 12 to tension the contact pressure spring 14 and the throw-off spring 15 and close the fixed contact 6 and the movable contact 7 of the vacuum switching chamber 8A.In addition, FIG. 8 shows that the contact pin 17, which is arranged inside the contact tube 10, is located in a position in which it has not yet reached the latching contact 19. This means that the electrical connection to the auxiliary contact arrangement has not yet been established, and the current flows exclusively via the main contact point 2.The state shown in FIG. 8 thus shows the start of the switch-on process, in which the contact tube 10 is moved in the switch-on direction R 2 in order to close the main contact point 2 and to enable the current flow. The operating slide 12 simultaneously starts to operate the toggle lever 13 to close the vacuum switching chamber 8A, which is further continued in the following phases of the turn-on operation.In Fig. 9, the moment of contact contact of the contacts within the vacuum switching chamber 8A is shown. This phase of the switch-on process shows how the contact tube 10 is moved in the direction of the arrow, as a result of which the toggle lever 13, the contact pressure spring 14 and the switch-off spring 15 are tensioned. This movement causes the contacts of the vacuum switching chamber 8A to close, which establishes the electrical connection between the fixed contact 6 and the movable contact 7.The illustration in FIG. 9 illustrates that the mechanical movement of the contact tube 10 and the associated actuation of the actuating slide 12 enable precise control of the switching processes. This precise control is decisive for the reliable functioning of the load interrupter 1, in particular with regard to the reliable and efficient extinguishing of the arc in the vacuum switching chamber 8A. The tension mechanisms provided by the toggle lever 13 as well as the contact pressure spring 14 and the cut-off spring 15 ensure a constant opening speed of the vacuum switching chamber 8A, which can be ensured independently of the speed of the contact tube 10 and which is indispensable for the safe operation of the load disconnect switch 1.FIG. 10 shows the state of a load disconnect switch, which is shown here only as a schematic circuit diagram, during the switching operation. In the initial state, both the main contact point 2 and the arc extinguishing device 8 are switched on. This means that the main current path and the bypass current path are closed and connected in parallel.In the next step, the main contact point 2 opens, as a result of which the current flow to the second contact point 3 is commutated with the arc extinguishing device 8 switched on.In the third step, an arc between the fixed contact 6 and the movable contact 7 ignites as soon as the arc extinguishing device 8 is opened. This arc remains until it is extinguished in the arc extinguishing device 8.After the arc has been extinguished in the arc extinguishing device 8, the third contact point 16 then opens in the fourth step.FIG. 11 is a schematic diagram showing the operation of turning on using circuit diagrams. Initially, both the main contact point 2 and the third contact point 16 are open, while the arc extinguishing device 8 is switched off.In the next step, both the main contact point 2 and the third contact point 16 close, with the vacuum switching chamber 8A continuing to remain switched off. In this case, a load or short-circuit switch-on takes place via the main contact point 2.In the third step, the main contact point 2 and the arc extinguishing device 8 are switched on, so that the main current path with the main contact point 2 and the secondary current path with the second contact point 3 and the third contact point 16 are closed.List of reference characters1 Load interrupter 2 Main contact point 3 Second contact point 4 Upper main contact piece 4A Stationary main contact piece 4B Contact finger 5 Lower main contact piece 6 Fixed contact 7 Movable contact 8 Arc extinguishing device 8A Vacuum switching chamber 9 Lower stationary contact 10 Contact tube 11 Sliding contact point 12 Actuating slide 13 Toggle lever 14 Contact pressure spring 15 Switch-off spring 16 Third contact point 17 Contact pin 18 Contact pin sliding contact point 19 Latching contact 20 Latching lug 21 Tension spring 22 Compression spring 23 Limiting element 24 Minimum separating distance R 1 Opening direction R 2 Switch-on directionReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 197 51 648 A1

[0008] DE 19859007 A

[0009]

Claims

Load interrupter (1) for use in medium-voltage networks of up to 24 kV, having a. a main contact point (2) which is designed as a sliding contact and carries the rated and load current, having an upper main contact piece (4) and a lower main contact piece (5) which is mounted in a linearly displaceable manner in a contact tube (10), and b. a secondary contact arrangement which is arranged electrically parallel to the main contact point (2) and is intended to take over the rated and load current during a switching-off operation, the secondary contact arrangement having a second contact point (3) which is designed as an arc extinguishing device (8) and has a fixed contact (6) and a movable contact (7) and a third contact point (16) which is arranged electrically in series with the second contact point, characterized in that the fixed contact (6) of the arc extinguishing device (8) is fixedly connected to the upper main contact piece (4).Load interrupter (1) according to Claim 1, characterized in that the arc quenching device (8) is designed as a vacuum switching chamber (8A).Load circuit breaker (1) according to either of Claims 1 and 2, characterized in that the load circuit breaker (1) has a commutator arrangement for the mechanical commutation of the rated or load current from the main contact point (2) to the auxiliary contact arrangement.Load interrupter (1) according to Claim 3, characterized in that the commutator arrangement has an actuating slide (12) which is arranged in the contact tube (10), the actuating slide (12) being coupled to a contact pressure spring (14) and a switch-off spring (15) for switching the arc extinguishing device (8).Load interrupter (1) according to one of Claims 1 to 4, characterized in that the contact tube (10) is designed and arranged in such a way that a displacement of the contact tube (10) which takes place during the switch-off operation results in mechanical actuation and electrical contacting of the arc extinguishing device (8).Load interrupter (1) according to one of Claims 1 to 5, characterized in that the contact tube (10) has a movably mounted contact pin (17) which is designed and arranged in such a way that it makes possible an electrical connection or an electrical disconnection of the arc extinguishing device (8) from the lower main contact piece (5) via the third contact point (16) by means of a latching contact (19).Load disconnect switch (1) according to one of Claims 1 to 6, characterized in that, when the main contact point (2) is closed, the main contact point (2) has a main resistance, and in that, when the second contact point (3) is closed and the third contact point (16) is closed, the auxiliary contact arrangement has an auxiliary resistance, the auxiliary resistance being at least 5 times the main resistance.Load interrupter (1) according to one of Claims 1 to 7, characterized in that the load interrupter (1) has a lower stationary contact (9) which is arranged in a fixed manner with respect to the upper main contact piece (4) and which realizes mechanical guidance and electrical contacting of the contact tube (10).Load disconnect switch (1) according to one of Claims 1 to 8, characterized in that the upper main contact piece (4) has contact fingers (4B) and the lower main contact piece (5) is designed as a contact blade.Load disconnect switch (1) according to one of Claims 1 to 9, characterized in that the contact tube (10) is arranged and designed in such a way that the second contact point (3) opens shortly after the main contact point (2) has been opened.Load interrupter (1) according to one of Claims 1 to 10, characterized in that the load interrupter (1) is designed as an internal load interrupter.

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