protective switching device

Abstract

The invention relates to a protective switching device (SG) for protecting a low-voltage circuit, comprising: - mains (L1, N1) and load-side (T1, N2) connections for conductors of the low-voltage circuit, - a current detection unit (SI) for determining the current in the low-voltage circuit, - a series connection of a mechanical switching contact unit (MK) and a semiconductor switching unit (EU), which is connected between the terminals (L1, N1, T1, N2) in the low-voltage circuit, wherein the switching contact unit (MK) has contacts (KN, KL) that can switch between an open and a closed switching position, and the semiconductor switching unit (EU) has at least one semiconductor switching element (W1, W2) that can switch between a high- and a low-resistance state, and - a control unit (SE) for controlling the switching contact unit (MK) and the electronic switching unit (EU), whereby the control unit (SE) can receive data regarding the determined current intensity from the current determination unit (SI), and wherein the switching contact unit (MK) has an actuating device (AV) with a switching lock (LH) for switching the contacts (KL, KN) by means of the switching lock (LH). The protective switching device (SG) is characterized in that the switching contact unit (MK) has a contactor drive (CM) for remotely controlled switching of the contacts (KN, KL).

Description

The invention relates to the technical field of low-voltage circuit breakers.Circuit breakers have long been known overcurrent protection devices which are used in electrical installation in low-voltage circuits. Circuit breakers usually have a fastening possibility for fastening on a mounting rail (top-hat rail, DIN rail, TH35). They protect lines and operating media from damage due to heating as a result of excessively high current and / or short circuit. A circuit breaker can automatically switch off a circuit in the event of overload and / or short circuit. A circuit breaker is, however, a non-automatically resetting safety element.Circuit breakers are nowadays generally of electromechanical design. In a housing, they have a mechanical switching contact or operating current release for interrupting (releasing) the electrical current. A bimetallic element or triggering electronics (ETU=Electronic Trip Unit) is usually used for triggering (interruption) in the case of a prolonged overcurrent (overcurrent protection) or in the case of thermal overload (overload protection). An electromagnetic trip with a coil or trip electronics is used for short-term trip when an overcurrent limit value is exceeded or in the case of a short circuit (short circuit protection). Means for extinguishing the arc, for example one or more arc quenching chambers, and also connection elements for conductors of the electrical circuit to be protected can be provided.Circuit breakers with a semiconductor switching unit are relatively novel developments. The semiconductor switching unit is an HL-based electronic switching unit (HL=conductor), i.e. the electrical current of the low-voltage circuit is conducted via semiconductor switching elements or semiconductor switches which can interrupt or conduct the electrical current. Protective switching devices with a semiconductor switching unit also often have a mechanical switching contact unit for galvanic isolation, which satisfies the disconnect properties required according to relevant standards for low-voltage circuits, wherein the contacts of the mechanical switching contact unit are connected in series with the semiconductor switching unit, i.e. the current of the low-voltage circuit to be protected is conducted both via the mechanical switching contact unit and via the semiconductor switching unit. Switching devices which have a galvanically interrupting mechanical switching contact unit and a semiconductor switching unit connected in series or also in parallel are called hybrid switching devices or hybrid protective switching devices. Such a hybrid switching device is described in DE102021210818A1 (Siemens AG) 30.03.2023.Hybrid switching devices, i.e. devices having two current path interruption points constructed in series connection, namely mechanical switching contact unit and semiconductor switching unit, switch in a defined sequence in order to arrive at one of the following states: ON=locked circuit (current-conducting state of the semiconductor switching unit by low-resistance semiconductor switching elements, current-conducting state of the mechanical switching contact unit by closed contacts), standby=interrupted circuit (current-blocking state of the semiconductor switching unit by high-resistance semiconductor switching elements, current-conducting state of the mechanical switching contact unit by closed contacts), OFF=unfectly interrupted circuit (current-blocking state of the mechanical switching contact unit by galvanic isolation of the contacts). Expediently, the semiconductor switching unit first interrupts the current and the mechanical switching contact unit then establishes an open air path in the circuit, either on the basis of normative regulations or for other reasons, either by means of relays which in turn have mechanically switching or galvanically isolating contacts, or by a kinematic chain which can be manually actuated, for example by a toggle or a rocker.In the above-mentioned prior art, switches constructed in this way and their function are described. The behavior in the event of a fault is also described: the semiconductor switching unit interrupts the current, and spring-biased kinematic mechanism (switching lock) is then triggered, for example by a signal (actuating signal), and opens the disconnection contact switch of the mechanical switching contact unit without current. The isolation contact switch remains open until it is acknowledged on site by manual operation by a device operator and is brought back into readiness for switching on.Remote reactivation, e.g. from a control room or a remote room, is not possible with the hybrid devices known hitherto. Hitherto, in the case of a desired remote switchability of protective switching devices, additional separate accessory devices, for example a motor remote drive, are required. This leads to additional costs, increases the susceptibility to faults and generates a large structural volume.It is the object of the present invention to improve a circuit breaker device, in particular to equip it with new operating functions.This object is achieved by a circuit breaker having the features of claim 1 and by a method according to claim 8.The circuit breaker serves to protect a low voltage electrical circuit or an electrical load such as a motor from damage caused by electrical faults. Electrical faults which can lead to damage are, for example, overcurrent, short circuit, earth fault (0.1 to 1 x In), oblique load, phase sequence, phase asymmetry, fault current with regard to personnel or machine safety, insulation faults; this enumeration is merely exemplary and is in no way restrictive.By low voltage is meant voltages of up to 1000 volts AC (~ / AC) or up to 1500 volts DC (= / DC). Low voltage means in particular voltages which are greater than the low voltage, with values of 50 volt AC voltage and 120 volt DC voltage, respectively.By low-voltage circuit or grid or installation is meant circuits with rated currents or rated currents of up to 125 amperes, in particular up to 63 amperes. By low-voltage circuit is meant in particular circuits with rated currents or rated currents of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values mentioned mean, in particular, rated or rated currents, i.e. the current which is normally conducted at maximum across the circuit or, if it is exceeded in a defined manner, the electric circuit is usually interrupted, for example by a protective device such as a circuit breaker, a circuit breaker or a circuit breaker. The rated currents can be staggered further; in general, a geometric series is used (quotient of two adjacent sequence elements is constant): a typical quotient is 1.25, with the following staggered relationship: 1A, 1.25A, 1.6A, 2A, 2.5A, 3.2A, 4A, 5A, 6.3A, 8A, 10A, etc. Or a somewhat larger quotient is 1.6, with the following staggered relationship: 1A, 1.6A, 2.5A, 4A, 6.3A, 10A, etc.The circuit breaker has mains-side and load-side connections to which the conductors of the low-voltage circuit (usually 1-phase, 2-phase or 3-phase) can be electrically connected, so that the circuit breaker is switched into the low-voltage circuit which forms an electrical connection between a voltage source, referred to here as "mains" or "feed", and an electrical load, referred to here as "load". In this case, the low-voltage circuit runs from the mains-side to the load-side connections along a current path through the protective switching device SG. The circuit breaker device has at least one or more connections on the mains side and on the load side (number of phases or poles). For example, the terminals on the mains side have at least one mains-side outer conductor terminal and optionally a mains-side neutral conductor terminal. For example, the terminals on the load side have at least one load-side outer conductor terminal and optionally a load-side neutral conductor terminal. A neutral conductor connection is rather atypical in a three-phase power supply system, but there are 4-pole devices with three phase conductors and one neutral conductor.The circuit breaker device has a current determination unit for determining the current intensity in the low-voltage circuit between the mains-side and the load-side connections. The current determination unit can be, for example, a current transformer, a GMR sensor (GMR= Gi Magneto-Resistance), a Rogowski coil, a Hall sensor or a shunt measuring resistor.The protective switching device has a series circuit of a mechanical switching contact unit and a semiconductor switching unit. In this case, the series circuit is connected into the current path between the grid-side and the load-side connections in the low-voltage circuit.The mechanical switching contact unit has switching contacts, or contacts for short, which can change between an open switching position (galvanic isolation by contact opening section), in which a current flow is prevented, or a closed switching position, in which a current flow is made possible. The contacts of the mechanical switching contact unit form a galvanically isolating contact system, also referred to below simply as "galvanic contact system" or "galvanic contacts".In the open switching position, the contacts form a galvanic isolation point as an essential technical requirement for achieving the isolation properties according to relevant standards for low-voltage circuits; often the word "main switch properties" is also used for this; in the standardization table, it is simply "insulation". Relevant for the separator function and its necessary technical requirements in the industrial sector are the standards IEC 60947-1:2020 (general requirements) and the IEC 60947-2:2019 (circuit breakers), to which reference is made here. For example, a 2-pole protection switching device may switch an active phase (L) and a neutral conductor (N). The protective switching device contains, for an outer conductor and a neutral conductor, in each case a mechanical break contact switch with a contact bridge which, in the open switching position, forms two air gaps which each have at least 2.8 mm contact opening distance.The semiconductor switching unit has at least one semiconductor switching element which can change between a high-resistance state in which a current flow is prevented and a low-resistance state in which a current flow is allowed.In a semiconductor switching unit, a high-resistance (de facto-non-conductive) state of the semiconductor switching elements (in order to avoid a current flow) is also referred to as a switched-off state (process: switching off) and a low-resistance (conductive) state of the semiconductor switching elements (in order to permit a current flow) is referred to as a switched-on state (process: switching on, current carrying).In this way, a current flow in the low-voltage circuit can be made possible by the closed switching position of the contacts of the mechanical switching contact unit and the low-resistance state of the at least one semiconductor switching element of the semiconductor switching unit, and a current flow in the low-voltage circuit can be prevented by the open switching position of the contacts of the mechanical switching contact unit and / or the high-resistance state of the at least one semiconductor switching element of the semiconductor switching unit.The protective switching device also has a control unit for controlling the mechanical switching contact unit and the semiconductor switching unit, wherein the control unit can receive data with respect to the determined current intensity from the current determination unit.The mechanical switching contact unit has an actuating device for switching the contacts of the mechanical isolation contact unit from the closed switching position into the open switching position with the aid of a latching mechanism. A latch is a mechanical device that enables the low voltage circuit to be cut off. For this purpose, in order to open the contacts of the mechanical switching contact unit, the energy of a tensioned spring is released, which has been tensioned via a tensioning mechanism when it is switched on. The latching mechanism has two essential areas: on the one hand, a switching mechanism is provided which, by spring force, causes the contacts of the mechanical switching contact unit to open and close. On the other hand, the latching mechanism has a release mechanism which, when a triggering criterion is reached, releases the energy stored in a spring of the latching mechanism, as a result of which the latching mechanism is triggered and the contacts of the mechanical switching contact unit are opened.The mechanical switching contact unit also has an electromagnetic drive, which for the sake of brevity is simply referred to as a "contactor drive", for remotely switching the contacts of the mechanical switching contact unit from the closed switching position into the open switching position and vice versa.In addition to the actuating device which acts on the contacts of the mechanical switching contact unit via a latch, the invention uses a multipolar contact system with an associated contactor drive instead of a relay for realizing a galvanically isolating disconnection contact switch. A contact system is understood to mean an arrangement of mechanical contacts which serve for simultaneously separating a plurality of current conductors in a common switching operation. While a relay has only relatively short insulation distances and thus generally insufficient insulation strengths, significantly longer insulation distances can be provided with a contact system moved by a contactor drive, which insulation distances in turn enable insulation voltages of several kilovolts required in the industrial environment. For example, in a 3-phase network with 400 V, at least 6 kV insulation voltage is required.Furthermore, this mechanical switching contact unit can meet further required requirements for the disconnect properties, in particular a) a kinematically constrained connection between a handle of the circuit breaker device and the contact system, or a visual visibility of the disconnect section, b) a closeability of the circuit breaker device or c) a non-closeability of the circuit breaker device in the case of incorrectly welded contacts, and d) a manual actuation capability of the mechanical contacts even without auxiliary energy.The invention therefore proposes a protective switching device in which the load current path can be switched in a current-blocking manner both by a galvanically isolating mechanical switching contact unit and by a semiconductor switching unit.Conventional circuit breakers often use a commercially available relay, in particular a printed circuit board relay, as a mechanical switching contact system which is connected in series with the semiconductor switching unit. A disadvantage of these conventional relays is a relatively low current capacity, up to a few 10 A, and a relatively short electrical service life, particularly in the event of a short motor start-up.Conventional protective switching devices also often have a galvanic isolation contact switch which can be switched (opened / closed) only by hand and by means of which the normally required isolation function in the current path is fulfilled. A disadvantage of these conventional circuit breakers is that the normative disconnect function (main switch characteristic) according to IEC 60947-1:2020 can be fulfilled only by manual actuation of the circuit breaker, for example by means of a handle such as an operating knob; consequently, remote re-switchability is also not given. Hybrid switching devices have become known from DE102021210818A1 (Siemens AG) 30.03.2023, for example, in which, after a fault, the opening of a galvanic isolation contact can take place by a device-internal trip unit, e.g. a maglach, and indeed also while complying with the normative isolation rules / isolation voltages. However, even in the case of these hybrid switching devices, after triggering, there is just no remote re-switchability, but manual confirmation on site on an operating knob of the device is still necessary by an operator.The configuration according to the invention of a hybrid circuit breaker device enables compliance with normative disconnect requirements by opening the contacts of the mechanical switching contact unit to a sufficient opening distance by means of a contactor drive. Nevertheless, the opened contacts can then be closed again remotely, for example from a control room; the configuration according to the invention of a hybrid circuit breaker thus ensures that the circuit breaker can be switched on remotely after the contacts of the mechanical switching contact unit have been opened.The object is also achieved by a method for operating a circuit breaker according to one of the device claims. The protective switching device has three different switching states OFF, STANDBY and ON. In the switching state OFF, the contacts are in the open switching position. In the switching state STANDBY, the contacts are in the closed switching position and the semiconductor switching elements are in the high-impedance state. In the switching state ON, the contacts are in the closed switching position and the semiconductor switching elements are in the low-ohmic state. In this case, a change between the switching state OFF and the switching state STANDBY takes place either by the actuating device by means of the latching mechanism or remotely by means of the contactor drive.The following premises apply to the method for operating a protective switching device: A) "normal" switching (ON<> STANDBY) takes place by switching the semiconductor switching elements of the semiconductor switching unit from a high-impedance state to a low-impedance state or vice versa. B) In the case of all switch-off commands which have the aim of the switching state OFF, firstly a switch is made to the switching state STANDBY; the semiconductor switching elements therefore interrupt the current and the mechanical disconnection contact unit does not have to interrupt the current; as a result, wear of the contacts due to arcs is avoided. C) When switching into the switching state OFF, both mechanisms, both with the contactor drive and with the latch, and also when operated by an operator, have a device which first brings the semiconductor switching elements into the high-impedance state (= STANDBY); only then does the mechanical opening of the contacts of the mechanical switching contact unit take place. D) In the event of a fault and under the condition of having to switch from the switching state ON to the switching state OFF, for example as a result of installation guidelines, the control unit first switches the semiconductor switching elements with high impedance (= STANDBY) and then causes them either in parallel or after a short period of time (depending on the programming / configuration):D.1) switching off the control voltage of the contactor drive, whereby the contacts of the mechanical switching contact unit are opened by the contactor drive, with the possibility of being closed again by remote control, orD.2) a control of the maglach for triggering via the latch or for opening the switching contacts via the latch.E) A movement of the contacts of the mechanical switching contact unit by means of the handle which acts on the latch lock always has priority over the contactor drive. In this case, the actuating voltage of the contactor drive is also switched off.Alternatively, the switching state OFF can also be considered to be divided into two different substates, OFF A and OFF B: the substate OFF A is reached from the switching state STANDBY by means of the contactor drive; the substate OFF B is reached from the switching state STANDBY by means of the latching mechanism. In order to return from the substate OFF A to the switching state STANDBY, it is sufficient to remotely actuate the contactor drive in such a way that it returns the contacts to the closed switching position. In order to change from the substate OFF B back into the switching state STANDBY, an operator must manually tension the latch again.Advantageous embodiments of the invention are specified in the dependent claims and in the exemplary embodiments.According to a preferred embodiment of the invention, the actuating device has a handle and a maglach which act on the latch. A maglach is a magnet-based, electrically and thus remotely actuatable electromagnetic device for acting on a lock. The spring of the latching mechanism, the energy of which is released for opening the mechanical contacts, can be tensioned by a tensioning mechanism, e.g. by means of a handle, when it is switched on. In the event of a fault, the maglach is actuated with low energy by the control unit, e.g. an MCU (= microcontroller), and actuates a locking lever in the latch lock to release the prestressed energy in order to open the mechanical contact system.It is possible for the mechanical switching contact unit to have a handle sensor for ascertaining position information of the handle. The handle sensor can be connected to the control unit so that the control unit has position information about the position or movement of the handle in the time lead to the movement of the contacts of the mechanical switching contact unit, in particular a closed or open state of the at least one contact that is aimed for by the handle.According to a preferred embodiment of the invention, the actuating device and the contactor drive can switch the contacts of the mechanical disconnect contact unit independently of one another. For a changeover from "current flow" to "no current flow", the contacts of the mechanical disconnect contact unit are switchable from the closed switching position of the contacts (current flow possible) to the open switching position of the contacts (current flow prevented): a) by means of the maglach and the lock, b) by means of the exclusively manually actuatable handle and the lock, or c) by means of the remotely actuatable contactor drive. For a changeover from "no current flow" to "current flow", the contacts of the mechanical switching contact unit are switchable from the open switching position of the contacts (current flow prevented) to the closed switching position of the contacts (current flow possible): a) by means of the exclusively manually actuatable handle and the latching mechanism, or b) by means of the remotely actuatable contactor drive.The mag latch in connection with the latch lock is not able to switch the contacts of the mechanical disconnect contact unit from the open switching position of the contacts (current flow prevented) to the closed switching position of the contacts (current flow possible) for a change from "no current flow" to "current flow" (no remote re-switching function of the mag latch!). In the event of a fault, the MagLatch exclusively triggers the latch, i.e. it "translates" the logic of the control unit into a mechanical action. The magLatch is brought, preferably pressed, into a prestressed and locked state by the latch upon mechanical switching on again.The contactor drive acts on a multipolar contact system on which the lock kinematics also present in the protective switching device acts in parallel when the toggle is manually operated or when the maglach is activated. Both mechanical active paths, contactor drive and latch, are designed such that they cannot block each other (there is no mechanical coupling): When the contacts are closed with the latch mechanism, the contactor drive can nevertheless open the contacts. In other words: Even if the contactor drive keeps the contacts closed and the semiconductor switching unit is switched to conduct current, the semiconductor switching unit can first switch off the current by means of the mechanical operating chain starting from the manually operated toggle during a switch-off operation (made possible by means of a movement detection element coupled to the handle). In the further course of the switch-off movement on the toggle, the still closed contact is pressed on via a mechanical operative connection. In support of this, the control voltage for the contactor coil can also be removed, initiated by the movement detection element for the toggle position. Advantage: the contact pressure forces for the mechanical contact system become lower, since the force of the contactor drive does not have to be overcome. The movement detection element detects a movement of the toggle, which leads to a disconnection of the contactor voltage.Since the current is generally interrupted by the semiconductor switching elements of the semiconductor switching unit before the contacts of the mechanical switching contact unit are opened or closed, the contacts, i.e. the galvanic contact system in the protective switching device, are thus predominantly switched to the zero current state; thus, the galvanic contact system only has to be able to carry the operating current and the temporarily limited overcurrents, but does not have to be able to switch off and cannot withstand arcing, and can therefore advantageously be of relatively small dimensions and thus space-saving and cost-effective dimensions. A suitable switching coordination of the mechanical contacts (only producing isolation path) and the semiconductor switching elements, e.g. MOSFETs (current switching), can be defined in a firmware of the protective switching device.It is possible for a parameterization and / or configuration of the circuit breaker device to be provided. For this purpose, the circuit breaker device can have a communication interface which enables wired or wireless communication between the circuit breaker device and a transmission device from which the circuit breaker device receives parameterization and / or configuration data. The communication interface is preferably connected to the control unit. One advantage in this case is that (status) information such as switching and fault states or current current values can be transmitted to another protective switching device or to a monitoring or management system. By means of the communication interface, a configuration of the circuit breaker device can be carried out. In addition, the contactor drive can be controlled by an external command unit via the communication interface. In this case, the type of avoidance of a current flow of the low-voltage current circuit can be configurable for exceeding at least one parameter, i.e. a previously configured type of avoidance of a current flow is initiated if a defined parameter is exceeded or undershot (exceeding or undershooting is dependent on the type of parameter). The parameter may be, for example, the electric current, the electric voltage, the temperature, a value for detecting a series arc fault, the electric resistance, the impedance, a ground fault current, or the like.Primarily, the behavior of the circuit breaker device is configured in the event of a fault. If a fault occurs, the semiconductor switching elements are always internally brought into a high-impedance switching state and thus the protective switching device is always brought into the STANDBY switching state. By means of a parameterization and / or configuration of the circuit breaker device, it can be established whether the circuit breaker device is subsequently also switched into the OFF switching state and, as this is to be done, is switched on again by means of the contactor drive (which can be switched on again remotely) or by means of the latch (which cannot be switched on again remotely).The avoidance of the current flow can be achieved in particular by:a high-resistance state of the semiconductor switching elements of the semiconductor switching unit;(additionally) due to an open state of the contacts of the mechanical switching contact unit, in particular a galvanic separation.That is to say, for example, when a current limit value or current time limit value is exceeded (when a current of a specific level is exceeded for a specific time), a high impedance formation of the semiconductor switching elements or an opening of the contacts of the mechanical switching contact unit (galvanic isolation) or both can be configured, for example, as a type which prevents current flow.For example, for a first current limit value or current time limit value (when a current of a specific level is exceeded for a specific time), a high impedance formation of the semiconductor switching elements can be configured as a current flow avoiding type.For example, for a second current limit value or current time limit value, a high impedance formation of the semiconductor switching elements and an open state of the contacts of the mechanical switching contact unit can be configured as a type that prevents current flow.For example, for a third current limit value or current time limit value, an open state of the contacts of the mechanical switching contact unit can be configured as a type avoiding current flow.That is, when the parameter is exceeded or undershot (exceeding or undershooting is dependent on the type of parameter), a previously configured type of avoidance of a current flow is initiated.According to a preferred embodiment of the invention, the circuit breaker device comprises a contactor having said contacts of the mechanical switching contact unit and said contactor drive as its integral components. In other words, a contactor or at least components of a contactor whose mechanical contacts and its contactor drive are used in the mechanical switching contact unit of the circuit breaker device are installed in the circuit breaker device. The advantage here is that completely developed and mature contactors or their components can be used with all their advantages for forming a galvanic isolation point.According to a preferred embodiment of the invention, the contacts of the mechanical switching contact unit have Lyra contacts. Lyra contacts have a high short-circuit load capacity and contact safety, even in the case of relatively high starting currents or short-circuit currents. The occurrence of so-called contact lifting devices, i.e. lifting of contacts pressed onto one another, which can occur in the case of relatively high overload or short-circuit currents, is significantly less frequently or even completely prevented by the use of in particular slotted finger-shaped lyra contacts. When using Lyra contacts, the contactor drive only has to be designed for contact plug forces, since the contact force holding the contacts to one another originates from the Lyra shape of the Lyra contacts acting as a retaining clip. Lyracontacts are described, for example, in the following patent documents: DE1669057U1 (Voigt & Haeffner AG) 24.12.1953 DE1061409B (Licentia Patent Management-GmbH) 16.07.1959 DE2621703B2 (Karl Prusterer GmbH) 24.11.1977 DE19538089C1 (Karl Prusterer GmbH) 30.01.1997According to a preferred embodiment of the invention, the protective switching device has a mechanical display device for displaying the switching position of the mechanical switching contact unit. The display device displays the position of the contacts, i.e. the contact position (open, closed) is signaled. This has the particular advantage that there is information about the contact position (open, closed). The position indicating unit is, for example, a mechanical position indicating unit. This has the particular advantage that this information can be displayed / is displayed even in the voltage-free state, preferably via a mechanical connecting element which is visible at the appliance front of the circuit breaker appliance.According to a preferred embodiment of the invention, the semiconductor switching unit is assigned to the load-side connections (load, energy sink) and the mechanical switching contact unit is assigned to the grid-side connections (energy source). Either the "self-supply" device concept is realized, i.e. the supply voltage for the control unit is generated from the (load) power supply. A power supply unit can then be connected to the conductors of the low-voltage circuit between the mechanical switching contact unit and the semiconductor switching unit, i.e. the protective switching device, in particular the control unit, is supplied with energy only if the contacts of the mechanical switching contact unit are closed. Or the device concept "external supply" is realized, i.e. the supply voltage for the control unit is always present irrespective of the position of the contacts of the mechanical switching contact unit. The latter is generally preferred.According to a preferred embodiment of the invention, the circuit breaker has a housing, wherein the load-side connections and the grid-side connections are arranged in the housing so as to be accessible from the outside.According to a preferred embodiment of the invention, a voltage failure of the mains and / or control voltage in the case of a corresponding parameterization leads to a spring-actuated opening of the contacts of the mechanical switching contact unit, since the contactor drive drops. Thus, a galvanically insulating separation path is automatically achieved, which increases the electrical safety of the circuit breaker device. The device reaction in the event of a voltage recovery can be parameterized, i.e. predefined. Additionally or instead, a mag latch release of the latch lock can also be parameterized for the protective switching device. Then, however, in order to perform the next ON switching, on-site acknowledgement is necessary.According to a preferred embodiment of the invention, the circuit breaker device has a power supply unit for supplying power to the circuit breaker device, in particular to the control unit. Alternatively, the supply voltage can be supplied separately from the outside, for example by means of the communication connection.It is possible that the circuit breaker device has, in addition to the current sensor unit which serves to determine the level of the current of the low-voltage circuit, a voltage sensor unit which serves to determine the level of the voltage of the low-voltage circuit and in conjunction with the current information of the applied power. In this case, the control unit is connected to the voltage sensor unit, the current sensor unit, the mechanical switching contact unit and the semiconductor switching unit, wherein if current or / and current time limits are exceeded, avoidance of a current flow of the low-voltage circuit is initiated. In this case, the protective switching device can be designed such that, when the contacts of the mechanical switching contact unit are closed and the semiconductor switching elements are low in resistance, the semiconductor switching elements become high in resistance when a voltage-reduced state of the low-voltage circuit occurs, and that after the voltage-reduced state has left, the semiconductor switching elements become low in resistance again. In the case of electromechanical circuit breakers, both self-starting (standard) and device triggering are implemented by under voltage triggers with subsequent acknowledgement.According to an advantageous embodiment of the invention, a voltage sensor unit connected to the control unit is provided. The voltage sensor unit is provided for determining the level of the voltage between the conductors of the low-voltage circuit, wherein the voltage sensor unit is connected to the conductors between the mechanical switching contact unit and the semiconductor switching unit. This has the particular advantage that the voltage of the low-voltage circuit can be monitored and, if appropriate, the circuit can be disconnected in the event of overvoltage or undervoltages. The architecture according to the invention thus supports an increased operational reliability of the protective switching device or in the circuit.According to an advantageous embodiment of the invention, the circuit breaker has a human machine interface (= H) connected to the control unit, for example in the form of a display unit. In this case, the HMI can serve in particular for indicating the high-impedance or low-impedance state of the semiconductor switching unit. This has the particular advantage that (status) information items of the protective switching device can be displayed, for example via switching and / or fault states.According to an advantageous embodiment of the invention, the protective switching device is designed in such a way that, when the handle is actuated to open the contacts, a signal is sent to the control unit before the contacts are opened, so that the HL switching elements of the semiconductor switching unit are placed in a high-impedance state. Furthermore, the control unit stores at least one current value or current time value of the current flow in the low-voltage circuit in a storage device independent of the mains voltage. This has the particular advantage that electroless (powerless) switching of the mechanical switching contact unit is supported, in particular that arcs or contact burn-off are avoided. This also has the advantage that the level of the current is detected before the e.g. initiated opening of the contacts and can be read out subsequently. This facilitates a determination of a cause of the fault.According to an advantageous embodiment of the invention, the control unit has a microcontroller. This has the particular advantage that the functions according to the invention for increasing the safety of a circuit breaker or of the low-voltage circuit to be protected can be realized by a preferably adaptable computer program product. Furthermore, changes and improvements in the function can thereby be individually loaded onto a circuit breaker device, for example also via the communication unit. A computer program product having software code sections stored on a computer-readable storage medium for carrying out the method described above can be transmitted from the storage medium to the control unit via the communication interface and executed by a computing unit, for example by the microcontroller of the control unit.According to an advantageous embodiment of the invention, a latch release is brought about via the maglach if, after a serious fault event, the contacts of the mechanical switching contact unit are opened such that operator-side on-site acknowledgement is necessarily required. The advantage here is that, in the event of a correspondingly severe fault situation, unintentional safety-risk reactivation via a remote control room is not possible; in the event of a severe fault situation, it is namely expedient to search for faults or to eliminate faults on site. By means of a latch having a mechanical operative connection to the contacts of the mechanical switching contact unit, it can be achieved in a safety-enhancing manner that, should only one of the mechanical contacts also be welded, this can be detected at a particular position of the operating knob. This thus provides additional safety-enhancing recognizability of the position of the contacts of the mechanical switching contact unit. The contacts of the mechanical switching contact unit can only be actuated via the contactor drive or the latch.According to an advantageous embodiment of the invention, the contacts of the mechanical switching contact unit, when they are in the open switching position in the switching state OFF by triggering the latching mechanism, can only be brought back into the closed switching position manually by means of the handle, and when they are in the open switching position in the switching state OFF by being acted upon by the contactor drive, can be brought back into the closed switching position manually by means of the handle and also by being acted upon by the contactor drive remotely. An advantage here is the remote re-switching on capability of the protective switching device.According to an advantageous embodiment of the invention, the control unit, which is connected to the current sensor unit, the mechanical switching contact unit and the HL switching unit, initiates a prevention of a current flow in the low-voltage circuit when at least one current limit value or one current time limit value is exceeded. An advantage in this case is that an operator of the circuit breaker has the possibility, via a parameterization of the control unit, of controlling the operating behavior of the circuit breaker.The described properties, features and advantages of this invention and the manner in which these are achieved become clearer and more clearly comprehensible in conjunction with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawing. The following shows: FIG. 1 is a block diagram of a protective switching device; FIG. 2 shows a first exemplary embodiment of a mechanical contact; FIG. 3 shows a further exemplary embodiment of a mechanical contact; FIG. 4 shows different switching states of a protective switching device; and FIG. 5 shows an exemplary embodiment of the mechanical switching contact unit.FIG. 1 shows a representation of a protective switching device SG for protecting an electrical low-voltage circuit, in particular a low-voltage alternating circuit.The circuit breaker device SG has a housing GEH with mains-side L1, L2, L3, N1 connections and load-side T1, T2, T3, N2 connections for conductors of the low-voltage alternating current circuit. The grid-side terminals comprise a grid-side neutral conductor terminal N 1 and three grid-side outer conductor terminals L 1, L 2, L 3. For reasons of simplification, only a single mains-side outer conductor connection L 1 is shown. The load-side terminals include a load-side neutral conductor terminal N 2 and load-side outer conductor terminals T 1, T 2, T 3. For reasons of simplification, only a single load-side outer conductor connection T 1 is shown. A power source, e.g. a low-voltage power supply system, can be connected to the power supply system-side connections L1, L2, L3, N1 or to the power supply system side G of the protective switching device SG. At least one further voltage distribution or at least one load or a load, e.g. a motor, can be connected to the load-side connections T 1, T 2, T 3, N 2 or the load side M of the circuit breaker device SG. A current path L, N in the form of at least one outer conductor L and one neutral conductor N extends from the mains-side terminals L 1, L 2, L 3, N 1 within the housing GEH to the load-side terminals T 1, T 2, T 3, N 2.The outer conductors Ln, where n=1, 2, 3,... are protected as "active poles" and are switched by means of a mechanical switching contact unit and an HL switching unit. The neutral conductor is a so-called "non-protected pole", i.e. there is no current monitoring and no electronic switching unit on the neutral conductor. However, the mechanical switching contact unit also switches the neutral conductor, i.e. all-pole interruption of the circuit is possible.The configuration of the low-voltage circuit L 1 / L 2 / L 3 / N with three outer conductors L 1 / L 2 / L 3 and one neutral conductor N shown in FIG. 1 is just one example; it is clear to the person skilled in the art that the exemplary embodiment shown can also be transferred to other low-voltage circuits, for example to a circuit L 1 / N with an outer conductor L 1 and a neutral conductor N, or to a circuit L 1 / L 2 / L 3 with three outer conductors L 1 / L 2 / L 3 and without a neutral conductor. For reasons of simplification, only one outer conductor L 1 is referred to in the following; however, any desired number of outer conductors L is included.The protective switching device SG has a mechanical switching contact unit MK connected to the mains-side connections L 1, N 1, with a disconnection contact switch KS, which is connected into the current path L, N and can form a galvanic disconnection point in the conductors (poles) there. The protective switching device SG also has an HL switching unit EU, which is connected to the load-side outer conductor terminal L 1 and has HL switching elements W 1, W 2, which is connected into the outer conductor L of the current path and which can form a high-resistance current blocking means of the outer conductor L. The protective switching device SG thus has a series circuit of a mechanical switching contact unit MK and an HL switching unit EU, wherein the mechanical switching contact unit MK is assigned to the connections L1, N1 on the grid side or to the grid side G and the HL switching unit EU is assigned to the connections T1, N2 on the load side or to the load side M. By means of this series circuit, a) can therefore allow a current flow in the low-voltage circuit through closed contacts KL, KN of the isolation contact switch KS of the mechanical switching contact unit MK and a low-resistance state of the HL switching elements W 1, W 2 of the HL switching unit EU, or b) a galvanic isolation can be prevented by open contacts KL, KN of the isolation contact switch KS of the switching contact unit MK, preventing a current flow in the low-voltage circuit and / or a current flow in the low-voltage circuit through a high-resistance state of the switching elements W 1, W 2 of the electronic switching unit EU.By high-resistance is meant a state in which only a current of negligible magnitude still flows. In particular, high-resistance values of greater than 1 kiloohm, better greater than 10 kiloohm, 100 kiloohm, 1 megaohm, 10 megaohm, 100 megaohm, 1 gigaohm or greater are meant.Low-resistance means a state in which the current value indicated on the protective switching device SG could flow. In particular, low-resistance values are meant which are less than 10 ohms, better less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less.The circuit breaker device SG has a current sensor unit SI, which is arranged in each conductor L of the current path between the mechanical switching contact unit MK and the HL switching unit EU, for determining the level of the current of the low-voltage circuit; in the exemplary embodiment of FIG. 1, the current sensor unit SI is arranged in the outer conductor L. The protective switching device SG further comprises a voltage sensor unit SU, which is arranged between conductors of the current path between the mechanical switching contact unit MK and the HL switching unit EU, for determining the level of the voltage between conductors of the low-voltage circuit.The circuit breaker device SG has a control unit SE which is connected via a signal line 9 to the current sensor unit SI, via a signal line 8 to the voltage sensor unit SU, via a signal line 13 to the HL switching unit EU and via signal lines 11, 12 to the mechanical switching contact unit MK, wherein the circuit breaker device SG is designed such that, in the event of a fault in the low-voltage circuit, for example in the event of current or / and current time limits being exceeded, prevention of a current flow of the low-voltage circuit is initiated. This can be effected by the HL switching elements W 1, W 2 of the HL switching unit EU becoming highly resistive and / or by the contacts KL, KN of the mechanical switching contact unit MK being opened.The control unit SE has a microcontroller MCU for controlling the circuit breaker device SG. The control unit SE can have a data memory (RAM, ROM) in which a computer program product is stored. The computer program product comprises instructions which, when the program is executed by the microcontroller MCU, cause the microcontroller to cause the latter to perform the functions mentioned for a protective switching device. A computer-readable storage medium on which the computer program product is stored may also be provided. A data carrier signal with which the computer program product is transmitted can likewise be provided. Thus, the computer program product or a new computer program product can pass from a computer-readable storage medium through a communication unit into the data memory of the circuit breaker device SG, where it is executed by the microcontroller MCU in order to carry out the method for operating the circuit breaker device SG.The circuit breaker device SG has a user interface HMI connected to the control unit SE via a signal line 19 for displaying status information of the circuit breaker device SG, in particular of the control unit SE.The circuit breaker device SG has a communication unit COM connected to the control unit SE via a signal line 18. This can enable a wired and / or wireless communication possibility.The HL switching unit EU has HL switching elements W 1, W 2 such as transistors, field effect transistors, MOSFET, IGBT, or the like. The HL switching elements W 1, W 2 can be controlled by a driver unit, wherein the driver unit is in turn controlled by the control unit SE. The HL switching unit EU can have an energy absorber such as an MOV or a TVS diode in order to avoid destructive voltage peaks or the absorption of switching energies (MOV=metal oxide varistor; TVS=transient voltage suppressor). This energy absorber can be fixedly installed in the circuit breaker SG or can be exchanged, e.g. plugged in.In the exemplary embodiment of FIG. 1, the HL switching unit EU is configured with a single pole for a conductor of the low-voltage circuit and is arranged in the outer conductor L. In the case of n-pole devices, the HL switching unit EU is designed to switch n-pole accordingly, n=1, 2, 3,...The break contact switch KS of the mechanical switching contact unit MK is embodied in two poles in the example, in both conductors L, N of the 1-phase low-voltage circuit. A two-pole design enables reliable galvanic isolation, since the isolation contact switch KS is designed according to the standard with isolation properties (distances, minimum air gaps, etc.). In n-pole devices, the break contact switch KS is designed to break n-pole accordingly. FIG. 1 illustrates a 2-pole circuit breaker SG that switches an active phase (outer conductor L) and a neutral conductor (N). The protective switching device SG has, for the outer conductor L and the neutral conductor N, in each case a mechanical disconnection contact switch KS with a contact bridge which, in the open switching position, forms two air gaps which in each case have a contact opening distance of at least 2.8 mm.The mechanical switching contact unit MK has a position display unit POSA which displays the (switching) position of the contacts KL, KN of the break contact switch KS of the mechanical switching contact unit MK. The position display unit POSA is mechanically connected to the contacts KL, KN by means of a connecting device 10, so that even in the voltage-free state, if no energy is available from the mains side G, a display of the contact position is possible.The mechanical switching contact unit MK has a handle HH for closing and opening the contacts KL, KN, which is accessible on the outside of the housing of the circuit breaker device, so that it can be manually operated by an operator. Actuation of the handle HH acts via a mechanical connection 16 on a pre-tensioned latch LH, which thereupon releases mechanical energy, which leads by means of a mechanical connection 17 to the opening of the contacts KL, KN of the break contact switch KS.The mechanical switching contact unit MK also has a maglach ML which can be actuated by an electrical signal, which is transported via the signal line 12, from the control unit SE. Actuation of the maglach ML acts via a mechanical connection 15 on the biased latch LH, which thereupon releases mechanical energy, which leads to the opening of the contacts KL, KN of the break contact switch KS.The mechanical switching contact unit MK also has a contactor drive CM, which can be actuated by an electrical signal, which is transported via the signal line 11, from the control unit SE. The contactor drive CM acts directly on the contacts KL, KN of the break contact switch KS without the intermediate connection of the switching lock LH via a mechanical connection 20. In this way, the contacts KL, KN can be both closed and opened by controlling the contactor drive CM, provided the handle HH is in the position STANDBY or ON. The contactor drive CM thus offers the possibility of switching on the break contact switch KS remotely, i.e. changing from a state with open contacts KL, KN to a state with closed contacts KL, KN, provided that the handle HH is not in OFF.For reasons of clarity, no control voltage supply is drawn in FIG. 1 ; for supplying voltage to the units of the protective switching device which require a voltage supply for their function, the voltage can be tapped from the current path L, N (internal voltage supply). However, an external voltage supply can also be provided, so that those units of the circuit breaker device which require a voltage supply for their function are supplied with voltage independently of the low-voltage circuit.The protective switching device SG or the mechanical switching contact unit MK is designed in such a way that, when the mechanical switching contact unit MK is actuated by the handle HH, a (actuation) signal is sent to the control unit SE via a signal line 14 before the contacts KL, KN are opened. The protective switching device SG or the control unit SE is configured such that the semiconductor-based switching elements W 1, W 2 of the electronic switching unit EU are then placed in a high-impedance state, so that a powerless switching with the mechanical switching contact unit MK is made possible.It is therefore to be stated in particular that in the circuit breaker device SG according to the invention, mechanical contacts KL, KN of a break contact switch KS in combination with HL switching elements W 1, W 2 of an HL switching unit EU assume the switching and protection functions of the circuit breaker device SG.FIG. 2 shows a representation of a first embodiment of a mechanical contact KL, KN from FIG. 1. the mechanical contact KL, KN is arranged at a break point of the outer conductor L or of the neutral conductor N of the current path running through the circuit breaker device SG. Fixed contact pieces 22a, 22b are arranged at the two conductor ends of the conductors L, N at the interruption point. The mechanical contact KL, KN has a movable contact bridge 23 with plate-shaped contact pieces 21 a, 21 barranged at the ends of the contact bridge 23, which contact bridge can be pulled into electrical contact with the fixed plate-shaped contact pieces 22 a, 22 bby an axial movement of a plunger 24 a, 24 bfixed to the contact bridge 23 counter to the force of a spring 25. In order to lift the movable contact pieces 21a, 21b from the fixed contact pieces 22a, 22b, the axial movement of the plunger 24a, 24b in the direction is reversed, whereby the force of the relaxing spring 25 assists the opening operation. The axial movement of the plunger 24 a, 24 bis thereby brought about by the latch LH or by the contactor drive CM, wherein the latch LH and the contactor drive CM can act independently of one another on the contact bridge 23: this independent loading is illustrated in FIG. 2 by the two plungers 24 aand 24 bshown separately of one another. The triggering or actuation of the switching lock LH can take place by means of the handle HH or by means of the mag latch ML, a trigger with a magnetic locking mechanism.The break contact switch KS, which has the mechanical contacts KL, KN, is also connected to a position display unit POSA. The position display unit POSA is a mechanical position display unit; this has the particular advantage that information about the contact position (contacts open=current flow prevents, contacts closed=current flow permits) of the mechanical contacts KL, KN of the break contact switch KS can be displayed / is displayed even in the voltage-free state. The movable contact bridge 23 of the mechanical contacts KL, KN is connected to the position display unit POSA via a mechanical connecting device 10. The position display unit POSA displays the position of the contact bridge 23 and thus the switching state of the mechanical contacts KL, KN, i.e. the switching state (contacts opened or closed) of the mechanical contacts KL, KN is signaled.FIG. 3 shows a representation of a second embodiment of a mechanical contact KL, KN of FIG. 1. the mechanical contact KL, KN corresponds in its function to the mechanical contact KL, KN of FIG. 2, the description of which is referred to above. The difference of the mechanical contact KL, KN of FIG. 3 from that of FIG. 2 lies in the form of the contact pieces 21 a, 21 b, 22 a, 22 b: the contact pieces 21 a, 21 bfixed to the contact bridge are formed as blade or push-in contacts, and the fixed contact pieces 22 a, 22 bare formed as lyra contacts. When changing from the open switching position of the contacts KL, KN (current flow prevented) to the closed switching position of the contacts KL, KN (current flow possible), the movable blade contacts 21 a, 21 bare pushed into the clamping slot between the two resilient fingers of the stationary blade contacts 22 a, 22 b.FIG. 4 describes an embodiment of a protective switching device SG which has the three following different switching states 31, 32, 33.A first switching state 31 of the protective switching device SG is the switching state "OFF". In this case, the mechanical contacts KL, KN of the break contact switch KS a) have been brought into the open switching position (=current flow prevented) by the contactor drive CM by the switching-off or the triggering of the switching lock LH or b).Here, "release" denotes an opening movement of the lock LH into the open switching position as a result of an abnormal fault operating situation, and "disconnection" denotes an opening movement of the lock LH into the open switching position as a normal operation-related process. The circuit breaker device SG thus has a normatively defined separation property. The opening movement of the latching mechanism LH can be effected manually by the handle HH or by the maglach ML.The circuit breaker device SG thus has a normatively defined separation property.In the switching state "OFF", the HL switching elements W 1, W 2 of the HL switching unit EU are in a high-impedance state (=current flow prevented). The HL-based switching elements W 1, W 2 were brought into this high-resistance state before the mechanical contacts KL, KN of the isolating contact switch KS were brought into the open switching position (=current flow prevented). A current flow between the grid-side terminals L 1, N 1 and the load-side terminals T 1, N 2 of the protective switching device SG is therefore not possible in the switching state "OFF".A further switching state 32 of the protective switching device SG is the switching state "STANDBY". In this case, the mechanical contacts KL, KN of the isolating contact switch KS are in the closed switching position (=current flow made possible). In the switching state "STANDBY", the HL-based switching elements W 1, W 2 of the electronic switching unit EU are in a high-impedance state (=current flow prevented). A current flow between the mains-side terminals L 1, N 1 and the load-side terminals T 1, N 2 of the protective switching device SG is therefore not possible in the switching state "STANDBY".A further switching state 33 of the protective switching device SG is the switching state "ON". In this case, the mechanical contacts KL, KN of the isolating contact switch KS are in the closed switching position (=current flow made possible). In the switching state "ON", the HL-based switching elements W 1, W 2 of the electronic switching unit EU are in a low-impedance state (=current flow made possible). A current flow between the grid-side terminals L 1, N 1 and the load-side terminals L 2, N 2 of the protective switching device SG is thus possible in the switching state "ON".The following changes of state are possible between the above-described switching states 31, 32, 33.A state change 36 bfrom the switching state "ON" into the switching state "STANDBY", e.g. due to a slight current overload, takes place by switching the HL switching elements W 1, W 2 of the HL switching unit EU from a low-impedance state (=current flow allowed) into a high-impedance state (=current flow prevented), while the switching state of the isolating contact switch KS remains current-conducting unchanged. The change of state 36 bfrom the switching state "ON" into the switching state "STANDBY" takes place, for example, if a relatively small fault such as a simple / temporary overload or short-circuit fault occurs in the low-voltage circuit. A reverse state change 36 afrom the switching state "STANDBY" into the switching state "ON" takes place by switching the HL switching elements W 1, W 2 of the HL switching unit EU from a high-impedance state (=current flow prevented) into a low-impedance state (=current flow enabled), while the switching state of the isolating contact switch KS remains current-conducting unchanged. In this case, a parameterization function can be provided, with which it can be established whether, after the cause of the fault has been eliminated, the protective switching device SG automatically changes from the switching state "STANDBY" back to the switching state "ON" or whether this state change should take place remotely only after a remote waiting clearing.A change of state from the switching state "STANDBY" 32 to the switching state "OFF" 31 is possible in two different ways: a) by an opening movement 34 bof the latching mechanism LH or b) through an opening 35 bof the mechanical contacts by the contactor drive CM.In this case, a parameterization function can be provided, with which it can be established whether the state change from the "STANDBY" switching state to the "OFF" switching state takes place by an opening movement 34 bof the switching lock LH or by an opening 35 bof the mechanical contacts by the contactor drive CM.The opening movement 34 bof the switching lock LH can be initiated either manually by the handle HH or by the maglach ML. Triggering (by the maglatch) is rather less frequent, since it occurs only in the event of a severe fault. Most frequently, the manual switching of the lock LH to OFF and ON occurs by the handle HH. A reverse state change 34 afrom the "OFF" switching state to the "STANDBY" switching state cannot be effected by remote control (no "remote switchability"), but instead an on-site acknowledgement is necessary: after fault recovery has taken place, an operator has to manually tension the latch LH again by means of the handle HH and in this way bring it into a position in which triggering of the latch LH leads to the mechanical contacts KL, KN of the disconnect contact switch KS being opened. A state change 34 bfrom the "STANDBY" switching state to the "OFF" switching state takes place by an opening movement 34 bof the latching mechanism LH if a massive fault occurs in the low-voltage circuit, for example a voltage drag at the device contact region and consequently a ground current.The opening 35 bof the mechanical contacts through the contactor drive CM is effected remotely by remote control, by switching the mechanical contacts KL, KN of the break contact switch KS into the open contact position (=current flow prevented) by means of the contactor drive CM. A reverse state change 35 afrom the "OFF" switching state to the "STANDBY" switching state by the contactor drive CM likewise takes place remotely by remote control. A state change 34 bfrom the "STANDBY" switching state to the "OFF" switching state through an opening 35 bof the mechanical contacts through the contactor drive CM takes place, for example, if a relatively large fault such as an existing short circuit, ground fault or phase error occurs in the low-voltage circuit.FIG. 5 shows an exemplary embodiment of the mechanical switching contact unit MK. A contactor SZ is connected to a load current path formed by an outer conductor L and a neutral conductor N of the low-voltage circuit. The contactor SZ has mechanical contacts KL, KN, which can change between an open and a closed switching position. The contacts meet the requirements required by the standard DIN EN 60947-1 for devices with suitability for disconnection function: according to Table 14, "Test voltages across the open contacts of devices with suitability for disconnection function" of the above-mentioned. At a height of 200 mUNN and a rated surge voltage strength of 6.0 kV, they meet a test voltage of 9.6 kV.The contactor SZ also has a contactor drive CM which brings about the mechanical movement of the contacts KL, KN which have a contact bridge with two cut-off points, as shown in FIGS. 2 and 3. In n-pole devices, n of these contact bridges are present in a manner insulated from one another.A control unit SE can actuate the contactor drive CM via a signal line 11: thus, both opening and closing of the contacts KL, KN can be controlled remotely. The contactor drive CM thus enables remote re-switching on of the circuit breaker device SG.In parallel with this and independently of the contactor drive CM, the contacts KL, KN can be opened by the spring energy stored in a latching mechanism LH, which acts on the contacts KL, KN via a mechanical connection 17; the latching mechanism LH can be actuated manually 15 via a handle HH or remotely controlled 12, 15 via a maglach.List of reference charactersAV actuating device CM contactor drive COM communication unit EU semiconductor switching unit, HL switching unit G mains side GEH housing HH handle HMI human machine interface KL contacts outer conductor KN contacts neutral conductor KS disconnection contact switch LH switching lock L outer conductor L 1 mains side connection (outer conductor) L 2 mains side connection (outer conductor) L 3 mains side connection (outer conductor) T 1 load side connection (outer conductor) T 2 load side connection (outer conductor) T 3 load side connection (outer conductor) M load side MCU microcontroller MK mechanical switching contact unit ML maglatch N neutral conductor N 1 mains side connection (neutral conductor) N 2 load side connection (neutral conductor) POSA position display unit SE control unit SG circuit breaker device SI current sensor unit SZ contactor W 1 semiconductor switching element W 2 semiconductor switching element 8 signal line 9 signal line 10 connecting device, mechanical 11 signal line 12 signal line 13 signal line 14 signal line 15 connection, mechanical 16 connection, mechanical 17 connection, mechanical 18 signal line 19 signal line 20 connection, mechanical 21 amoovable contact 21 bmoovable contact 22 afixed contact 22 bfixed contact 23 contact bridge, movable 24 atranstrob 24 btransbtrob 25 spring 26 clamping slot 27 finger 31 OFF state 32 STANDBY state 33 ON state 34 astate change 34 bstate change 35 astate change 35 bstate change 36 astate change 36 bstate changeReferences 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 102021210818A1 [0004, 0028]DE 1669057U1

[0049] DE 1061409B

[0049] DE 2621703B2

[0049] DE 19538089C1

[0049]

Claims

Protective switching device (SG) for protecting a low-voltage circuit, having: - connections on the mains side (L1, N1) and on the load side (T1, N2) for conductors of the low-voltage circuit, - a current determination unit (SI) for determining the current intensity in the low-voltage circuit between the connections on the mains side (L1, N1) and on the load side (T1, N2), - a series circuit of a mechanical switching contact unit (MK) and a semiconductor switching unit (EU) which is connected between the connections on the mains side (L1, N1) and on the load side (T1, N2) in the low-voltage circuit, wherein the mechanical switching contact unit (MK) has contacts (KN, KL) which can change between an open and a closed switching position, and the semiconductor switching unit (EU) has at least one semiconductor switching element (W1, W2) which can change between a high-impedance state and a low-impedance state, and - a control unit (SE) for driving the mechanical switching contact unit (MK) and the electronic switching unit (EU), wherein the control unit (SE) can receive data with respect to the determined current intensity from the current determination unit (SI), wherein the mechanical switching contact unit (MK) has an actuating device (AV) which has a switching lock (LH) for switching the contacts (KL, KN) by means of the switching lock (LH), characterized in that, the mechanical switching contact unit (MK) also has a contactor drive (CM) for the remote-controlled switching of the contacts (KN, KL).The safety switching device (SG) according to claim 1, wherein the actuating device (AV) has a handle (HH) and a mag latch (ML) which act on the latch (LH).Circuit breaker device (SG) according to one of the preceding patent claims, wherein the actuating device (AV) and the contactor drive (CM) can switch the contacts (KL, KN) of the mechanical switching contact unit (MK) independently of one another.Circuit breaker device (SG) according to one of the preceding patent claims, having a contactor (SZ) which has the contacts (KN, KL) and the contactor drive (CM) as its integral components.Circuit breaker device (SG) according to one of the preceding patent claims, having a communication unit (COM) via which the contactor drive (CM) can be actuated by an external command unit.Circuit breaker device (SG) according to one of the preceding patent claims, wherein the contacts (KL, KN) have lyra contacts.Circuit breaker device (SG) according to one of the preceding patent claims, having a mechanical display device (POSA) for displaying the switching position of the mechanical switching contact unit (MK).Method for operating a circuit breaker device (SG) according to one of Claims 1 to 7, wherein the circuit breaker device (SG) has three different switching states OFF (31), STANDBY (32) and ON (33), wherein - in the switching state OFF (31) the contacts (KL, KN) are in the open switching position; - in the switching state STANDBY (32) the contacts (KL, KN) are in the closed switching position and the semiconductor diodes (W1, W2) are in the high-impedance state; in the switching state ON (33), the contacts (KL, KN) are in the closed switching position and the semiconductor switching elements (W1, W2) are in the low-ohmic state, wherein a change between the switching state OFF (31) and the switching state STANDBY (32) takes place either by the actuating device (AV) by means of the switching lock (LH) or by remote control by means of the contactor drive (CM).Method according to claim 8, wherein the contacts (KL, KN), when they are in the open switching position, can be brought into the closed switching position either manually by means of the handle (HH) or remotely by means of the contactor drive (CM).Method according to one of Claims 8 or 9, wherein the control unit (SE), which is connected to the current sensor unit (SI), the mechanical switching contact unit (MK) and the electronic switching unit (EU), initiates a prevention of a current flow in the low-voltage circuit if at least one current limit value or one current time limit value is exceeded.Computer program product having software code sections for carrying out the steps according to one of Claims 8 to 10 when the computer program product runs on a computing unit.A computer readable storage medium having stored thereon the computer program product of claim 11.

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