Circuit breaker device and method

Abstract

The invention relates to a circuit breaker device for low-voltage AC circuits, comprising: a mechanical separating contact unit (MK) which is connected in series with an electronic interruption unit (EU); a first current sensor unit (SI1) for determining the level of a current from at least two conductors of the low-voltage AC circuit, the conductors being connected to the circuit breaker device; and a control unit ( SE) which is connected to the mechanical separating contact unit (MK) and to the electronic interruption unit (EU), the circuit breaker device being designed in such a way that if the level of the current exceeds current limit values or current time limit values, a process of preventing a current flow is initiated. A first measurement value preparation unit (MA1) having a first current measurement range is provided which is connected to the first current sensor unit (SI1) and to the control unit (SE) such that a first current signal having a first prepared current level is transmitted from the first measurement value preparation unit (MA1) to the control unit (SE), and a second measurement value preparation unit (MA2) having a second current measurement range is provided which is connected to the first current sensor unit (SI1) and to the control unit (SE) such that a second current signal having a second prepared current level is transmitted from the second measurement value preparation unit (MA2) to the control unit (SE). The circuit breaker device is designed in such a way that a difference between the first prepared current level and the second prepared current level is determined. The magnitude of the difference is compared with a first threshold value and if the threshold value is exceeded: a) information is signaled or b) a process of preventing a current flow is initiated.

Description

[0001] 202422268

[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.

[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. Within a housing, they contain a mechanical switching contact or shunt trip for interrupting (tripping) the electrical current. Typically, a bimetallic element is used for tripping (interruption) in the event of a sustained 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)202422268

[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 202422268

[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 11.

[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 the current in the low-voltage alternating current circuit,

[0039] - a control unit, (which receives the current level determined (indirectly) by the first current sensor unit and) which is connected to the mechanical disconnect contact unit as well as the 202422268

[0040] 5

[0041] is connected to an electronic interruption unit

[0042] - 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,

[0043] - that a first measurement signal processing unit (first device for processing the measurement signal) having a first current measurement range is provided, which is connected on the one hand to the first current sensor unit and on the other hand to the control unit, so that a first current signal with a first processed current level is transmitted from the first measurement signal processing unit to the control unit,

[0044] - that a second measurement signal processing unit (second device for processing the measurement signal) with a second current measurement range is provided, which is connected on the one hand to the first current sensor unit and on the other hand to the control unit, so that a second current signal with a second processed current level is transmitted from the second measurement signal processing unit to the control unit,

[0045] that the protective switching device is designed in such a way that a difference between the first conditioned level of the current and the second conditioned level of the current is determined (specifically using RMS values ​​of the current level)

[0046] that the amount of the difference is compared with a first threshold and, if this threshold is exceeded:

[0047] a) information is signaled, or

[0048] b) an avoidance of current flow is initiated.

[0049] This has the advantage that two modules (measurement processing units MA1 and MA2) are provided for processing the measured current level of the low-voltage AC circuit. The processed current levels of these modules are compared to each other, allowing a fault in the current measurement to be detected. The dual measurement processing provides (partial) redundancy for the current measurement in the protective switching device. If the first and second current signals deliver different values, this may indicate a fault in one of the two current measurements.

[0050] The measured value processing is available. Consequently, this can be signaled, or steps can be initiated to bring about a safe state of the protective switching device, such as preventing current flow to ensure safety in the low-voltage AC circuit.

[0051] Further advantageous embodiments of the invention are specified in the dependent claims and in the exemplary embodiment.

[0052] 6

[0053] 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.

[0054] 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.

[0055] In an advantageous embodiment of the invention, the current flow is prevented by a high-resistance state of the switching elements of the electronic interruption unit.

[0056] This has the particular advantage of enabling a rapid prevention of current flow.

[0057] In an advantageous embodiment of the invention, after preventing current flow by means of a high-resistance state of the switching elements of the electronic interruption unit, the switching capability to a low-resistance state of the switching elements is blocked.

[0058] This has the particular advantage that the protective switching device assumes a safe state, so that a protective switching device with a defective determination of the magnitude of a current prevents a current flow, thus ensuring safety in the circuit to be protected by the protective switching device.

[0059] In an advantageous embodiment of the invention, the current flow is avoided 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, after preventing current flow by means of an open state of the contacts of the mechanical isolating contact unit, the switching of the contacts to a closed state is blocked.

[0062] This has the particular advantage that the protective switching device assumes a safe state, so that a protective switching device with a defective determination of the magnitude of a current can have a202422268

[0063] 7

[0064] Current flow is prevented, thus ensuring safety in the circuit to be protected by the protective switching device.

[0065] In an advantageous embodiment of the invention, the protective switching device is designed such that the method of preventing current flow is configurable.

[0066] This has the particular advantage of allowing flexible configuration of the protective switching device in the event of such defects.

[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 information (defect).

[0068] This has the particular advantage that a visualization of a defective state of the protective switching device is provided on the protective switching device itself.

[0069] In an advantageous embodiment of the invention, a communication unit connected to the control unit is provided such that the signaling of the information is carried out by means of 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] In an advantageous embodiment of the invention, a second current sensor unit is provided for determining the magnitude of the current in the at least two conductors of the low-voltage AC circuit connected to the protective switching device. This second current sensor unit is connected to the second measurement processing unit in place of the first current sensor unit.

[0072] This has the particular advantage of providing further redundancy, so that not only the measurement processing but also the current sensor unit is duplicated.

[0073] In an advantageous embodiment of the invention, the second current measuring range is a multiple of the first current measuring range. For example, the second current measuring range is, for instance, 2, 3, 4, 5, ... 10, ... 20 times the first current measuring range.

[0074] This has the particular advantage of providing a large current measurement range while simultaneously achieving high measurement accuracy at low current levels or signal values.

[0075] 8

[0076] 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.

[0077] The method for a protective switching device for the protection of a low-voltage alternating current electrical circuit with at least two conductors, comprising:

[0078] - 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 low-voltage alternating current circuit,

[0079] - 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,

[0080] - 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,

[0081] - a first current sensor unit 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 (which receives (indirectly) the magnitude of the current determined by the first current sensor unit (SI1) and) which is connected to the mechanical disconnecting contact unit and the electronic interruption unit,

[0082] - 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,

[0083] - that a first measurement signal conditioning unit (device for conditioning the measurement signal) having a first current measurement range is provided, which is connected on the one hand to the first current sensor unit and on the other hand to the control unit, so that a first current signal with a first conditioned level of current is transmitted from the first measurement signal conditioning unit to the control unit,

[0084] - that a second measurement signal processing unit (device for processing the measurement signal) with a second current measuring range is provided, which is connected on the one hand to the first current sensor unit and on the other hand to the control unit, so that a second current signal with a second processed level is provided by the second measurement signal processing unit.

[0085] 9

[0086] of the current is transferred to the control unit,

[0087] that the protective switching device is designed in such a way that a difference between the first conditioned level of the current and the second conditioned level of the current is determined (specifically using the RMS values)

[0088] that the amount of the difference is compared with a first threshold value and if this threshold is exceeded:

[0089] a) information is signaled, or

[0090] b) an avoidance of current flow is initiated.

[0091] Advantageously, the current flow is prevented by a high-resistance state of the switching elements of the electronic interruption unit.

[0092] Advantageously, after preventing current flow by means of a high-resistance state of the switching elements of the electronic interruption unit, the switching capability of the electronic interruption unit to a low-resistance state of the switching elements is blocked.

[0093] Advantageously, the current flow is avoided by keeping the contacts of the mechanical isolating contact unit in an open state.

[0094] Advantageously, after preventing current flow by means of an open state of the contacts of the mechanical isolating contact unit, the switching capability of the contacts of the mechanical isolating contact unit to a closed state is blocked.

[0095] The protective switching device is advantageously designed in such a way that the method of preventing current flow can be configured.

[0096] Advantageously, an optical display unit is provided which is connected to the control unit, such that the signaling of the information is carried out by the optical display unit.

[0097] Advantageously, a communication unit is provided which is connected to the control unit, such that the signaling of the information takes place through communication, in particular wireless or conductorless communication.

[0098] Advantageously, a second current sensor unit is provided to determine the magnitude of the current in the at least two conductors connected to the protective switching device of the 202422268

[0099] 10

[0100] low-voltage alternating current circuit, which is connected to the second measurement processing unit in place of the first current sensor unit.

[0101] All embodiments, both in dependent form relating back to patent claim 1 or

[0102] 11, 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.

[0103] 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.

[0104] The drawing shows:

[0105] Figure 1 shows a first representation of a protective switching device,

[0106] Figure 2 shows a second representation of a protective switching device,

[0107] Figure 3 shows a third representation of a protective switching device,

[0108] 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:

[0109] - 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 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 (protection switch-internal) phase conductor L and the neutral conductor is routed inside the housing as (protection switch-internal) neutral conductor N,

[0110] A power source is usually connected to the grid side.

[0111] A consumer is usually connected to the load side;

[0112] - a (two-pole) mechanical disconnect contact unit MK with load-side connection points APLL, APNL and network-side connection points APLG, APNG, 202422268

[0113] 11

[0114] 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.

[0115] 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,

[0116] - 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

[0117] 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,

[0118] - 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 (indirectly) connected to the first current sensor unit SI1, the mechanical disconnect contact unit MK, and the electronic interruption unit EU, wherein, 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. A unit RE may be provided on the protective switching device SG, which is connected, for example, to the control unit SE, for instance, for an external control signal.

[0119] 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 values, of the low-voltage AC circuit, especially at the mains-side connections LG, NG, specifically between the mains-side neutral conductor connection NG and the mains-side phase conductor connection LG. Advantageously, the switching of the electronic interruption unit EU to the low-impedance state occurs when the 202422268

[0120] 12

[0121] The magnitude of the instantaneous value of the voltage falls below a first voltage limit, which in particular is less than or equal to 50 volts (or 25 volts or 10 volts).

[0122] 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.

[0123] 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).

[0124] The control unit SE can contain a microcontroller MP (microcontroller unit).

[0125] 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.

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

[0127] In the example shown in Figure 1, the electronic interruption unit EU is single-pole, in this example 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 202422268

[0128] 13

[0129] This connection can be omitted in the protective switching device, as can the neutral conductor contact KKN, the mechanical isolating contact unit.

[0130] 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.

[0131] 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.

[0132] 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).

[0133] The protective switching device SG has a power supply NT, for example, a power supply unit. In particular, the power supply NT is provided for the control unit SE, as 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 mains-side neutral conductor terminal NG and the mains-side phase conductor terminal LG. A fuse SS, in particular a cartridge fuse, and / or a switch can advantageously be provided in the connection to the mains-side neutral conductor terminal NG (and / or phase conductor terminal LG).

[0134] In the case of a purely single-pole protective switching device, the power supply is provided by an external power source / additional connections. 202422268

[0135] 14

[0136] 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.

[0137] Low resistance refers to a state in which the current value specified on the protective switching device could flow.

[0138] 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.

[0139] 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.

[0140] In a second variant of the mechanical disconnect contact unit MK, the neutral conductor also has mechanical contacts, as shown in Figure 1.

[0141] 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:

[0142] -Minimum air gap according to standard (minimum distance between contacts),

[0143] - (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,

[0144] meant.

[0145] 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.

[0146] 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.

[0147] 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 in the context of air for impulse voltage resistance (see page 202422268).

[0148] 15

[0149] This depends on the degree of pollution. The impulse voltage withstand capability is the resistance to being subjected to a corresponding impulse voltage. Only if this minimum length (minimum distance) is present does the isolating contact unit or protective switching device exhibit an isolating function (isolating property).

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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.

[0154] The term "mechanical isolating contact unit" specifically does not refer to a relay contact.

[0155] Furthermore, a (especially wireless or cableless) communication unit COM is provided, which is connected to or part of the control unit SE.

[0156] 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.

[0157] Figure 2 shows a representation according to Figure 1, with the difference that the protective switching device according to Figure 1 is shown in a simplified form. Furthermore, the measured value processing according to the invention is shown in more detail. A first measured value processing unit MA1, comprising a first current measuring range, is provided, which is connected on the one hand to the first current sensor unit SI1 and on the other hand to the control unit SE, so that

[0158] 16

[0159] A first current signal with a first processed current amplitude is transmitted from the first signal processing unit MA1 to the control unit SE. Furthermore, a second signal processing unit MA2, comprising a second current measuring range, is provided. This second signal is connected to the first current sensor unit SI1 on one side and to the control unit SE on the other, so that a second current signal with a second processed current amplitude is transmitted from the second signal processing unit MA2 to the control unit SE. The protective switching device is designed such that a difference between the first processed current amplitude and the second processed current amplitude is determined. The magnitude of this difference is compared with a first threshold value, and if this threshold is exceeded: a) information is signaled, or (and)

[0160] b) initiates the prevention of a current flow.

[0161] The first threshold can, for example, be larger (or slightly higher) than the sum of the measurement tolerances of the two signal processing units, including the current sensor unit(s). If the measurement tolerances are, for example, 1 mA per signal processing unit, a difference of 2 mA would still be within the margin of error. With a threshold of approximately 3 or 4 mA for the difference between the two current measurements, a deviation in one of the two current measurements can then be detected early. Larger thresholds of 5, 6, ... or 10 mA are also possible, depending on whether the fault diagnosis needs to be robust (i.e., a larger threshold) or more sensitive (i.e., a smaller threshold).

[0162] Figure 3 shows a representation according to Figure 2, with the difference of a further embodiment of the measured value processing. In Figure 3, a second current sensor unit SI2 is provided, in particular in the phase conductor L, for determining the magnitude of a current in the at least two conductors of the low-voltage AC circuit connected to the protective switching device. Instead of the first current sensor unit SI1, the second measured value processing unit MA2 is connected to the second current sensor unit SI2.

[0163] This means that the current, for example in the phase conductor, is determined by the first and second current sensor units. The measured current level is then fed to the first and second signal conditioning units, respectively, which forward this current level to the control unit (SE). The protective switching device or the control unit determines a difference (deviation) between the first processed current level and the second processed current level. If the magnitude of the difference (deviation) is greater than a first threshold value, a) information is signaled, or b) current flow is prevented.

[0164] 17

[0165] The second current sensor unit SI2 can, for example, be implemented using the second voltage sensor unit SUB. This allows the voltage across the electronic interrupt unit EU to be used as a second current measurement signal. The voltage (with a low-resistance (conducting) interrupt unit) is proportional to the current (and the temperature of the semiconductor-based switching elements (power semiconductors)) and can be used to determine the current magnitude.

[0166] The first measurement processing stage, MA1, can, for example, perform (precise) measurement processing at relatively low currents. The second measurement processing stage, MA2, can, for example, perform a second measurement processing stage, MA2, at relatively high currents.

[0167] The signal conditioning circuit, for example, is essentially an analog electronic circuit that adapts very small electrical signals, usually electrical voltages (or currents) in the millivolt range of, for example, 10mV, 50mV, 100mV, 500mV, to electrical signals that match the input voltage range of subsequent components or...

[0168] Units such as analog-to-digital converters with, for example, 1V, 3V, 5V, or 12V outputs are compatible. The signal processing is therefore an analog adjustment of the electrical levels of the measured values ​​acquired by the current sensor unit.

[0169] These analog adjustments of electrical signals or levels always have an upper and a lower signal or level limit. Measured values, or their electrical signal or level, above or below these limits are therefore no longer correctly recorded. The area between these limits is typically called the (current) measurement range, i.e., the range in which the determined or measured value, e.g., current or voltage, can be recorded.

[0170] A first measurement processing stage, MA1, can, for example, have a smaller measuring range of, say, + / -30A, and thus still detect small currents below 1A with low measurement tolerance and high accuracy. However, large currents exceeding 30A cannot be accurately detected with this stage. For this purpose, a second measurement processing stage, MA2, can be provided, whose (current) measuring range is a multiple (e.g., 2, 3, 4, 5, 10, 20 times) of the first current measuring range. For example, the measuring range of the second measurement processing stage, MA2, can be + / -200A. Large currents of up to 200A can be detected with this stage; however, this measurement acquisition stage, MA2, has a significantly larger measurement tolerance (i.e., a measurement error) at small currents than the measurement processing stage MA1 with its smaller measuring range.

[0171] 18

[0172] This combination of two measurement processing methods has the advantage that a large measurement range is available and at the same time high measurement accuracy is achieved for small measured values ​​or their levels or signals.

[0173] Advantageously, the method of preventing current flow (by a user at the protective switching device) is configurable. Current flow can be prevented by a high-resistance state of the switching elements of the electronic interruption unit (EU). After current flow has been prevented by a high-resistance state of the switching elements of the electronic interruption unit (EU), the switching capability to a low-resistance state of the switching elements may be blocked.

[0174] Current flow can be prevented by leaving the contacts of the mechanical isolating contact unit MK in an open state. However, after preventing current flow by leaving the contacts of the mechanical isolating contact unit MK in an open state, the contacts may be blocked from switching to a closed state ("permanent slippage").

[0175] The invention is described in more detail below, partly using different words.

[0176] 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:

[0177] • Non-triggering

[0178] • False triggering

[0179] • Undesirable changes in the tripping characteristic of the protective switching device (the upward shift of the current-time characteristic is particularly critical).

[0180] 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.

[0181] The present invention allows defects in determining the current level to be detected in order to increase safety.

[0182] Two modules (measurement processing 1 and 2) are used to subsequently relate the current measurements (current magnitude) to each other. The dual implementation of the measurement processing provides (partial) redundancy for the current measurement in the 202422268.

[0183] 19

[0184] A protective switching device is present. If both current signals deliver different current levels, this may indicate a defect in one of the two current measurements or...

[0185] The measured value processing is available. The protective switching device can initiate steps that put the protective switching device into a safe state.

[0186] For intact assemblies, the difference between the measured values ​​is at most approximately the sum of the measurement tolerances of the two data processing systems, including the current sensor units. If this difference is greater, a fault condition can be detected according to the invention.

[0187] It can be advantageous to design the measurement processing units for different current ranges. One measurement processing unit can then cover a large current range (measuring range), while the other has higher precision in a smaller current range (e.g., at lower currents). In this case, for example, the fault detection according to the invention can then be performed if at least one of the measured values ​​lies within the first and second current measuring ranges (the two current measuring ranges).

[0188] (Outside the current measurement range, the respective measurement is not used, for example.)

[0189] When a fault condition occurs, the current flow can be prevented by the contacts becoming high-resistance and / or opening.

[0190] 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

202422268 20 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) 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 (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) connected to the mechanical disconnect 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 a first measurement processing unit (MA1) having a first current measurement range is provided, which is connected on the one hand to the first current sensor unit (SI1) and on the other hand to the control unit (SE), so that a first current signal with a first processed level of current is transmitted from the first measurement processing unit (MA1) to the control unit (SE), - that a second measurement processing unit (MA2) with a second current measurement range is provided, which is connected on the one hand to the first current sensor unit (SI1) and on the other hand to the control unit (SE), so that a second current signal with a second processed current level is transmitted from the second measurement processing unit (MA2) to the control unit (SE), that the protective switching device is designed in such a way that a difference between the first conditioned level of the current and the second conditioned level of the current is determined, 202422268 21 that the amount of the difference is compared with a first threshold and, if this threshold is exceeded: a) information is signaled, or b) an avoidance of current flow is initiated.

2. Protective switching device (SG) according to claim 1, characterized by that the prevention of current flow is achieved through a high-resistance state of the switching elements of the electronic interruption unit (EU).

3. Protective switching device (SG) according to claim 2, characterized by that after the current flow is prevented by a high-resistance state of the switching elements of the electronic interruption unit (EU), the switching capability to a low-resistance state of the switching elements is blocked.

4. Protective switching device (SG) according to claim 1 , characterized by that the prevention of current flow is achieved by an open state of the contacts of the mechanical isolating contact unit (MK).

5. Protective switching device (SG) according to claim 4, characterized by that after preventing current flow by means of an open state of the contacts of the mechanical isolating contact unit (MK), the switching of the contacts to a closed state is blocked.

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, 202422268 22 that an optical display unit is provided which is connected to the control unit (SE) such that the signaling of the 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 information takes place through communication, in particular wireless / cableless communication.

9. Protective switching device (SG) according to one of the preceding patent claims, characterized by that a second current sensor unit (SI2) is provided for determining the magnitude of a current of the at least two conductors of the low-voltage alternating current circuit connected to the protective switching device, which is connected to the second measured value processing unit (MA2) in place of the first current sensor unit (SI1).

10. Protective switching device (SG) according to one of the preceding patent claims, characterized by that the second current measuring range is a multiple of the first current measuring range.

11. Method for a 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) 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 (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,202422268 - 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) connected to the mechanical disconnect 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 a first measurement processing unit (MA1) having a first current measurement range is provided, which is connected on the one hand to the first current sensor unit (SI1) and on the other hand to the control unit (SE), so that a first current signal with a first processed level of current is transmitted from the first measurement processing unit (MA1) to the control unit (SE), - that a second measurement processing unit (MA2) with a second current measurement range is provided, which is connected on the one hand to the first current sensor unit (SI1) and on the other hand to the control unit (SE), so that a second current signal with a second processed current level is transmitted from the second measurement processing unit (MA2) to the control unit (SE), that the protective switching device is designed in such a way that a difference between the first conditioned level of the current and the second conditioned level of the current is determined, that the amount of the difference is compared with a first threshold value and if this threshold is exceeded: a) information is signaled, or b) an avoidance of current flow is initiated.

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