Circuit breaker device and method

Abstract

The invention relates to a circuit breaker device for low-voltage AC circuits, comprising: - a mechanical isolating contact unit (MK), which is connected in series with an electronic interruption unit (EU), - wherein a current level of the low-voltage AC circuit is determined, - wherein, if the current level exceeds current limit values or current time limit values, a measure is initiated to prevent current flow, - wherein a) in the event of a high-resistance state of the switching elements of the electronic interruption unit (EU), the current level is compared with a first threshold value and if this is exceeded, i) a current flow is prevented by an open state of the contacts of the mechanical isolating contact unit (MK), or ii) a switching of the electronic interruption unit (EU) into a low-impedance state of the switching elements is blocked, or b) when the contacts of the mechanical isolating contact unit (MK) are in an open state, the current level is compared with a second threshold value, and if this is exceeded, the ability of the contacts to switch to a closed position is blocked.

Description

[0001] 202501381

[0002] 1

[0003] Description

[0004] Protective switching device and procedure

[0005] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0006] The invention relates to the technical field of a protective switching device for a low-voltage alternating current circuit with an electronic interruption unit and a method for a protective switching device for a low-voltage alternating current circuit with an electronic interruption unit.

[0007] Low voltage refers to voltages up to 1000 volts AC or up to 1500 volts DC. In particular, low voltage refers to voltages higher than extra-low voltage, defined as 50 volts AC or 120 volts DC.

[0008] Low-voltage AC circuits, networks, or installations refer to circuits with rated currents of up to 125 amperes, or more specifically, up to 63 amperes. Low-voltage AC circuits specifically include circuits with rated currents of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes, or 10 amperes. These current values ​​refer specifically to rated, rated, and / or tripping currents, i.e., the maximum current that normally flows through the circuit or at which the electrical circuit is typically interrupted, for example, by a protective device such as a circuit breaker, miniature circuit breaker, or miniature circuit breaker. The rated currents can be further staggered, from 0.5 A through 1 A, 2 A, 3 A, 4 A, 5 A, 6 A, 7 A, 8 A, 9 A, 10 A, etc. up to 16 A.

[0009] Miniature circuit breakers (MCBs) are long-established overcurrent protection devices used in electrical installations in low-voltage AC circuits. They protect conductors from damage caused by overheating due to excessive current and / or short circuits. A MCB can automatically disconnect the circuit in case of overload and / or short circuit. A MCB is a non-resetting safety device. 202501381

[0010] 2

[0011] Unlike miniature circuit breakers (MCBs), power circuit breakers are designed for currents greater than 125 A, and sometimes even as low as 63 A. MCBs are therefore simpler and more delicate in design. MCBs typically have a mounting option for installation on a DIN rail (also known as a top-mounted rail or TH35 rail).

[0012] Miniature circuit breakers (MCBs) are electromechanical devices. They contain a mechanical switching contact or shunt trip within a housing to interrupt (trigger) the electrical current. Typically, a bimetallic element is used for tripping (interruption) in the event of a prolonged overcurrent (overcurrent protection) or thermal overload (overload protection). An electromagnetic trip with a coil is used for momentary tripping when an overcurrent limit is exceeded or in the event of a short circuit (short-circuit protection). One or more arc-quenching chambers or devices are provided. Furthermore, they include connection elements for conductors of the electrical circuit to be protected.

[0013] Protective switching devices with an electronic interruption unit are relatively new developments. These devices feature a semiconductor-based electronic interruption unit. This means that the electrical current flow of the low-voltage AC circuit is routed through semiconductor components or semiconductor switches that can interrupt the electrical current flow or be switched to conductivity. Protective switching devices with an electronic interruption unit also frequently feature a mechanical disconnect contact unit, particularly with isolating characteristics according to relevant standards for low-voltage AC circuits. The contacts of the mechanical disconnect contact unit are connected in series with the electronic interruption unit, meaning that the current of the low-voltage AC circuit to be protected is routed through both the mechanical disconnect contact unit and the electronic interruption unit.

[0014] The invention relates in particular to low-voltage alternating current circuits with an alternating voltage, usually a time-dependent sinusoidal alternating voltage with frequency f. The time dependence of the instantaneous voltage value u(t) of the alternating voltage is given by the equation:

[0015] u(t) = II * sin (2TT * f * t)202501381

[0016] 3

[0017] described. Whereby:

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

[0019] U = Amplitude of the voltage

[0020] A harmonic alternating voltage can be represented by the rotation of a phasor whose length corresponds to the amplitude (II) of the voltage. The instantaneous displacement is the projection of the phasor onto a coordinate system. One oscillation period corresponds to one full rotation of the phasor, and its full angle is 2TT (2π) or 360°. The angular frequency is the rate of change of the phase angle of this rotating phasor. The angular frequency of a harmonic oscillation is always 2TT times its frequency, i.e.,

[0021] w = 2TT*f = 2TT / T = angular frequency of the alternating voltage

[0022] (T = period of the oscillation)

[0023] The angular frequency (w) is often preferred over the frequency (f), since many formulas in oscillation theory can be represented more compactly using the angular frequency due to the occurrence of trigonometric functions whose period is by definition 2TT:

[0024] u(t) = U * sin(wt)

[0025] In the case of angular frequencies that are not constant over time, the term instantaneous angular frequency is also used.

[0026] In the case of a sinusoidal, especially time-constant, alternating voltage, the time-dependent value of the angular velocity w and the time t corresponds to the time-dependent angle cp(t), which is also called the phase angle cp(t).

[0027] This means the phase angle cp(t) periodically traverses the range O...2TT or 0°...360°. This means the phase angle periodically assumes a value between 0 and 2TT or 0° and 360° (cp = n*(0...2TT) or cp = n*(0°...360°), due to periodicity; simplified: (p = O...2TT or (p = 0°...360°).

[0028] The instantaneous voltage value u(t) therefore refers to the instantaneous value of the voltage at time t, i.e., in the case of a sinusoidal (periodic) alternating voltage, the value of the voltage at the phase angle cp (cp = 0...2TT or cp = 0°...360°, of the respective period). In contrast to the instantaneous voltage value or instantaneous current value, there is 202501381

[0029] 4

[0030] The RMS value of the voltage or the RMS value of the current. In electrical engineering, the RMS value is understood to be the root mean square of a time-varying physical quantity. The term is preferably applied to alternating quantities.

[0031] The effective value of a variable quantity is equal to the value of an equivalent quantity that would dissipate the same amount of electrical energy in a resistive load over a representative period of time. An equivalent statement can be made for electrical power. The effective value depends on both the peak value and the waveform. In English, the effective value is denoted by RMS (abbreviation for Root Mean Square).

[0032] The object of the present invention is to improve a protective switching device of the type mentioned above, in particular to achieve a higher level of safety in current measurement.

[0033] This problem is solved by a protective switching device with the features of claim 1, and by a method according to claim 10.

[0034] According to the invention, a protective switching device for the protection of a low-voltage alternating current electrical circuit is proposed, comprising:

[0035] - an enclosure with at least two mains-side connections and at least two load-side connections, for connecting at least two conductors (in particular phase conductors and neutral conductors) of the low-voltage alternating current circuit,

[0036] - a mechanical isolating contact unit which can be switched by a closed state of the contacts to allow current flow in the conductors of the low-voltage alternating current circuit or by an open state of the contacts to prevent current flow by means of galvanic isolation of the conductors of the low-voltage alternating current circuit, - that the mechanical isolating contact unit is connected in series with an electronic interruption unit,

[0037] - that the electronic interruption unit can be switched by semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow in at least one conductor or a low-resistance state of the switching elements to allow current flow in the low-voltage alternating current circuit,

[0038] - a first current sensor unit, for determining the magnitude of a current in the low-voltage alternating current circuit,

[0039] - a control unit that receives the current level determined by the first current sensor unit (and is specifically connected to the first current sensor unit and) which is labelled with 202501381

[0040] 5

[0041] connected to the mechanical disconnect contact unit and the electronic interruption unit,

[0042] - that the protective switching device is designed in such a way that (especially when the contacts are closed and the switching elements are in a low-resistance state) if the current exceeds current limits or current time limits, a current flow prevention is initiated,

[0043] - that the protective switching device is designed in such a way that

[0044] a) in a high-resistance state of the switching elements of the electronic interruption unit (EU), the magnitude of the current is compared with a first threshold value and if this threshold is exceeded

[0045] i) a current flow is avoided by an open state of the contacts of the mechanical isolating contact unit (MK) or

[0046] ii) the switching of the electronic interruption unit (EU) to a low-resistance state of the switching elements is blocked,

[0047] or

[0048] b) when the contacts of the mechanical isolating contact unit (MK) are in an open state, the current level is compared with a second threshold value and, if this threshold is exceeded, the switching of the contacts to a closed state is blocked.

[0049] The first and second threshold values ​​can be identical.

[0050] This has the advantage of allowing verification of the correct operation of the current measurement, specifically of the current sensor unit and downstream components. The measured current is linked to the switching state of the electronic interrupt unit or the mechanical isolating contact unit. With a high-resistance electronic interrupt unit, no significant current should flow (only leakage or residual currents). Similarly, with open contacts of the mechanical isolating contact unit, no significant current should flow. If currents exceeding a first or second threshold are present, a faulty current measurement can be assumed. Appropriate safety measures (disconnecting the contacts, blocking the low-resistance state, and blocking the closing of the contacts) are then implemented. This ensures safety in the low-voltage circuit.

[0051] In particular, a first measurement signal processing unit (first device for processing the measurement signal) having a first current measurement range can be provided, which is connected on the one hand to the first current sensor unit and on the other hand to the control unit202501381

[0052] 6

[0053] It is connected so that a first current signal with a processed current level is transmitted from the first measurement processing unit to the control unit. An example of a downstream unit.

[0054] Further advantageous embodiments of the invention are specified in the dependent claims and in the exemplary embodiment.

[0055] In an advantageous embodiment of the invention, the mechanical disconnect contact unit is assigned to the load-side connection and the electronic interruption unit to the network-side connection. In particular, the mechanical disconnect contact unit can be operated by a mechanical handle to switch the contacts open or closed.

[0056] This has the particular advantage that a structure for a protective switching device is provided in which the functionality of the protective switching device is ensured even when the contacts of the mechanical isolating contact unit are open, so that the possibility of monitoring the current sensing is always available.

[0057] In an advantageous embodiment of the invention, if the current exceeds current limits or current time limits, the current flow is prevented by a high-resistance state of the switching elements of the electronic interruption unit.

[0058] This has the particular advantage of enabling a rapid prevention of current flow.

[0059] In an advantageous embodiment of the invention, if the current exceeds current limits or current time limits, the current flow is prevented by an open state of the contacts of the mechanical isolating contact unit.

[0060] This has the particular advantage of enabling galvanically isolated prevention of current flow.

[0061] In an advantageous embodiment of the invention, the protective switching device is designed such that the method of preventing current flow is configurable.

[0062] This has the particular advantage of allowing flexible configuration of the protective switching device in the event of such defects. 202501381

[0063] 7

[0064] In an advantageous embodiment of the invention, when the switching elements of the electronic interruption unit (EU) are in a high-impedance state, the current level is compared with the first threshold value and, if this threshold is exceeded, a first piece of information is signaled.

[0065] This has the particular advantage that, in addition to the protective measure, information about the defect and its cause is available to the user / operator.

[0066] In an advantageous embodiment of the invention, when the contacts of the mechanical isolating contact unit (MK) are open, the current level is compared with a second threshold value, and if this threshold is exceeded, a second piece of information is signaled. This has the particular advantage that, in addition to the protective measure, information about the defect and its cause is available to the user / operator.

[0067] In an advantageous embodiment of the invention, a display unit connected to the control unit is provided, which has display means visible on the protective switching device for signaling the (first and / or second) information (defect).

[0068] This has the particular advantage that a visualization of a defective state of the protective switching device is provided at the protective switching device (for a user).

[0069] In an advantageous embodiment of the invention, a communication unit connected to the control unit is provided, such that the signaling of the (first and / or second) information is carried out by communication, in particular wireless or conductorless communication.

[0070] This has the particular advantage that it is possible to signal a defective state of the protective switching device to, for example, a higher-level monitoring or management system.

[0071] According to the invention, a corresponding method for a protective switching device for a low-voltage alternating current circuit with electronic (semiconductor-based) switching elements is claimed, offering the same and further advantages.

[0072] The method for a protective switching device for the protection of a low-voltage alternating current electrical circuit with at least two conductors, comprising:

[0073] - a housing with at least two mains-side connections and at least two load-side connections, for connecting the at least two conductors of the

[0074] Low-voltage alternating current circuit, 202501381

[0075] 8

[0076] - a mechanical isolating contact unit which can be switched by a closed state of the contacts to allow current flow in the conductors of the low-voltage alternating current circuit or by an open state of the contacts to prevent current flow by means of galvanic isolation of the conductors of the low-voltage alternating current circuit, - that the mechanical isolating contact unit is connected in series with an electronic interruption unit,

[0077] - that the electronic interruption unit can be switched by semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow in at least one conductor or a low-resistance state of the switching elements to allow current flow in the low-voltage alternating current circuit,

[0078] - a first current sensor unit for determining the magnitude of a current (of the at least two conductors connected to the protective switching device) of the low-voltage alternating current circuit, - that (with the contacts closed and the switching elements in a low-resistance state) if the magnitude of the current exceeds current limits or current time limits, a current flow prevention is initiated,

[0079] - that

[0080] a) in a high-resistance state of the switching elements of the electronic interruption unit, the magnitude of the current is compared with a first threshold value and, if this threshold is exceeded,

[0081] i) a current flow is avoided by an open state of the contacts of the mechanical isolating contact unit or

[0082] ii) the switching of the electronic interruption unit (EU) to a low-resistance state of the switching elements is blocked,

[0083] or

[0084] b) when the contacts of the mechanical isolating contact unit are open, the current level is compared with a second threshold value, and if this threshold is exceeded, the contacts are blocked from being switched to a closed state.

[0085] Advantageously, when the switching elements of the electronic interruption unit are in a high-resistance state, the current level is compared with the first threshold value, and an initial information signal is sent when this threshold is exceeded.

[0086] Advantageously, when the contacts of the mechanical isolating contact unit are open, the current level is compared with the second threshold value, and a second piece of information is signaled if this threshold is exceeded. 202501381

[0087] 9

[0088] Advantageously, if the current exceeds current limits or current time limits, the current flow is prevented by a high-resistance state of the switching elements of the electronic interruption unit.

[0089] Advantageously, if the current exceeds current limits or current time limits, the current flow is prevented by an open state of the contacts of the mechanical isolating contact unit.

[0090] The method of preventing current flow is configurable, which is advantageous.

[0091] Advantageously, the first or second piece of information is signaled by an optical display unit.

[0092] Advantageously, the signaling of the first or second piece of information is carried out by a communication device or communication unit, in particular wireless or cableless.

[0093] All embodiments, both in dependent form relating back to patent claim 1 or

[0094] 10, as well as referring back only to individual features or combinations of features of patent claims, in particular also a reference of the dependent arrangement claims to the independent method claim (and vice versa), result in an improvement of a protective switching device, in particular an improvement of the safety of a protective switching device.

[0095] The described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more easily understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawing.

[0096] The drawing shows:

[0097] Figure 1 shows a first representation of a protective switching device.

[0098] Figure 1 shows a representation of a protective switching device SG for the protection of a low-voltage alternating current electrical circuit with a housing GEH, comprising:

[0099] - a mains-side neutral conductor connection NG, a mains-side phase conductor connection LG, a load-side neutral conductor connection NL, a load-side phase conductor connection LL for 202501381

[0100] 10

[0101] at least two conductors of the low-voltage alternating current circuit; in particular a phase conductor and a neutral conductor, wherein the phase conductor is routed inside the housing as (protective switch-internal) phase conductor L and the neutral conductor is routed inside the housing as (protective switch-internal) neutral conductor N,

[0102] A power source is usually connected to the grid side.

[0103] A consumer is usually connected to the load side;

[0104] - a (two-pole) mechanical disconnect contact unit MK with load-side connection points APLL, APNL and network-side connection points APLG, APNG,

[0105] where a load-side connection point APNL is provided for the neutral conductor, a load-side connection point APLL for the phase conductor, a network-side connection point APNG for the neutral conductor, and a network-side connection point APLG for the phase conductor. The load-side connection points APNL and APLL are connected to the load-side neutral and phase conductor connections NL and LL, respectively, so that the opening of contacts KKN and KKL to prevent current flow or the closing of the contacts to allow current flow in the low-voltage AC circuit can be switched.

[0106] The mechanical disconnect contact unit can also be designed as a single-pole mechanical disconnect contact unit, i.e. with one contact, wherein the contact KKL is preferably arranged in the (protective switch internal) phase conductor L,

[0107] - an electronic interruption unit EU, in particular a single-pole unit, (which in the case of a single-pole design is in particular arranged in the (protective switching device internal) phase conductor L,) with a network-side connection point EUG, which is in electrical connection with the network-side phase conductor connection LG, and

[0108] a load-side connection point EUL which is electrically connected to the network-side connection point APLG of the mechanical disconnect contact unit MK, wherein the electronic interruption unit has a high-resistance state of the switching elements to prevent current flow or a low-resistance state of the switching elements to allow current flow in the low-voltage alternating current circuit by means of semiconductor-based switching elements,

[0109] - a first current sensor unit SI1, for determining the magnitude of the current in the low-voltage AC circuit, which is arranged in particular in the phase conductor L, - a control unit SE, which is (directly or indirectly) connected to the first current sensor unit SI1, the mechanical disconnect contact unit MK and the electronic interrupt unit EU, wherein (with closed contacts and low-resistance electronic interrupt unit) if the magnitude of the current is exceeded by current and / or current-time limits (i.e., if a current of a certain magnitude is present for a certain time), a current flow in the low-voltage AC circuit is prevented. 202501381

[0110] 11

[0111] A unit RE may be provided on the protective switching device SG, which is connected, for example, to the control unit SE, for example for an external control signal.

[0112] Furthermore, a first voltage sensor unit SUA connected to the control unit SE can be provided, which determines the voltage level, in particular instantaneous voltage levels, of the low-voltage AC circuit, especially at the mains-side terminals LG, NG, specifically between the mains-side neutral terminal NG and the mains-side phase terminal LG. Advantageously, the electronic interruption unit EU switches to the low-impedance state when the instantaneous voltage level falls below a first voltage limit, which is in particular less than or equal to 50 volts (or 25 volts or 10 volts).

[0113] The same principle applies to the high-impedance switching of the electronic interruption unit EU. When switching the electronic interruption unit EU at high impedance, a first current limit can be used as an alternative to the first voltage limit.

[0114] In general, the mechanical disconnect contact unit MK and the electronic interruption unit EU form a series circuit. This series circuit is connected to both the mains-side and load-side terminals (in this case, the neutral conductor passes through the (imaginary) two-pole electronic interruption unit, whereby the neutral conductor is, or can be, free of semiconductor-based switching elements). The mechanical disconnect contact unit MK can advantageously be assigned to the load-side terminal and the electronic interruption unit EU to the mains-side terminal, as shown in Figure 1. The mechanical disconnect contact unit MK can be operated by a mechanical handle HH to switch the opening or closing of contacts, similar to a conventional miniature circuit breaker (MCB).

[0115] The control unit SE can contain a microcontroller MP (microcontroller unit).

[0116] Furthermore, a second voltage sensor unit SUB connected to the control unit SE may be provided, which determines the voltage level between the grid-side connection point EUG and the load-side connection point EUL of the electronic interruption unit EU.

[0117] A measuring impedance ZM can be connected between the mains-side connection points APLG and APNG of the mechanical disconnect contact unit MK. The measuring impedance ZM202501381

[0118] 12

[0119] The measuring impedance can be, for example, an electrical resistor and / or capacitor. It can also be an inductor. In particular, the measuring impedance can be a series or parallel connection of a resistor and / or capacitor and / or inductor.

[0120] In the example shown in Figure 1, the electronic interruption unit EU is single-pole, located in the phase conductor. Here, the mains-side connection point APNG for the neutral conductor of the mechanical disconnect contact unit MK is connected to the mains-side neutral conductor connection NG of the housing GEH. In a single-pole version of the protective switching device, this connection, as well as the neutral conductor contact KKN of the mechanical disconnect contact unit, can be omitted.

[0121] The protective switching device SG is advantageously designed such that the contacts of the mechanical isolating contact unit MK can be opened but not closed by the control unit SE, which is indicated by an arrow from the control unit SE to the mechanical isolating contact unit MK.

[0122] The mechanical disconnect contact unit MK can be operated by a mechanical handle HH on the protective switching device SG to manually open or close the contacts KKL and KKN. The mechanical handle HH indicates (specifically through a mechanical connection between the contacts and the handle) the switching state (open or closed) of the contacts of the mechanical disconnect contact unit MK on the protective switching device.

[0123] The mechanical disconnect contact unit MK is advantageously designed such that (manual) closing of the contacts by the mechanical handle is only possible after an enable signal. This is also indicated by the arrow from the control unit SE to the mechanical disconnect contact unit MK. That is, the contacts KKL and KKN of the mechanical disconnect contact unit MK can only be closed by the handle HH when the enable signal (from the control unit) is present. Without the enable signal, the handle HH can be actuated, but the contacts cannot be closed ("permanent slip"), i.e., a blockage occurs (the contacts cannot be switched to a closed state).

[0124] The protective switching device SG has a power supply NT, for example a power supply unit. In particular, the power supply NT is intended for the control unit SE, which is 202501381

[0125] 13

[0126] This is indicated by a connection between the power supply NT and the control unit SE in Figure 1. The power supply NT is (on the other hand) connected to the network-side neutral conductor connection NG and the network-side phase conductor connection LG. A fuse SS, in particular a cartridge fuse, and / or a switch can advantageously be provided in the connection to the network-side neutral conductor connection NG (and / or phase conductor connection LG).

[0127] In the case of a purely single-pole protective switching device, the power supply is provided by an external power source / additional connections.

[0128] High resistance refers to a state in which only a negligible current flows. Specifically, high resistance values ​​greater than 1 kilohm, preferably greater than 10 kilohms, 100 kilohms, 1 megahms, 10 megahms, 100 megahms, 1 gigahms, or higher.

[0129] Low resistance refers to a state in which the current value specified on the protective switching device could flow.

[0130] In particular, low resistance values ​​are meant to be less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less.

[0131] The mechanical disconnect contact unit MK can, in one variant, interrupt a single pole. This means that only one conductor (of the two / multiple conductors), specifically the live conductor or phase conductor, is interrupted, i.e., it has a mechanical contact. The neutral conductor is then without contact, i.e., the neutral conductor is directly connected.

[0132] In a second variant of the mechanical disconnect contact unit MK, the neutral conductor also has mechanical contacts, as shown in Figure 1.

[0133] The term "mechanical disconnect contact unit MK" refers specifically to a (standard-compliant) disconnect function, implemented by the disconnect contact unit MK. The following points are included with the disconnect function:

[0134] -Minimum air gap according to standard (minimum distance between contacts),

[0135] - (Mechanical) contact position indicator of the contacts of the mechanical isolating contact unit, -Free release, i.e., actuation to interrupt the contacts of the mechanical isolating contact unit by the handle or control unit is always possible, so that no (permanent) blocking of the contacts in the closed state by the handle is possible,

[0136] meant. 202501381

[0137] 14

[0138] Furthermore, the standard-compliant disconnect function can include the ability to lock the disconnect contact unit or the handle in the switched-on or switched-off state.

[0139] The minimum air gap between the contacts of the isolating contact unit is essentially voltage-dependent. Other parameters include the degree of pollution, the type of field (homogeneous, inhomogeneous), and the air pressure or altitude above sea level.

[0140] There are corresponding regulations and standards for these minimum clearances or creepage distances. These regulations specify, for example, the minimum clearance for an inhomogeneous and a homogeneous (ideal) electric field, depending on the degree of pollution, in the case of air required for impulse voltage withstand capability. Impulse voltage withstand capability is the resistance to being applied when a corresponding impulse voltage is applied. Only if this minimum length (minimum distance) is present does the isolating contact unit or protective switching device exhibit an isolating function (isolating property).

[0141] For the purposes of the invention, the standards DIN EN 60947 and IEC 60947 are relevant for the separator function and its properties, and reference is made to them here.

[0142] The isolating contact unit is advantageously characterized by a minimum air gap between the open isolating contacts in the OFF position (open position, contacts open), depending on the rated impulse withstand voltage and the degree of pollution. The minimum air gap is, in particular, between (at a minimum) 0.01 mm and 14 mm.

[0143] In particular, the minimum air gap is advantageously between 0.01 mm at 0.33 kV and 14 mm at 12 kV, especially for pollution degree 1 and especially for inhomogeneous fields.

[0144] The pollution levels and field types correspond to those defined in the standards. This advantageously allows for the creation of a standard-compliant protective switching device dimensioned according to the rated impulse withstand voltage.

[0145] The term "mechanical isolating contact unit" specifically does not refer to a relay contact.

[0146] Furthermore, a communication unit COM (especially wireless or cableless) is provided, which is connected to or part of the control unit SE. 202501381

[0147] 15

[0148] Furthermore, a display unit AE is 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 the control unit SE or is part of it. The display unit AE has visible indicators on the protective switching device, in particular for signaling information.

[0149] According to the invention, the protective switching device is designed such that

[0150] a) in a high-resistance state of the switching elements of the electronic interruption unit EU, the magnitude of the current is compared with a first threshold value and if this threshold is exceeded

[0151] i) a current flow is avoided by an open state of the contacts of the mechanical isolating contact unit MK or

[0152] ii) the switching of the electronic interruption unit EU into a low-resistance state of the switching elements is blocked,

[0153] or

[0154] b) when the contacts of the mechanical isolating contact unit MK are open, the current level is compared with a second threshold value, and if this threshold is exceeded, the contacts are blocked from being switched to a closed state.

[0155] Furthermore, it is advantageous that, in the case of a high-impedance state of the switching elements of the electronic interruption unit EU, the magnitude of the current can be compared with a first threshold value and, if this threshold is exceeded, an initial information signal can be given.

[0156] Furthermore, it is advantageous to compare the current level with a second threshold value when the contacts of the mechanical isolating contact unit (MK) are open, and to signal a second piece of information when this threshold is exceeded.

[0157] The threshold value can be, for example, in the range of 1 mA, 2 mA, 3 mA, ... 6 mA, ... up to 10 mA. Depending on the measurement tolerance of the existing current measurement or the rated current of the device, a different value can also be selected.

[0158] To achieve increased safety, the threshold can also be set to 0.5 mA or less. In the high-impedance state of the electronic interruption unit, no current should flow in a fault-free (non-defective) state of the protective switching device. If a current exceeding this threshold is detected, a problem or defect in the device can be inferred. Appropriate measures can then be taken to increase the safety of the protective switching device. 202501381

[0159] 16

[0160] The method of current flow prevention (by a user at the protective switching device) is advantageously configurable. If the current exceeds current limits or current time limits, current flow can be prevented by a high-resistance state of the switching elements of the electronic interruption unit EU. Alternatively, if the current exceeds current limits or current time limits, current flow can be prevented by an open state of the contacts of the mechanical disconnect contact unit MK.

[0161] The invention is described in more detail below, partly using different words.

[0162] A defect or aging of electronic measuring devices can lead to distortions in the recorded measurement data, e.g., measurement offsets or changes in the gain of the measurement signal. Such distortions can lead to faulty behavior of a protective switching device, for example:

[0163] • Non-triggering

[0164] • False triggering

[0165] • Undesirable changes in the tripping characteristic of the protective switching device (the upward shift of the current-time characteristic is particularly critical).

[0166] All of the aforementioned defects lead to risks in a low-voltage alternating current circuit or electrical installation that needs protection, for electrical equipment and persons.

[0167] The present invention allows defects in determining the current level to be detected in order to increase safety.

[0168] With the electronic interrupt unit switched at high resistance and the contacts closed, also known as the STANDBY state of the protective device, the current flow through the electronic interrupt unit is interrupted. Only leakage currents are possible, which are a thousand times smaller than the rated current of the protective device. These leakage currents are typically below the measuring range / resolution for determining the current level / current sensor unit. If the current level exceeds the first threshold, a fault in the current level measurement can be assumed, and appropriate measures, which may be configurable, can be taken. A first fault condition is detected. 202501381

[0169] 17

[0170] With the contacts of the mechanical disconnect contact unit open (the state is detected by the protective switching device, e.g., via handle detection or contact position monitoring), no current flows under normal conditions. Therefore, the current level can be expected to be zero or close to zero; that is, at most, there may be measurement noise. If the current level exceeds the second threshold, a fault in the current level measurement can be assumed, and appropriate measures, which may be configurable, can be taken.

[0171] A second error condition is detected.

[0172] Thus, if a second fault condition occurs, the activation of the isolating contact unit can be blocked ("permanent slip"). If the first fault condition occurs, the low-resistance state can be blocked. Alternatively or additionally, the contacts can be opened. If, after the contacts have opened, the second fault condition is also present, the activation of the isolating contact unit can be blocked ("permanent slip").

[0173] Although the invention has been illustrated and described in detail by the exemplary embodiment, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

Claims

202501381 18 Patent claims 1. Protective switching device for low-voltage alternating current circuits, comprising: - an enclosure (GEH) with at least two mains-side connections and at least two load-side connections, for connecting at least two conductors of the low-voltage alternating current circuit, - a mechanical isolating contact unit (MK) that can be switched by a closed state of the contacts to allow current flow in the conductors of the low-voltage alternating current circuit or by an open state of the contacts to prevent current flow by means of galvanic isolation of the conductors of the low-voltage alternating current circuit, - that the mechanical isolating contact unit (MK) is connected in series with an electronic interruption unit (EU), - that the electronic interruption unit (EU) can be switched by semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow in at least one conductor or a low-resistance state of the switching elements to allow current flow in the low-voltage alternating current circuit, - a first current sensor unit (SI1) for determining the magnitude of a current in the at least two conductors of the low-voltage alternating current circuit connected to the protective switching device, - a control unit (SE) which receives the magnitude of the current determined by the first current sensor unit (SI1) and which is connected to the mechanical disconnecting contact unit (MK) and the electronic interruption unit (EU), - that the protective switching device is designed in such a way that, if the current exceeds current limits or current time limits, a current flow prevention is initiated, characterized by that the protective switching device is designed in such a way that a) in a high-resistance state of the switching elements of the electronic interruption unit (EU), the magnitude of the current is compared with a first threshold value and if this threshold is exceeded i) a current flow is avoided by an open state of the contacts of the mechanical isolating contact unit (MK) or ii) switching of the electronic interruption unit (EU) to a low-resistance state of the switching elements is blocked, or b) when the contacts of the mechanical isolating contact unit (MK)202501381 are open 19 The current level is compared with a second threshold value, and if this threshold is exceeded, the contacts are blocked from being switched to a closed state.

2. Protective switching device (SG) according to claim 1, characterized by that when the switching elements of the electronic interruption unit (EU) are in a high-resistance state, the current level is compared with a first threshold value and, if this threshold is exceeded, a first piece of information is signaled.

3. Protective switching device (SG) according to claim 1 or 2, characterized by that when the contacts of the mechanical isolating contact unit (MK) are open, the current level is compared with a second threshold value and, if this threshold is exceeded, a second piece of information is signaled.

4. Protective switching device (SG) according to one of the preceding patent claims, characterized by that if the current exceeds current limits or current time limits, the current flow is prevented by a high-resistance state of the switching elements of the electronic interruption unit (EU).

5. Protective switching device (SG) according to one of the preceding claims 1 to 3, characterized in that, that if the current exceeds current limits or current time limits, the current flow is prevented by an open state of the contacts of the mechanical isolating contact unit (MK).

6. Protective switching device (SG) according to one of the preceding patent claims, characterized by that the protective switching device is designed in such a way that the method of preventing current flow is configurable.

7. Protective switching device (SG) according to one of the preceding patent claims, characterized by, 202501381 20 that an optical display unit is provided which is connected to the control unit (SE) such that the signaling of the first or second information is carried out by the optical display unit.

8. Protective switching device (SG) according to one of the preceding patent claims, characterized by that a communication unit is provided which is connected to the control unit (SE) such that the signaling of the first or second information is carried out by communication, in particular wireless or conductorless communication.

9. Protective switching device (SG) according to one of the preceding patent claims, characterized by that the mechanical isolating contact unit (MK) is assigned to the load-side connection and the electronic interruption unit (EU) to the network-side connection, in particular that the mechanical isolating contact unit (MK) can be operated by a mechanical handle to switch the opening or closing of contacts.

10. Method for a protective switching device for low-voltage alternating current circuits, comprising: - a mechanical isolating contact unit (MK) which can be switched by a closed state of the contacts to allow current flow in the conductors of the low-voltage alternating current circuit or by an open state of the contacts to prevent current flow by means of galvanic isolation of the conductors of the low-voltage alternating current circuit, - that the mechanical disconnect contact unit (MK) is connected in series with an electronic interruption unit (EU), - that the electronic interruption unit (EU) can be switched by semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow in at least one conductor or a low-resistance state of the switching elements to allow current flow in the low-voltage alternating current circuit, - that the magnitude of a current in the low-voltage alternating current circuit is determined, - that if the magnitude of the current exceeds current limits or current time limits, a current flow prevention measure is initiated, characterized by the fact that a) in a high-resistance state of the switching elements of the electronic interruption unit (EU), the magnitude of the current was compared with a first threshold value. 202501381 21 will be and when its exceedance i) a current flow is avoided by an open state of the contacts of the mechanical isolating contact unit (MK) or ii) switching of the electronic interruption unit (EU) to a low-resistance state of the switching elements is blocked, or b) when the contacts of the mechanical isolating contact unit (MK) are in an open state, the current level is compared with a second threshold value and, if this threshold is exceeded, the switching of the contacts to a closed state is blocked.

11. Method according to claim 10, characterized by that when the switching elements of the electronic interruption unit (EU) are in a high-resistance state, the current level is compared with the first threshold value and, if this threshold is exceeded, initial information is signaled.

12. Method according to claim 10 or 11, characterized by that when the contacts of the mechanical isolating contact unit (MK) are open, the current level is compared with the second threshold value and, if this threshold is exceeded, a second piece of information is signaled.

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