Short-circuit device for use in low-voltage installations and method for initiating a short circuit

Abstract

The invention relates to a short-circuiting device (100, 200) for use in low-voltage systems for the protection of property and persons, comprising a switching device (10); - a first and a second fixed contact electrode (2, 3), and means for supplying current which are connected to the first and to the second contact electrode (2, 3); - a movable contact electrode (4) which is in electrical contact with the first fixed contact electrode (2) and is under a mechanical prestress with respect to the second fixed contact electrode (3) and is designed to carry out a relative movement to the second fixed contact electrode (3) in the event of a short circuit with the aid of spring force; - a sacrificial element (5) as a movement block for the movable contact electrode (4), which is arranged in a tensile manner between the first fixed contact electrode (2) and the movable contact electrode (4) or in a compressive manner between the movable contact electrode (4) and the second fixed contact electrode (3); - an electrical connection between the sacrificial element (5) and the switching device (10) on the one hand and one of the fixed contact electrodes (2, 3) on the other hand, whereby a current-flow-induced thermal deformation or destruction of the sacrificial element (5) can be brought about in a targeted manner, wherein the current-flow-induced thermal deformation of the sacrificial element (5) can be monitored and a degree of thermal deformation can be deduced.

Description

[0001] The present invention relates to a short-circuiting device for use in low-voltage systems and a method for initiating a short circuit, in particular for DC applications.

[0002] Known state-of-the-art short-circuiters for AC applications can use a sacrificial element, whereby at least two contacts can be held in compression or tension by a spring force and a sacrificial element arranged between them under mechanical tension. A control system can send a control signal to the short-circuiter in the event of an arc being detected. After such a control of the short-circuiter, a current can flow through the sacrificial element, which can deform or dissolve due to the thermal stress. At least two contacts can then be brought together to create a metallic short circuit, allowing the arc to be specifically extinguished within the low-voltage system.

[0003] DE 10 2013 001 612 A1 describes an arrangement for protecting systems and personnel in the low-voltage range, comprising a short-circuiting device with a switching element that can be triggered by an arc fault detection device. According to the invention, the electrical energy for triggering the switching element results exclusively from the energy of the occurring arc fault. The short-circuiting device can comprise two contacts that are movable relative to one another and held at a distance by a sacrificial element. Furthermore, the sacrificial element can be influenced with the aid of the switching element in such a way that the movable contacts enter a short-circuit state.

[0004] DE 10 2005 048 003 A1 describes a short-circuiting device with a sacrificial element between two contacts, whereby after actuating a switch, a current can be diverted via the sacrificial element in the event of a short circuit. It is also planned to use a switch that is self-extinguishing at zero current crossing and to additionally use an impedance so that the current can be limited via the switch and the sacrificial element. These measures are intended to prevent a permanent metallic short circuit from necessarily initiating in the case of small fault currents, since such arc faults with low current in AC are still automatically extinguished. Although this measure can possibly prevent the immediate shutdown of the system by the upstream overcurrent protection in the event of minor faults, timely maintenance of the system and inspection or replacement of components is essential.Reversible operation of the protective device is not possible, as damage may already be present due to the current load on the switch and the sacrificial element. This damage can result not only in the loss of further functionality but also in an undefined dielectric strength of both the isolating gap of the contacts due to creeping movement, and of the switch due to overload.

[0005] Particularly in DC systems with frequently changing short-circuit powers and sometimes very low powers, safe and multiple reversible operation (switching the short circuit on and off again) while ensuring unrestricted functionality and a high short-circuit capacity would be advantageous. This could eliminate or reduce the effort required to check or replace components of the short-circuiting device after each trip. Maintenance would only be necessary after a permanent metallic short circuit in the system due to extreme loads or after reaching a defined aging state.

[0006] Against this background, the present invention is based on the object of specifying a short-circuiting device for use in low-voltage systems, in particular also for DC networks, with reliable, reversible operation, as well as a method for initiating a short circuit in low-voltage systems using a short-circuiting device. A first object of the invention is the reliable assessment of aging or wear of the sacrificial element during reversible use of the short-circuiting device. A further object is to ensure reliable function of both the short-circuiting device during reversible operation and of the internal switching device in the tripping circuit of the short-circuiting device in AC and DC networks with undefined short-circuit powers.A further task is to ensure the safe operation of the short-circuiting device when leaving the reversible operating range, both in the main metallic path and in the short-circuiting device's tripping circuit. Another task is to enable the interaction of a short-circuiting device with an externally controllable switching device with reversible use of the entire arrangement, also enabling automatic reclosing (AR) of the system.

[0007] According to the invention, this object is achieved by a short-circuiting device for use in low-voltage systems according to the features of claim 1 and by a method for initiating a short circuit in low-voltage systems using a short-circuiting device according to the features of claim 11. The inventive solutions, which enable safe, reversible operation of the short-circuiting device, result in several advantages. Already during the formation of arcs, rapid arc detection by briefly switching the internal switching device in the control of the short-circuiting device on and off can clarify to what extent the fault will develop into a high-energy arc fault or not. If this prerequisite is not met, further fault development is prevented.In systems with varying short-circuit power or in systems with lower currents anyway, shutdown of the systems can be avoided and safe continued operation of the system can be ensured.

[0008] This advantage also enables an improvement in selectivity in systems with short-circuiting devices in the main distribution board and in the sub-distribution boards by using such short-circuiting devices or by combining them with separate overcurrent devices.

[0009] The inventive safe, reversible short-circuiting device can also be used, particularly in sub-distribution boards, in combination with fast-acting overcurrent protection devices to disconnect faulty outgoing circuits. For this purpose, a fast switching device, particularly one with opening times of less than 10 ms, can be directly controlled from the short-circuiting device. This also enables the integration of such a switching device into the sequence of automatic on / off cycles, resulting in advantages for system availability and selectivity.

[0010] In the event of a fault, it is advantageous to assume a state after which the entire system does not always have to be short-circuited immediately, but which still allows the option of selectively extinguishing the arc. This is preferably achieved by briefly switching on the internal switching device of the short-circuiting device control. The current flow in the control path can, however, be switched off by an internal or external switching device. Subsequently, when the load is within the permissible reversible range, the short-circuiting device is automatically reset to the high-impedance operating state while remaining fully functional. The system continues to operate. There is no need to check the system or perform maintenance on the part of the short-circuiting device. Therefore, checking or shutting down the system is only necessary in the event of a permanent metallic short circuit of the main contacts of the short-circuiting device.

[0011] According to the invention, the short-circuiting device for use in low-voltage systems for the protection of property and persons comprises a switching device which can be actuated by a trigger signal from an internal control unit; a first and a second fixed contact electrode which are opposite one another and means for supplying current which are connected to the first and the second contact electrode, said means being contactable to an electrical circuit with terminals of different potential; a movable contact electrode which is in electrical contact with the first fixed contact electrode and is subject to a mechanical prestress with respect to the second fixed contact electrode and is designed to carry out a relative movement to the second fixed contact electrode with the aid of spring force in the event of a short circuit;a sacrificial element as a movement block for the prestressed movable contact electrode, which is arranged under tensile load between the first fixed contact electrode and the movable contact electrode or under pressure between the movable contact electrode and the second fixed contact electrode; an electrical connection between the sacrificial element and the switching device, on the one hand, and one of the fixed contact electrodes, on the other hand, whereby a current-flow-induced thermal deformation or destruction of the sacrificial element can be brought about in a targeted manner, wherein the switching device comprises a control device configured to monitor the current-flow-induced thermal deformation of the sacrificial element and to infer a degree of thermal deformation;and in addition to the control device or instead of the short-circuiting device, the short-circuiting device further comprises a position detection device with which a position of the movable contact electrode relative to the second fixed contact electrode can be detected and is comparable to a minimum separation distance of the movable contact electrodes from the second fixed contact electrode;

[0012] The arrangement of the two fixed contact electrodes, the movable contact electrode, the sacrificial element (and any position sensing component) and the spring can be referred to as a mechanical part of the short-circuiting device or simply as a "mechanical short-circuiter".

[0013] The internal control unit can be integrated into the short-circuiting device or be implemented separately and connected externally to it. The internal control unit itself can trigger the mechanical short-circuiter even without an arc fault or without a signal indicating a fault in the low-voltage system. The minimum separation distance, i.e. the minimum permissible clearance and creepage distances, correspond to the normative regulations according to the network structure and the operating voltage.

[0014] In new condition, a sufficient distance can be easily adjusted while observing the tolerances. Aging due to environmental conditions (including temperature changes, vibration, etc.) can also be simulated with appropriate long-term tests and thus at least partially taken into account. However, a switched current pulse of undefined duration and magnitude can also damage the sacrificial element. The damage depends on the cooling conditions, the current environmental conditions, the mechanical load, the force vectors, and possibly also a current pulse sequence. These combined loads, which act on the sacrificial element during reversible use, are difficult to take into account. As a result of such loads and also geometric tolerances, small deformations can occur, for example, as a result of heating, the application of pressure or tension from a spring, or even changing force vectors.

[0015] The deformations do not necessarily lead to a loss of the mechanical strength of the sacrificial element, but they can lead to a reduction in the distance and cause the minimum separation distance or the required dielectric strength to be exceeded.

[0016] State-of-the-art short-circuiters, however, cannot indicate this impairment. If an indicator is present, it can only indicate the states "contacts open or contacts metallically closed." This is sufficient, as a reduction in the gap due to repeated current loading does not occur, as this use (multiple loading without maintenance or replacement) was not previously provided for.

[0017] According to the invention, however, the relative movement of the contact electrodes to one another can advantageously be detected, which represents aging. This can be achieved by a suitable detector of the position detection device. The position detection device can have at least one sensor that can detect the movement in real time. This enables an assessment of aging or an estimation of the remaining service life, even with reversible operation of the short-circuiting device. This not only enables reliable reversible operation, but also advantageously enables needs-based or predictive maintenance.

[0018] With the short-circuiting device according to the invention, a permanent short circuit can also be created, creating a so-called "direct metallic short circuit." This can be done intentionally through continuous activation or automatically by very high current loads. In this case, the sacrificial element is melted or even vaporized. At the same time or subsequently, the moving contact electrode is also moved toward the counter electrode due to the spring force, according to the state of the art.

[0019] In previous AC applications, such short-circuiting devices were only used in systems with high prospective short-circuit currents, since, on the one hand, arcs self-extinguish at low currents up to approximately 1 kA, and medium currents up to a few kiloamperes have only a low damage potential. The short-circuiting devices are therefore only designed for currents of approximately 5 kA in terms of detection and function. In the AC range with such defined minimum short-circuit currents, the behavior of the sacrificial elements is defined. In DC systems or systems with variable short-circuit power, neither the self-extinguishing of arcs with lower currents nor the rapid or adiabatic melting or evaporation of the sacrificial elements of the short-circuiting device can be guaranteed.At low currents, the sacrificial elements may soften and deform, which may result in a shortening of the minimum separation distance due to the contact movement starting or stopping if the current load is interrupted or reduced.

[0020] In the case of deliberate continuous activation or overload due to high currents, safe operation requires ensuring the metallic closure of the contact electrodes of the mechanical short-circuiter and also avoiding overloading of the internal switching device of the control. Particularly in the case of a replaceable mechanical short-circuiter with a separate control, it is advantageous that the control unit (fault detection device, internal control unit including the internal switching device) remains usable for continued operation. The specification "internal" can refer to the short-circuiting device itself, for example, with regard to its components and / or a housing of the short-circuiting device and thus be part of or included in the short-circuiting device.

[0021] Inventively, a material can be selected for the sacrificial element that is work-hardened during production and is not stress-relieved after production through heat treatment as is usual with wire or tube drawing. In particular, a work-hardening of > 10%, but preferably 30%, is aimed for. Loading the sacrificial element in the desired reversible current range only leads to heating, which does not cancel out the work-hardening of the material of the sacrificial element. In the case of deliberate triggering or at higher current loads, heating of the sacrificial element leads to a softening of the material, which, as a result of the spring force, causes reliable deformation or rapid tearing. This means that deformation, melting and evaporation can be avoided if the movement of the contacts during closing persists in all overload cases.

[0022] Furthermore, the control of the current flow through the sacrificial element, i.e. the magnitude and duration as well as the overload behavior, can be improved by an extended circuit and control.

[0023] Inventively, the current flow in the control system can be recorded and evaluated by an internal switching device. This measurement can be used, on the one hand, to evaluate the load in reversible operation (number, total load, limit value determination), e.g., for assessing predictive maintenance, and, on the other hand, to assess the risk of overloading the components or leaving the reversible operating range.

[0024] According to the invention, a second parallel switching element with higher short-circuit power but without DC breaking capacity can be provided in the control path, which is activated before the load limit of the first switching element is reached or when permanent control is desired. Permanent control can be advantageous, among other things, when operating with an externally controllable switching device or when leaving the reversible operating range. The first switching element with DC breaking capacity is thus protected from overload and can also be designed inexpensively. The short-circuit power of the second switching element, on the other hand, is selected so that overloading can be ruled out. For this purpose, it is coordinated with the behavior of the sacrificial element and the contact movement so that arcing in the mechanical short-circuiter or, at the latest, a metallic short circuit completely relieves the internal switching device.

[0025] This significantly increases the safety of the device in a cost-effective design and also enables a cost-effective separation of the mechanical short-circuiter and the internal control unit, meaning that in the event of a metallic short circuit, only the mechanical short-circuiter needs to be replaced or serviced.

[0026] As a result of environmental influences such as temperature changes, vibrations, material fatigue, or similar, the spring preload of the contact electrodes can lead to a shortening of the isolating distance without triggering, which can be attributed to aging or wear of the sacrificial element. If the minimum isolating distance is reached or even exceeded, the probability of arcing between the isolating electrodes under normal operating conditions can be increased. The position detection device can advantageously enable a condition assessment, which can detect a shortening of the distance between the contact electrodes before or before the minimum isolating distance is exceeded, in order to detect aging of the sacrificial element due to environmental influences or during reversible (short-circuit) operation in a timely manner.

[0027] By using the position detection device, an aging indicator for the sacrificial element can advantageously be realized in real time and it can be estimated whether further reversible operation of the device is still possible and furthermore, for example by evaluating the data of the position indicator, it can also be estimated how long reversible operation without maintenance is still possible.

[0028] Following a signal from the internal control unit, the internal switching device of the short-circuiting device can briefly generate a short circuit across the sacrificial element, for example, for approximately 1 ms, and then shut it down again. After this predetermined time, the internal control unit can re-evaluate whether an arc fault is still present; this can be registered as a fault / error. If the arc fault persists, the short circuit can be conducted again or permanently across the sacrificial element, subjecting it to further brief or permanent stress. In the latter case, the sacrificial element is destroyed, and a permanent metallic short circuit occurs across the contact electrodes.

[0029] However, if no further arc fault detection occurs after the brief current flow and the switching element has been switched off, the arc has been successfully extinguished and the system and the short-circuiting device are returned to the normal operating state.

[0030] The short-term current flow through the switching element with DC switching capability can be controlled not only by fixed time control but also by load control or a combination of both. After switching on, the current, charge, or energy can be evaluated. For low loads in the reversible range, the duty cycle can be extended, or, if there is a risk of overload, the internal parallel switching element can be activated before a specified time.

[0031] The fault detection and evaluation device (control device) used for this purpose can be a separate controller or computer, or it can be integrated into the control device of the system and / or the short-circuiting device (internal control unit). Integration of the control device directly into the switching device itself is possible and can preferably be provided in the internal control unit of the short-circuiting device.

[0032] If a suitable external switching device is present in the system's supply path, for example in an outgoing branch, the internal control unit for switching off the current through the short-circuiting device can control this directly and use it to switch off the induced short-circuit current. In this case, the internal switching device does not necessarily require a switchable switching element itself. The process described above is identical except for the use of the external switching device for switching off the current. The reactivation of the external switching device in reversible operation can be carried out by the internal control unit of the short-circuiting device or by a higher-level central control unit of the grid operator. As an alternative to a permanent short circuit, the activation of the external switching device, i.e. the restart of the grid, can also be blocked in this case.

[0033] The relative movement can be triggered by a short-term or permanent short-circuit. The sacrificial element can be a spacer or a retaining cable for the relative movement. Thermal deformation or destruction can occur through a switched current in the sacrificial element. The position detection device can be connected to the evaluation device and the control unit, and an evaluation of the wear or the current distance between the contact electrodes can be carried out via these. In addition to the "arc fault" fault, the device can also be used in other fault situations to decommission the system or to create a low-resistance metallic short circuit.

[0034] In this case, the short-circuiting device can be activated via one or more separate signal inputs of the internal control unit, for example, from an external central control unit of the network or system operator. Connection to other safety devices that serve fire, system, or personnel protection is also possible via such signal inputs.

[0035] According to a preferred embodiment of the short-circuiting device, the position detection device comprises a position sensor which is arranged in or on a first fixed contact electrode or on a housing of the short-circuiting device or on a base of a pluggable part of the short-circuiting device and the position detection device further comprises a position sensor as a permanent magnet or dielectric, wherein the position sensor is arranged in or on the movable contact electrode.

[0036] According to a preferred embodiment of the short-circuiting device, it is designed in several parts and a mechanical short-circuiter of the short-circuiting device can be plugged into a base (for example the lower part of a fuse switch disconnector) of the short-circuiting device and can be exchanged, wherein the mechanical short-circuiter comprises the two fixed contact electrodes, the movable contact electrode and the sacrificial element.

[0037] According to a preferred embodiment of the short-circuiting device, the position detection device comprises at least one capacitive and / or inductive touch, displacement and / or position sensor or at least one magnetic field sensor or a Hall sensor.

[0038] The position sensor itself can preferably be installed in the fixed (immovable) contact electrode or the housing of the mechanical short-circuiter, for example in a recess provided for this purpose or on a suitable surface. If the short-circuiting device comprises a plug-in mechanical short-circuiter, the position sensor can also be installed in its base. If necessary, a position sensor can be inserted or attached in the form of a permanent magnet or a plate with a defined dielectric in the moving contact electrode or coupled to it, such that the position sensor can detect and evaluate its movement. As the sacrificial element ages, a relative movement and / or change in the distance to the position sensor can be detected.

[0039] The position detection device can detect advanced aging or wear as the predefined minimum separation distance is approaching or falling below it and can signal or read when a replacement of the sacrificial element or the mechanical short-circuiter is necessary.

[0040] The position sensor can be used as an alternative to or in addition to the standard status indicator, which, according to the state of the art, can provide information about triggered metallic short circuits or open contacts. With short-circuiting with a reversible function, the number, magnitude, and duration of electrical loads can also be recorded and evaluated. This can be achieved, on the one hand, by the number of activations and the evaluation of the position sensor, and, on the other hand, if available, by evaluating the current in the activation path or in the short-circuit path. This provides several options for proactively planning maintenance or replacement.In the event of a sudden critical reduction in the separation distance, the mechanical short-circuiter can be permanently controlled from the internal control unit or from a control center in order to quickly achieve the safe “metallic short-circuit” state as an alternative to maintenance or the targeted shutdown of the system.

[0041] To ensure safe behavior of the mechanical short-circuiter in the event of overload, the sacrificial element can be used in the cold-formed state. The strength can preferably be increased by at least 30% compared to the tempered, stress-relieved material (recrystallization annealing).

[0042] The sacrificial element preferably has the geometry of a hollow cylinder, a wire, or a rope. High-strength steels with low elongation can be used as the material, for example. The electrical loads during reversible operation are deliberately applied only up to temperatures (recrystallization temperature) below which no softening occurs; in the case of steel, for example, even below the so-called A1 temperature.

[0043] According to a preferred embodiment of the short-circuiting device, the switching device is connected in series with the sacrificial element and comprises a first switching element and a second switching element, wherein at least one short-circuit current can be switched on and off again over a respective predetermined or determined period of time with the first switching element and a permanent short-circuit current can be switched on and off again with the second switching element.

[0044] According to a preferred embodiment of the short-circuiting device, the first switching element comprises at least one IGBT and / or the second switching element comprises at least one thyristor.

[0045] A short-term short-circuit can be achieved in the circuit device by using an IGBT arranged in parallel with the thyristor of the short-circuiting device. In the case of small and / or medium loads, the IGBT can be controlled and conduct the current through the sacrificial element for a predetermined or determined period of time, approximately 1 ms. If this is not sufficient to extinguish the arc and the fault persists, repeated switching on and off attempts of the IGBT or subsequently the thyristor can be controlled, creating a permanent current path through the sacrificial element until it is overloaded.

[0046] As already mentioned, a switching device or switching element with a short turn-on delay and DC breaking capacity, for example an IGBT or similar, can be advantageously used for the initial switching on and off after an arc fault is detected. This switching device can be activated for a short time, and this time can be fixed or adjusted depending on the current load. A current flow through the switching device can be detected and evaluated, for example, by the switching element itself or by a suitable current measuring device. The total current in the short-circuit path can also be measured for this purpose. Criteria for evaluating the current can also include current magnitude, current threshold values, current increases, and current duration. If the load until shutdown is within the capacity of the internal switching device and the sacrificial element, the process can be completed.If no fault message is generated or does not recur within the known arc fault detection time, the system can continue to operate without a short circuit. The system and the short-circuiting device are automatically switched to operating mode by switching off the short-term fault current and are loaded with the applied voltage.

[0047] However, if an overload of components cannot be ruled out due to the evaluation options, or if the minimum separation distance is not met, as an alternative to the maintenance instructions, a permanent control of the mechanical short-circuiter can be forced until a metallic short circuit occurs.

[0048] According to a preferred embodiment of the short-circuiting device, the internal control unit is configured to receive or generate a detection signal from a fault detection device, process and evaluate measurement data from the internal sensors regarding load or aging, and subsequently control internal and / or external switching devices for reversible use of the mechanical short-circuiter or for triggering a permanent short circuit. The internal control unit can also be configured to receive and implement higher-level control commands.

[0049] Higher-level control commands are those which trigger the internal control unit to immediately and permanently trigger the switching devices.

[0050] This can be a signal sent via a separate interface of the internal control unit, for example, by an external central control unit of the grid operator. Tripping can also be triggered if, in the case of a suitable external fault detection device that can also evaluate the intensity of an arc fault, the internal control unit simultaneously reports the "arc fault" message and the "high-intensity arc fault" message. In this case, the internal control unit immediately triggers permanent control of the switching device. In this way, in addition to pure arc fault detection, the "intense arc fault" assessment can also be implemented, whereby at least two pieces of information can be passed to the internal control unit.

[0051] The control unit thus enables the frequency, duration and switching sequence for switching from temporary short circuits to permanent short circuits, depending on the load.

[0052] According to a preferred embodiment of the short-circuiting device, the internal control unit is configured to receive or determine a respective predetermined or determined time period, whereby the switching device can be switched over the predetermined or determined time period and switched off again or switched on permanently depending on the presence of the fault.

[0053] The switching devices (external or internal) are always activated via the internal control unit, which can evaluate information from the internal or external load, control, status, and fault detection devices. The internal control unit can determine the duty cycle and selection of the switching devices or switching elements.

[0054] According to a preferred embodiment of the short-circuiting device, the internal control unit is configured to determine a current in a path of the short-circuiting device and to evaluate it against a fault / error in the low-voltage system and to determine a respective predetermined or determined time period or a permanent circuit.

[0055] The internal control unit can access internal and external sensors, measuring equipment, and information from third-party facilities for the assessment. Based on this information and the internal assessment facilities, the optimal procedure for resolving the fault / error caused by a short-term or permanent short circuit is then implemented. In addition to ensuring the safety of the plant and personnel, the focus is always on ensuring rapid resumption of plant operation.

[0056] According to a preferred embodiment of the short-circuiting device, the internal control unit is suitable, on the basis of the signals of a fault detection device (including a sensor for current and light) and the internal current evaluation devices in the control or main path of the short-circuiting device, for eliminating faults, in particular arc faults, as quickly as possible with the aid of the internal or also a controllable external switching device and for ensuring the continued operation of the system on the grid as far as possible and for causing a permanent metallic short circuit or the shutdown of the system only in the case of very serious faults.

[0057] Instead of a permanent short circuit, selective disconnection of the faulty outgoing circuit is also possible in DC systems by integrating fast-switching switching devices (mechanical, hybrid, semiconductor) with a response time of < 10 ms. The internal control unit automatically varies the use of the existing switching devices or their switching elements, the duty cycle, and the number of disconnection attempts, up to and including a permanent shutdown or a permanent short circuit.

[0058] According to a preferred embodiment of the short-circuiting device, the position detection device comprises a wear indicator for the sacrificial element, with which the reaching of a predetermined wear of the sacrificial element after aging or reversible short-circuiting can be indicated, wherein the reversible short-circuiting corresponds in each case to an on- and off-cycle of the short-circuit current over at least a predetermined or determined period of time.

[0059] In contrast to the prior art, the switching device can be arranged in series with the sacrificial element, using, for example, a parallel connection of IGBT and thyristor. In this case, the IGBT can advantageously have a performance adapted to the reversible load capacity of the sacrificial element and can be used, for example, for short-term switching on and off. In the event of an overload fault or if the arc cannot be successfully extinguished, the thyristor can be switched. This is advantageous for permanent short circuits, as thyristors can have a significantly higher current-carrying capacity than IGBTs with the same size.

[0060] The short-circuit conduction of the thyristor and the behavior of the mechanical short-circuiter are coordinated so that the mechanical short-circuiter reliably relieves the thyristor from exceeding its power limit due to internal arcing or a metallic short circuit. The thyristor can be protected at very high short-circuit power levels by an additional impedance in the control path. Furthermore, thyristors can be selected that short-circuit in a defined manner upon overload, so that even in this case, the activation of the metallic short circuit can be reliably achieved by overloading the sacrificial element. The aforementioned parallel connection of the switching elements can enable a more cost-effective selection of components and functionally more favorable coordination options for the overall function of the conditionally reversible short-circuiting behavior while maintaining high performance and safety.

[0061] According to the invention, an occurring reduction in the distance between the contact electrodes, which are permanently subjected to tension or compression by a spring tension, can advantageously be detected before a critical separation distance is reached and before the metallic short circuit occurs, which can represent increased safety and can improve a needs-based replacement.

[0062] To enable quick and sustainable replacement at low cost, the control unit and the mechanical short-circuiter can be designed separately. During maintenance, only the mechanical short-circuiter needs to be replaced. The mechanical short-circuiter can be designed as a plug-in component, which is compatible with fuse bases, for example.

[0063] The mechanical short-circuiter itself also allows for the replacement of the sacrificial element. This is particularly advantageous for use in systems with low to medium short-circuit currents, since these loads generally only result in deformation of the sacrificial element until a short circuit occurs, meaning the contact electrode remains in mint condition even after a metallic short circuit.

[0064] By applying a work-hardened sacrificial element, rapid softening of the material can occur at loads that lead to temperatures significantly above the recrystallization range, enabling faster closing of the contact electrodes of the mechanical short-circuiter, even at lower spring forces. Furthermore, the limit of the reversible load can be determined more precisely and better controlled.

[0065] According to a preferred embodiment of the short-circuiting device, the sacrificial element comprises a work-hardened material.

[0066] According to the invention, in the method for initiating a short circuit in low-voltage systems using a short-circuiting device according to the invention, the presence of a fault as a defect in the low-voltage system and the need for a short-circuit circuit are detected; a switching device is activated and a short-circuit circuit is thereby triggered with a short-circuit current over a predetermined or determined period of time or permanently; the short-circuit current is limited (as a result of the activation and switching) by the switching device by means of the sacrificial element and a current of the fault is commutated to the short-circuiting device;interrupting the short-circuit current after the predetermined or determined period of time and re-loading the low-voltage installation with mains voltage, wherein the thermal deformation of the sacrificial element caused by the current flow is monitored by a control device (the control device can control the switching device but can also belong to the internal control unit) and a degree of thermal deformation of the sacrificial element is deduced and / or a position of the movable contact electrode relative to the second fixed contact electrode is detected and compared with a minimum separation distance between the movable contact electrode and the second fixed contact electrode, and wherein the position detection and / or the monitoring of the thermal deformation takes place before the switching device is activated and / or after the short-circuit current is interrupted;and, if necessary, a renewed activation of the switching device and triggering of a short-circuit circuit with a further short-circuit current for a further predetermined or further determined period of time or permanently in the event of a renewed or permanent fault and destruction of the sacrificial element in the event of a permanent fault and generation of a permanent short circuit.;

[0067] According to a preferred embodiment of the method, the internal control unit receives or determines trigger signals and acts after a respectively predetermined or determined period of time, wherein the first switching element switches and switches off again once or several times over the predetermined or determined period of time depending on the presence of the fault, or in the case of a permanent fault, permanently switches the short-circuit current via the second switching element and destroys the sacrificial element in the case of a permanent short-circuit current.

[0068] If a fault detection device is used to detect the arc fault, which can also evaluate the intensity of the arc fault, corresponding information in the internal control unit can be used for the evaluation. It is also possible to initiate permanent short-circuiting immediately at extremely high intensities.

[0069] According to a preferred embodiment of the method, after or during the first short-term activation of the short-circuiting device, a current is determined in at least one path of the short-circuiting device and evaluated against the load capacity of the components of the short-circuiting device and, taking into account the behavior of the fault / error in the low-voltage system, a further short-term activation with a predetermined duration, an extended activation with a determined duration or a permanent activation is determined.

[0070] According to a preferred embodiment of the method, the internal control unit receives or determines a respective predetermined or determined time period and the first switching element switches on and off again over the predetermined or determined time period depending on the presence of the fault or, in the case of a permanent fault, the short-circuit current is permanently switched via the second switching element and, in the case of a permanent short-circuit current, the sacrificial element is destroyed.

[0071] According to a preferred embodiment of the method, a duration and / or magnitude and / or number of switched short-circuit currents is determined and taken into account in a wear assessment of the sacrificial element as well as in a maintenance recommendation.

[0072] According to a preferred embodiment of the method, a current is detected and evaluated by a current measuring means or the switching element itself in a path of the short-circuiting device in order to determine the load of the switching device.

[0073] According to a preferred embodiment of the method, a current in a path of the short-circuiting device is detected and evaluated by the switching device and / or by a current measuring means of the short-circuiting device in order to determine the fault.

[0074] According to a preferred embodiment of the method, a position of the movable contact electrode relative to the second fixed contact electrode is determined by means of a position sensor on a housing of the short-circuiting device or on the first fixed contact electrode and a position sensor as a permanent magnet or dielectric on the movable contact electrode.

[0075] In particular, a short-circuiting device for direct current and alternating current can be realized, which requires only a small additional effort within the scope of its reversibility, i.e. a short-term switching on and off for the purpose of extinguishing arc faults.

[0076] It may be advantageous to assess the extent to which reversible operation (re-deactivation of the short circuit), i.e., the continued operation of the short-circuiting device in the network, is possible, even when the short-circuit path is activated and until it is deactivated. For this purpose, a current in the path itself can be evaluated according to predetermined criteria. If continued operation according to a specified specification is not guaranteed, a permanent metallic short circuit can be initiated.

[0077] The features and their advantages mentioned in the context of the short-circuiting device also apply analogously to the method according to the invention, and vice versa. The present invention is explained in more detail below with reference to the exemplary embodiments shown in the schematic figures. They show: Fig. 1 a schematic representation of an arrangement of short-circuiting devices in a DC network with BUS system and outgoing branch. Fig. 2 is a schematic representation of a short-circuiting device with a circuit diagram of a circuit device and internal control unit according to an embodiment of the present invention with a sacrificial element which is subjected to tensile stress; Fig. 3 is a schematic representation of a short-circuiting device with a circuit diagram of a circuit device and internal control unit according to an embodiment of the present invention with a sacrificial element which is subjected to pressure; Fig. 4 is a circuit diagram of the switching device of the short-circuiting device according to an embodiment of the present invention; Fig. 5 a mechanical short-circuiter according to Fig. 4 with a sacrificial element under pressure, which after the Fig. 5a is new, after the Fig. 5b is slightly aged and after the Fig. 5c has aged considerably. Fig. 6 a schematic representation of a mechanical short-circuiter with position detection device in a fuse switch disconnector in a plan view of the Fig. 6a, in a sectional view of the Fig. 6b and a zoom view of the Fig. 6b in Fig. 6c Fig. 7 is a schematic cross-sectional view of the mechanical short-circuiter according to an embodiment of the present invention; Fig. 8 a block diagram of method steps of the method according to an embodiment of the present invention. Fig. 9 exemplary functional sequence of a reversible short-circuiting device of an embodiment of the present invention Fig. 10 exemplary functional sequence of a reversible short-circuiting device with external switching device of a further embodiment of the present invention

[0078] Further features and advantages of embodiments of the invention will become apparent from the following description with reference to the accompanying drawings. Other embodiments and many of the aforementioned advantages will become apparent with reference to the drawings. The elements of the drawings are not necessarily shown to scale.

[0079] In the figures of the drawing, identical, functionally identical and acting elements, features and components are provided with the same reference symbols, unless otherwise stated.

[0080] In Fig. Figure 1 illustrates, as an example, the use of one short-circuiting device in the bus system and one in an outgoing branch for a DC network. The short-circuiting devices (100, 200) each comprise an internal control unit SE, which includes a fault detection device 1, a switching device 10, and mechanical short-circuiters KB, KA. The internal control unit SE can be connected to suitable detectors D or a combination thereof. The detectors can detect, for example, light and / or current or other variables such as pressure, sound, etc.

[0081] In the case of a DC network with positive, negative, and neutral conductors (grounded), a mechanical short-circuiter is used between the positive and neutral conductors, and between the negative and neutral conductors. The short-circuiting device 100 in the bus system can be controlled not only by its own internal control unit SE, but also by the control unit of the short-circuiting device 200 in the outgoing branch or by a central control unit ZSE, regardless of an arc fault in the bus system.

[0082] The switching devices S1 and S2 are shown as examples in the outgoing branch. Here, S2 corresponds to an overcurrent protection device of the outgoing branch, which may be designed to be controllable. The switching device S1 is a controllable switching device, preferably with at least one load switching capacity, which, after being controlled, can interrupt the current in the outgoing branch within a time of less than 10 ms. The switching device S1 can be automatically reconnected once or several times, either separately or by integration into the central control unit ZSE. The switching device can be used by the short-circuiting device 200 to implement a reversible mode of operation. The series connection with the switching devices S1 and their control enables a selective, possibly only brief, shutdown of the outgoing branch in the event of a fault.

[0083] In the event of a failed arc fault extinguishing, selectivity to the bus system can also be achieved through the passive protective function of S2 or by actively controlling S2 without automatic reset. If the fault cannot be rectified by the external switching device S2, the SE of the short-circuiting device 200 can also trigger the control of the short-circuiting device 100 on the bus system, thus shutting down the entire system.

[0084] The mechanical short-circuiter KB in the bus system may need to be permanently connected to the busbars for high short-circuit powers and, due to its size, may include the switching device 10 and, if applicable, the internal control unit SE. If the short-circuiting device 100 is triggered, at least the mechanical short-circuiter KB is subjected to such a high load that restarting the system without replacing this component is not advisable.

[0085] Due to its lower power, the mechanical short-circuiter (KA) in the outgoing branch can be designed to be smaller and, if necessary, pluggable. The internal control unit and switching device are not damaged when the mechanical short-circuiter (KA) is triggered and can be put back into operation after the KA has been replaced or serviced.

[0086] The Fig. Figure 2 shows a schematic representation of a short-circuiting device with a circuit diagram of a circuit device 10 and error detection device 1, which is connected to or belongs to the internal control unit SE. Fig. 2 therefore shows a short-circuiting device 100 (200) according to an embodiment of the present invention with a sacrificial element 5 which is subjected to a tensile force.

[0087] The short-circuiting device 100, 200 for use in low-voltage systems for the protection of property and persons comprises a switching device 10 which can be actuated by a trigger signal from an internal control unit SE, two fixed contact electrodes 2 and 3 which are opposite one another and means for supplying current which are connected to the contact electrodes 2, 3, wherein these can be contacted to a circuit with connections of different potential, wherein a movable contact electrode 4 which, for example, has the potential of the first fixed contact electrode 2 and which is under a mechanical prestress is designed to carry out a relative movement to the first contact electrode 2 and to the second contact electrode 3 in the event of a short circuit, supported by spring force and tensioned by a spring F;a sacrificial element 5, which, in its intact state, prevents relative movement and has an electrical connection, on the one hand, to the first contact electrode 2 and, on the other hand, via the switching device 10, to the second fixed contact electrode 3, whereby a current-flow-induced thermal deformation or destruction of the sacrificial element 5 can be deliberately brought about. After overloading of the sacrificial element 5, the movable electrode 4 is pressed towards the second contact electrode 3 by spring force, whereby the mechanical and electrical contact with the first contact electrode 2 is maintained during and after the end of the movement. After the end of the movement, there is thus a metallic short circuit in the circuit between the fixed contact electrodes 2 and 3 via the movable contact electrode 4. The contact electrodes 2 and 3 are anchored in a housing or are part of the same.

[0088] The switching device 10 can advantageously be connected in series with the sacrificial element 5 and comprise a first switching element 10a and a second switching element 10b, wherein at least one short-circuit current can be switched on and off again with the first switching element 10a for a respective predetermined or determined period of time and a permanent short-circuit current can be switched on with the second switching element 10b, depending on the control via the internal control unit SE. The first switching element 10a can be at least one IGBT and the second switching element 10b can be at least one thyristor, which can be switched on with a control current, advantageously by the internal control unit SE if a fault still exists in the system even after a short-circuit has already occurred and is detected by the internal control unit SE.If the conditions for a short-term and switchable short-circuit are present and are detected by the internal control unit SE, the control unit SE can also control and switch the first switching element 10a over the predetermined time.

[0089] The movable contact electrode 4 can move in an inner region (a recess) in the first contact electrode 2, in which the spring F can also be attached to the first contact electrode and connected to the movable contact electrode 4 in order to move it towards the second contact electrode 3. During the movement of the movable contact electrode 4, it can always have a mechanical and thus electrical contact with the first contact electrode 2. The movable contact electrode can, for example, have a cylindrical structure and be pressed out from the interior of the first contact electrode 2, wherein the first contact electrode 2 can surround the movable contact electrode 4 as a cylindrical shell. The spring F can be attached to the cylindrical axis of symmetry of the first and movable electrode and act along this. The sacrificial element 5 can Fig. 2 can be arranged within this recess and between an insulation region on the axis of symmetry of the first contact electrode 2 (electrically insulated from it, whereby the connection to the switching device can run through this insulation to the sacrificial element 5) and the movable contact electrode 4 and can be subjected to tensile stress against the spring action. Several short-term and reversible switching operations on the sacrificial element 5 can reduce its cross-section and lengthen the sacrificial element, thereby reducing the minimum separation distance to the second contact electrode (the movable electrode). The movable electrode 4 can rest on the second contact electrode 3 after the sacrificial element 5 has been destroyed, since any recess in the second electrode 3 is either missing or smaller in diameter than the diameter of the movable electrode 4, which creates a short circuit when the two come into mechanical contact.

[0090] The Fig. 3 shows a circuit diagram of the switching device of the short-circuiting device according to an embodiment of the present invention with a sacrificial element which is subjected to pressure.

[0091] In Fig. 3 a similar arrangement is used for Fig. 2. In contrast to Fig. 2 will be in Fig. 3, a sacrificial element 5 is used, which is not subjected to tension but to compression by the spring F. The functioning of the two arrangements is otherwise comparable. The symmetries of the electrodes 2, 3 and 4 can be that of the Fig. 2. In this case, the second electrode 3 can also have a recess in its center, which is smaller in diameter than the diameter of the movable electrode 4 and the sacrificial element 5 can be arranged in this recess and connected via an insulation through the second electrode 3 to the switching device 10 and insulated from the second electrode 3. Just as in the Fig. 2 can also be in mechanical and electrical contact with both the first electrode 2 and the second electrode 3 when the movable electrode 4 is placed on the second electrode 3 (with the sacrificial element destroyed). The spring F presses the movable electrode 4 toward the second electrode 3 and exerts pressure on the sacrificial element 5, which lies between the movable electrode and the second electrode 3. If the sacrificial element 5 is briefly short-circuited several times, it can be shortened or destroyed.

[0092] In the Fig. 4 is a detailed area of the Fig. 3, which relates to the switching device 10. An additional impedance Z can be present or correspond to the sacrificial element. In the Fig. 4 further shows in detail an example of an internal overload control 11, which can also be connected to the second switching element 10b, for example the thyristor. The internal overload control 11 can be designed and configured by dimensioning the electronic components according to the application. The overload control 11 can also provide information to the internal control unit, so that the current load of the switching element 10a and / or the current load of the impedance Z in the internal control unit are available, in addition to the information from the fault detection device, for the needs-based control of the switching device 10. The circuit 11 shown as an example evaluates the magnitude and duration of the current through the additional impedance Z. If the limit values set via the dimensioning of the components are exceeded, the thyristor 10b is controlled.The switching and evaluation of partial currents can, of course, also be performed in a different and more complex manner. The evaluation can be performed directly via the overload control 11 or in combination with the internal control unit in accordance with the disclosed functionalities.

[0093] The thyristor 10 b can of course also be controlled directly by the internal control unit without prior control of the IGBT according to Fig. 1 can be controlled.

[0094] The Fig. 5a-c shows an example of an arrangement according to Fig. 3 with a supporting sacrificial element 5 the aging due to environmental influences or the reversible use of such a short-circuiting device. In Fig. 5, only the mechanical short-circuiter of the short-circuiting device is used according to Fig. 3. The Fig. 5a shows a “new” condition and the distance A between the movable electrode 4 and the second fixed contact electrode 3 is greater than the required minimum separation distance B. After slight aging, slight deformations 6 of the sacrificial element 5 may occur, whereby the distance A changes slightly to A'. Fig. 5b, but still above the required minimum separation distance B. Continued operation in this condition is unproblematic. Fig. 5c, the sacrificial element 5 continues to deform and the distance A'' is shortened to the minimum separation distance B. Continued operation in this condition is only of limited use and an indication of maintenance or necessary replacement should be given at this point at the latest. An inventive arrangement with a positioning sensor must therefore evaluate the absolute value of A or the relative change of A with respect to the new state.

[0095] In Fig. 6a-c illustrate the use of a mechanical short-circuiter 300 in a fuse switch disconnector 301 with a position detection device 7. For reasons of clarity, a pivoting mechanism and cable feedthrough are omitted. The mechanical short-circuiter 300 is constructed, as an example for this use, in the geometry of a low-voltage fuse, in particular an NH-00 fuse. The mechanical short-circuiter 300 has, as an example for use in the fuse switch disconnector, conventional fuse contact blades 302 as electrical connections.The position detection device 7 can comprise a position sensor 7a and position transmitter 7b and, in this exemplary application, is designed with a separate and pluggable mechanical short-circuiter such that when the mechanical short-circuiter 300 is replaced, the position sensor 7a remains in the lower part of the fuse switch disconnector and the function of the position detection device 7 is retained after the use of a new mechanical short-circuiter with position transmitter 7b.

[0096] The position sensor 7b is advantageously inexpensive and is mounted directly in the mechanical short-circuiter, for example in a recess of the moving contact electrode 4.

[0097] However, with a different geometry of the mechanical short-circuiter or with a short-circuiting device without a detachable mechanical short-circuiter, the attachment and design of the position detection device can be varied almost as desired.

[0098] For example, it is very easy to integrate the position sensor 7a directly into the housing or a fixed contact electrode (e.g., the first fixed contact electrode) and to place the position sensor 7b in any desired area of the movable contact electrode 4. As an alternative to precise movement detection, an electronic or mechanical system with only one threshold value can also be used, which can refer exclusively to maintaining the minimum separation distance.

[0099] In the Fig. 6 shows the mechanical short-circuiter in plan view in the lower part of the fuse switch disconnector (base), where in the Fig. 6a shows the plug socket 303 without a section of the mechanical short-circuiter 300. This serves to connect the switching device 10 to the sacrificial element 5 in the mechanical short-circuiter 300 using a suitable plug-in cable. The second connection of the switching device 10 to the fixed contact electrode 3 is correspondingly Fig. 3 is in the Fig. 6 not shown. In the Fig. 6b, the mechanical short-circuiter 300 is shown as a section in the lower part of the fuse switch disconnector (base) 301. In the Fig. 6c shows a zoom area of the cut from Fig. 6b for a better visualization of the individual components. In this version, the position sensor 7a is located directly in the lower part of the fuse switch disconnector.

[0100] In Fig. Figure 7 shows a cross-section of the mechanical short-circuiter 300 in the lower part of the fuse switch disconnector 301. The electrical contacts and the sacrificial element 5 of the mechanical short-circuiter 300 essentially have a cylindrical geometry.

[0101] The mechanical short-circuiter 300 may include grip tabs 304, which allow insertion into the pivoting mechanism (not shown) of the fuse switch disconnector, similar to the use of fuses. This allows for easy and safe replacement of the mechanical short-circuiter 300 if necessary.

[0102] The cross-sectional view shows the position of the components of the positioning device 7 in the mechanical short-circuiter and the fuse switch disconnector. The position sensor 7b can be permanently connected to the movable contact electrode 4, and the position sensor 7a can be mounted in the lower part of the fuse switch disconnector. The position sensor 7b can comprise a permanent magnet or a dielectric, whereby the position sensor 7b can be arranged in or on the movable contact electrode 4 and can move with it.

[0103] From the presentation in Fig. 6c and Fig. 7 it becomes clear that when the sacrificial element 5 ages, the movable contact electrode 4 in the mechanical short-circuiter 300 and with it the position of the position transmitter 7b shifts relative to the position sensor 7a. This makes it possible to assess aging and, in particular, to maintain the minimum separation distance, for example in the internal control unit.

[0104] The Fig. 8 shows a block diagram of method steps of the method according to an embodiment of the present invention.

[0105] According to the invention, in the method for initiating a short circuit in low-voltage systems using a short-circuiting device according to the invention, the presence of a fault as a defect in the low-voltage system and the need for a short-circuit circuit are detected (ST1); a switching device is activated (ST2) and a short-circuit circuit is thereby triggered with a short-circuit current over a predetermined or determined period of time or permanently; the short-circuit current is limited (ST3) by the switching device by means of the sacrificial element and a current of the fault is commutated to the short-circuiting device.interrupting ST4 the short-circuit current after the specified or determined period of time and re-loading the low-voltage installation with mains voltage, whereby the thermal deformation of the sacrificial element caused by the current flow is monitored by a control device of the switching device and a conclusion is drawn about the degree of thermal deformation of the sacrificial element and / or; a position of at least one of the movable contact electrodes relative to the second fixed contact electrode is detected and compared with a minimum separation distance of the movable contact electrode from the second fixed contact electrode, and wherein the position detection and / or monitoring of the thermal deformation takes place before the switching device is activated and / or after the short-circuit current is interrupted; and optionally, re-activating the switching device and triggering a short-circuit circuit with a further short-circuit current for a further predetermined or further determined period of time or permanently in the event of a renewed or permanent fault, and destroying the sacrificial element in the event of a permanent fault and generating a permanent short circuit.

[0106] In Fig. 9 shows an exemplary reduced flow chart of a fault rectification with a short-circuiting device with position detection device and a switching device 10, which comprises the two parallel switching elements 10a and 10b.

[0107] During normal operation of the low-voltage system, the internal control unit (SE) of the short-circuiting device is operational. In the event of a fault that is not necessarily due to an arc fault, the network operator's central control unit (ZSE) can directly activate switching element 10b to permanently trigger the mechanical short-circuiter by sending a signal to the internal control unit (SE). In this case, a maintenance notice will be displayed in addition to the display. Additionally, if possible, an upstream external switching device or another short-circuiting device can be activated.

[0108] In the case of arc fault detection by the fault detection device, if it is possible to distinguish the intensity of the arc fault in the system, in the case of intensive arc faults the internal control unit SE can also immediately activate the switching element 10b and thus permanently activate the short-circuiting device.

[0109] However, if the intensity of the arc is low, or if there is no possibility of differentiation, the switching element 10a of the short-circuiting device is activated. As already explained, the activation duration can be time- or load-dependent. Fig. Figure 9 shows an example of time-variable activation. When switching element 10a is activated for the first time, it is switched off after, for example, 1 ms. After activation, a check is made to determine whether the minimum separation distance B is still being maintained and to what extent switching element 10a has been loaded. If there is no hazard, the number of times the short-circuiting devices have been activated is recorded. If, after switching element 10a has been switched off, an error message from error detection device 1 is still present on the internal control unit SE within, for example, 20 ms, the time for activation of switching element 10a is increased by a certain period of time. Switching element 10a can be activated several times, each time for a longer period of time. However, if the activation time is increased above, for example, 3 ms, switching element 10b is switched on permanently. The switching element 10b is activated without delay even if the switching element 10a is endangered or if the minimum separation distance is exceeded.

[0110] If a certain number of reversible switching operations of the short-circuiting device are exceeded, a maintenance warning is also given. The activation time of the switching element 10a is reset to the starting value after successful arc fault extinguishing and / or, for example, after a maximum of 20 ms.

[0111] The flow chart clearly shows that the use of switching element 10a and its load control, as well as its coordination with the sacrificial element, already allows sufficient control of reversible use even without the position detection device. The redundant use of both devices increases safety, but is not always absolutely necessary.

[0112] The Fig. Figure 10 shows a possible flow chart for the reversible use of a short-circuiting device with external switching device S1. In this case, the short-circuiting device does not necessarily require a switching element 10a and its load monitoring, but only a switching element 10b. Even if the operation of a central control unit is not shown in the illustration, such a device can be added. In the case of arc fault detection, the switching element 10b is activated and, at the same time, the external switching device S1 is activated, for example, accordingly. Fig.1 is triggered to open. Until switch S1 opens, the short-circuiting device creates a short circuit. During this time, the current commutates from the fault location to the mechanical short-circuiter, and a potential arc fault can be extinguished. After the known opening time of switching device S1, the internal control unit SE checks whether an error message, in particular an arc fault message, is still present. In this case, an upstream switching device S2 or, if not possible, another upstream short-circuiting device is activated. If the fault is no longer present and the minimum separation distance is maintained, the switching device S1 is closed again (automatic reclosure (AR) is possible). The activation of the switching device S1 as a result of a load on the short-circuiting device is detected and, when a limit value is reached (e.g., the number of activations by the internal control unit), maintenance is initiated or signaled. If the minimum separation distance is not reached, an upstream external switching device S2 is also activated, a maintenance message is issued, and the reclosure of the external switching device S1 is prevented.

[0113] Although the present invention has been fully described above with reference to the preferred embodiments, it is not limited thereto but can be modified in many ways. Designations: 1 fault detection device (arc fault detection) 2 fixed contact electrodes 3 fixed contact electrodes 4 movable contact electrodes 5 Sacrificial element 6 Deformations 7 Position detection device 7a Position sensor 7b Position sensor 10 internal switching device 10a switching element IGBT 10b Switching element thyristor 11 Overload control 100 short-circuiting device 200 short-circuiting device 300 mechanical short circuiter 301 Base / lower part of the fuse switch disconnector 302 contact knife 303 socket 304 grip tab D Arc fault detection sensors SE internal control unit ZSE Central Control Unit KA mechanical short-circuiter outgoing branch KB mechanical short-circuiter bus system S1 external switching device / fast load break switch controllable and resettable S2 external switching device / overcurrent protection device controllable F spring Z Impedance R resistance U voltage tap D diodes C capacity A Distance between contact electrodes with different potential B Minimum separation distance

Claims

[1] Short-circuiting device (100, 200) for use in low-voltage installations for the protection of property and persons, comprising - a switching device (10) which can be actuated by a trigger signal from an internal control unit (SE); - a first and a second fixed contact electrode (2, 3) which are opposite one another and means for supplying current which are connected to the first and to the second contact electrode (2, 3), which can be contacted to an electrical circuit with terminals of different potential; - a movable contact electrode (4) which is in electrical contact with the first fixed contact electrode (2) and is under a mechanical prestress with respect to the second fixed contact electrode (3) and is designed to carry out a relative movement to the second fixed contact electrode (3) in the event of a short circuit with the aid of spring force; - a sacrificial element (5) as a movement block for the prestressed movable contact electrode (4), which is arranged in a tensile manner between the first fixed contact electrode (2) and the movable contact electrode (4) or in a compressive manner between the movable contact electrode (4) and the second fixed contact electrode (3); - an electrical connection between the sacrificial element (5) and the switching device (10) on the one hand and one of the fixed contact electrodes (2, 3) on the other hand, whereby a current-flow-induced, thermal deformation or destruction of the sacrificial element (5) can be brought about in a targeted manner, wherein the switching device (10) comprises a control device which is designed to monitor the current-flow-induced thermal deformation of the sacrificial element (5) and to infer a degree of the thermal deformation; and in addition to the control device or instead of it, the short-circuiting device (100, 200) further comprises a position detection device (7) with which a position of the movable contact electrode (4) relative to the second fixed contact electrode (3) can be detected and is comparable to a minimum separation distance of the movable contact electrodes (4) from the second fixed contact electrode (3). [2] Short-circuiting device (100, 200) according to claim 1, wherein the position detection device (7) comprises a position sensor (7a) which is arranged in or on the first fixed contact electrode (2) or on a housing of the short-circuiting device (100) or on a base of the short-circuiting device (100) and the position detection device (7) further comprises a position sensor (7b) as a permanent magnet or dielectric, wherein the position sensor (7b) is arranged in or on the movable contact electrode (4). [3] Short-circuiting device (100, 200) according to claim 2, wherein the position detection device (7) comprises at least one capacitive and / or inductive contact, displacement and / or position sensor or at least one magnetic field sensor or a Hall sensor. [4] Short-circuiting device (100, 200) according to one of claims 1 to 3, in which the switching device (10) is connected in series with the sacrificial element (4) and comprises a first switching element (10a) and a second switching element (10b), wherein with the first switching element (10a) at least one short-circuit current can be switched on and off again over a respective predetermined or determined period of time and with the second switching element (10b) a permanent short-circuit current can be switched. [5] Short-circuiting device (100, 200) according to claim 4, wherein the first switching element (10a) comprises at least one IGBT and / or the second switching element (10b) comprises at least one thyristor. [6] Short-circuiting device (100, 200) according to one of claims 1 to 5, in which the internal control unit (SE) is designed to receive or determine a respective predetermined or determined time period and to switch the switching device (10) over the predetermined or determined time period and to switch it off again or to switch it permanently depending on the presence of the fault. [7] Short-circuiting device (100, 200) according to claim 6, wherein the internal control unit (SE) is configured to determine a current in a path of the short-circuiting device (100, 200) and to evaluate it against a fault / error in the low-voltage system and to determine a respective predetermined or determined time period or a permanent circuit. [8] Short-circuiting device (100, 200) according to one of claims 1 to 7, wherein the position detection device (7) comprises a wear indicator for the sacrificial element (5), with which the reaching of a predetermined wear of the sacrificial element (5) after aging or reversible short-circuiting can be indicated, wherein the reversible short-circuiting corresponds to switching and switching off the short-circuit current over at least a predetermined or determined period of time. [9] Short-circuiting device (100, 200) according to one of claims 1 to 8, wherein the sacrificial element (5) comprises a work-hardened material. [10] Short-circuiting device (100, 200) according to one of claims 1 to 9, which is designed in several parts and a mechanical short-circuiter (300) of the short-circuiting device (100, 200) can be plugged into a base (301) of the short-circuiting device (100, 200) and can be exchanged, wherein the mechanical short-circuiter (300) comprises the two fixed contact electrodes (2, 3), the movable contact electrode (4) and the sacrificial element (5). [11] Method for initiating a short circuit in a low-voltage installation using a short-circuiting device (100, 200) according to one of claims 1 to 10, comprising the steps: - Detection (ST1) of the presence of a fault as a fault in the low-voltage installation and the need for a short-circuit; - controlling (ST2) the switching device (10) and thereby triggering a short-circuit circuit with a short-circuit current over a predetermined or determined period of time or permanently; - limiting (ST3) the short-circuit current through the switching device (10) by means of the sacrificial element (5) and commutating a current of the fault to the short-circuiting device (100); - interrupting (ST4) the short-circuit current after the predetermined or determined period of time and re-loading the low-voltage system with mains voltage, wherein the control device of the switching device (10) monitors the current-flow-induced thermal deformation of the sacrificial element (5) and infers a degree of thermal deformation of the sacrificial element (5) and / or detects a position of the movable contact electrodes (4) relative to the second fixed contact electrode (3) and compares this with a minimum separation distance between the movable contact electrode (4) and the second fixed contact electrode (3), and wherein the position detection and / or monitoring of the thermal deformation takes place before the switching device (10) is actuated and / or after the short-circuit current is interrupted; and - if necessary, renewed activation (S2a) of the switching device (10) and triggering of a short-circuit circuit with a further short-circuit current over a further predetermined or further determined period of time or permanently in the event of a renewed or permanent fault and destruction of the sacrificial element (5) in the event of a permanent fault and generation of a permanent short circuit. [12] Method according to claim 11, in which the internal control unit (SE) receives or determines a respective predetermined or determined time period and switches the first switching element (10a) depending on the presence of the fault over the predetermined or determined time period and switches it off again or in the case of a permanent fault, switches the short-circuit current permanently via the second switching element (10b) and in the case of a permanent short-circuit current, destroys the sacrificial element (5). [13] Method according to one of claims 11 or 12, in which a current in a path of the short-circuiting device (100, 200) is determined and evaluated against a fault / error in the low-voltage system and a respective predetermined or determined time period or a permanent circuit is determined. [14] Method according to one of claims 11 to 13, in which a duration and / or level and / or number of the switched short-circuit currents is determined and taken into account in a wear assessment of the sacrificial element (5). [15] Method according to one of claims 11 to 14, in which a current in a path of the short-circuiting device (100, 200) is detected and evaluated by the switching device (10) and / or by a current measuring means of the short-circuiting device (100, 200) to determine the fault. [16] Method according to one of claims 11 to 15, in which a position of the movable contact electrode (4) relative to the second fixed contact electrode (3) is determined with a position sensor (7a) on a housing of the short-circuiting device (100, 200) or on the first fixed contact electrode (2) and a position sensor (7b) as a permanent magnet or dielectric on the first fixed contact electrode (2).

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