Circuit breaker device and method

Abstract

The invention relates to a circuit breaker device (SG) for protecting an electric low-voltage AC circuit, wherein - a mechanical separating contact unit (MK) is provided which provides a closed state of a neutral conductor contact (KKN) and of a phase conductor contact (KKL) for a current flow in the low-voltage AC circuit or an open state of the neutral conductor contact and of the phase conductor contact for a current flow-preventing galvanic isolation in the low-voltage AC circuit, - an electronic interrupting unit (EU) is provided which is connected in the phase conductor of the low-voltage AC circuit in series with the mechanical separating contact unit and which, by means of semiconductor-based switching elements, provides a high-ohmic state of the switching elements in order to prevent a current flow or a low-ohmic state of the switching elements for a current flow in the phase conductor, and - the level of a differential current between the neutral conductor and the phase conductor of the low-voltage AC circuit is ascertained. When the differential current exceeds first differential current time limit values, a process of preventing a current flow in the phase conductor is initiated using a high-ohmic state of the switching elements of the electronic interrupting unit while the neutral conductor contact and the phase connector contact are in the closed state. After the current flow is prevented in the phase conductor, a check is carried out in order to determine whether the differential current has exceeded higher second differential current time limit values, and if so, the neutral conductor contact and the phase conductor contact are opened so that a different trigger behavior is allowed when using discharge currents of the phase conductor than when using discharge currents of the neutral conductor.

Description

[0001]202320309 1 Description Protective switching device and method The invention relates to the technical field of a protective switching device for a low-voltage alternating current circuit according to the preamble of patent claim 1 and to a method for a protective switching device for a low-voltage alternating current circuit according to the preamble of patent claim 6. Low voltage means voltages of up to 1000 volts alternating voltage or up to 1500 volts direct voltage. Low voltage means, in particular, voltages that are greater than extra-low voltage, with values ​​of 50 volts alternating voltage or 120 volts direct voltage. Low-voltage alternating current circuit or network or system means circuits with nominal currents or rated currents of up to 125 amperes, more specifically up to 63 amperes. Low-voltage alternating current circuits include, in particular, circuits with nominal currents or rated currents of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes,16 amps or 10 amps. The current values ​​mentioned refer in particular to nominal, rated, and / or breaking currents, i.e., the maximum current that is normally carried through the circuit or at which the electrical circuit is usually interrupted, for example, by a protective device such as a protective switching device, circuit breaker, or power switch. The nominal currents can be further graded, from 0.5 A through 1 A, 2 A, 3 A, 4 A, 5 A, 6 A, 7 A, 8 A, 9 A, 10 A, etc., up to 16 A / up to 25 A / up to 32 A. Circuit breakers have long been known overcurrent protection devices.which are used in electrical installation technology in low-voltage circuits. These protect cables from damage caused by overheating due to excessive current and / or short circuits. A miniature circuit breaker can automatically switch off the circuit in the event of an overload and / or short circuit. A miniature circuit breaker is a non-self-resetting fuse element. In contrast to miniature circuit breakers, circuit breakers are designed for currents greater than 125 A, sometimes even from 63 A. Miniature circuit breakers are therefore simpler and more delicate in design. Miniature circuit breakers usually have a mounting option for attachment to a so-called top-hat rail (support rail, DIN rail,TH35). State-of-the-art circuit breakers are electromechanically constructed. They contain a mechanical switching contact or shunt release in a housing to interrupt (trip) the electrical current. Typically, a bimetallic protective element or bimetallic element is used to trip (interrupt) the electrical current in the event of a prolonged overcurrent (overcurrent protection) or thermal overload (overload protection). An electromagnetic release with a coil is used for brief tripping when an overcurrent limit is exceeded or in the event of a short circuit (short-circuit protection). One or more arc-quenching chambers or arc-quenching devices are provided. Furthermore, connection elements for conductors of the electrical circuit to be protected. Residual current circuit breakers for electrical circuits, particularly for low-voltage circuits or systems,are generally known. Residual current devices are also known as residual current devices, or RCDs for short. Residual current devices measure the current sum (or the differential current from the forward (positive sign) and return conductors (negative sign)) in an electrical circuit, which is normally zero, and interrupt the electrical circuit if a differential current value is exceeded, i.e. a current sum not equal to zero that exceeds a certain (differential) current value or residual current value. 202320309 3 Almost all previous residual current devices have a summation current transformer, the primary winding of which is formed by the conductors of the circuit and the secondary winding of which outputs the current sum (or an image of the differential current), which is used directly or indirectly to interrupt the electrical circuit. For this purpose, two or more conductors,Usually, the forward and return conductors or the outer conductors (or phase conductors) and the neutral conductor in a single-phase alternating current system, all three outer conductors or all three outer conductors and the neutral conductor in a three-phase alternating current system, are passed through a current transformer, usually with a ring-shaped core made of ferromagnetic material. Only the differential current, i.e., a current from the conductors that differs from the forward and return current, is converted. The total current in an electrical circuit is usually zero. This allows fault currents to be detected. If, for example, a current flows to earth on the energy sink side or the consumer side, this is referred to as a fault current or leakage current. A fault occurs, for example, when there is an electrical connection from a phase conductor of the electrical circuit to earth. For example,when a person touches the phase conductor. Then, part of the electrical current does not flow back via the neutral conductor as usual, but via the person and the earth. This residual current can now be detected using the summation current transformer, since the detected sum of the incoming and returning current (the difference in the currents) is not equal to zero. A relay or a holding magnet release, for example with an associated mechanism, interrupts the circuit, e.g., at least one, some, or all of the lines. Residual current circuit breakers for detecting alternating residual currents are generally known from the publication DE 4432 643 A1. 202320309 4 The main function of residual current circuit breakers is to protect people from electrical currents (electric shock), as well as systems,Machines or buildings from fire due to electrical insulation faults. If the residual current device or its summation current transformer is designed in such a way that the secondary energy of the summation current transformer is sufficient to actuate a tripping unit or an interruption unit or a release, then such residual current devices are called mains voltage-independent. If auxiliary power is required or used for the tripping circuit, which is usually generated by a power supply unit provided in the residual current device, such residual current devices are called mains voltage-dependent. This means that mains voltage-dependent residual current devices contain a power supply unit to supply energy to a residual current detector (mains voltage-independent devices do not). These power supplies are required, for example,to detect fault currents in DC voltage networks and mixed DC / AC networks, or in high-frequency circuits. Circuit breakers with an electronic interruption unit are relatively new developments. These feature a semiconductor-based electronic interruption unit. This means that the electrical current flow in the low-voltage circuit is conducted via semiconductor components or semiconductor switches, which can interrupt the electrical current flow or be made conductive. Circuit breakers with an electronic interruption unit also often feature a mechanical isolating contact system, particularly with isolating properties in accordance with relevant standards for low-voltage circuits, with the contacts of the mechanical isolating contact system connected in series with the electronic interruption unit.i.e., the current of the low-voltage circuit to be protected is conducted via both the 202320309 5 mechanical isolating contact system and the electronic interruption unit. The present invention relates in particular to low-voltage alternating current circuits with an alternating voltage, usually with a time-dependent sinusoidal alternating voltage with the frequency f. The time dependence of the instantaneous voltage value u(t) of the alternating voltage is described by the equation: u(t) = U * sin (2π * f * t). Where: u(t) = instantaneous voltage value at time t U = amplitude of the voltage A harmonic alternating voltage can be represented by the rotation of a vector,whose length corresponds to the amplitude (U) of the voltage. The instantaneous deflection is the projection of the pointer onto a coordinate system. One oscillation period corresponds to one full rotation of the pointer, and its full angle is 2π (2Pi) or 360°. The angular frequency is the rate of change of the phase angle of this rotating pointer. The angular frequency of a harmonic oscillation is always 2π times its frequency, ie: ω = 2π*f = 2π / T = angular frequency of the alternating voltage (T = period of the oscillation) The angular frequency (ω) is often preferred to the frequency (f), since many formulas of oscillation theory can be represented more compactly using the angular frequency due to the occurrence of trigonometric functions whose period is by definition 2π: u(t) = U * sin(ωt) 202320309 6 In the case of angular frequencies that are not constant over time, the term instantaneous angular frequency is also used. For a sinusoidal,In particular, for a temporally constant alternating voltage, the time-dependent value of the angular velocity ω and the time t corresponds to the time-dependent angle φ(t), which is also referred to as the phase angle φ(t). This means that the phase angle φ(t) periodically passes through the range 0…2π or 0°…360°. This means that the phase angle periodically assumes a value between 0 and 2π or 0° and 360° (φ = n*(0…2π) or φ = n*(0°…360°), due to periodicity; in short: φ = 0…2π or φ = 0°…360°). The instantaneous voltage value u(t) is therefore the instantaneous value of the voltage at time t, i.e., in the case of a sinusoidal (periodic) alternating voltage, the value of the voltage at the phase angle φ (φ = 0…2π or φ = 0°…360°, of the respective period). The object of the present invention is to improve a protective switching device of the type mentioned above,In particular, to ensure protection against (fault) currents caused by persons while simultaneously ensuring supply security or availability of electrical systems, i.e., to achieve immunity against non-critical (fault) currents or leakage currents that would lead to false tripping of the protective switching device. This means, on the one hand, to ensure personal protection and, on the other hand, to improve the supply security of a low-voltage AC circuit. Alternatively, to create a novel concept for such a protective switching device. This object is achieved by a protective switching device with the features of patent claim 1 and by a method according to patent claim 6. 202320309 7 According to the invention, a protective switching device for protecting (fault current protection) an electrical low-voltage AC circuit is provided, comprising: - a housing with (at least): ^ a mains-side phase conductor connection, ^ a load-side phase conductor connection,for a phase conductor of the low-voltage AC circuit; ^ a mains-side neutral conductor connection, ^ a load-side neutral conductor connection, for a neutral conductor of the low-voltage AC circuit; - a differential current sensor unit for determining the magnitude of a differential current (caused by leakage currents (of the phase conductor or (and) neutral conductor against earth or the protective conductor)) between the neutral conductor and the phase conductor of the low-voltage AC circuit, - a mechanical isolating contact unit having a closed state of a neutral conductor contact and (at least) one phase conductor contact for current flow in the low-voltage AC circuit or an open state of the neutral conductor contact and the phase conductor contact for galvanic isolation in the low-voltage AC circuit that prevents current flow, - an electronic interruption unit,which is connected in series with the mechanical isolating contact unit in the phase conductor and which, through semiconductor-based switching elements, has a high-resistance state of the switching elements to prevent a current flow or a low-resistance state of the switching elements to prevent a current flow in the phase conductor, - a control unit connected to the differential current sensor unit, the mechanical isolating contact unit, and the electronic interruption unit. The protective switching device, in particular the control unit, is designed such that, when the differential current exceeds first differential current time limits, the avoidance of a current flow in the phase conductor is initiated by a high-resistance state of the switching elements of the electronic interruption unit when the neutral conductor contact and the phase conductor contact are closed.that after preventing current flow in the phase conductor (due to the high-resistance state of the switching elements of the electronic interruption unit when the neutral conductor contact and the phase conductor contact are closed), a test is carried out to determine whether the residual current has exceeded, in particular larger, second residual current time limits. If this is exceeded, the neutral conductor contact and the phase conductor contact are opened. This has the advantage of enabling different tripping behavior for phase conductor leakage currents compared to neutral conductor leakage currents. Larger or higher second residual current time limits refer to second residual current time limits.whose second differential current limit value (portion) is greater in magnitude than the first differential current limit value (portion). Alternatively or additionally, the second time limit value (portion) can be greater than the first time limit value (portion). In general, a differential current time limit value means a limit value that a differential current (of a certain magnitude) must be present for a certain time before the differential current time limit value is exceeded. This means that the differential current time limit value has a differential current limit value portion and a time limit value portion. Advantageous embodiments of the invention are specified in the subclaims and in the exemplary embodiment. In an advantageous embodiment of the invention, a time-delayed tripping behavior is enabled for differential currents caused by a leakage current of the phase conductor compared to differential currents caused by a leakage current of the neutral conductor. 202320309 9 This has the particular advantage thatthat selectivity regarding the tripping conditions can be achieved. Critical residual fault currents / leakage currents of the phase conductor are switched off quickly. Less critical residual fault currents / leakage currents of the neutral conductor can be switched off more slowly (or with a time delay). In an advantageous embodiment of the invention, the presence of a leakage current on the phase conductor or the neutral conductor is (determined and) communicated. For this purpose, a communication unit, for example with an input unit, can advantageously be provided. This has the particular advantage of providing an overview, for example in a higher-level management system.about the type of differential current / fault current / leakage current causing the fault. The mechanical isolating contact unit can advantageously be operated by a mechanical handle. Switching on and off using the electronic interruption unit cannot be operated (directly) on the device. In an advantageous embodiment of the invention, the mechanical isolating contact unit is assigned to the load-side terminals. This has the particular advantage of providing an architecture that supports the inventive behavior of the protective switching device, since, on the one hand, the current flow is interrupted with a high-impedance interruption unit, but testing can still be carried out (using the load-side terminals) through the (load-side) closed contacts. Furthermore, the control unit and the electronic interruption unit continue to be supplied with power.regardless of the closed or open state of the neutral conductor contact and the phase conductor contact. The test for the presence of the residual current exceeding the second residual current time limit values ​​is carried out in the high-impedance state of the electronic interruption unit (in the phase conductor) (with the neutral conductor contact and the phase conductor contact closed). According to the invention, a corresponding method for a protective switching device for protecting an electrical low-voltage AC circuit with (at least) one phase conductor and one neutral conductor is claimed, in which - a mechanical isolating contact unit,which is provided with a closed state of a neutral conductor contact (in the neutral conductor) and a phase conductor contact (in the phase conductor) for a current flow in the low-voltage AC circuit or an open state of neutral conductor contact and phase conductor contact for a current-preventing galvanic isolation in the low-voltage AC circuit, - an electronic interruption unit which is connected in series with the mechanical isolating contact unit in the phase conductor of the low-voltage AC circuit and which is provided with a high-resistance state of the switching elements to prevent a current flow or a low-resistance state of the switching elements to allow current flow in the phase conductor by means of semiconductor-based switching elements,- the magnitude of a differential current (caused by leakage currents (of the phase conductor and / or neutral conductor) (to earth or the protective conductor)) between the neutral conductor and the phase conductor of the low-voltage AC circuit is determined. The protective switching device is designed in such a way that if the differential current exceeds the first differential current time limit values ​​(in terms of magnitude and / or duration), a current flow in the phase conductor is prevented by a high-resistance state of the switching elements of the electronic interruption unit with the neutral conductor contact and the phase conductor contact closed. After the current flow in the phase conductor has been prevented (by the high-resistance state of the switching elements of the electronic interruption unit and the closed state of the neutral conductor contact and the phase conductor contact), a test is carried out to determine whether the differential current has exceeded the first differential current time limit values ​​(in terms of magnitude and / or duration).In particular, larger, second differential current time limits are implemented, and if these are exceeded, the neutral conductor contact and the phase conductor contact are opened; thus enabling a different triggering behavior for leakage currents of the phase conductor compared to leakage currents of the neutral conductor. In advantageous embodiments of the method: - a temporally offset triggering behavior for differential currents caused by a leakage current of the phase conductor compared to differential currents caused by a leakage current of the neutral conductor can be enabled, and / or - the presence of a leakage current on the phase conductor or the neutral conductor can be (determined and) communicated. According to the invention, a corresponding computer program product for a protective switching device is claimed. The computer program product comprises commands,which, when the program is executed by a microcontroller (for example in the control unit), cause the microcontroller to support or carry out the above method (or the above statements), in particular, if the differential current exceeds the first differential current time limit values, to initiate the avoidance of a current flow in the phase conductor by a high-resistance state of the switching elements of the electronic interruption unit when the neutral conductor contact and the phase conductor contact are closed, after the current flow in the phase conductor has been avoided, to initiate a check for the existence of the differential current being exceeded via second differential current time limit values, and if the limit values ​​are exceeded, to initiate the opening of the neutral conductor contact and the phase conductor contact,so that a different tripping behavior is enabled for leakage currents of the phase conductor compared to leakage currents of the neutral conductor. The microcontroller is part of the protective switching device, in particular of the control unit. 202320309 12 According to the invention, a corresponding computer-readable storage medium on which the computer program product is stored is claimed. According to the invention, a corresponding data carrier signal that the computer program product transmits is claimed. All embodiments, both in dependent form referring back to patent claim 1 or 6, as well as referring back only to individual features or combinations of features of patent claims, in particular also a reference of the pending arrangement claims to the independent method claim, bring about an improvement in a protective switching device,In particular, they improve personal safety and supply security in low-voltage AC circuits and provide a new, safe concept for a protective switching device. The described properties, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawing. The drawing shows: Figure 1 shows a first schematic diagram of a protective switching device, Figure 2 shows a second schematic diagram of a protective switching device, Figure 3 shows an electrical distribution board with a protective switching device, Figure 4 shows a schematic diagram of a functional chain. 202320309 13 Figure 1 shows a diagram of a protective switching device SG for protecting an electrical low-voltage AC circuit with a housing GEH,comprising: - (at least) one grid-side phase conductor connection LG, - (at least) one load-side phase conductor connection LL, for a phase conductor L of the low-voltage AC circuit; - a grid-side neutral conductor connection NG, - a load-side neutral conductor connection NL, for a neutral conductor N of the low-voltage AC circuit; - an energy source is usually connected to the grid-side connections LG, NG / the grid side Grid, - a consumer is usually connected to the load-side connections LL, NL / the load side Load; - a (two-pole) mechanical isolating contact unit MK with load-side connection points APLL, APNL and grid-side connection points APLG, APNG, whereby a load-side connection point APNL is provided for the neutral conductor N, a load-side connection point APLL is provided for the phase conductor L, and a grid-side connection point APNG is provided for the neutral conductor N,A mains-side connection point APLG is provided for the phase conductor L. The load-side connection points APNL, APLL are connected to the load-side neutral and phase conductor connections NL, LL, whereby the (two-pole) mechanical isolating contact unit MK has a closed state of a neutral conductor contact KKN (for the neutral conductor) and (at least) one phase conductor contact KKL (for the phase conductor) for a current flow in the low-voltage AC circuit or an open state of the neutral conductor contact KKN and phase conductor contact KKL for a current-preventing galvanic isolation in the low-voltage AC circuit, so that the opening of the contacts KKN, KKL to prevent a current flow or the closing of the contacts KKN, KKL to allow a current flow in the low-voltage AC circuit can be switched, - a (single-pole) electronic interruption unit EU,202320309 14 which is connected in series with the mechanical isolating contact unit MK in the phase conductor L, with a mains-side connection point EUG, which is electrically connected to the mains-side phase conductor connection LG, and a load-side connection point EUL, which is electrically connected or connected to the mains-side connection point APLG of the mechanical isolating contact unit MK, wherein the electronic interruption unit EU has or can be switched to a high-resistance state of the switching elements to prevent a current flow or a low-resistance state of the switching elements to allow current flow in the phase conductor L by means of semiconductor-based switching elements (not shown), - a differential current sensor unit ZCT,to determine the level of a differential current (caused by leakage currents (of the phase conductor L or (and) neutral conductor N against earth or the protective conductor PE)) of the neutral conductor and phase conductor of the low-voltage alternating current circuit, the differential current sensor unit ZCT is arranged in the example between the electronic interruption unit EU and the mechanical isolating contact unit MK, it can alternatively be provided (arranged) between the mechanical isolating contact unit MK and the load-side neutral and phase conductor connections NL, LL, as well as alternatively between the electronic interruption unit EU and the mains-side connections NG,LG may be provided (arranged). The differential current sensor unit ZCT determines the magnitude of the differential current of the conductors of the low-voltage alternating current circuit (to be protected) routed through the protective switching device. In the example, for a single-phase alternating current circuit, this is the neutral conductor N and the phase conductor L. The differential current sensor unit ZCT can be a conventional summation current transformer. The primary side of the summation current transformer is formed by the conductors of the low-voltage alternating current circuit (in the example, the phase conductor L and the neutral conductor N). The secondary side of the summation current transformer is connected to the control unit SE. 202320309 15 - In addition, a current sensor unit SI can be provided to determine the magnitude of the current in the low-voltage alternating current circuit, which is located in particular in the phase conductor L (current path of the phase conductor or phase conductor current path), - a control unit SE that is connected to the differential current sensor unit ZCT,connected to the (optional) current sensor unit SI, the mechanical isolating contact unit MK, and the electronic interruption unit EU. The protective switching device is designed in such a way that if the residual current determined by the residual current sensor unit ZCT exceeds the first residual current time limit values, the prevention of current flow in the phase conductor L is initiated by a high-resistance state of the switching elements of the electronic interruption unit EU with the neutral conductor contact KKN and the phase conductor contact KKL closed. After the prevention of current flow in the phase conductor L (by the high-resistance state of the switching elements of the electronic interruption unit EU with the neutral conductor contact KKN and the phase conductor contact KKL closed), a test is carried out to determine whether the residual current has been exceeded, in particular by larger,second residual current time limits are implemented. If exceeded, the neutral conductor contact KKN and the phase conductor contact KKL are opened. This has the advantage of enabling different tripping behavior for phase conductor leakage currents compared to neutral conductor leakage currents. Larger or higher second residual current time limits refer to second residual current time limits whose second residual current limit value (portion) is greater in magnitude than the first residual current limit value (portion). Alternatively or additionally, the second time limit value (portion) can be greater than the first time limit value (portion). In general, a residual current time limit refers to a limit value at which a residual current (of a certain magnitude - residual current limit value portion) must be present for a certain period of time.before the differential current time limit is exceeded. This means that the differential current time limit has a differential current limit component and a time limit component. In addition, the protective switching device can be designed such that if current and / or current time limit values ​​are exceeded (i.e., if a current of a certain magnitude is present in the circuit for a certain time), a current flow prevention in the low-voltage AC circuit is initiated for a current level of the low-voltage AC circuit determined by the current sensor unit SI. In the example, the mechanical isolating contact unit MK is arranged on the load side, while the electronic interruption unit EU is arranged on the grid side. The grid side, with the energy source, is normally energized. An electrical consumer is usually connected to the load side Load. This has the advantage thatthat no other (especially live) parts or components are located between the contacts of the mechanical isolating contact unit / load-side connection points APLL, APNL of the mechanical isolating contact unit and the two load-side connections LL, NL. This architecture or design ensures that, when contacts KKL, KKN are open, no voltage is present at the load-side connections LL, NL under any circumstances. This increases the safety of the protective switching device in the low-voltage AC circuit. In contrast, in other architectures where the mechanical isolating contact unit is arranged on the mains side, (non-galvanically isolated) electronic units are often located upstream of the load-side connection. The protective switching device can be designed in such a way thatthat the voltage level across the electronic interruption unit EU can be determined. This means that the level of a first voltage 202320309 17 between the mains-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU can be determined or is being determined. For this purpose, in the example according to Figure 1, a first voltage sensor unit SU1 connected to the control unit SE is provided, which determines the voltage level between the mains-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU. When measuring the voltage by the first voltage sensor unit SU1, the voltage across the series connection of the electronic interruption unit EU and the current sensor SI can alternatively be determined, as shown in Figure 1. The current sensor unit SI has a very low internal resistance,so that the determination of the voltage level is not affected or only negligibly affected. Advantageously, a second voltage sensor unit SU2 can be provided, which determines the voltage level between the mains-side neutral conductor connection NG and the mains-side phase conductor connection LG. Between the mains-side connection points APLG,A measuring impedance ZM can be connected to APNG of the mechanical isolating contact unit MK. The measuring impedance ZM can be, for example, an electrical resistor and / or capacitor. The measuring impedance can also be an inductance. In particular, the measuring impedance can be a series or parallel connection of a resistor and / or capacitor and / or inductance. The electronic interruption unit EU is arranged in the phase conductor L (Figure 1). The mains-side connection point APNG for the neutral conductor of the mechanical isolating contact unit MK is connected to the mains-side neutral conductor connection NG of the housing GEH. This connection is made, as shown in Figure 1, through the residual current sensor unit ZCT, for example its summation current transformer. 202320309 18 The protective switching device SG is advantageously designed such that the contacts KKL, KKN of the mechanical isolating contact unit MK are opened by the control unit SE.but cannot be closed, which is indicated by an arrow OEF from the control unit SE to the mechanical isolating contact unit MK. The mechanical isolating contact unit MK can be operated by a mechanical handle HH on the protective switching device SG to manually open or close the contacts KKL, KKN. Both contacts are switched simultaneously, for example. The mechanical handle HH indicates the switching state (open or closed) of the contacts of the mechanical isolating contact unit MK on the protective switching device. Furthermore, the contact position (or the position of the handle, closed or open) can be transmitted to the control unit SE. The contact position (or the position of the handle) can be determined, for example, using a sensor.such as a position sensor. The contact position or the switching state can be transmitted to the control unit SE. The position sensor can be part of the mechanical isolating contact unit MK. Alternatively, the position sensor can be a component in the electronic first part (EPART, Figure 2). For example, a Hall sensor can be provided in the electronic first part (EPART), which detects and transmits the position of the contacts and / or the handle without contact. The mechanical isolating contact unit MK is advantageously designed such that (manual) closing of the contacts by the mechanical handle is only possible after an enable signal, in particular an enable signal. This is also indicated by the arrow from the control unit SE to the mechanical isolating contact unit MK. This means that the contacts KKL,KKN of the mechanical isolating contact unit MK can only be closed by the handle HH when the enable signal or the enable signal (from the 202320309 19 control unit) is present. Without the enable signal or the enable signal, the handle HH can be operated, but the contacts cannot be closed ("permanent slipping"). The protective switching device SG has a power supply or power supply NT, for example a switched-mode power supply. In particular, the power supply / power supply NT is provided for the control unit SE, which is indicated by a connection between the power supply / power supply NT and the control unit SE in Figure 1. The power supply / power supply NT is (on the other hand) connected to the mains-side neutral conductor connection NG and the mains-side phase conductor connection LG. A fuse SS can be advantageously installed in the connection to the mains-side neutral conductor connection NG (or / and phase conductor connection LG),In particular, a fuse, or (and) a switch Sch may be provided. According to the invention, the NT power supply unit is normally continuously supplied with power, specifically from the mains-side connections. It is protected by the SS fuse if necessary or can be switched off by the Sch switch. Advantageously, the SCH / Sch switch can be designed so that the switch can only be opened when the contacts are open. This increases the safety of the device, since the control unit (electronics) cannot be switched off when the contacts are closed. The SS fuse not only serves the purpose of protecting the power supply via the NT power supply unit, but is also intended, particularly in the case of a two-part design, to protect the "electronic" part or its entire units (such as the control unit, electronic interruption unit, summation current transformer, voltage sensor(s) if necessary).(if necessary, current sensor, if necessary, measuring impedance, etc.). 202320309 20 The low-voltage AC circuit can be a three-phase AC circuit, with one neutral conductor and three phase conductors. The protective switching device can be designed as a three-phase variant for this purpose and, for example, have additional mains-side and load-side phase conductor connections. Electronic interruption units according to the invention and contacts of the mechanical isolating contact unit are provided in an analogous manner between the additional mains-side and load-side phase conductor connections. The respective conductors (three phase conductors L1, L2, L3, neutral conductor N) are routed through the differential current unit ZCT. Current sensor units and voltage detection devices (e.g., by first voltage sensor units) can also be provided. High-impedance refers to a state in which only a negligible current flows. In particular, high-impedance refers to resistance values ​​greater than 1 kiloohm.better greater than 10 kiloohms, 100 kiloohms, 1 megaohm, 10 megaohms, 100 megaohms, 1 gigaohm or greater. Low resistance means a state in which the current value specified on the protective switching device could flow. In particular, low resistance means resistance values ​​that are less than 10 ohms, better less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less. Figure 2 shows a representation similar to Figure 1, with the difference that the protective switching device is constructed in two parts. It contains an electronic first part EPART, for example on a printed circuit board. The first part EPART can have the control unit SE, optionally the first voltage sensor unit SU1, optionally the second voltage sensor unit SU2, optionally the current sensor unit SI, the electronic interruption unit EU, and the power supply NT. Furthermore, the first part can contain the fuse SS, a switch SCH, the measuring impedance ZM,a temperature sensor TEM (particularly for the electronic interruption unit EU), a communication unit 202320309 21 COM, a display unit AE, and, as a variant, a position sensor unit POS. The communication unit COM can, in particular, be a wireless communication unit. The communication unit COM can have a (manual) input unit on the protective switching device for the (manual) acknowledgment of states on the protective switching device SG. Acknowledgment can also be carried out (wired and / or wirelessly) via the communication unit COM. Furthermore, the communication unit COM can have a display function. A separate display unit can also be provided. The protective switching device contains a second part MPART, in particular a mechanical one. The second part MPART can have the mechanical isolating contact unit MK, the handle HH, and a release unit FG. Furthermore, the second part can have a position unit POS,for reporting the position of the contacts of the mechanical isolating contact unit MK to the control unit, as well as the (neutral conductor) connection(s). The second part MPART has the residual current sensor unit ZCT, like a summation current transformer, as is known, for example, from classic residual current circuit breakers. Additional, unspecified units may be provided. By splitting the unit in two, a compact protective switching device according to the invention with a simplified design can be advantageously realized. The release unit / release function FG enables the actuation of the contacts of the mechanical isolating contact unit by the handle HH when an enable signal is present. This means that the contacts KKL close.KKN can only be closed by the handle when the enable signal (from the SE control unit) is present. Otherwise, closing is not possible ("permanent slippage" of the HH handle). 202320309 22 The contacts remain in the open position / switching state. Furthermore, the release unit FG can cause the contacts to open (second function of the release unit FG) when an opening signal OEF (from the SE control unit) is present. The release unit / release function FG then acts as a tripping unit for opening the contacts of the mechanical isolating contact unit MK. The protective switching device SG, in particular the SE control unit, is further designed such that, when current limits or current-time limits are exceeded (i.e., when a current limit is exceeded for a specific period of time), the prevention of current flow in the low-voltage AC circuit is initiated.in particular to avoid a short-circuit current. This is achieved in particular by the electronic interruption unit EU switching from the low-resistance state to the high-resistance state. The initiation of the prevention of a current flow in the low-voltage AC circuit occurs, for example, by a first interruption signal off that is sent from the control unit SE to the electronic interruption unit EU. The electronic interruption unit EU can be switched to the low-resistance state by a switch-on signal on. The mechanical isolating contact unit MK can be controlled alternatively or additionally by the control unit SE.to initiate the prevention of current flow in the low-voltage AC circuit when current limits or current-time limits are exceeded. Specifically, galvanic isolation is achieved if necessary. The initiation of the prevention of current flow or, if necessary, a galvanic interruption of the low-voltage AC circuit is carried out, for example, by a second interruption signal (OEF) sent from the control unit SE to the mechanical isolating contact system MK. 202320309 23 The electronic interruption unit EU can contain semiconductor components such as bipolar transistors, field-effect transistors (FETs), isolated-gate bipolar transistors (IGBTs), metal-oxide-layer field-effect transistors (MOSFETs), or other (self-commutated) power semiconductors. IGBTs and MOSFETs are particularly suitable due to their low forward resistance.High junction resistance and good switching behavior are particularly well-suited for the protective switching device according to the invention. The mechanical isolating contact unit MK refers in particular to a (standard-compliant) isolating function, implemented by the isolating contact unit MK. The isolating function refers to the following points: - Minimum clearance according to the standard (voltage-dependent) (minimum distance between the contacts), - Contact position indication of the contacts of the mechanical isolating contact system, - Opening of the mechanical isolating contact system is always possible (no blocking of the isolating contact system - in particular by the handle, trip-free). For the purposes of the invention, the DIN EN 60947 and IEC 60947 series of standards are relevant, for example, for the isolating function and its properties; these are incorporated herein by reference. The protective switching device can be designed as a DIN rail-mountable protective switching device SG with a width of, for example, 2 TE with two-pole connections (phase conductor L,Neutral conductor N). In electrical installation and switchgear cabinet construction, the width of built-in devices such as circuit breakers, miniature circuit breakers, residual current devices, etc., is specified in modular units (TE). The width of one modular unit is approximately 18 mm. According to DIN 43880: 1988-12, the installation width of the devices should be between 17.5 and 18.0 mm, or be calculated by multiplying this dimension by 0.5 or an integer multiple thereof, i.e.: k x 0.5 x 18 mm or k x 0.5 x 17.5 mm (with k = 1, 2, 3, ...). For example, a single-pole miniature circuit breaker, according to the state of the art, has a width of 1 TE. The components of electrical distribution boards are matched to the modular units, e.g., the width of mounting rails / top-hat rails, in accordance with DIN 43871 "Small distribution boards for built-in devices up to 63 A." According to the invention, the protective switching device SG,In particular, the control unit SE is designed in such a way that, when the first residual current time limits are exceeded, the prevention of current flow in the low-voltage AC circuit is initiated by a high-impedance state of the switching elements of the electronic interruption unit when the isolating contacts are closed. The first residual current time limits can be limits according to relevant standards, such as DIN EN 61008-1. For example, 30 mA for personal protection in Europe in a 230 V low-voltage circuit, 6 mA for personal protection in North America, 300 mA for fire protection (230 V rms value). The standard DIN EN 61008-1, Residual current operated circuit-breakers without integral overcurrent protection (RCCBs) for domestic installations and similar applications, in particular Part 1: General Requirements, is incorporated herein by reference. For example, this standard states:that a 30mA residual current device (RCD) must trip within 300ms at the rated fault current (30mA). At twice the rated fault current (60mA) within 150ms. At 5 times or more the rated fault current must trip within 40ms. After current flow has been avoided by a high-impedance state of the switching elements of the electronic interruption unit and the contacts closed, a test is carried out to determine whether second residual current time limits have been exceeded. The level of the second residual current time limits is greater than that of the first residual current time limits. 202320309 25 The level of the second residual current limit (current component of the residual current time limit) can be a multiple of the first residual current limit: e.g. E.g. the 1.5-, 2-, 3-, 5-, 10-,or 20 times (intermediate values ​​are possible). The length of the second time limit (time component of the residual current time limit) can be a multiple of the length (or duration) of the first time limit: e.g., 1.5, 2, 3, 5, 10, 20, 50, 100, or 1000 times. The first residual current time limits can be values ​​from known standards / product standards (especially manufacturer-specific standards). For example, the first residual current time limit values ​​can be values ​​from the standard for residual current devices: DIN EN 61008-1 or (and) DIN EN 61009-1 (e.g. VDE 0664-10) or from other standards for residual current devices (with built-in overcurrent protection (RCBOs) for domestic installations and similar applications). The protective switching device SG, in particular the control unit SE, can have a microcontroller (= microprocessor) running a computer program product, comprising instructions,which, when the program is executed by the microcontroller, cause it to perform a behavior or test (as described above and below) for a protective switching device. The control unit with microprocessor can have a memory. A tripping curve with specific (first / second) residual current time limit values ​​can then be stored in the control unit, in particular in the memory. The tripping curve can be taken from the memory. The values ​​of the selected tripping curve are compared with the determined level of the residual current in the control unit (e.g., with the help of the microprocessor). If exceeded, a corresponding current-preventing tripping is initiated. The computer program product can advantageously be stored on a computer-readable storage medium; such as a USB stick, CD-ROM, etc.; 202320309 26,to enable, for example, an upgrade to an extended version. The computer program product can alternatively also advantageously be transmitted via a data carrier signal. The invention is further explained below in other words and with further figures. Today's residual current devices (RCDs) serve (among other things) to protect people (protection goal: protection against electric shock) and, when a residual current occurs (also referred to as differential fault current or fault current) that exceeds the residual current time limit values, they trip and disconnect the existing circuit on the phase conductor L (also referred to as L conductor) and neutral conductor N (also referred to as N conductor). The residual current devices (RCDs) typically measure the occurring residual current via a summation current transformer (or differential current transformer). The protective devices do not differentiate whether the residual current,on the N or L conductor. For example, if a person touches the phase conductor L (L conductor or active conductor), the person must be protected from a dangerous electric shock, and the protective switching device disconnects the load output from the grid connection within a specific (and standardized) current-time tripping limit (residual current time limit values). The neutral conductor N (called the "N conductor" or "neutral conductor") normally has a voltage of approximately zero volts, since the N conductor and the protective conductor (also called the PE conductor) are typically connected to each other in the electrical distribution system (typically at the feed-in transformer). Nevertheless, small voltages (in the range of a few volts or even 10 to 20 volts) are possible between the neutral conductor N and the protective conductor (PE conductor). The reason for this is, for example, currents on the N conductor,which lead to a voltage drop 202320309 27 on the N conductor. Or the capacitive coupling between the N and L conductors, which can occur more frequently, especially in the case of EMC interference. This leads to, for example, an electrically conductive (or very low-resistance) connection between the N and PE conductors (e.g., due to contact between the two conductors), a differential fault current can flow on the N conductor. If this (N-conductor) differential current exceeds the tripping limit, a modern residual current device (RCD) trips. Due to their design (with the existing residual current transformer), residual current devices cannot distinguish whether the fault current (leakage current) is flowing on the N conductor or the L conductor and thus (always trip) in the same way. The invention proposes a solution,How a protective switching device can trip in different ways (in terms of current magnitude and / or tripping time) when a differential fault current occurs on the L conductor or the N conductor. This means that the protective switching device no longer trips immediately for L and N fault currents (leakage currents). Figure 3 shows a schematic representation of an electrical power distribution system with a protective switching device SG according to the invention. On the grid side, a grid-side feed-in phase conductor L1E, a grid-side feed-in neutral conductor NE, and a protective conductor PE are provided. The grid side of the protective switching device SG is connected to the grid-side feed-in phase conductor L1 and the grid-side feed-in neutral conductor NE. Between them, an (upstream) fuse F1 and an (upstream) first circuit breaker F2 are provided in the phase conductor.as per Figure 3. A load-side sub-distribution phase conductor L1S and a load-side sub-distribution neutral conductor NS are connected to the load side Load of the protective switching device SG. 202320309 28 Furthermore, the protective conductor PE of the feed-in side is connected through to the load side, as per Figure 3. In the example, an SDV socket with an electrical consumer VBR is connected to the load-side sub-distribution phase conductor L1S and the load-side sub-distribution neutral conductor NS. A further, second circuit breaker F4 is provided in the phase conductor of this connection. The SDV socket is also connected to the protective conductor PE. The SDV socket can have an electrical connection (electrical bridge) between the neutral conductor and the protective conductor PE. The terms mains-side feed-in phase conductor L1E, mains-side feed-in neutral conductor NE, load-side sub-distribution phase conductor L1S,The load-side sub-distribution neutral conductors NS are sometimes used synonymously with phase conductors and neutral conductors or abbreviated. A specialist knows what and how this is meant. A current i flows through the consumer VBR via the phase conductors and neutral conductors. load , which is protected by fuse F1, the first circuit breaker F2, and the second circuit breaker F4 – and is advantageously also protected by the protective switching device SG with current sensor unit SI. This could potentially eliminate the first circuit breaker F2 and / or the second circuit breaker F4. The diagram shows a person HUM touching the phase conductor between the SDV socket and the VBR consumer. A phase-conductor-side leakage current / phase-conductor-side differential current i flows. fLthrough the person HUM to earth (earth symbol). If there is a potential difference between the neutral conductor N and the protective conductor PE, a neutral conductor-side leakage current / neutral conductor-side differential current i fNflow away, as indicated in Figure 3. 202320309 29 The protective switching device SG typically has a summation current transformer that detects the level of the differential current between the two conductors (L and N) of the low-voltage network. The device now has a different chain of effects and shutdown limits (residual current time limits) for the two different conductors of the low-voltage network. If a fault current occurs on the phase conductor L, it is detected by the residual current sensor unit ZCT (synonymously known as summation current transformer) and sent to the control unit (evaluation electronics including μController). Here, it is initially not possible to distinguish whether this residual current flows on the L conductor or the N conductor.After the first differential current time limit values ​​DSG1 are exceeded (a first shutdown limit is exceeded), the device switches the electronic interruption unit EU (its electronic switch) to the high-impedance state, thus interrupting the current path in the L conductor and thus also the flowing differential current. If a differential current flows on the N conductor, the electronic interruption unit EU is also switched to the high-impedance state when the first differential current time limit values ​​DSG1 (first shutdown limit) are reached. The leakage current of the neutral conductor ("neutral conductor differential current") can continue to flow, however, because current flow via the neutral conductor is still possible (no electronic interruption unit EU in the neutral conductor). The level of the differential current continues to be monitored by the differential current sensor unit and the control unit.For this purpose, there are second differential current time limits (second shutdown limit), which are greater than the first shutdown limit. The protective switching device remains in the high-impedance state of the electronic interruption unit EU as long as the second differential current time limits (second shutdown limit) are not exceeded. If the second differential current time limits are exceeded, the contacts are opened and the differential current on the N conductor is interrupted (avoided). This is indicated in Figure 4. The protective switching device thus offers the option of implementing different tripping behavior, depending on which conductor (L or N) a leakage current (differential current) is flowing on. If one takes into account that the two conductors (L and N) pose different risks, particularly with regard to personal protection, a sensible new device behavior results.The L conductor is typically below a dangerous mains voltage of, for example, 230V. The neutral conductor (N conductor), on the other hand, typically does not have a dangerous voltage. A differential current (leakage current) on the L conductor is therefore significantly more dangerous in terms of personal protection than a differential current (leakage current) on the N conductor. The shutdown limit in relation to the differential current level and the tripping time can therefore be higher or longer for the N conductor. This would prevent false tripping caused by opening the contacts of the mechanical isolating contact unit. This advantageously allows for fast and sensitive current avoidance (tripping) in the case of differential currents (leakage currents) of the phase conductor (L conductor) and slow and robust current avoidance in the case of differential currents (leakage currents) of the neutral conductor. This behavior can be advantageously configured or activated.The first and second residual current time limits can be advantageously configured or activated (depending on the area of ​​use / application of the protective switching device). This has the particular advantage that after a faulty residual current event, for example caused by a person touching a (phase) conductor (critical event) or by a technically caused leakage current (non-critical for persons, i.e., non-critical event) (for example, due to switched capacitances), immediate prevention of current flow in the low-voltage AC circuit is initiated by a high-resistance state of the switching elements of the electronic interruption unit. Immediate prevention of current flow means, in particular, the electronic interruption unit becoming high-resistance within 10 ms, in particular 5 ms or 1 ms.(Today's residual current circuit breakers typically trip after at least / greater than 20 ms.) After preventing current flow by maintaining a high-impedance state of the switching elements of the electronic interruption unit and a closed state of the contacts, a test is performed to determine whether second residual current limits or second residual current time limits have been exceeded. This further tests for faulty residual current events and, if necessary, distinguishes critical events from non-critical events, thus ensuring both personal protection and system availability. A completely new operating concept for a protective switching device is presented.Although the invention has been illustrated and described in detail by the embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the scope of the invention.

Claims

202320309 32 patent claims 1. A protective switching device (SG) for protecting an electrical low-voltage AC circuit, comprising: - a housing with: a mains-side phase conductor connection (LG), a load-side phase conductor connection (LG) for a phase conductor (L) of the low-voltage AC circuit; a mains-side neutral conductor connection (NG), a load-side neutral conductor connection (NL) for a neutral conductor (N) of the low-voltage AC circuit; - a differential current sensor unit (ZCT) for determining the magnitude of a differential current between the neutral conductor (N) and the phase conductor (L) of the low-voltage AC circuit, - a mechanical isolating contact unit (MK),which has a closed state of a neutral conductor contact (KKN) and a phase conductor contact (KKL) for a current flow in the low-voltage AC circuit or an open state of the neutral conductor contact (KKN) and the phase conductor contact (KKL) for a current-preventing galvanic isolation in the low-voltage AC circuit, - an electronic interruption unit (EU) which is connected in series with the mechanical isolating contact unit (MK) in the phase conductor (L) and which, through semiconductor-based switching elements, has a high-resistance state (EUh) of the switching elements to prevent a current flow or a low-resistance state (EUn) of the switching elements for current flow in the phase conductor (L), - a control unit (SE) which is connected to the differential current sensor unit (ZCT), the mechanical isolating contact unit (MK) and the electronic interruption unit (EU), characterized inthat the protective switching device (SG) is designed in such a way that if the differential current is exceeded via the first differential, 202320309 33 current time limit values ​​(DSG1) an avoidance of a current flow (VS) in the phase conductor (L) is initiated by a high-resistance state (EUh) of the switching elements of the electronic interruption unit when the neutral conductor contact (KKN) and the phase conductor contact (KKL) are closed, that after the avoidance of the current flow (VS) in the phase conductor (L) a test is carried out to determine whether the residual current has been exceeded via second residual current time limit values ​​(DSG2) and if this is exceeded the neutral conductor contact (KKN) and the phase conductor contact (KKL) are opened, so that a different tripping behavior is possible for leakage currents of the phase conductor compared to leakage currents of the neutral conductor.

2. Protective switching device (SG) according to claim 1, characterized in that the second differential current time limit values ​​(DSG2) are greater than the first differential current time limit values ​​(DSG1).Protective switching device (SG) according to claim 1 or 2, characterized in that a temporally offset tripping behavior is enabled for differential currents caused by a leakage current of the phase conductor compared to differential currents caused by a leakage current of the neutral conductor.

4. Protective switching device (SG) according to claim 1, 2 or 3, characterized in that the presence of a leakage current on the phase conductor or the neutral conductor is communicated.

5. Protective switching device (SG) according to one of the preceding claims, characterized in that the mechanical isolating contact unit (MK) is assigned to the load-side connections (LL, NL). 202320309 34 6. Method for a protective switching device (SG) for protecting an electrical low-voltage AC circuit, in which - a mechanical isolating contact unit (MK) is provided, which provides a closed state of a neutral conductor contact (KKN) and a phase conductor contact (KKL) for current flow in the low-voltage AC circuit or an open state of the neutral conductor contact (KKN) and the phase conductor contact (KKL) for galvanic isolation in the low-voltage AC circuit to prevent current flow, - an electronic interruption unit (EU) is connected in series with the mechanical isolating contact unit (MK) in the phase conductor (L) of the low-voltage AC circuit and which, by means of semiconductor-based switching elements, provides a high-resistance state (EUh) of the switching elements to prevent current flow or a low-resistance state (EUn) of the switching elements for current flow in the phase conductor (L),- the magnitude of a differential current between the neutral conductor (N) and the phase conductor (L) of the low-voltage alternating current circuit is determined, characterized in that if the differential current exceeds first differential current time limits (DSG1), the avoidance of a current flow (VS) in the phase conductor (L) is initiated by a high-resistance state (EUh) of the switching elements of the electronic interruption unit when the neutral conductor contact (KKN) and the phase conductor contact (KKL) are closed; that after the avoidance of the current flow (VS) in the phase conductor (L), a test is carried out to determine whether the differential current has exceeded second differential current time limits (DSG2), and if the differential current is exceeded, the neutral conductor contact (KKN) and the phase conductor contact (KKL) are opened, thus enabling a different tripping behavior for leakage currents of the phase conductor compared to leakage currents of the neutral conductor.202320309 35 7. Method according to claim 6, characterized in that the second differential current time limit values ​​(DSG2) are greater than the first differential current time limit values ​​(DSG1).

8. Method according to claim 6 or 7, characterized in that a temporally offset tripping behavior is enabled for differential currents caused by a leakage current of the phase conductor compared to differential currents caused by a leakage current of the neutral conductor.

9. Method according to claim 6, 7 or 8, characterized in that the presence of a leakage current on the phase conductor or the neutral conductor is communicated.

10. Computer program product comprising commands which, when the program is executed by a microcontroller, cause the microcontroller to support or carry out the method according to one of claims 6 to 9.In particular, if the differential current exceeds first differential current time limits (DSG1), to initiate the prevention of a current flow (VS) in the phase conductor (L) by means of a high-resistance state (EUh) of the switching elements of the electronic interruption unit when the neutral conductor contact (KKN) and the phase conductor contact (KKL) are closed; after the prevention of the current flow (VS) in the phase conductor (L), to initiate a check for the existence of an exceedance of the differential current above second differential current time limits (DSG2); and, if exceeded, to initiate an opening of the neutral conductor contact (KKN) and the phase conductor contact (KKL), thus enabling a different tripping behavior for leakage currents of the phase conductor compared to leakage currents of the neutral conductor.

11. Computer-readable storage medium on which the computer program product according to claim 10 is stored. 202320309 36 12. Data carrier signal which the computer program product according to claim 10 transmits.

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