Protection switch device and method

Abstract

The invention relates to a protective switching device (SG) for protecting a low-voltage circuit for an alternating voltage, in which a magnitude of a differential current of a conductor of the low-voltage circuit is determined, and-when a first differential current-time threshold value (DSG1) is exceeded, a) in a closed state of a separating contact, the magnitude of the differential current is determined by a high-resistance state of a switching element of an electronic interruption unit, or b) initiating the avoidance of the current flow in the low voltage circuit by separating the open state of the contacts; and starting the avoidance of the current flow in the low-voltage circuit by the high-resistance state of the switching element of the electronic interruption unit in the closed state of the separating contact when a second differential current threshold value (DSG2) is exceeded.

Description

Technical Field

[0001] The invention relates to the technical field of a protective switching device for a low-voltage circuit with an electronic interruption unit according to the preamble of claim 1 and a method for a protective switching device for a low-voltage circuit with an electronic interruption unit. Background Art

[0002] Low voltage refers to voltages up to 1000 V AC or 1500 V DC. Low voltage specifically refers to voltages greater than minimum voltage, which is 50 V AC or 120 V DC.

[0003] A low voltage circuit or a low voltage network or a low voltage system refers to a circuit with a rated current or a nominal current of up to 125 amperes, more particularly up to 63 amperes. A low voltage circuit refers in particular to a circuit with a rated current or a nominal current of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values ​​mentioned refer in particular to the rated current, the nominal current and / or the cut-off current, i.e. the maximum current that is conducted through the circuit under normal circumstances, or the current that is usually interrupted by the circuit, for example by a protective device, such as a protective switchgear or a line protection switch or a circuit breaker. The rated current can be further graded from 0.5A through 1A, 2A, 3A, 4A, 5A, 6A, 7A, 8A, 9A, 10A, etc. up to 16A.

[0004] Circuit breakers are overcurrent protection devices that have been known for a long time and are used in low-voltage circuits in electrical installation technology. Circuit breakers protect circuits from damage caused by overcurrent and / or short circuits. Circuit breakers can automatically switch off the circuit in the event of an overload and / or short circuit. Circuit breakers are non-automatically resettable fuse elements.

[0005] Unlike line circuit breakers, circuit breakers are designed for currents greater than 125 amperes, in some cases also starting at 63 amperes. The line circuit breaker is therefore simpler and more compact in design. Line circuit breakers usually have a mounting option for mounting on a so-called top hat rail (support rail, DIN rail, TH35).

[0006] According to the prior art, line protection switches adopt an electromechanical structure. In the housing, they have mechanical switch contacts or working current triggers for interrupting (triggering) the current. Usually, bimetallic protection elements or bimetallic elements are used to trigger (interrupt) in the case of long-term overcurrent (overcurrent protection) or thermal overload (overload protection). Electromagnetic triggers with coils are used to trigger for a short time when the overcurrent limit value is exceeded or a short circuit occurs (short-circuit protection). One or more arc extinguishing chambers or devices for arc extinguishing are provided. In addition, connection elements for conductors of the circuit to be protected are provided.

[0007] Residual current circuit breakers for circuits, in particular for low-voltage circuits or low-voltage devices, are generally known. Residual current circuit breakers are also called residual current devices (RCDs). Residual current circuit breakers determine the sum of the currents in the circuit (in general, the sum of the currents is zero) and interrupt the circuit when a differential current value, i.e. a sum of the currents that is not equal to zero, is exceeded (the sum of the currents exceeds a certain (differential) current value or a fault current value).

[0008] Almost all residual current circuit breakers known to date have a summation current transformer, whose primary winding is formed by the conductors of the circuit and whose secondary winding outputs a current sum which is used directly or indirectly to interrupt the circuit.

[0009] For this purpose, two or more conductors, usually the outgoing conductor and the return conductor or the outer conductor and the neutral conductor in a single-phase AC network, all three outer conductors or all three outer conductors and the neutral conductor in a three-phase AC network, are led through a current transformer, which usually has a ring-shaped core made of ferromagnetic material. Only the differential current in the conductors, i.e. the current that deviates from the outgoing current and the return current, is converted. The sum of the currents in the circuit is usually equal to zero. Therefore, a fault current can be detected.

[0010] If, for example, a current flows from the energy sink or the consumer to the ground, this is called a fault current in this context. A fault occurs, for example, when there is an electrical connection between the phase conductor of a circuit and the ground. This happens, for example, when a person touches a phase conductor. Part of the current then does not flow back as usual via the neutral conductor or zero conductor, but instead flows back via the person and the ground. This fault current can now be detected with the aid of a summing current transformer, since the sum of the incoming and return currents detected according to the values ​​is not equal to zero. By means of a relay or a holding magnet trigger For example, a relay or a holding magnet trigger connected to a mechanical device is used to interrupt the circuit, for example, to interrupt at least one, part or all of the lines. A residual current circuit breaker for collecting AC residual currents is generally known from DE 44 32643 A1.

[0011] The main functions of a residual current circuit breaker are to protect people from electric current (electric shock) and to protect equipment, machines or buildings from fire due to electrical insulation faults.

[0012] If a residual current circuit breaker or its summing current transformer is designed in such a way that the energy on the secondary side of the summing current transformer is sufficient to actuate a tripping unit or an interruption unit or a release, then such a residual current circuit breaker is said to be independent of the mains voltage.

[0013] If the triggering circuit requires or uses auxiliary energy, which is usually generated by a power supply provided in the residual current circuit breaker, then such a residual current circuit breaker is said to be grid-voltage-dependent. In other words, a grid-voltage-dependent residual current circuit breaker contains a power supply which is used for the energy supply for residual current detection (not independent of the grid voltage). For example, these power supplies are required for detecting residual currents in DC grids and DC / AC hybrid grids or in high-frequency circuits.

[0014] Protection switchgear with electronic interruption units are a relatively recent development. Protection switchgear has an electronic interruption unit based on semiconductors. That is, the current of the low-voltage circuit is conducted through a semiconductor device or a semiconductor switch, which can interrupt the current or switch to conduction. Protection switchgear with an electronic interruption unit also usually has a mechanical separation contact system, which has a separation characteristic in particular according to the relevant standards for low-voltage circuits, wherein the contacts of the mechanical separation contact system are connected in series to the electronic interruption unit, i.e. the current of the low-voltage circuit to be protected is conducted both through the mechanical separation contact system and through the electronic interruption unit.

[0015] The invention relates in particular to a low-voltage AC circuit having an AC voltage, which is usually a time-dependent sinusoidal AC voltage with a frequency f. The time dependence of the instantaneous voltage value u(t) of the AC voltage is described by the following equation:

[0016] u(t)=U*sin(2π*f*t).

[0017] in:

[0018] u(t) = instantaneous voltage value at time t

[0019] U = voltage amplitude

[0020] A harmonic AC voltage can be represented by the rotation of a pointer, the length of which corresponds to the amplitude of the voltage (U). Here, the instantaneous deflection is the projection of the pointer on the coordinate system. The oscillation period corresponds to a 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, that is:

[0021] ω = 2π*f = 2π / T = angular frequency of the AC voltage (T = duration of the oscillation cycle)

[0022] The specification of angular frequency (ω) is usually preferred to frequency (f) because many vibration theory formulas can be expressed more compactly in terms of angular frequency due to the presence of trigonometric functions, which by definition have a period of 2π:

[0023] u(t)=U*sin(ωt)

[0024] In the case of an angular frequency that is not constant over time, the term instantaneous angular frequency is also used.

[0025] In the case of a sinusoidal, in particular temporally constant, alternating voltage, the time-dependent value corresponding to the angular velocity ω and the time t corresponds to the time-dependent angle This angle is also called the phase angle

[0026] That is, the phase angle Periodically passes through the range of 0...2π or 0°...360°. That is, the phase angle periodically takes on values ​​between 0 and 2π or 0° and 360° or Due to periodicity; abbreviations are: or ).

[0027] Therefore, the instantaneous voltage value u(t) or the instantaneous current value or the instantaneous differential current value refers to the instantaneous value of the voltage / the instantaneous value of the current / the instantaneous value of the differential current at the time point t, that is, in the case of a sinusoidal (periodic) alternating voltage, it refers to the instantaneous value of the voltage / the instantaneous value of the current / the instantaneous value of the differential current with respect to the phase angle The voltage value / current value / difference current value ( or for the corresponding period). Summary of the invention

[0028] The technical problem to be solved by the present invention is to improve a protective switchgear of the type mentioned at the outset, in particular to ensure protection against fault currents caused by personnel, while achieving power supply reliability or availability of electrical equipment, i.e. to achieve immunity against technically caused (fault) currents, which would lead to erroneous triggering of the protective switchgear. That is, on the one hand, personnel protection is ensured, and on the other hand, the power supply reliability of the low-voltage circuit is improved. Alternatively, a new concept is created for such a protective switchgear.

[0029] This object is achieved by a circuit breaker assembly having the features of claim 1 and by a method according to claim 12 .

[0030] According to the present invention, a protection switch device for protecting a low-voltage circuit, in particular a low-voltage AC circuit, is provided, the protection switch device comprising:

[0031] a housing having line-side and load-side connections for conductors of the low-voltage circuit,

[0032] a differential current sensor unit for determining the magnitude of a differential current in a conductor of a low-voltage circuit, in particular for detecting a change over time of an instantaneous value of the differential current,

[0033] a mechanically disconnecting contact unit having a closed state of the contacts for current flow in the low-voltage circuit or an open state of the contacts for galvanic disconnection in the low-voltage circuit for preventing current flow,

[0034] The mechanically isolating contact unit can be operated and switched, in particular, by a mechanical handle, so that the opening of the contact for preventing the flow of current or the closing of the contact for the flow of current in the low-voltage circuit can be switched (by the handle), whereby (in particular) the galvanic separation in the low-voltage circuit can be switched;

[0035] In a mechanically separated contact unit, the opening of the contacts is also called release, and the closing of the contacts is called making-in;

[0036] an electronic interruption unit which is connected in series with the mechanically isolating contact unit on the circuit side and which, by means of a semiconductor-based switching element, has a high-resistance (in particular non-conductive) state of the switching element for preventing a current flow or a low-resistance state of the switching element for a current flow in the low-voltage circuit;

[0037] In the electronic interruption unit, the high-resistance (in particular non-conductive) state of the switching element (for the prevention of current flow) is also referred to as the off-state (process: off), and the low-resistance (conductive) state of the switching element (for current flow) is referred to as the on-state (process: on);

[0038] A control unit which is connected to the differential current sensor unit, the mechanical separation contact unit and the electronic interruption unit.

[0039] According to the invention, the protection switching device, in particular the control unit, is designed such that, when a first differential current-time limit value is exceeded (in particular in terms of magnitude),

[0040] a) in the closed state of the separating contacts, through the high-impedance state of the switching element of the electronic interruption unit, or

[0041] b) the disconnected state by separating the contacts,

[0042] To initiate the avoidance of current flow in the low voltage circuit.

[0043] Furthermore, when the second differential current limit value is exceeded in magnitude, in the closed state of the disconnecting contacts, prevention of a current flow in the low-voltage circuit is initiated by the high-resistance state of the switching element of the electronic interruption unit.

[0044] This has the particular advantage that a double evaluation is provided for the detected differential current.

[0045] On the one hand, for the first differential current-time limit value, this corresponds to the conventional evaluation currently used in residual current protection switches according to the prior art. However, the result of the evaluation can be the avoidance of two possible current flows. On the one hand, the conventional avoidance of current flows in the low-voltage circuit by the open state of the disconnecting contacts, i.e. galvanic disconnection. On the other hand, the novel avoidance by the high-impedance state of the switching element of the electronic interruption unit in the closed state of the disconnecting contacts.

[0046] For the evaluation of the first differential current-time limit value, the effective value of the differential current can advantageously be used. For example, the differential current is determined by an RMS value (root mean square = effective value). When a corresponding standard-compliant (FI circuit breaker) current / time limit value is exceeded, one of the two current flow avoidances mentioned is performed.

[0047] On the other hand, the instantaneous value of the differential current is advantageously used for a parallel evaluation of a second differential current limit value, so that when exceeded in magnitude, the high-resistance state of the switching element which “immediately” activates the electronic interruption unit is immediately switched off in the closed state of the disconnecting contacts.

[0048] Advantageously, when the second differential current limit value is exceeded, a current flow in the low-voltage circuit is avoided by the high-resistance state of the switching element of the electronic interruption unit during a first switch-off time, which is in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms, 1 ms, 500 μs or 100 μs.

[0049] Advantageously, after the prevention of a current flow in the low-voltage circuit due to exceeding the second differential current limiting value, the switching element of the electronic interruption unit changes to a low resistance.

[0050] This has the particular advantage that automatic restarting occurs, thus achieving a high availability of the energy supply.

[0051] In particular, the low resistance is achieved when the magnitude of the instantaneous value of the AC voltage (applied to the protection switch device) is less than a first voltage limit. The first voltage limit is in particular less than 10 volts or less than 5 volts. In particular, the switching element of the electronic interruption unit can be changed to a low resistance at the zero crossing of the AC voltage. That is, the protection switch device switches to the standby state and automatically switches to the On state again, for example, at the next voltage zero crossing.

[0052] This further has the particular advantage that, after a faulty differential current event, for example due to a person touching a (phase) conductor (critical event) or due to a technically induced operating current (not critical for the person, i.e. a non-critical event) (e.g. due to a connected capacitor), an immediate avoidance of a current flow in the low-voltage circuit is initiated by the high-resistance state of the switching element of the electronic interruption unit.

[0053] After the current flow is prevented through the high-resistance state of the switching element of the electronic interruption unit and the closed state of the contacts through the second differential current limit value is changed to low resistance, it is possible to further check whether there is a faulty differential current event. Thus, important events and non-important events can be distinguished while providing maximum energy supply reliability in the circuit, so as to ensure personnel protection on the one hand and the availability of the device on the other hand.

[0054] Thus, the state of the load-side connection can be further monitored for the presence of a differential current limit value or a differential current-time limit value. In the event of a change in state, further actions can be advantageously performed, for example according to another advantageous embodiment of the invention.

[0055] Therefore, a completely new protection design or operation design of the (FI) protection switchgear is proposed.

[0056] Further advantageous embodiments of the invention are specified in the dependent claims and in the exemplary embodiments.

[0057] Advantageously, only the mechanical disconnecting contact switch can be actuated by the mechanical handle. Switching on and off by means of the electronic disconnecting unit cannot be actuated (directly) on the device.

[0058] In an advantageous embodiment of the invention, after the change to low resistance, the second differential current limit value is detected again. Change to high resistance, then to low resistance. If the second differential current limit value is exceeded again (and changes to high resistance and low resistance), this is only performed until there is a first number of exceedances.

[0059] The electronic interruption unit then remains in the high impedance state. This can be done until a further time limit is exceeded. Alternatively or additionally, this state is transmitted via the communication unit.

[0060] Alternatively or additionally, the contacts of the mechanically separated contact unit can be opened.

[0061] This has the particular advantage that a robust design of the circuit breaker device is provided which ensures a high availability of the energy supply.

[0062] In an advantageous embodiment of the present invention, the protective switch device is designed so that the second differential current limit value is higher in magnitude than the first differential current limit value or the first differential current-time limit value (differential current component). In particular, the second differential current limit value is a value in the range of 2 to 100 times the first differential current limit value or the first differential current-time limit value.

[0063] This has the particular advantage that an immediate shutdown is only carried out when an instantaneous value of the differential current occurs which is always greater than the permanently permissible differential current. In addition, the second differential current limit value can be adjusted so that the limit or threshold value can be adapted to the given operating situation and the existing events or disturbances that meet the operating conditions in the differential current sequence.

[0064] In an advantageous embodiment of the invention, a voltage sensor unit connected to the control unit is provided for determining the magnitude of the voltage of the conductor of the low-voltage circuit, in particular the magnitude of the instantaneous value of the voltage. The protective switchgear is designed such that after the avoidance of the current flow in the low-voltage circuit due to exceeding the second differential current limit value, the switching element of the electronic interruption unit becomes low-resistance, wherein in particular the low-resistance is changed when the magnitude of the instantaneous value of the AC voltage is less than the first voltage limit.

[0065] The first voltage limit is, for example, less than 20 V or less than 10 V or less than 5 V. In particular, at a zero crossing of the AC voltage, the switching element of the electronic interruption unit changes to a low resistance.

[0066] In an advantageous embodiment of the invention, a current sensor unit connected to the control unit is provided for determining the magnitude of the current in the conductor of the low-voltage circuit. The protective switchgear, in particular the control unit, is designed to initiate the prevention of the current flow in the low-voltage circuit by the high-impedance state of the switching element of the electronic interruption unit in the closed state of the separating contacts when a first current limit value or a first current-time limit value is exceeded.

[0067] This has the particular advantage that, in addition to the differential current detection and the protective functions associated therewith, overcurrent / short-circuit current detection is also provided, so that a combined residual current / line protection switchgear device is advantageously provided.

[0068] In an advantageous embodiment of the invention, the mechanically isolating contact unit is associated with the load-side connection.

[0069] This has the particular advantage that an architecture is provided which supports the properties according to the invention of the circuit breaker device, since on the one hand the current flow is interrupted in the case of a high-resistance interruption unit, but the circuit breaker device continues to be supplied with energy even when the contacts are open, so that continued operation according to the invention is possible.

[0070] According to the invention, a corresponding method for a protective switching device for a low-voltage circuit having electronic (semiconductor-based) switching elements is claimed, which has the same advantages and further advantages.

[0071] According to the present invention, a corresponding computer program product for a protective switchgear is claimed. The computer program product comprises instructions which, when executed by a microcontroller, cause the microcontroller to support or execute the design or method of the protective switchgear according to the present invention. In particular,

[0072] - when a first differential current-time limit value is exceeded,

[0073] a) in the closed state of the separating contacts, through the high-impedance state of the switching element of the electronic interruption unit, or

[0074] b) the disconnected state by separating the contacts,

[0075] to initiate the avoidance of current flow in low voltage circuits,

[0076] When the second differential current limit value is exceeded, the prevention of a current flow in the low-voltage circuit is initiated by the high-resistance state of the switching element of the electronic interruption unit in the closed state of the disconnecting contacts.

[0077] The microcontroller is part of a protective switching device, in particular a control unit.

[0078] According to the invention, protection is claimed for a corresponding computer-readable storage medium on which a computer program product is stored.

[0079] According to the invention, a corresponding data carrier signal is claimed which transmits a computer program product.

[0080] All design schemes, not only in the form of dependent reference to claim 1 or 11, but also merely in the form of reference to individual features or feature combinations of the claims, and in particular in the form of device claims to be processed reference to independent method claims, achieve improvements in the protective switchgear, in particular in terms of personnel safety and power supply reliability in low-voltage circuits, and provide a new and reliable scheme for protective switchgear. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] The described characteristics, features and advantages of the present invention and the implementation thereof will become clearer and more easily understood in conjunction with the following description of the embodiments, which are described in detail in conjunction with the accompanying drawings.

[0082] Here, in the accompanying drawings:

[0083] Figure 1 shows a first principle illustration of a protective switchgear,

[0084] Figure 2 A second principle diagram of a protective switchgear is shown,

[0085] Figure 3 A first diagram showing the switching characteristics,

[0086] Figure 4 A second diagram showing the switching characteristics,

[0087] Figure 5 A diagram of the functional flow is shown. DETAILED DESCRIPTION

[0088] Figure 1 The diagram shows a circuit breaker device SG for protecting a low-voltage circuit, in particular a low-voltage AC circuit, which circuit breaker device SG has a housing GEH and has:

[0089] - grid-side connections, which in particular comprise a grid-side neutral conductor connection NG and a grid-side phase conductor connection LG,

[0090] - load-side connections, which in particular comprise a load-side neutral conductor connection NL and a load-side phase conductor connection LL;

[0091] - These connectors are designed for low voltage circuits;

[0092] - An energy source is usually connected to the grid-side connection / grid-side Grid,

[0093] - Electrical consumers are usually connected to the load-side connector / load-side Load;

[0094] a (two-pole) mechanically isolating contact unit MK having connection points APLL, APNL on the load side and connection points APLG, APNG on the grid side,

[0095] The connection point APNL on the load side is set for the neutral conductor, the connection point APLL on the load side is set for the phase conductor, the connection point APNG on the grid side is set for the neutral conductor, and the connection point APLG on the grid side is set for the phase conductor. The connection points APNL and APLL on the load side are connected to the neutral conductor connection and the phase conductor connections NL and LL on the load side, so that the opening of the contacts KKN and KKL for preventing the flow of current or the closing of the contacts KKN and KKL for the flow of current can be switched in the low-voltage circuit.

[0096] an electronic interruption unit EU, in particular a unipolar one (which in the case of a unipolar embodiment is in particular arranged in the phase conductor),

[0097] A grid-side connection point EUG is provided, which is electrically connected to a grid-side phase conductor connection LG, and

[0098] a load-side connection point EUL, which is electrically connected or connected to a grid-side connection point APLG of the mechanical disconnecting contact unit MK,

[0099] The electronic interruption unit EU has or can switch, via a semiconductor-based switching element (not shown) in the low-voltage circuit, a high-resistance state of the switching element for preventing a current flow or a low-resistance state of the switching element for a current flow,

[0100] - a differential current sensor unit ZCT, which is used to determine the magnitude of the differential current of the conductor of the low-voltage circuit (in particular the time curve of the instantaneous value of the differential current), which is arranged between the electronic interruption unit EU and the mechanical disconnection contact unit MK in this example, and can be alternatively arranged (arranged) between the mechanical disconnection contact unit MK and the neutral conductor connection and the phase conductor connection NL, LL on the load side, and can also be alternatively arranged (arranged) between the electronic interruption unit EU and the connections NG, LG on the grid side. The differential current sensor unit ZCT determines the magnitude of the differential current of the conductor of the low-voltage circuit (to be protected) which is guided through the protective switchgear. In this example, in the case of a single-phase AC circuit, it is the neutral conductor and the phase conductor.

[0101] The differential current sensor unit ZCT may be a typical sum current transformer. The primary side of the sum current transformer is formed by the conductors of the low voltage circuit (in the example, the phase conductor and the neutral conductor). The secondary side of the sum current transformer is connected to the control unit SE.

[0102] - (optional) a current sensor unit SI for determining the magnitude of the current of the low-voltage circuit, which current sensor unit SI is arranged in particular in a current path of a phase conductor or in a phase conductor current path,

[0103] A control unit SE which is connected to the differential current sensor unit ZCT, optionally to the current sensor unit SI and to the mechanical isolating contact unit MK and to the electronic interruption unit EU.

[0104] According to the invention, the protection switching device SG, in particular the control unit SE, is designed such that

[0105] - when the first differential current-time limit value DSG1 is exceeded (ie, the differential current limit value is exceeded for a first time duration; ie, when the magnitude of the differential current exceeds the first differential current limit value for a first time duration),

[0106] a) in the closed state of the separating contacts, through the high-impedance state of the switching element of the electronic interruption unit, or

[0107] b) the disconnected state by separating the contacts,

[0108] To initiate the avoidance of current flow in the low voltage circuit.

[0109] (One of these two variations may be implemented. Alternatively, both variations may be implemented and pre-configured or chosen by the user to be avoided).

[0110] For this purpose, for example, the effective value of the differential current can be used when the first differential current-time limit value DSG1 is exceeded. By forming the effective value, a mean value over time is already formed.

[0111] According to the present invention, the protection switch device, in particular the control unit SE, is further designed to:

[0112] When the second differential current limiting value DSG2 is exceeded, in the closed state of the disconnecting contacts, the prevention of a current flow in the low-voltage circuit is initiated by the high-resistance state of the switching element of the electronic interruption unit.

[0113] For this purpose, the instantaneous value of the differential current is advantageously used with respect to exceeding the second differential current limiting value DSG2 .

[0114] When the second differential current limit value DSG2 is exceeded, a current flow in the low-voltage circuit can therefore be avoided by the high-resistance state of the switching element of the electronic interruption unit during a first switch-off time, which is in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms, 1 ms, 500 μs or 100 μs. Thus, an immediate switch-off is achieved to a certain extent.

[0115] An optionally arranged current sensor unit SI connected to the control unit SE for determining the magnitude of the current in the conductor of the low-voltage circuit can enable the protective switch device SG to initiate the prevention of current flow in the low-voltage circuit by means of the high-resistance state of the switching element of the electronic interruption unit when the separation contacts are in the closed state, when a first current limit value is exceeded (i.e., when the magnitude of the current exceeds the first current limit value (value)) or a first current-time limit value (i.e., when the first current limit value is exceeded for a first duration; i.e., when the magnitude of the current (value) exceeds the first current limit value for a first duration).

[0116] In this example, the mechanical disconnecting contact unit MK is arranged on the load side, and according to the invention, the electronic interruption unit EU is arranged on the grid side.

[0117] The grid side GRID with the energy source is normally under voltage. Electrical consumers are usually connected to the load side LOAD.

[0118] This has the advantage that there are no other (especially voltage-exposed) parts or components between the contacts of the mechanically isolating contact unit / the load-side connection point (APLL, APNL) of the mechanically isolating contact unit and the two load-side connections (LL, NL). Thus, due to this structure or construction, it can be ensured that when the contacts KKL, KKN are open, no voltage is present at the load-side connections LL, NL in any case. This increases the reliability of the protective device.

[0119] In contrast thereto, in other architectures in which the mechanically isolating contact unit is arranged on the network side, there is often a (non-galvanically isolating) electronics unit upstream of the connection on the load side.

[0120] The protection switchgear can be designed so that the magnitude of the voltage across the electronic interruption unit can be determined, that is, the magnitude of a first voltage between the grid-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU can be determined or determined.

[0121] To this end, according to Figure 1In the example of FIG. 4 , a first voltage sensor unit SU1 connected to the control unit SE is provided, which determines the magnitude of the voltage between the grid-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU.

[0122] Alternatively, when measuring the voltage via the first voltage sensor unit SU1, the voltage across the series circuit of the electronic interruption unit EU and the current sensor SI can also be determined, as in Figure 1 As shown in . The current sensor unit SI has a very small internal resistance, so that it has no influence or a negligible influence on the determination of the voltage magnitude.

[0123] The circuit breaker device can be designed to provide a second voltage sensor unit SU2 which determines the magnitude of the voltage between the grid-side neutral conductor connection NG and the grid-side phase conductor connection LG.

[0124] The first voltage sensor unit can also be replaced by using two voltage measurements (before and after the electronic interruption unit). The voltage at the electronic interruption unit is determined by difference formation.

[0125] Thus, a second voltage sensor unit SU2 connected to the control unit SE can be provided, which determines the magnitude of a second voltage between the neutral conductor connection NG on the grid side and the phase conductor connection LG on the grid side. Furthermore, a third voltage sensor unit SU3 (not shown) connected to the control unit can be provided, which determines the magnitude of a third voltage between the neutral conductor connection NG on the grid side and the connection point EUL on the load side of the electronic interruption unit EU. The protective switchgear is designed such that the magnitude of a first voltage between the connection point EUG on the grid side and the connection point EUL on the load side of the electronic interruption unit EU is determined from the difference between the second voltage and the third voltage.

[0126] A measuring impedance ZM can be connected between the connection points APLG, APNG on the grid side of the mechanical separation contact unit MK. The measuring impedance ZM can be, for example, a resistor and / or a capacitor. The measuring impedance can also be an inductor. In particular, the measuring impedance can be a series circuit or a parallel circuit of a resistor and / or a capacitor and / or an inductor.

[0127] In accordance with Figure 1 In the example of , the electronic interruption unit EU is embodied as a single pole, in the present example in the phase conductor. Here, the grid-side connection point APNG for the neutral conductor of the mechanically disconnecting contact unit MK is connected to the grid-side neutral conductor connection NG of the housing GEH.

[0128] The protective switching device SG is advantageously designed in such a way that the contacts of the mechanical disconnecting contact unit MK can be opened by the control unit SE, but cannot be closed, as indicated by the arrow from the control unit SE to the mechanical disconnecting contact unit MK.

[0129] The mechanical separation contact unit MK can be operated by a mechanical handle HH on the protective switch device SG in order to switch the contacts KKL, KKN manually (manually) open or closed. The mechanical handle HH indicates the switching state (open or closed) of the contacts of the mechanical separation contact unit MK on the protective switch device (in particular, through a (pure) mechanical connection). In addition, the contact position (or the position of the handle, closed or open) can be transmitted to the control unit SE. For example, the contact position (or the position of the handle) can be determined with the aid of 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 separation contact unit MK. Alternatively, the position sensor can be an electronic first part (EPART, Figure 2 ) components. For example, a Hall sensor can be provided in the first electronic part (EPART), which detects and transmits the position of the contacts and / or the handle in a contactless manner.

[0130] The mechanical disconnecting contact unit MK is advantageously designed so that the contacts can only be closed (manually) by a mechanical handle after a release (Enable), in particular a release signal. This is also indicated by an arrow from the control unit SE to the mechanical disconnecting contact unit MK. That is, the contacts KKL, KKN of the mechanical disconnecting contact unit MK can only be closed by the handle HH when there is a release or a release signal (from the control unit). In the absence of a release or a release signal, the handle HH can be operated, but the contacts are not closed ("Dauerrutscher, continuous sliding").

[0131] The protection switchgear SG has an energy supply or power supply NT, for example a switching power supply. In particular, the energy supply / power supply NT is provided for the control unit SE, which is achieved by Figure 1 The connection between the energy supply device / power supply unit NT and the control unit SE is shown in FIG. The energy supply device / power supply unit NT is (on the other hand) connected to the neutral conductor connection NG on the grid side and to the phase conductor connection LG on the grid side. In the connection to the neutral conductor connection NG on the grid side (or / and the phase conductor connection LG), a fuse SS, in particular a blow-through fuse or a switch Sch ( Figure 2 ).

[0132] According to the invention, the power supply unit NT is normally continuously supplied with energy, in particular from a grid-side connection. If necessary, it is protected by a fuse SS or can be disconnected by a switch SCH.

[0133] The switch Sch can advantageously be designed so that it can only be opened when the contacts are in the open state. This increases the reliability of the device, because the electronic device (in particular the control unit) cannot be opened when the contacts are closed.

[0134] The purpose of the fuse SS is not only to protect the energy supply by means of the power supply unit NT, but also to be designed in two parts (see Figure 2 ) in the case of protecting the "electronic" first part EPART or in particular its entire unit (for example, in particular the control unit, the electronic interruption unit, (if necessary) the voltage sensor unit, the differential current sensor unit, (if necessary) the current sensor unit, (if necessary) the measuring impedance, etc.).

[0135] Alternatively, the measuring impedance ZM can be connected to the neutral conductor connection NG on the grid side via a fuse SS. Thus, a three-pole electronic unit or the first part of the electronics EPART ( Figure 2 ), for example as a module with three connections on the low-voltage circuit, namely a neutral conductor connection and two phase conductor connections. The electronic first part EPART can have further connections, in particular for control information or measurement information, for example for release signal Enable / enable, disconnection signal OEF, position information (of position unit POS) or / and a differential current signal (magnitude of the differential current) of the differential current sensor unit ZCT.

[0136] Electronic unit or the first part of the electronics EPART ( Figure 2 ) for example comprises an electronic interruption unit EU, a control unit SE, a power supply device NT (in particular including a fuse SS), a current sensor unit SI, an optional first voltage sensor unit SU1 and / or an optional second voltage sensor unit SU2.

[0137] With regard to the three connections on the low-voltage circuit of the first electronic part EPART, there is therefore the advantage that only the two phase conductor connections must have a high conductivity (several amperes for conducting the load current) and the neutral conductor connection must only have a (relatively) low conductivity (e.g. less than 1 A, a few milliamperes (depending on the energy requirement of the control unit)). This simplifies the construction and increases the reliability of the device, since in the event of a fault in the first electronic part EPART, no large short-circuit currents flow through these connections.

[0138] The low-voltage circuit can be a three-phase AC circuit with a neutral conductor and three phase conductors. For this purpose, the protective switchgear can be designed as a three-phase variant and, for example, have additional grid-side and load-side phase conductor connections. The contacts of the electronic interruption unit and the mechanical separation contact unit according to the invention are respectively arranged between these additional grid-side and load-side phase conductor connections in a similar manner. The individual conductors (three phase conductors LI, L2, L3, neutral conductor N) are led through a differential current unit ZCT.

[0139] Likewise, a current sensor unit and a voltage determination (for example by means of a first voltage sensor unit) may be provided.

[0140] High resistance refers to a state in which only a negligible current still flows. High resistance refers in particular to resistance values ​​greater than 1 kOhm, preferably greater than 10 kOhm, 100 kOhm, 1 MOhm, 10 MOhm, 100 MOhm, 1 kOhm or more.

[0141] Low resistance refers to the state in which a current value specified at the protective switching device can flow.

[0142] Low resistance refers in particular to resistance values ​​less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less.

[0143] Figure 2 Shown according to Figure 1 The difference is that the protective switching device is designed in two parts.

[0144] The circuit breaker device comprises an electronic first part EPART, for example on a circuit board / printed circuit board.

[0145] The first part EPART can have a control unit SE, a first voltage sensor unit SU1, a second voltage sensor unit SU2, a current sensor unit SI, an electronic interruption unit EU, and an energy supply device NT. In addition, the first part can have a fuse SS, a switch SCH, a measuring impedance ZM, a temperature sensor TEM (in particular for the electronic interruption unit EU), a communication unit COM, a display unit AE, and as a variant, a position sensor unit POS.

[0146] The first part of the electronics EPART has only three connectors for low voltage circuits:

[0147] a grid-side phase conductor connection LG as a first connection,

[0148] a (second) connection for or to a grid-side phase conductor connection point APLG of the mechanical disconnecting contact unit MK,

[0149] - A third connection EN for connection to the neutral conductor connection NG on the grid side.

[0150] The two connections: the connection LG for connecting to the phase conductor on the grid side and the connection for or connecting to the phase conductor connection point APLG on the grid side, have high conductivity, for example several amperes, greater than 10A / 16A (depending on the nominal current or rated current of the low-voltage circuit), in particular for carrying load currents also in the event of a short circuit or overload.

[0151] The third connection EN for connection to the neutral conductor connection NG on the grid side has a (relatively) low conductivity, for example less than 1 A, a few mA (depending on the energy requirement of the supplied unit, in particular in the electronic first part EPART). The third connection EN is designed with low conductivity in order to provide current for the power supply and for voltage measurement between the phase conductors and the neutral conductor of the low-voltage circuit. In particular, the third connection EN is protected by a fuse SS. This can be achieved by a fuse or a low-cost conductor track fuse (thin conductor tracks on the circuit board with corresponding length and thickness).

[0152] This has the particular advantage that the lower electrical conductivity in the line or at the third connection EN improves the safety against short circuits occurring within the electronic first part (EPART) (or (electronic) unit), for example on the power supply or control unit side.

[0153] This means that in the event of a failure or malfunction of an electronic component of a unit within the first electronic part EPART, no dangerous short-circuit current (supplied from the grid-side connections LG, NG) will occur, which could lead to a fire in the device.

[0154] This short-circuit current is supplied by the grid via the grid-side connection. The protection switch arranged upstream often has a much higher triggering current and supplies the low-voltage circuit arranged in parallel. Therefore, in the event of a fault in the protection switch device (protection switch device of the protected low-voltage circuit) and the protection switch arranged upstream triggers, the parallel circuit without fault will also be disconnected, thus avoiding this situation.

[0155] The communication unit COM can be a wireless communication unit in particular. The communication unit COM can have a (manual) input unit on the protective switch device for (manually) responding to the status on the protective switch device SG. The response can also be made (wired or and / or wirelessly) via the communication unit COM.

[0156] Furthermore, the communication unit COM may have a display function. A separate display unit may also be provided.

[0157] The protection switchgear comprises a second part MPART, in particular a mechanical one. The second part MPART can have a mechanical disconnecting contact unit MK, a handle HH, a release unit FG. In addition, the second part can have a position unit POS for reporting the position of the contacts of the mechanical disconnecting contact unit MK to a control unit and a (neutral conductor) connection. The second part MPART has a differential current sensor unit ZCT, such as a summation current transformer known, for example, from conventional fault current protection switches.

[0158] Further units not shown in detail may be provided.

[0159] The division into two parts advantageously enables a compact protection switchgear device according to the invention to be realized with a simplified construction.

[0160] When there is a release signal enable, the release unit / release function FG causes the release of the operation of the contacts of the mechanical separation contact unit by the handle HH. That is, only when there is a release signal enable (from the control unit SE) can the contacts KKL and KKN be closed by the handle. Otherwise, they cannot be closed (continuous sliding of the handle HH). The contacts remain in the disconnected position / switch state. In addition, when there is a disconnection signal OEF (from the control unit SE), the release unit FG can cause the disconnection of the contacts (the second function of the release unit FG). The release unit / release function FG then serves as a trigger unit for disconnecting the contacts of the mechanical separation contact unit MK.

[0161] Furthermore, the protective switching device SG, in particular the control unit SE, is designed to initiate the avoidance of a current flow in the low-voltage circuit, in particular to avoid a short-circuit current, when a current limit value or a current-time limit value is exceeded (i.e. when the current limit value is exceeded for a certain period of time). This is achieved in particular by switching the electronic interruption unit EU from a low-impedance state to a high-impedance state. The avoidance of a current flow in the low-voltage circuit is initiated, for example, by a first interruption signal sent from the control unit SE to the electronic interruption unit EU.

[0162] Alternatively or additionally, the mechanical isolating contact unit MK can be controlled by the control unit SE so as to initiate the avoidance of the current flow of the low-voltage circuit when a current limit value or a current-time limit value is exceeded. In this case, in particular, a galvanic disconnection is brought about if necessary. For example, the avoidance of the current flow of the low-voltage circuit or the initiation of a necessary galvanic interruption is carried out by a second interruption signal sent from the control unit SE to the mechanical isolating contact system MK.

[0163] The electronic interruption unit EU can have semiconductor elements, such as bipolar transistors, field effect transistors (FET), insulated gate bipolar transistors (IGBT), metal oxide field effect transistors (MOSFET) or other (self-commutated) power semiconductors. In particular, IGBTs and MOSFETs have low flow resistance. The high cut-off layer resistance and the good switching characteristics make it particularly suitable for use in the protection switching device according to the invention.

[0164] The mechanical disconnecting contact unit MK refers in particular to the disconnecting function (compliant with the standard) which is implemented by the disconnecting contact unit MK. The disconnecting function refers to the following:

[0165] - (voltage-dependent) minimum air gap (minimum distance between contacts) according to the standard,

[0166] - contact position indication for contacts of mechanically separated contact systems,

[0167] - Mechanically disconnecting contact system is always able to disconnect (disconnecting contact system cannot be blocked (especially by handle), free triggering).

[0168] In this context, the DIN EN 60947 and IEC 60947 series of standards are relevant in the context of the present invention with regard to the function of the separator and its properties, to which reference is hereby made.

[0169] The protection switchgear can be designed as a top-hat rail-mountable protection switchgear SG with two-pole connections (L, N), for example, with a width of 1TE, 1.5TE or 2TE. In electrical installations and in switch cabinet structures, the width of built-in devices such as protection switchgear, line protection switches, fault current protection switches, etc. is given in pitch units (abbreviated as TE). The width of one pitch unit is ~18mm. According to the DIN 43880:1988-12 standard, the built-in width of the device should be between 17.5 and 18.0mm, or calculated by multiplying this dimension by 0.5 or an integer multiple thereof, that is: kx 0.5x18mm or kx 0.5x 17.5mm (where k=1,2,3,...). Therefore, according to the prior art, a single-pole line protection switch has, for example, a width of 1TE. The built-in electrical installation switchboard is based on DIN 43871 "Installationskleinverteiler für bis 63A (small installation switchboard for built-in devices up to 63A)" matches the width of the pitch unit, such as the support rail / top hat rail.

[0170] According to the invention, the protective switchgear SG, in particular the control unit SE, is designed to initiate the prevention of the current flow in the low-voltage circuit when a first differential current-time limit value is exceeded, in the closed state of the disconnecting contacts, for example by the high-resistance state of the switching element of the electronic interruption unit. The first differential current-time limit value can be a limit value according to relevant standards such as DIN EN 61008-1. For example, in Europe, in a 230-volt low-voltage circuit, this is 30 mA and a time of 300 ms, 150 ms, 40 ms or 20 ms for personnel protection; in North America, this is 6 mA and the same time for personnel protection and 300 mA and the same time for fire protection (230 volts effective value).

[0171] The second differential current limiting value DSG2 can be higher in magnitude than the first differential current-time limiting value DSG1. In particular, the second differential current limiting value DSG2 is a value in the range of 2 to 100 times the first differential current-time limiting value DSG1.

[0172] The second differential current limit value DSG2 may be, for example, a value of 200 mA. This means that, for example, when the differential current value reaches 200 mA, current flow is (pretty much) immediately avoided, ie, in particular for less than 20 ms, in particular for less than 15 ms, 10 ms, 5 ms, 1 ms, 500 μm or 100 μm.

[0173] In one embodiment, after the current flow in the low-voltage circuit is prevented due to exceeding the second differential current limit value DSG2, the switching element of the electronic interruption unit becomes low-impedance. In particular, it becomes low-impedance when the magnitude of the instantaneous value of the AC voltage is less than a first voltage limit. The first voltage limit can be, for example, less than 10 volts or less than 5 volts. More specifically, the switching element of the electronic interruption unit becomes low-impedance at a zero crossing of the AC voltage.

[0174] After the change to low resistance, the second differential current limit value DSG2 is detected again. Then, it is possible to change to high resistance again, and then to low resistance, until the first number (x) is exceeded. The first number of times exceeded can be, for example, a value in the range of 2 or 3 times up to 20 times. If the first number (x) is exceeded, for example, the contacts of the mechanical separation contact unit MK (for current separation) are disconnected. Alternatively, the electronic interruption unit can also remain in the high resistance state.

[0175] The corresponding status can be reported via the communication unit or displayed via the display unit AE.

[0176] Figure 3 The above-mentioned differential current i caused by, for example, a ground fault current is shown by way of example. f characteristics. Figure 3In the above diagram the difference current i is shown over time t. f The magnitude of the change over time or the change over time, and the avoidance of current flow OFF or current flow ON for the residual current protection switch (=current flow capacity of the protective switching device) caused by the disconnected state (galvanic separation) of the separation contacts according to the prior art.

[0177] In the middle diagram, the AC voltage u at the grid-side connection of the protective switching device in a low-voltage circuit (eg, 50 Hz) is shown over the time t (in milliseconds ms). G size or changes over time.

[0178] In the following graph, the difference current i is shown over time t. f The size or change over time of a graph is shown with the following markers showing the events associated with it:

[0179] - OFF = prevention of current flow due to the open state (galvanic separation) of the separating contacts,

[0180] -STB = avoidance of current flow due to the high impedance state of the electronic interruption unit,

[0181] ON = current flow for the protection switching device according to the invention (=current flow capability of the protection switching device).

[0182] In the above graph for the characteristics of a fault current protection switch according to the prior art, an event that causes a differential current, such as a ground fault current, occurs at a time point t of approximately 5 ms. In this example, the magnitude of the differential current is approximately 400 mA. Subsequently, in a conventional fault current protection switch, the avoidance of the current flow is turned OFF (disconnected) after approximately 17 ms (at a time point of approximately 22 ms). That is, from this event until the avoidance of the current flow, the current flow is turned ON in the low-voltage circuit, and only then the avoidance of the current flow is turned OFF by the disconnected contacts.

[0183] In the following diagram for the characteristics of the protection switchgear according to the invention, an event that causes a differential current, such as a ground fault current, occurs at a time t of approximately 5 ms. In this example, the magnitude of the differential current would theoretically also reach a value of approximately 400 mA. According to the invention, when a second differential current limit value DSG2 (e.g. 200 mA) is reached, the current flow is (to a certain extent) immediately avoided, so that a possible differential current (limit) of, for example, 400 mA is not reached during the switch-off time. The avoidance of the current flow STB is carried out by the high-impedance state of the switching element of the electronic interruption unit. For example, by means of an instantaneous value evaluation of the magnitude of the differential current by means of the control unit SE.

[0184] For example, subsequently, when the magnitude of the instantaneous value of the alternating voltage is less than the first voltage limit, the switching element of the electronic interruption unit EU becomes low-resistance. Figure 3 In the example of , at the zero crossing of the AC voltage, specifically at the next (or the next) zero crossing of the AC voltage (for example, depending on the time point of the event causing the differential current), the switching element of the electronic interruption unit becomes low resistance. f If the first differential current-time limit value DSG1 is subsequently reached, the current flow is prevented in the low-voltage circuit as indicated. For example, the current flow is prevented at the next zero crossing of the AC voltage as indicated. In the closed state of the separation contacts, the current flow can be prevented STB by the high-impedance state of the switching element of the electronic interruption unit. Alternatively, the current flow can be prevented OFF (in a conventional manner) by the open state of the separation contacts.

[0185] That is, in the protective switch device according to the present invention, after exceeding the second differential current limit value DSG2 and immediately avoiding the current flow in the low-voltage circuit to a certain extent, it becomes low resistance again (in a test manner) to check whether there is an event causing the differential current.

[0186] Figure 4 Shown according to Figure 3 , except that the differential current i caused by a pulse differential current corresponding to the operating conditions is shown by way of example. f characteristics.

[0187] In the above diagram for the characteristics of a residual current circuit breaker according to the prior art, an event that causes a differential current occurs at a time point t of approximately 5 ms, such as a pulse differential current that meets operating conditions or a pulse differential current that is caused by technology, which may occur during a switching operation, in particular during a switch-on process, and in a frequency converter in a low-voltage AC circuit. Such pulse differential currents are usually unimportant from the perspective of personnel protection, since they are not caused by personnel, but by an undesirable technical circuit. In the past, some measures have been taken to make conventional residual current circuit breakers resistant to pulse differential currents that meet operating conditions or are caused by technology, in order to avoid (technically caused) false triggering or to achieve a high power supply reliability in the low-voltage circuit.

[0188] In this example, the magnitude of the differential current is (again) greater than 400 mA, for example. Subsequently, in a conventional fault current protection switch according to the prior art, the current flow is prevented from being turned off (disconnected contacts, turned off) after, for example, 17 ms (at a time point of, for example, 22 ms) (falling edge of the pulse differential current). That is, from this event until the current flow is prevented, the current flow is turned on in the low-voltage circuit, and then the current flow is prevented from being turned off by the disconnected contacts.

[0189] In the lower diagram of the behavior of the circuit breaker device according to the invention, an event occurs at a time t of approximately 5 ms which causes a differential current, in the present example a pulsed differential current corresponding to operating conditions or a technically induced pulsed differential current.

[0190] In this example, the magnitude of the differential current would theoretically also reach values ​​of approximately or greater than 400 mA. According to the invention, when the second differential current limit value DSG2 (e.g. 200 mA) is reached, the current flow STB (high-resistance interruption unit) is (to a certain extent) immediately avoided (especially during the switch-off time), so that a possible differential current (limit) of, for example, (greater than) 400 mA is not reached. The current flow STB is avoided by the high-resistance state of the switching element of the electronic interruption unit. For example, by evaluating the magnitude of the differential current by means of the control unit SE.

[0191] For example, subsequently, when the magnitude of the instantaneous value of the alternating voltage is less than the first voltage limit, the switching element of the electronic interruption unit EU becomes low-resistance. Figure 4 In the example, at the zero crossing of the AC voltage, specifically at the next (or the next) zero crossing of the AC voltage (eg depending on the time point of the event causing the differential current), the switching element of the electronic interruption unit becomes low resistance.

[0192] If the differential current i f If the first differential current-time limit value DSG1 is then reached, current flow is prevented in the low-voltage circuit. If, as shown, the first differential current-time limit value DSG1 or the second differential current limit value DSG2 is not reached, as shown, the electronic interruption unit remains in the low-resistance state for current flow ON.

[0193] Figure 5 The functional sequence with various functional blocks and status blocks is shown. The differential current sensor unit ZCT / 10 determines the magnitude of the differential current of the conductors of the low-voltage circuit and detects or provides an instantaneous value of the differential current, for example transmitting it to the control unit SE.

[0194] The instantaneous value of the differential current of the differential current sensor unit ZCT / 10 is fed on the one hand to a first evaluation 100 which determines, for example, the differential current I Diff,rms The effective value (root mean square (RMS) = rms) (block RMS / 101) is checked to see whether it exceeds the first differential current-time limit value DSG1 ("I Diff,rms >DSG1" / 102). When the first differential current-time limit value DSG1 is exceeded,

[0195] a) in the closed state of the separating contacts, by the high-impedance state of the switching element of the electronic interruption unit (“standby” block STB2 / 401),

[0196] b) by separating the open state of the contacts (OFF / 400=>block OFF),

[0197] Avoidance of current flow in low voltage circuits.

[0198] Whether to execute a) or b) (or / 110) is determined or set / specified through the device configuration (conf / 111).

[0199] The instantaneous value of the differential current is on the other hand fed to a second evaluation (“|i Diff,rms (t)|>DSG2" 200), in the present example, the second evaluation uses the magnitude of the instantaneous value of the differential current in terms of exceeding the second differential current limit value DSG2. When the second differential current limit value DSG2 is exceeded, in the closed state of the separation contacts, the avoidance STB (=>block STB / 201) of the current flow in the low-voltage circuit is initiated through the high-resistance state of the switching element of the electronic interruption unit.

[0200] The avoidance of a current flow in the low-voltage circuit by the high-impedance state of the switching element of the electronic interruption unit STB takes place within a first switch-off time which is in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms, 1 ms, 500 μs or 100 μs.

[0201] After avoiding the current flow STB / 201, the switching element of the electronic interruption unit becomes low-resistance (ON / 402), wherein it becomes low-resistance in particular when the magnitude of the instantaneous value of the AC voltage is less than a first voltage limit, for example less than 10 volts ("(at|u(t)|<10V)" / 402).

[0202] If the second differential current limit value DSG2 is exceeded again after the change to low resistance, this is recorded by the counter 300. If the first count (Count) x is exceeded, in particular the contacts of the mechanical separation contact unit MK are opened to prevent the current flow from being OFF (=> block OFF / 400). Alternatively, in the closed state of the separation contacts, a continuous or intermittent high-resistance state STB2 / 401 of the switching element of the electronic interruption unit can also be adopted (=> block STB2 / 401).

[0203] If the first number has not been reached, the switch element of the electronic interruption unit becomes low resistance to turn the current flow ON (=> block ON / block 402).

[0204] The circuit breaker device SG, in particular the control unit SE, can have a microcontroller (=microprocessor) on which runs a computer program product containing instructions which, when the program is executed by the microcontroller, cause the microcontroller to carry out checks on the circuit breaker device (as described above and below).

[0205] The computer program product can advantageously be stored on a computer-readable storage medium; for example a USB stick, a CD-ROM or the like; in order to be able to upgrade to an extended version, for example.

[0206] Alternatively, the computer program product can also advantageously be transmitted via a data carrier signal.

[0207] The control unit SE can:

[0208] * implemented by means of digital circuits, for example by means of a (further) microprocessor; the (further) microprocessor may also contain analog parts;

[0209] *Implemented using digital circuits with analog circuit portions.

[0210] Although the present invention has been illustrated and described in detail through embodiments, the present invention is not limited to the disclosed examples and those skilled in the art may derive other variations therefrom without departing from the scope of protection of the present invention.

Claims

1. A protective switchgear (SG) for protecting a low-voltage circuit for an AC voltage, the protective switchgear comprising: a housing having line-side and load-side connections (LG, NG, LL, NL) for conductors of the low-voltage circuit, a differential current sensor unit (ZCT) for determining the magnitude of a differential current of a conductor of the low-voltage circuit, a mechanically disconnecting contact unit (MK) having a closed state of contacts for current flow in the low-voltage circuit or an open state of contacts for galvanic disconnection in the low-voltage circuit for preventing current flow, an electronic interruption unit (EU) which is connected in series with the mechanically isolating contact unit (MK) on the circuit side and which, by means of a semiconductor-based switching element, has a high-resistance state of the switching element for preventing a current flow or a low-resistance state of the switching element for a current flow in the low-voltage circuit, - a control unit (SE) connected to the differential current sensor unit (ZCT), the mechanical separation contact unit (MK) and the electronic interruption unit (EU), It is characterized in that The protective switching device (SG), in particular the control unit (SE), is designed to: - when a first differential current-time limit value (DSG1) is exceeded, a) in the closed state of the separating contacts, by the high-impedance state of the switching element of the electronic interruption unit, or b) by the disconnected state of the separating contacts, to initiate the prevention of current flow in the low voltage circuit; When a second differential current limiting value (DSG2) is exceeded, in the closed state of the disconnecting contacts, the prevention of a current flow in the low-voltage circuit is initiated by a high-resistance state of the switching element of the electronic interruption unit.

2. The protective switchgear (SG) according to claim 1, It is characterized in that When the first differential current-time limit value (DSG1) is exceeded, the effective value of the differential current is used.

3. The protective switchgear (SG) according to claim 1 or 2, It is characterized in that When the second differential current limiting value (DSG2) is exceeded, the instantaneous value of the differential current is used.

4. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that When the second differential current limit value (DSG2) is exceeded, a current flow in the low-voltage circuit is prevented during a first switch-off time by a high-resistance state of the switching element of the electronic interruption unit, The first switch-off time is in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms, 1 ms, 500 μs or 100 μs.

5. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that After the prevention of a current flow in the low-voltage circuit due to exceeding the second differential current limit value (DSG2), the switching element of the electronic interruption unit changes to a low resistance, In particular, a voltage sensor unit connected to the control unit is provided, the voltage sensor unit being used to determine the magnitude of the voltage of the conductor of the low-voltage circuit, In particular, when the magnitude of the instantaneous value of the AC voltage is smaller than the first voltage limit, a low resistance is obtained.

6. The protective switchgear (SG) according to claim 5, It is characterized in that The first voltage limit is less than 20 volts or less than 10 volts or less than 5 volts, In particular, at the zero crossing of the AC voltage, the switching element of the electronic interruption unit becomes low-resistance.

7. Protection switchgear (SG) according to claim 5 or 6, It is characterized in that After the resistance becomes low, the second differential current limit value (DSG2) is exceeded again, becomes high resistance, then low resistance, until the first number (x) is exceeded. In particular, the contacts of the mechanically isolating contact unit (MK) are then opened.

8. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The protective switching device is designed so that the second differential current limit value (DSG2) is higher in magnitude than the first differential current limit value or the first differential current-time limit value (DSG1), in particular the second differential current limit value is a value in the range of 2 to 100 times the first differential current limit value or the first differential current-time limit value (DSG1).

9. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that A current sensor unit (SI) connected to the control unit (SE) is provided, the current sensor unit (SI) being used to determine the magnitude of the current of the conductor of the low-voltage circuit, The protective switching device (SG), in particular the control unit (SE), is designed to initiate the prevention of a current flow in the low-voltage circuit by means of a high-resistance state of a switching element of the electronic interruption unit in the closed state of the disconnecting contacts when a first current limit value or a first current-time limit value is exceeded.

10. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The mechanically isolating contact unit (MK) is associated with the load-side connections (LL, NL).

11. A method for a protective switchgear (SG) for protecting a low-voltage circuit for an alternating voltage, In the method, the magnitude of the differential current of the conductors of the low voltage circuit is determined, and - when a first differential current-time limit value (DSG1) is exceeded, a) in the closed state of the separating contacts, through the high-impedance state of the switching element of the electronic interruption unit, or b) by the disconnected state of the separating contacts, to initiate the avoidance of current flow in the low voltage circuit, When a second differential current limiting value (DSG2) is exceeded, in the closed state of the disconnecting contacts, the prevention of a current flow in the low-voltage circuit is initiated by a high-resistance state of the switching element of the electronic interruption unit.

12. The method according to claim 11, It is characterized in that When a first differential current limiting value or a first differential current-time limiting value (DSG1) is exceeded, the effective value of the differential current is used.

13. The method according to claim 11 or 12, It is characterized in that When the second differential current limiting value (DSG2) is exceeded, the instantaneous value of the differential current is used.

14. The method according to any one of the preceding claims 11 to 13, It is characterized in that When the second differential current limit value (DSG2) is exceeded, a current flow in the low-voltage circuit is prevented during a first switch-off time by a high-resistance state of the switching element of the electronic interruption unit, The first switch-off time is in particular less than 20 ms, in particular less than 15 ms, 10 ms, 5 ms, 1 ms, 500 μs or 100 μs.

15. The method according to any one of the preceding claims 11 to 14, It is characterized in that After the prevention of a current flow in the low-voltage circuit due to exceeding the second differential current limit value (DSG2), the switching element of the electronic interruption unit changes to a low resistance, In particular, when the magnitude of the instantaneous value of the AC voltage is smaller than the first voltage limit, a low resistance is obtained.

16. The method according to claim 15, It is characterized in that After the resistance becomes low, the second differential current limit value (DSG2) is exceeded again, becomes high resistance, then low resistance, until the first number (x) is exceeded. In particular, the contacts of the mechanically disconnecting contact unit (MK) are then opened.

17. The method according to any one of the preceding claims 11 to 16, It is characterized in that The magnitude of the current in the conductor of the low-voltage circuit is determined and, when a first current limit value or a first current-time limit value is exceeded, prevention of the current flow in the low-voltage circuit is initiated by the high-resistance state of the switching element of the electronic interruption unit in the closed state of the separating contacts.

18. A computer program product comprising instructions which, when executed by a microcontroller, cause the microcontroller to support or perform the method according to any one of claims 11 to 17.

19. A computer-readable storage medium having stored thereon the computer program product according to claim 18.

20. A data carrier signal transmitting a computer program product according to claim 18.

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