Protecting switchgear and method

Abstract

This invention relates to a protective switching device for providing standard-compliant fault current protection for low-voltage AC circuits, wherein: - when the magnitude of the fault current exceeds a specific trigger current-time value forming a trigger curve, current flow avoidance is initiated; - a standard pre-defined fault current / differential current protection switch includes: a) a trigger current-time limit value (disconnect) such that current flow in the low-voltage AC circuit must be avoided, and b) a non-trigger current limit value (connect) such that current flow in the low-voltage AC circuit must be carried; the trigger current-time limit value and the non-trigger current limit value mark a trigger range (AB); - a specific trigger current-time value lies within this trigger range; - for this trigger range, at least one first trigger curve (robust) and a second trigger curve (sensitive) can be selected within this trigger range, thereby enabling the selection of different trigger behaviors within the trigger range marked in a standard manner.

Description

Technical Field

[0001] This invention relates to the field of protective switchgear for standard fault current protection of low-voltage AC circuits, and to a method for using a protective switchgear for standard fault current protection of low-voltage AC circuits. Background Technology

[0002] Protective switchgear refers to low-voltage protective switchgear, particularly fault current protection switches. Low voltage refers to voltages up to 1000 volts AC or 1500 volts DC. More specifically, low voltage refers to voltages greater than a small voltage of 50 volts AC or 120 volts DC.

[0003] Circuits used for low voltage refer to circuits used for currents up to 6300 amps, more specifically for currents up to 1600 amps, 1200 amps, 630 amps, 125 amps, 63 amps, 40 amps, 32 amps, 16 amps, 10 amps, or 6 amps. In particular, the current values ​​mentioned refer to the design current (formerly known as the rated current and / or breaking current), i.e., the current that the circuit or protective switching device can continuously carry under standard conditions (e.g., the cross-sectional area and length of the copper conductor joint) at a defined ambient temperature (e.g., 40°C) without causing damage. This point is specified in the relevant product standards (e.g., DIN EN 60947-2 or 60898-1 and 61008-1 or 61009-1). In simpler terms, it refers to the maximum current that the circuit can carry under normal conditions, or the current at which the circuit is typically interrupted by protective switching devices, such as line protection switches or circuit breakers.

[0004] Fault current protection switches are particularly suitable for rated current ranges of 6, 10, 16, 25, 32, 40, 63, 80 or 125 amps or up to 6, 10, 16, 25, 32, 40, 63, 80 or 125 amps.

[0005] Fault current protection switches used in circuits, especially in low-voltage AC circuits or low-voltage AC equipment, are generally known. These fault current protection switches are also called FI protection switches or residual current devices (RCDs). Fault current protection switches according to the prior art are known from the following patent applications: DE 102013 219 292 A1; DE 10 2015 224 890 A1; DE 10 2015 225 423 A1; DE 10 2015 225910 A1; DE 10 2015 218 911 A1; DE 10 2015 215 456 A1; DE 10 2016 213 875 A1; DE10 2016 205 101 A1; DE 10 2017 217 040 A1; DE 10 2017 217 267 A1; DE 10 2017 217411 A1; DE 10 2018 200 714 A1.

[0006] A fault current protection switch determines the sum of currents (i.e., total current or differential current, depending on the current direction / power flow direction) between two or more conductors in a circuit. This sum of currents is normally zero, and the switch interrupts the circuit when a fault current or differential current value exceeds a specific differential current-current limit (differential current threshold, response current value, fault current value, or fault response current value), i.e., a non-zero sum of currents. This is also called triggering. More precisely, these fault current values ​​or differential current values ​​are fault current-time (limit) values ​​or differential current-time (limit) values; that is, a fault current value or differential current value exceeding a certain magnitude must persist for a certain period of time. Common differential current thresholds are, for example, 30 mA for personal protection and 300 mA for fire protection (IEC standard system, 230V / 400V rated voltage grid). In cases with special requirements for personal protection, the differential current threshold is typically 10 mA or 6 mA.

[0007] Almost all fault current protection switches to date have a total current transformer, whose primary winding is formed by the conductors of the circuit, and whose secondary winding outputs, for example, a voltage (or current) equivalent of a total current or differential current, which is used directly or indirectly to interrupt the circuit.

[0008] For this purpose, two or more conductors, typically the outgoing and returning conductors or phase conductors (= external conductors) and neutral conductor in a single-phase AC power grid, or all three phase conductors (= external conductors) or all three phase conductors (= external conductors) and neutral conductor in a three-phase AC power grid, are guided through a current transformer, which typically has a toroidal core made of ferromagnetic material. Only the differential current in the conductors, i.e., the current that deviates from the outgoing and returning currents, is converted (or transferred to the secondary winding). The sum of the currents in the circuit is usually equal to zero. Therefore, fault currents can be identified.

[0009] For example, if there is current flowing to ground on the energy absorption side or the equipment side, this is called a fault current. This is, for example, when a person comes into contact with a live conductor. In this particular case, the current flowing to ground is called a fault current.

[0010] In contrast, electrical operating equipment (such as power supply units or frequency converters) may also conduct current to ground due to, for example, so-called Y capacitors. This current is usually referred to as leakage current.

[0011] For example, a fault occurs when there is a conductive connection from a phase conductor or external conductor in the circuit to ground. This can happen when a person touches a phase conductor. Instead of returning through the neutral or zero conductor as is common, some current flows to ground through the person. This fault current can now be measured using a total current transformer because the sum of the outflow and return currents measured according to the magnitude is not zero. The circuit, for example, is interrupted by a holding magnet trigger (= self-holding magnet) or relay or trigger coil, generally speaking, an interrupting unit, with connecting mechanical devices and contacts.

[0012] The main function of a fault current protection switch is to protect people from electric shock and to protect equipment, machinery or buildings from fires caused by electrical insulation failures.

[0013] When a fault current protection switch or its total current transformer is configured such that the energy on the secondary side is sufficient to operate the triggering unit, interrupting unit, or trigger, then such a fault current protection switch is said to be independent of the grid voltage; otherwise, it is said to be dependent on the grid voltage.

[0014] If a power supply is provided for fault current identification, it is a grid voltage-dependent fault current protection switch. These grid voltage-dependent fault current protection switches are needed, for example, to identify fault currents in DC grids, mixed DC / AC grids, or circuits utilizing high frequencies.

[0015] Fault current protection switches exist in different implementations, which are referred to as types and indicated by letters or letter combinations, such as AC, A, F, G, K, S, B, B+. Each type collects a specific type of fault current. Currently, fault current protection switches are known for two poles (L+N) for phase conductors and neutral conductor, three poles (L1, L2, L3) for three phase conductors, and four poles (L1, L2, L3, N) for three phase conductors and neutral conductor.

[0016] For example, the AC type only collects pure sinusoidal fault current. The A type collects not only pure sinusoidal AC current but also pulsed DC fault current. The F type is a fault current protection device sensitive to mixed frequencies. It collects all types of fault current as the A type and is also suitable for collecting fault currents consisting of frequency mixtures up to 1 kHz. The S type is a selective fault current protection switch, which can be graded in terms of design differential current and triggering time. The B type fault current protection switch (= fault current protection device) is used to collect smooth DC fault currents in addition to the F type fault current form. Furthermore, it is suitable for fault currents with frequencies up to 2 kHz. For the B+ type fault current protection switch, the same conditions apply as for the B type. The frequency range for collecting fault currents is an extended range up to 20 kHz. The K type fault current protection switch contains the characteristics of the A type, but with a short delay in its interruption behavior. The K type is also referred to as over-tolerant.

[0017] Product standards DIN EN 61008-1 (FI protection switches) and DIN EN 61009-1 (FI / LS switches) describe the behavior of fault current protection switches, particularly the limits of their tripping time.

[0018] Protective switchgear with electronic interruption units is a relatively new development. It features a semiconductor-based electronic interruption unit. That is, the current flow in the low-voltage AC circuit is directed through a semiconductor component or semiconductor switch capable of interrupting the current flow or being switched to conduction. Furthermore, protective switchgear with electronic interruption units often includes a mechanically disconnectable contact system, which in particular has separation characteristics according to relevant standards for low-voltage AC circuits. The contacts of this mechanically disconnectable contact system are connected in series with the electronic interruption unit; that is, the current (at least partially) of the low-voltage AC circuit to be protected is directed through both the mechanically disconnectable contact system and the electronic interruption unit. Summary of the Invention

[0019] The technical problem this invention aims to solve is to improve protective switching devices, particularly fault current protection switches, especially by achieving greater flexibility in triggering behavior.

[0020] The aforementioned technical problem is solved by a protective switchgear having the features of claim 1 and a method having the features of claim 11.

[0021] According to the present invention, a protective switching device, particularly a fault current protection switch, for protecting low-voltage AC circuits using AC voltage is provided, which has the following features:

[0022] - A housing having at least two grid-side terminals and at least two load-side terminals for connecting at least two conductors of a low-voltage AC circuit, particularly the phase conductor and neutral conductor of the low-voltage AC circuit (alternately, the two phase conductors for the low-voltage AC circuit; the phase conductor (and the neutral conductor)).

[0023] - Differential current sensor unit for determining the magnitude of the fault current (differential current) of at least two conductors (connected to a protective switchgear) in a low-voltage AC circuit (i.e., the differential current between a phase conductor and a neutral conductor (or, alternatively, the differential current between two phase conductors)).

[0024] - A mechanically disconnecting contact unit, which is in particular (optionally) connected in series with an electronic interruption unit, (wherein the series circuit is connected to at least one of the terminals on the power grid side and at least one of the terminals on the load side on the other side).

[0025] This mechanically separated contact unit can be switched to a closed state for current flow in conductors of low-voltage AC circuits, or an open state for current separation of current-limited conductors of low-voltage AC circuits.

[0026] (That is, for example, a phase conductor and a neutral conductor, or two phase conductors, a phase conductor (and a neutral conductor))

[0027] - The optional electronic interruption unit can be switched via a semiconductor-based switching element to a high-ohmic state for preventing current flow in at least one conductor (e.g., a phase conductor), or a low-ohmic state for current flow in a low-voltage AC circuit.

[0028] - A control unit, which is connected to a differential current sensor unit, a mechanical disconnect contact unit, and an optional electronic interrupt unit.

[0029] Specifically, when the magnitude of the fault current exceeds the specific trigger current-time value that forms the trigger curve, the avoidance of starting current flow is crucial.

[0030] - Standards are pre-defined for fault current / differential current protection switches:

[0031] a) The current-time limit for triggering must be set to prevent current flow in low-voltage AC circuits, and

[0032] b) The current limit that does not trigger the circuit, which must be able to carry the current flow in the low-voltage AC circuit.

[0033] The current-time limit value for triggering and the current limit value for not triggering are marked to indicate the trigger range.

[0034] - The specific trigger current-time value falls within this trigger range.

[0035] - This protective switchgear is designed to be,

[0036] For this trigger range, at least one first trigger curve and one second trigger curve can be selected within this trigger range.

[0037] This allows for the selection of different trigger behaviors within a trigger range that is marked in a standard manner.

[0038] In other words, the protective switchgear has two trigger curves, such that within the trigger range, either a first trigger curve (with a specific current-time value) or a second trigger curve (with a specific current-time value) is used to trigger, i.e., to prevent current flow in the low-voltage AC circuit to be protected by the protective switchgear.

[0039] Current flow is prevented by disconnecting the contacts of the mechanically disconnecting contact unit. Alternatively, current flow can be prevented (instead of disconnecting the contacts of the mechanically disconnecting contact unit) by a high-ohmic state of the semiconductor-based switching element of the electronic interrupt unit (if the electronic interrupt unit is provided).

[0040] The first trigger curve may, for example, have first specific current-time values ​​that are close to or almost identical to the current-time limit for triggering. Therefore, within the trigger range, the protective switching device triggers only when it is close to or shortly before triggering as required by the standard. This achieves high power supply safety because a brief period exceeding the trigger range does not necessarily lead to a trigger that prevents current flow.

[0041] The second trigger curve may, for example, have a second specific current-time value, which is close to or almost identical to the current-time limit for non-triggered operation. Therefore, within the trigger range, the protective switching device triggers shortly after leaving or immediately upon leaving a (safe) load where current flow is required by standard procedures. This achieves high (personnel) safety because within the trigger range, especially briefly or slightly exceeding it, will not trigger a current-avoidance mechanism.

[0042] The triggering range cannot be changed on the protective switchgear side. This is similar to currently available fault current protection switches.

[0043] This has the advantage that triggering behavior can be selected within a trigger range (of triggering features), meaning that tiered triggering behavior can be achieved using the trigger range. Within the standard limits of the standardized trigger range, tiered setting possibilities can be configured. Therefore, trigger ranges defined in a standard manner can be used to, for example, achieve more robust or more sensitive triggering behavior.

[0044] Therefore, laypeople can advantageously modify the triggering behavior in a standard-compliant manner within the triggering scope.

[0045] In a favorable design, this can be achieved in protective switching devices, particularly through an electronic interruption unit combined with a corresponding control unit, thereby enabling precise and rapid prevention of current flow in a simple manner. Therefore, the triggering behavior can be modified and precisely implemented without deviating from standard triggering behavior.

[0046] In particular, "standard" refers to manufacturer-specific standards, either EN (European Standard) or DIN standards, which are voluntary standards developed under the guidance of the German Institute for Standardization (DIN) that provide uniform specifications for tangible and intangible objects. DIN standards are formed at the suggestion and initiative of relevant stakeholders (usually German companies), in which all parties reach a consensus.

[0047] Advantageous designs of the invention are given in the dependent claims.

[0048] In an advantageous embodiment of the invention, the mechanical disconnect contact unit is associated with a connector on the load side. (An optional electronic interruption unit is associated, in particular, with a connector on the power grid side.)

[0049] This has the particular advantage of providing an architecture that supports the behavior of the protective switching device according to the invention, since power is still supplied to the control unit and the electronic interruption unit regardless of whether the contacts are in a closed or open state.

[0050] In an advantageous design of the invention, the contacts of the mechanically disconnecting contact unit can be disconnected by the control unit, but cannot be closed by the control unit.

[0051] This has the particular advantage of providing high safety for the protective switchgear because the contacts will not be mistakenly closed inside the protective switchgear.

[0052] In an advantageous embodiment of the invention, the mechanically disconnecting contact unit can be operated by a mechanical handle to switch the contact open or closed.

[0053] In an advantageous embodiment of the invention, the contacts of the mechanically disconnecting contact unit have a free-switching function. This free-switching function can be configured according to standard conditions. Specifically, it allows the contacts to be disconnected via the control unit even when the mechanical handle is locked, i.e., when the handle is locked / locked for a closed contact state.

[0054] This offers the particular advantage of providing high safety and standard-compliant protective switching equipment for low-voltage AC circuits. Current flow can be interrupted at any time by disconnecting the contacts.

[0055] In an advantageous embodiment of the invention, for a given trigger range, a third trigger curve (standard) can be selected within that trigger range. Therefore, additional triggering behavior can be selected within that trigger range.

[0056] This has the particular advantage that the triggering behavior can be further selected within the triggering range (of the triggering feature).

[0057] In other words, the triggering range is supplemented by a third triggering curve (with a third specific current-time value) that may be located between the first and second triggering curves. This allows for further hierarchical triggering behavior.

[0058] In an advantageous embodiment of the invention, similarly, for one trigger range, at least one other trigger curve (or additional trigger curve) can be selected within that trigger range. Therefore, at least one other (or additional) triggering behavior can be selected within that trigger range.

[0059] This has the following particular advantage: it allows for further granular selection of triggering behavior within the trigger range, achieving a higher level of granularity.

[0060] In an advantageous design of the invention, the standard is for fault current / differential current protection switches, particularly for fault current / differential current protection switches (RCBO) with built-in overcurrent protection (for home installations and similar applications), specifically DIN EN 61009 (VDE 0664-20).

[0061] Alternatively, the standard is a manufacturer-specific standard (for fault current protection switches).

[0062] This has the particular advantage that there are standard trigger ranges (trigger characteristics) here, and according to the invention, these trigger ranges can be further classified in a layman-operable manner.

[0063] In an advantageous embodiment of the invention, the control unit has a microprocessor and a memory. The trigger curve (trigger characteristic curve) is stored in the control unit, and particularly in its memory.

[0064] This has the particular advantage that it allows the selection of only previously stored feature curves as trigger curves, thus enabling previously known and verified triggering behavior. For example, all stored feature curves can be verified together (according to standard testing). This ensures that specific triggering is performed according to standards (even when feature curves differ).

[0065] In an advantageous embodiment of the invention, the protective switching device is designed such that the triggering of current flow is prevented by a high-ohmic state of the switching element of the electronic interruption unit, particularly when at least one contact of the mechanically disconnecting contact unit remains closed.

[0066] This has the particular advantage of providing fast and flexible current flow avoidance, and avoiding the switching time of mechanical current flow avoidance.

[0067] According to the present invention, protection is sought for a corresponding method for fault current protection of low-voltage AC circuits for AC voltage, and in particular for fault current protection switches, having the same and other advantages.

[0068] The method for providing standard-compliant fault current protection for low-voltage AC circuits according to the present invention includes:

[0069] - When the magnitude of the fault current exceeds the specific trigger current-time value that forms the trigger curve, the avoidance of current flow (initiated by the protective switching equipment) is activated.

[0070] - Standards are pre-defined for fault current / differential current protection switches:

[0071] The current-time limits for triggering necessitate the avoidance of current flow in low-voltage AC circuits, and

[0072] The current limit that prevents triggering necessitates the ability to handle the current flow in a low-voltage AC circuit.

[0073] The current-time limit value for triggering and the current limit value for not triggering are marked to indicate the trigger range.

[0074] - The specific trigger current-time value falls within this trigger range.

[0075] - For this trigger range, it is possible to select at least one first trigger curve and one second trigger curve within this trigger range.

[0076] This allows for the selection of different trigger behaviors within a trigger range that is marked in a standard manner.

[0077] In an advantageous design of the method, a third trigger curve can be selected within the trigger range.

[0078] In an advantageous design of the method, the prevention of current flow in the protective switching device is achieved through the high-ohmic state of the switching element of the electronic interruption unit.

[0079] Especially when at least one contact of the mechanically disconnecting contact unit remains closed.

[0080] According to the present invention, protection is claimed for a corresponding computer program product for protecting switchgear, particularly fault current protection switches. This computer program product contains instructions that, when executed by a microprocessor, cause the microprocessor to perform or support a design or method for protecting switchgear according to the present invention.

[0081] In particular, when the magnitude of the fault current exceeds the specific trigger current-time value that forms the trigger curve, the avoidance of the initiation (protective switching equipment) current flow is crucial.

[0082] Regarding the trigger range, it is possible to select at least one first trigger curve and a second trigger curve within that trigger range.

[0083] This allows for the selection of different trigger behaviors within a trigger range that is marked in a standard manner.

[0084] According to the present invention, protection is sought for a corresponding computer-readable storage medium having the computer program product stored thereon.

[0085] According to the present invention, protection is sought for a data carrier signal corresponding to the transmission of the computer program product.

[0086] All design solutions, not only by referencing dependent claims 1 or 11, but also by referencing individual features or combinations of features of the claims, and especially by referencing the independent method claim in the device dependent claims, achieve improvements in the protection of switchgear, particularly fault current protection switches. In general, a new design for protecting switchgear, especially fault current protection switches, is provided. Attached Figure Description

[0087] The features, characteristics, and advantages of the present invention, as well as its implementation, will become clearer and easier to understand in conjunction with the following description of the embodiments, which are described in detail with reference to the accompanying drawings.

[0088] Here, in the attached diagram:

[0089] Figure 1 A diagram of a protective switchgear is shown.

[0090] Figure 2 The graph is shown. Detailed Implementation

[0091] Figure 1 A diagram is shown of a protective switchgear SG for protecting low-voltage AC circuits, having a housing GEH. The protective switchgear SG has:

[0092] - A housing GEH having at least two grid-side connectors and at least two load-side connectors for connecting at least two conductors of a low-voltage AC circuit, specifically:

[0093] - (at least one) phase conductor joint LG on the grid side,

[0094] - (at least one) phase conductor joint LL on the load side,

[0095] Phase conductor L used in low-voltage AC circuits;

[0096] - Neutral conductor connection NG on the grid side

[0097] - Neutral conductor connector NL on the load side,

[0098] Neutral conductor N for low-voltage AC circuits;

[0099] - At the LG and NG terminals on the grid side, or the grid-side connection, an energy source is typically connected.

[0100] - Electrical equipment is typically connected at the LL and NL joints on the load side / Load side.

[0101] - A mechanically disconnecting contact unit MK, which may optionally be connected in series with an electronic interruption unit EU.

[0102] Among them, according to Figure 1 In the example, the electronic interruption unit EU is designed as a single-pole (arranged in the phase conductor L) electronic interruption unit EU, and the second pole (in the neutral conductor N) is (or will be) through in this example;

[0103] - The mechanically disconnecting contact unit (MK) can be switched to a closed state for current flow in conductors of low-voltage AC circuits, or an open state for current-limited (galvanische) disconnection of contacts for preventing current flow in conductors of low-voltage AC circuits.

[0104] according to Figure 1 The (two-pole) mechanically disconnecting contact unit MK has load-side connection points APLL and APNL and grid-side connection points APLG and APNG.

[0105] Specifically, for the neutral conductor N, a load-side connection point APNL is provided; for the phase conductor L, a load-side connection point APLL is provided; for the neutral conductor N, a grid-side connection point APNG is provided; and for the phase conductor L, a grid-side connection point APLG is provided. The load-side connection points APNL and APLL are connected to the load-side neutral conductor connector and the phase conductor connectors NL and LL.

[0106] The (two-pole) mechanically separating contact unit MK has a closed state of a neutral conductor contact KKN (for the neutral conductor) and a (at least one) phase conductor contact KKL (for the phase conductor) for current flow in a low-voltage AC circuit, or an open state of a neutral conductor contact KKN and a phase conductor contact KKL for current separation to prevent current flow in a low-voltage AC circuit.

[0107] This allows for switching the opening of contacts KKN and KKL used to prevent current flow or the closing of contacts KKN and KKL used to prevent current flow in low-voltage AC circuits.

[0108] - Optional (unipolar) electronic interrupt unit EU,

[0109] The electronic interruption unit EU is specifically connected in series with the mechanical separation contact unit MK in the phase conductor L.

[0110] The electronic interrupt unit EU has a grid-side connection point EUG, which is electrically connected to the grid-side phase conductor connector LG.

[0111] The load-side connection point EUL is electrically connected to the grid-side connection point APLG of the mechanical disconnect contact unit MK.

[0112] The electronic interruption unit, through a semiconductor-based switching element (not shown), has or can switch between a high-ohmic state for preventing current flow and a low-ohmic state for current flow in at least one conductor, particularly phase conductor L.

[0113] - Differential current sensor unit ZCT is used to determine the magnitude of the fault current (= differential current) of at least two conductors connected to a protective switching device in a low-voltage AC circuit, specifically the neutral conductor and the phase conductor in this example, due to leakage current (flowing to ground or the phase conductor L of the protective conductor PE and / or the neutral conductor N).

[0114] In this example, the differential current sensor unit ZCT is arranged between the electronic interruption unit EU and the mechanical disconnect contact unit MK. Alternatively, the differential current sensor unit ZCT can be arranged between the mechanical disconnect contact unit MK and the neutral conductor terminal and phase conductor terminals NL, LL on the load side, and also alternatively between the electronic interruption unit EU and the terminals NG, LG on the grid side. The differential current sensor unit ZCT determines the magnitude of the fault current (differential current) of the low-voltage AC circuit that is guided through the conductors (to be protected) of the protective switching device. In this example, in the case of a single-phase AC circuit, it is the magnitude of the fault current (differential current) of the neutral conductor N and the phase conductor L.

[0115] The differential current sensor unit ZCT can be a conventional summing current transformer. The primary side of the summing current transformer is formed by the conductors of the low-voltage AC circuit (in this example, the phase conductor L and the neutral conductor N). The secondary side of the summing current transformer is connected to the control unit SE.

[0116] - A current sensor unit SI can be additionally provided to determine the magnitude of the current in the low-voltage AC circuit. This current sensor unit SI is particularly arranged in the phase conductor L (the current path of the phase conductor or the phase conductor current path).

[0117] - Control unit SE, which is connected to differential current sensor unit ZCT, (optional) current sensor unit SI, mechanical disconnect contact unit MK and electronic interrupt unit EU.

[0118] Protective switching equipment is designed to prevent the flow of initiating current when the magnitude of the fault current exceeds the specific trigger current-time value that forms the trigger curve. Standards for fault current / differential current protection switches are predefined:

[0119] - The current-time limits for triggering must be set to prevent current flow in low-voltage AC circuits, and

[0120] - The current limit that does not trigger the current flow must be carried in the low-voltage AC circuit.

[0121] The trigger range is marked by the current-time limit value for triggering and the current limit value for not triggering. The specific trigger current-time value falls within this trigger range.

[0122] The protective switchgear is designed such that, for a given triggering range, at least one first trigger curve (robust) and a second trigger curve (sensitive) can be selected within that range. Therefore, it is advantageous to select different triggering behaviors within a triggering range that is marked in a standard manner.

[0123] For this trigger range, a third trigger curve (standard) can be selected within this trigger range, thereby allowing the selection of another trigger behavior within the trigger range.

[0124] For this trigger range, another trigger curve can be selected within this trigger range, thereby allowing at least one additional trigger behavior to be selected within this trigger range.

[0125] The standard is specifically for fault current / differential current protection switches, and more specifically for fault current / differential current protection switches (RCBO) with built-in overcurrent protection for home installations and similar applications, specifically standard DIN EN 61009 (VDE 0664-20).

[0126] The control unit may have a microprocessor and memory. The trigger curve can then be stored in the control unit, particularly in the memory. The selected trigger curve can be retrieved from the memory. In the control unit (e.g., using a microprocessor), the value of the selected trigger curve is compared with the determined magnitude of the fault current. If the magnitude is exceeded, a current-prevention trigger is activated.

[0127] The protective switching device can be designed to prevent current flow triggering by using the high-ohmic state of the switching element of the electronic interrupt unit EU, particularly when the contacts of the mechanical disconnect contact unit MK remain closed. Alternatively or additionally, the contacts of the mechanical disconnect contact unit MK can also be opened. The triggering behavior for preventing current flow can be configurable.

[0128] Generally speaking, the differential current-time limit refers to the following limit value: before exceeding the differential current-time limit value, a (specific magnitude) differential current (the differential current limit value portion) must persist for a certain period of time. In other words, the differential current-time limit value has a differential current limit value portion and a time limit value portion.

[0129] Additionally, the protective switching device can be designed to initiate the avoidance of current flow in the low-voltage AC circuit when one of the magnitudes of the current in the low-voltage AC circuit, determined by the current sensor unit SI, exceeds the current limit or / and current-time limit (i.e., when a specific magnitude of (effective) current on the load side persists in the circuit for a specific time).

[0130] In this example, the mechanical disconnect contact unit MK is arranged on the load side, and the electronic interrupt unit EU is arranged on the power grid side.

[0131] Under normal circumstances, the grid side, which has an energy source, is energized. Electrical equipment is typically connected to the load side.

[0132] This has the advantage that there are no additional (especially live) parts or components between the contacts / load-side connection points APLL, APNL of the mechanically disconnecting contact unit and the two load-side terminals LL, NL. Therefore, based on this architecture or construction, it can be ensured that there is absolutely no voltage on the load-side terminals LL, NL when contacts KKL, KKN are open. This improves the safety of protected switching equipment / low-voltage AC circuits.

[0133] In contrast, in other architectures where the mechanically separated contact units are arranged on the grid side, there are often electronic units (without galvanisch isolation) before the connectors on the load side.

[0134] The protective switching device can be designed to determine the magnitude of the voltage across the electronic interrupt unit EU. That is, it can determine or ascertain the magnitude of the first voltage between the grid-side connection point EUG and the load-side connection point EUL of the electronic interrupt unit EU.

[0135] Therefore, according to Figure 1 In the example, a first voltage sensor unit SU1 connected to the control unit SE is provided. The first voltage sensor unit SU1 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.

[0136] When measuring voltage using the first voltage sensor unit SU1, the voltage on the series circuit between the electronic interrupt unit EU and the current sensor SI can also be determined alternatively, such as... Figure 1 As shown. The current sensor unit SI has very low internal resistance, so it does not adversely affect the determination of the voltage magnitude, or the effect is negligible.

[0137] Advantageously, a second voltage sensor unit SU2 can be provided, which determines the magnitude of the voltage between the neutral conductor joint NG on the grid side and the phase conductor joint LG on the grid side.

[0138] A measuring impedance ZM can be connected between the connection points APLG and APNG on the power grid side of the mechanical disconnect contact unit MK. This measuring impedance ZM can be, for example, a resistor and / or a capacitor. Alternatively, the measuring impedance can 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.

[0139] The electronic interruption unit EU is arranged in the phase conductor L ( Figure 1 The mechanical disconnect contact unit MK's connection point APNG for the neutral conductor on the grid side is connected to the neutral conductor connector NG on the grid side of the housing GEH. According to... Figure 1 The connection is guided through the differential current sensor unit ZCT, such as its sum current transformer.

[0140] The protective switchgear SG is advantageously designed such that the contacts KKL and KKN of the mechanically disconnecting contact unit MK can be disconnected by the control unit SE, but cannot be closed by the control unit SE, as indicated by the arrow OEF from the control unit SE to the mechanically disconnecting contact unit MK.

[0141] The mechanically disconnecting contact unit MK can be operated via a mechanical handle HH on the protective switchgear SG to manually open or close contacts KKL and KKN. For example, two contacts can be switched simultaneously. The mechanical handle HH indicates the on / off state (open or closed) of the contacts of the mechanically disconnecting contact unit MK on the protective switchgear. Furthermore, the contact position (or handle position, closed or open) can be transmitted to the control unit SE. For example, the contact position (or handle position) can be determined using a sensor, such as a position sensor. The contact position or on / off state can be transmitted to the control unit SE. The position sensor can be part of the mechanically disconnecting contact unit MK. For example, a Hall effect sensor can be used to acquire and transmit the position of the contacts and / or handle in a non-contact manner.

[0142] The mechanically disconnecting contact unit MK is advantageously designed so that the contacts can only be closed (manually) via a mechanical handle after being enabled, particularly after a release signal is enabled. This is also indicated by the arrow from the control unit SE to the mechanically disconnecting contact unit MK. That is, the contacts KKL and KKN of the mechanically disconnecting contact unit MK can only be closed via the handle HH when a release or a release signal (from the control unit) is present. In the absence of a release or release signal, the handle HH can be operated, but the contacts will not close ("Dauerrutscher, continuous sliding").

[0143] The protective switchgear SG has an energy supply device or power supply element NT, such as a switching power supply element. Specifically, the energy supply device / power supply element NT is configured for use with the control unit SE, which... Figure 1 The connection between the energy supply unit / power supply device NT and the control unit SE is represented in the diagram. The energy supply unit / power supply device NT (on the other hand) is connected to the neutral conductor terminal NG and the phase conductor terminal LG on the grid side. In the connection with the neutral conductor terminal NG (or / and the phase conductor terminal LG) on the grid side, it is advantageous to install a safety device SS, in particular a fusible fuse or / and a switch Sch.

[0144] According to the present invention, under normal circumstances, power is continuously supplied to the power supply unit NT, especially from the connection on the grid side. If necessary, the power supply unit NT is protected by a fuse device SS, or the power supply unit NT can be disconnected by a switch Sch.

[0145] Advantageously, the switch SCH / Sch can be implemented such that it can only be disconnected when the contacts are in the open state. This improves the safety of the device because the control unit (electronic equipment) cannot be disconnected when the contacts are closed.

[0146] The safety device SS is used not only to protect the energy supply via the power supply component NT, but also, especially in the case of a two-part structure, to protect the "electronic" part or in particular all its units (e.g., control unit, electronic interrupt unit, total current transformer, possible voltage sensor, possible current sensor, possible measuring impedance, etc.).

[0147] The low-voltage AC circuit can be a three-phase AC circuit with a neutral conductor and three phase conductors. For this purpose, the protective switching device can be designed as a three-phase variant, and for example, has additional phase conductor connections on the grid side and the load side. According to the invention, contacts of electronic interruption units and mechanical separation contact units are correspondingly arranged between these additional grid-side and load-side phase conductor connections in a similar manner. The corresponding conductors (the three phase conductors L1, L2, L3, and the neutral conductor N) are guided through the differential current unit ZCT.

[0148] Similarly, a current sensor unit or a voltage determination device (e.g., implemented through a first voltage sensor unit) can be set up.

[0149] High ohms refers to a state in which only a negligible current flows. In particular, high ohms refers to a resistance value greater than 1 kiloohm, preferably greater than 10 kiloohms, 100 kiloohms, 1 megaohm, 10 megaohms, 100 megaohms, 1 gigaohms or greater.

[0150] Low ohms refers to a state in which a given current value can flow through a protective switching device. In particular, low ohms refers to a resistance value of less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm, or less.

[0151] In particular, the mechanically separating contact unit MK refers to the (standard-compliant) separation function achieved through the separating contact unit MK. The separation function includes the following:

[0152] - According to the standard minimum air gap (minimum distance between contacts).

[0153] - Mechanical contact position indication of the contacts in a mechanically disconnecting contact unit.

[0154] - Free trigger or free switch function, that is, it can always be operated by the handle or control unit to interrupt the contacts of the mechanically disconnecting contact unit, so that the contacts cannot be (continuously) locked in the closed state by the handle.

[0155] In particular, the free-trigger or free-switch function means that the contacts can be disconnected by the control unit even if the mechanical handle (e.g., in the ON state) is locked.

[0156] In addition, the standard separation function can have the ability to disconnect the contact unit or handle in both the on and off states.

[0157] Regarding the minimum air gap between the contacts of the separation contact unit, it is essentially voltage-related. Other parameters include the degree of contamination, field type (uniform, non-uniform), and air pressure or altitude.

[0158] For these minimum air gaps or creepage paths, there are corresponding (alternative) regulations or standards. These (alternative) regulations, for example, specify minimum air gaps based on the degree of contamination, for non-uniform and uniform (ideal) electric fields, when air is used for impulse withstand voltage. Impulse withstand voltage is the ability to withstand a corresponding impulse voltage. Only when this minimum length (minimum gap) exists does the disconnecting contact unit or protective switching device have a disconnecting function (disconnector characteristic).

[0159] Here, in the sense of the present invention, the function and characteristics of the separator are particularly relevant to the DIN EN 60947 or IEC 60947 series of standards.

[0160] The disconnecting contact unit is advantageously characterized, based on the nominal impulse withstand voltage and the degree of contamination, by the minimum air gap of the disconnected contact in the open position (open circuit position, contact disconnected). This minimum air gap is particularly between 0.01 mm and 14 mm. Especially for contamination level 1 and especially for non-uniform electric fields, the minimum air gap is advantageously between 0.01 mm at 0.33 kV and 14 mm at 12 kV.

[0161] In particular, mechanically disconnected contact units do not refer to relay contacts.

[0162] Protective switchgear may have (especially wireless / wireless) communication unit COM, which is connected to or is part of the control unit SE.

[0163] In addition, a display unit AE can be provided. The display unit AE can be designed as a combined display and input unit. The display unit AE (display and input unit) is connected to or is part of the control unit SE. The display unit has a display device visible on the protective switching equipment, particularly for displaying the high-ohm or low-ohm state of the electronic interrupt unit EU. Using the combined display and input unit, for example, a first or second (or third / additional) trigger curve can be selected.

[0164] Alternatively or additionally, for example, the first or second (or third / other) trigger curve can be selected via the communication unit COM.

[0165] The standard for fault current / differential current protection or its protective switch is, for example, DIN EN 61009 (VDE 0664-20) for fault current / differential current protection switches (RCBO) with built-in overcurrent protection for home installations and similar applications.

[0166] The following Table 2 (part 5.3.8.1 - Grenzwerte der Abschalt- und Nichtauslösezeit für Wechselströme(Effektivwerte) für RCBOs des Typs AC und des Typs A (Limits for cut-off time and non-trigger time for AC and A type RCBOs for AC current (RMS value)) is excerpted from the 2016 (October) edition of the aforementioned standard (page 89).

[0167] Table 2 - Limits for RCBO (Remote Cut-off Time and Non-Trigger Time) for AC and Type A Fault Currents (RMS)

[0168]

[0169] Other key points and explanations can be found in the standard.

[0170] Figure 2 A graph illustrating the current-time behavior is shown. The current is measured in milliamperes on the horizontal X-axis. The fault current is illustrated in units (differential fault current = AC fault current according to the table above). ,Right now The fault current The graph is plotted logarithmically.

[0171] The trigger time t is plotted in seconds on the vertical Y-axis. This trigger time t (in seconds) is plotted logarithmically in the graph.

[0172] exist Figure 2 In the graph, the (test) points obtained from the aforementioned standards and the resulting ranges are clearly plotted:

[0173] a) Avoiding "disconnection" of current flow in low-voltage AC circuits (current-time limits for triggering).

[0174] b) The (safe) current carrying capacity of the current flow in low-voltage AC circuits is "on" (the current limit that does not trigger).

[0175] And the resulting trigger range AB.

[0176] exist Figure 2 In the diagram, squares (diamonds) erected on the spikes mark the current-time limits for triggering (to prevent the current flow from "breaking"). Figure 2 The area on the right), in this example:

[0177] The first current-time limit value V1 for triggering ( ): 30mA in 300ms

[0178] The second current-time limit V2 for triggering is 60mA at 150ms.

[0179] The third current-time limit V3 for triggering is 150mA at 40ms.

[0180] The fourth current-time limit V4 for triggering is 250mA at 40ms.

[0181] The fifth current-time limit value V5 for triggering is 5A at 40ms.

[0182] In other words, in the case of a fault current of 30mA or starting from 30mA, the fault current protection switch or the protection switch device according to the present invention must prevent (interrupt) current flow within 300 ms.

[0183] In the event of a fault current of 60mA or starting from 60mA, the fault current protection switch or the protection switch device according to the present invention must prevent current flow within 150ms.

[0184] In the event of a fault current of 150 mA (or higher), the fault current protection switch or the protection switch device according to the present invention must prevent current flow within 40 ms.

[0185] On the other hand, the range of current flow in a low-voltage AC circuit that is "connected" is obtained (safely) through a non-triggered current limit of 15 mA. (In this example, it is equal to half of the "normal" fault current) ) to mark ( Figure 2 (The area on the left). That is to say, the fault current protection switch or the protection switch device according to the invention must be able to carry a fault current up to 15 mA indefinitely over time without preventing current flow (therefore, in this example, according to the standard, it is the current limit value, not the current-time limit value).

[0186] This yields the trigger range AB marked by the (test) point, which is exemplarily marked by a correspondingly drawn straight line:

[0187] In the left-hand region (“On”), a non-triggered current limit of 15 mA is used. ( () marked with a vertical straight line;

[0188] In the region on the right (“disconnected”), vertical and horizontal straight lines are obtained by the current-time limit values ​​V1, V2, V3 (V4, V5) triggered by the current.

[0189] The triggering range AB lies between the "on" state of the non-triggered range and the "off" state of the triggered range (the already triggered range). Triggering typically occurs within the transition range between (safe) current carrying and (safe) current avoidance. That is, current can still be carried here, or triggering can occur here, where the precise (specific) triggering current-time limit is not defined in detail.

[0190] Importantly, current is carried (not triggered) within the "on" range (safely connected), while current is safely avoided (pre-triggered) within the "off" range (triggered range). In other words, specific trigger current-time values ​​lie within the trigger range AB, and triggering is achieved through the protective switching device at these specific trigger current-time values ​​(avoidance of starting current flow). These specific trigger current-time values ​​form the trigger curve of the protective switching device. Figure 2 The trigger curve AK is illustrated in the example, which is the third trigger curve (standard) in this example.

[0191] Now, according to the present invention, for a trigger range AB, at least one first trigger curve and a second trigger curve can be selected within the trigger range AB, thereby allowing different trigger behaviors to be selected within the trigger range AB marked in a standard manner.

[0192] According to Figure 2 The example illustrates a first trigger curve, "Robust," which can be selected within the trigger range AB (closer to the trigger range "off"), and a second trigger curve, "Sensitive," which can be selected (closer to the (safe) current-carrying range "on"). Therefore, different compliant trigger behaviors can be selected within the compliantly labeled trigger range AB in a layman's manner.

[0193] The first trigger curve is "robust" and the trigger range on the right side is "disconnected," allowing it to carry a larger fault current or a longer fault current for a longer period of time (or a larger fault current for a longer period of time). Therefore, triggering occurs shortly before the (mandatory) trigger range is "disconnected."

[0194] The second trigger curve is "sensitive" and close to the non-triggered range on the left. Therefore, when leaving this non-triggered range and "turning on," a small (excessive) fault current or a fault current present for a short period of time may cause triggering. Thus, triggering occurs shortly after leaving this non-triggered range and "turning on."

[0195] In addition, Figure 2 Within the trigger range AB, a third trigger curve "standard" is set, which is roughly positioned in the middle of the trigger range AB. Therefore, a different (or older) trigger behavior can be selected within the trigger range.

[0196] Similarly, additional trigger curves can be set within the trigger range. Therefore, at least one additional trigger behavior can be selected within the trigger range.

[0197] In particular, laypeople can select the trigger curve within the trigger range on or for the protective switchgear. It is advantageous to use an electronic interrupt unit (EU) to prevent current flow during triggering, thus enabling precise triggering in time and adherence to the selected trigger curve, which can be achieved in a slightly more expensive manner using a mechanical solution (mechanical disconnect contact unit).

[0198] The high-ohmic state of the switching element of the electronic interrupt unit EU is advantageously used to prevent the triggering of current flow. This is especially true when the contacts of the mechanical disconnect contact unit MK remain closed.

[0199] The invention and other aspects will now be described using other terminology. According to standards, fault current protection switches have triggering ranges, allowing modern devices conforming to the same standards to still exhibit different triggering behaviors.

[0200] The standard provides three ranges. The first is the non-triggered range, where the protective switchgear must safely carry current. The second is the triggered (triggered) range, where the current must safely be interrupted. The third is the so-called triggering range. The protective switchgear must trigger within this intermediate range to comply with the standard according to this type. However, how the triggering characteristic curve operates within this triggering / intermediate range is open.

[0201] Here, according to the present invention, different trigger characteristic curves can be realized by means of electronic measurement technology (differential current sensor unit) and digital algorithm (control unit) of novel electronic protection switchgear.

[0202] Figure 2 An example of how this can be implemented is shown. Three trigger characteristic curves or operating modes can be provided and selected on the protection switchgear through simplified setup possibilities: "Standard", "Sensitive", and "Robust".

[0203] The triggering behavior is defined by a corresponding digital algorithm (e.g., in the device firmware of the control unit). According to the present invention, it is now possible to retroactively change the triggering behavior of the protective switching device within existing standard limits.

[0204] This invention enables the possibility of a simple change to the triggering behavior of protective switchgear without altering the standardized triggering characteristics (used for electrical planning of the equipment).

[0205] Therefore, the possibility of installing electronic protection switchgear that conforms to existing standards has been obtained.

[0206] Because it allows for changes to the triggering behavior without altering the standardized triggering scope (standardized triggering characteristics), even laypeople can use this possibility of change in a simplified way.

[0207] The differential current sensor unit ZCT determines the fault current (differential current) of at least two conductors L and N (connected to a protective switching device) in a low-voltage AC circuit. Size,

[0208] In other words, especially instantaneous fault current ,in, It refers to the magnitude of the phase conductor current (in phase conductor L), that is, the magnitude of the current flowing between the phase conductor terminal LG on the grid side and the phase conductor terminal LL on the load side.

[0209] and It is the magnitude of the neutral conductor current, that is, the magnitude of the current flowing between the neutral conductor terminal NG on the grid side and the neutral conductor terminal NL on the load side.

[0210] In a circuit, the phase conductor current (in protective switching equipment) The magnitude corresponds to the neutral conductor current (in protective switching equipment). The magnitude of the fault current. The size of is usually equal to zero under normal circumstances.

[0211] This invention can be used in Europe, particularly with an effective value of 230 volts AC voltage from the phase conductor to the neutral conductor or 400 volts AC voltage between the two phase conductors (not shown).

[0212] The neutral conductor is typically grounded on the energy source side. A neutral conductor terminal on the grounding side is usually provided as a protective earth (PE) terminal.

[0213] Although the invention has been described and illustrated in detail with reference to embodiments, the invention is not limited to the disclosed examples and other variations can be derived by those skilled in the art without departing from the scope of protection of the invention.

Claims

1. A protective switchgear for providing standard-compliant fault current protection to a low-voltage AC circuit, the protective switchgear comprising: - A housing (GEH) having at least two grid-side connectors and at least two load-side connectors for connecting at least two conductors of the low-voltage AC circuit. - A mechanically disconnecting contact unit (MK) capable of switching between a closed state for current flow in the conductor of the low-voltage AC circuit and an open state for current separation of the current-carrying contacts to prevent current flow in the conductor of the low-voltage AC circuit. - Differential current sensor unit (ZCT) for determining the magnitude of fault current in at least two conductors of the low-voltage AC circuit connected to the protective switchgear. - Control unit (SE), which is connected to the differential current sensor unit (ZCT) and the mechanically disconnecting contact unit (MK). in, When the magnitude of the fault current exceeds the specific trigger current-time value that forms the trigger curve, the flow of the initiating current is avoided. - Standards are pre-defined for fault current / differential current protection switches: a) The current-time limit for triggering must be set such that current flow in the low-voltage AC circuit must be avoided, and b) The current limit value that is not triggered, which must carry the current flow in the low-voltage AC circuit. The current-time limit value for triggering and the current limit value for not triggering are marked as trigger ranges (AB). - The specific trigger current-time value is within the trigger range (AB). - The protective switchgear is designed to be, For the trigger range (AB), at least one first trigger curve (robust) and one second trigger curve (sensitive) can be selected within the trigger range (AB). This allows for the selection of different trigger behaviors within a trigger range (AB) marked in a standard manner.

2. The protective switchgear (SG) according to claim 1. Its features are, The mechanical disconnect contact unit (MK) is connected in series with the electronic interrupt unit (EU). The electronic interruption unit (EU) can be switched via a semiconductor-based switching element to a high-ohmic state for preventing current flow in at least one conductor, or to a low-ohmic state for current flow in the low-voltage AC circuit. The control unit (SE) is connected to the electronic interrupt unit (EU). The protective switchgear is designed to be, Triggering to prevent current flow is achieved by using the high-ohmic state of the switching element of the electronic interruption unit (EU). Especially when the contacts of the mechanically disconnecting contact unit (MK) remain in the closed state.

3. The protective switchgear (SG) according to claim 1 or 2. Its features are, The mechanically disconnecting contact unit (MK) is associated with the connector on the load side.

4. The protective switchgear (SG) according to any one of the preceding claims. Its features are, The contacts of the mechanically disconnecting contact unit (MK) can be disconnected by the control unit (SE), but cannot be closed by the control unit.

5. The protective switchgear (SG) according to any one of the preceding claims. Its features are, The mechanically disconnecting contact unit (MK) can be operated via a mechanical handle (HH) to switch the contact open or closed.

6. The protective switchgear (SG) according to claim 5. Its features are, The contacts of the mechanical disconnect contact unit (MK) have a free-switching function, which allows the contacts to be disconnected by the control unit (SE) even if the mechanical handle (HH) is locked.

7. The protective switchgear (SG) according to any one of the preceding claims. Its features are, For the aforementioned trigger range, a third trigger curve (standard) can be selected within the trigger range. This allows for the selection of additional triggering behaviors within the triggering range.

8. The protective switchgear (SG) according to any one of the preceding claims. Its features are, For the aforementioned trigger range, at least one additional trigger curve can be selected within the trigger range. This allows for the selection of at least one additional triggering behavior within the triggering range.

9. The protective switchgear (SG) according to any one of the preceding claims. Its features are, The standard is for fault current / differential current protection switches, and in particular for fault current / differential current protection switches with built-in overcurrent protection, specifically DIN EN 61009-1 or 61008-1 (VDE 0664-20).

10. The protective switchgear (SG) according to any one of the preceding claims. Its features are, The control unit has a microprocessor and a memory. The trigger curve is stored in the control unit.

11. A method for protecting a switchgear, said switchgear being used to provide standard-compliant fault current protection for low-voltage AC circuits. - When the magnitude of the fault current exceeds the specific trigger current-time value that forms the trigger curve, the flow of the starting current is avoided. - Standards are pre-defined for fault current / differential current protection switches: a) The current-time limit for triggering must be set such that current flow in the low-voltage AC circuit must be avoided, and b) The current limit value that is not triggered, which must carry the current flow in the low-voltage AC circuit. The current-time limit value for triggering and the current limit value for not triggering mark the trigger range. - The specific trigger current-time value is within the trigger range. - For the trigger range, at least one first trigger curve (robust) and one second trigger curve (sensitive) can be selected within the trigger range. This allows for the selection of different trigger behaviors within a trigger range that is marked in a standard manner.

12. The method according to claim 11, Its features are, For the aforementioned trigger range, a third trigger curve (standard) can be selected within the trigger range.

13. The method according to claim 11 or 12, Its features are, The prevention of current flow in the protective switching device is achieved through the high-ohmic state of the switching element of the electronic interruption unit (EU). In particular, when at least one contact of the mechanically disconnecting contact unit (MK) remains closed.

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