Protection switching device and method

Abstract

The invention relates to a protective switching device (SG) for protecting a multi-phase low-voltage alternating current circuit, comprising:-series connections of mechanical phase contacts (K1, K2, K3) and electronic switches (S1, S2, S3), each series connection electrically connecting a network-side phase connection (LG1, LG2, LG3) to a load-side phase connection (LL1, LL2, LL3); the mechanical phase contacts (K1, K2, K3) can be switched to open together to avoid a current flow or to close together for the current flow, the electronic switch (S1, S2, S3) can be switched by means of the semiconductor-based switching element into a high-resistance state of the switching element to avoid a current flow or into a low-resistance state of the switching element for the current flow, the electronic switches can be switched independently of one another into a high-resistance state or a low-resistance state to avoid or enable current flow depending on the phase conductors.

Description

Technical Field

[0001] The present invention relates to the technical field of protective switching devices for low-voltage circuits with electronic switches and a method for a protective switching device for a low-voltage circuit with an electronic switch. Background Art

[0002] Low voltage refers to an alternating voltage up to 1000 volts or a direct voltage up to 1500 volts. Low voltage especially refers to a voltage greater than a small voltage, and the value of the small voltage is 50 volts alternating voltage or 120 volts direct voltage.

[0003] A low-voltage circuit or a low-voltage power grid or a low-voltage system refers to a circuit with a rated current or a nominal current up to 125 amperes, more particularly up to 63 amperes. A low-voltage circuit especially refers to a circuit with a rated current or a nominal current up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The mentioned current values especially refer to the rated current, the nominal current or / and the breaking current, that is, the maximum current that is normally conducted through the circuit, or the current at which the circuit is usually interrupted, for example, interrupted by a protection device such as a protective switching device or a line protection switch or a circuit breaker. The rated current can be further classified, 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.

[0004] A line protection switch is an overcurrent protection device that has been known for a long time and is used in low-voltage circuits in electrical installation technology. The line protection switch protects the line from damage caused by overheating due to excessive current and / or short circuit. The line protection switch can automatically turn off the circuit in case of overload and / or short circuit. The line protection switch is a non-automatic reset fuse element.

[0005] Different from the line protection switch, the current of a circuit breaker is set to be greater than 125 amperes and, in some cases, also starts from 63 amperes. Therefore, the structure of the line protection switch is simpler and more delicate. The line protection switch usually has the following fixing possibilities, that is, fixing on a so-called top-hat rail (support rail, DIN rail, TH35).

[0006] The line protection switch adopts an electromechanical structure. In the housing, they have mechanical switch contacts or working current triggers for interrupting (triggering) the current. Usually, a bimetal protection element or a bimetal element is used to trigger (interrupt) in case of long-term overcurrent (overcurrent protection) or thermal overload (overload protection). An electromagnetic trigger with a coil is used to trigger briefly in case of exceeding the overcurrent limit value or in case of a short circuit (short-circuit protection). One or more arc extinguishing chambers or devices for arc extinguishing are provided. In addition, connection elements for the conductors of the circuit to be protected are provided.

[0007] Protective switching devices with an electronic interruption unit or an electronic switch are a relatively recent development. The protective switching device has a semiconductor-based electronic interruption unit / electronic switch. That is, the current in the low-voltage circuit is guided through a semiconductor device or a semiconductor switch, which can interrupt the current or switch to a conductive state. The protective switching device with an electronic interruption unit / electronic switch also usually has a mechanical separating contact system, which has separating characteristics especially according to the relevant standards of the low-voltage circuit, wherein the contacts of the mechanical separating contact system are connected in series to the electronic interruption unit / electronic switch, that is, the current in the low-voltage circuit to be protected is guided both through the mechanical separating contact unit and through the electronic interruption unit.

[0008] The invention particularly relates to a low-voltage alternating current circuit, which has an alternating voltage, which usually has a time-dependent sinusoidal alternating voltage with a frequency f. The time dependence of the instantaneous voltage value u(t) of the alternating voltage is described by the following equation:

[0009] u(t) = U * sin(2π * f * t)

[0010] where:

[0011] u(t) = the instantaneous voltage value at time t

[0012] U = the amplitude of the voltage

[0013] The harmonic alternating voltage can be represented by the rotation of a pointer, the length of the pointer corresponding to the amplitude (U) of the voltage. Here, the instantaneous deflection is the projection of the pointer on the coordinate system. The oscillation period corresponds to a full rotation of the pointer, and its full angle is 2π (2Pi) or 360°. The angular frequency is the rate of change of the phase angle of this rotating pointer. The angular frequency of a harmonic oscillation is always 2π times its frequency, that is:

[0014] ω = 2π * f = 2π / T = the angular frequency of the alternating voltage (T = the period duration of the oscillation)

[0015] The description of the angular frequency (ω) is usually preferred over the frequency (f) because many vibration theory formulas can be represented more compactly with the help of the angular frequency due to the occurrence of trigonometric functions, which, by definition, have a period of 2π:

[0016] u(t) = U * sin(ωt)

[0017] In the case of an angular frequency that is not constant in time, the term instantaneous angular frequency is also used.

[0018] In the case of a sinusoidal, especially time-constant alternating voltage, the time-dependent value according to the angular velocity ω and the time t corresponds to the time-dependent angle This angle is also called the phase angle

[0019] That is, the phase angle periodically passes through the range of 0...2π or 0°...360°. That is, the phase angle periodically assumes values between 0 and 2π or 0° and 360° ( or due to periodicity; abbreviated as: or ).

[0020] Therefore, the instantaneous voltage value u(t) refers to the instantaneous value of the voltage at the time point t, i.e., in the case of a sinusoidal (periodic) alternating voltage, it refers to the voltage value with respect to the phase angle ( or for the corresponding period). The same applies to the instantaneous current value i(t), etc. SUMMARY OF THE INVENTION

[0021] The technical problem to be solved by the present invention is to improve the protection switch device of the type mentioned above, in particular to present a new concept for a multi-phase protection switch device and to enable greater flexibility of the multi-phase protection switch device.

[0022] The above technical problem is solved by a protection switch device having the features of claim 1 and by a method according to claim 17.

[0023] According to the present invention, there is provided a protection switch device for protecting a multi-phase low-voltage alternating current circuit, in particular a three-phase alternating current circuit, having:

[0024] - a housing having a grid-side phase connection and a load-side phase connection (a connection for connecting an external conductor to the housing) for the phase conductors of the low-voltage alternating current circuit,

[0025] - a series circuit of mechanical phase contacts and electronic switches,

[0026] wherein each series circuit electrically connects one of the grid-side phase connections to one of the load-side phase connections respectively,

[0027] - the mechanical phase contacts can be switched to open together to avoid current flow or switched to close together for current flow, in particular the mechanical contacts are connected to each other by mechanical coupling,

[0028] - the electronic switches can be switched to a high-resistance state of the switching element to avoid current flow or switched to a low-resistance state of the switching element for current flow by means of semiconductor-based switching elements,

[0029] - the electronic switches can be switched to a high-resistance state or a low-resistance state independently of each other.

[0030] This has the advantage that the phase conductors can be switched to the high-resistance state or the low-resistance state independently of one another. So far, protective switching devices, especially the widely used classical electromechanical protective switching devices (line protective switches, circuit breakers, residual current protective switches), do not have this possibility because there the mechanical separating contact units open or close all contacts simultaneously (multipole devices).

[0031] This gives the protective switching device greater flexibility and more flexible switching characteristics.

[0032] Further advantageous embodiments of the invention are given in the dependent claims and the embodiments.

[0033] In an advantageous embodiment of the invention, a current sensor unit is provided for each series circuit respectively, for correspondingly determining the magnitude of the current of the corresponding phase conductor. In particular, the instantaneous current value is present (and determined).

[0034] In an advantageous expansion thereof, a control unit is provided, which is connected to the current sensor unit, the mechanical phase contacts and the electronic switches. When at least one current threshold in the conductor is exceeded, the avoidance of the current flow of the conductor concerned, in particular the avoidance of the current flow for a first time period, is initiated by the electronic switch concerned.

[0035] This has the particular advantage that when a specified current threshold or current-time threshold is exceeded (i.e., when the current threshold is exceeded within a defined time period), only the conductor (or the plurality of conductors) concerned is selectively interrupted. Furthermore, current flow can still be achieved in the other conductors (the conductors not concerned) in a polyphase low-voltage AC circuit.

[0036] By avoiding for a first time period, it is advantageously switched on again or to the low-resistance state again after the first time period, thereby further ensuring the power supply safety or it can be further checked whether the current threshold is exceeded. This is advantageously carried out, in particular, by evaluating the instantaneous value of the current magnitude.

[0037] In an advantageous embodiment of the invention, the first time period is less than 20 ms, especially less than 10 ms.

[0038] This has the particular advantage that for a half-wave or full-wave of the voltage or current in an AC circuit, in this example (20 ms, 10 ms) with respect to the grid frequency of 50 Hz, the interruption is carried out, thereby providing power supply safety again using the next full-wave or half-wave. In particular, it is possible to switch to the low-resistance state in the region of the next zero crossing (in the zero crossing, or in the region 1 ms before or after it) after the interruption.

[0039] In an advantageous embodiment of the present invention, the protective switching device is designed such that when at least one second current threshold value, in particular the effective value, in at least one phase conductor (or two phase conductors, in particular three phase conductors) is exceeded for at least a first time period, the avoidance of current flow is initiated by opening the contact. The second current threshold value can advantageously be numerically higher than the first current threshold value.

[0040] The first time period can be less than 100 ms, 20 ms, in particular less than 10 ms.

[0041] This has the particular advantage that if one or more electronic switches remain in a faulty low resistance and thus exceed the second current threshold value, the avoidance of current flow in the low-voltage AC circuit is initiated, and thus the safety of the circuit is improved.

[0042] In an advantageous embodiment of the present invention, the mechanical phase contact is part of a mechanical separating contact unit that opens or closes the phase contacts together. In particular, the mechanical separating contact unit has a handle that is accessible on the protective switching device for manually opening or closing the phase contacts (of the mechanical separating contact unit).

[0043] This has the particular advantage that, in contrast to the phase-related avoidance of current flow in the electronic switch becoming high resistance, complete current isolation of all phase conductors is achieved simultaneously. Compatibility characteristics according to classical electromechanical protective switching devices can be achieved via the handle.

[0044] In an advantageous embodiment of the present invention, the protective switching device is designed such that the mechanical separating contact unit can be opened by the control unit, but cannot be closed. In particular, the mechanical separating contact unit can be closed by the handle only after being released by the control unit.

[0045] This has the particular advantage that the safety of the protective switching device is improved because the control unit does not accidentally (erroneously) close the contacts.

[0046] In an advantageous embodiment of the present invention, the electronic switch is part of an electronic interruption unit, where the electronic switches can be switched independently of each other.

[0047] This has the particular advantage that a compact electronic interruption unit is provided that combines the electronic switches, enabling a space-saving design and utilization of the synergistic effects of the components.

[0048] In an advantageous embodiment of the present invention, the electronic interruption unit / electronic switch has a bidirectional voltage withstand strength. In particular, overvoltage protection is provided for semiconductor-based switching elements.

[0049] This has the particular advantage that it provides robustness against overvoltages and can interrupt the induced line circuit.

[0050] In an advantageous embodiment of the invention, the mechanical phase contacts are associated with the load-side phase connectors, and the electronic switches are associated with the grid-side phase connectors.

[0051] This has the particular advantage that it provides an advantageous design that supports phase-related switching of the electronic switches and enables self-testing (in particular self-testing of the electronic switches or the electronic interruption unit) even when the contacts are open. In addition, the energy supply of the protective switching device is ensured even when the contacts are open.

[0052] In an advantageous embodiment of the invention, the protective switching device has at least the following switching states:

[0053] - All mechanical phase contacts are open, and all electronic switches are in a high-impedance state.

[0054] - All mechanical phase contacts are closed, and all electronic switches are in a low-impedance state.

[0055] - All mechanical phase contacts are closed, and all electronic switches are in a high-impedance state.

[0056] - All mechanical phase contacts are closed, one electronic switch is in a low-impedance state, and the other electronic switches are in a high-impedance state.

[0057] - All mechanical phase contacts are closed, one electronic switch is in a high-impedance state, and the other electronic switches are in a low-impedance state.

[0058] In another advantageous embodiment of the invention, the protective switching device has at least the following switching states:

[0059] - All mechanical phase contacts are closed, a part of the electronic switches is in a low-impedance state, and another part of the electronic switches is in a high-impedance state.

[0060] In another advantageous embodiment of the invention, the protective switching device has at least the following switching states:

[0061] - All mechanical phase contacts are open, a part of the electronic switches is in a low-impedance state, and another part of the electronic switches is in a high-impedance state.

[0062] In particular, two electronic switches are in a low-impedance state, while another (additional) electronic switch is in a high-impedance state.

[0063] Alternatively or additionally, the protective switching device has the following switching state:

[0064] - All mechanical phase contacts are open, and all electronic switches are in a low-impedance state.

[0065] In particular, when measuring resistors R12, R13, and R23 are provided between the phase conductors, these switching states are provided. For this purpose, in one design, measuring resistors are provided between L1 and L2, between L2 and L3, and between L1 and L3.

[0066] These switching states are advantageously intended to check whether the electronic switches can be turned on or off. This means that when the mechanical phase contacts are open, the electronic switches are briefly turned on or off in order to check functionality (with respect to turn-on ability or ( / and) turn-off ability). Here, the measuring current flows through the corresponding measuring resistors.

[0067] In an advantageous design of the invention, in which the polyphase low-voltage AC circuit is a three-phase low-voltage AC circuit, that is to say, in which first, second, and third electronic switches are provided, a solution for a classical three-phase power grid is advantageously provided, and the protective switching device has at least the following switching states:

[0068] - All mechanical phase contacts are open and all electronic switches are high impedance.

[0069] - All mechanical phase contacts are closed and all electronic switches are low impedance.

[0070] - All mechanical phase contacts are closed and all electronic switches are high impedance.

[0071] - All mechanical phase contacts are closed, the first electronic switch is low impedance, and the second and third electronic switches are high impedance.

[0072] - All mechanical phase contacts are closed, the second electronic switch is low impedance, and the first and third electronic switches are high impedance.

[0073] - All mechanical phase contacts are closed, the third electronic switch is low impedance, and the first and second electronic switches are high impedance.

[0074] In another advantageous design of the invention, in which the polyphase low-voltage AC circuit is a three-phase low-voltage AC circuit, that is, in which first, second, and third electronic switches are provided, the protective switching device has at least the following switching states:

[0075] - All mechanical phase contacts are open and all electronic switches are high impedance.

[0076] - All mechanical phase contacts are closed and all electronic switches are low impedance.

[0077] - All mechanical phase contacts are closed and all electronic switches are high impedance.

[0078] - All mechanical phase contacts are closed, the first and second electronic switches are low impedance, and the third electronic switch is high impedance.

[0079] - All mechanical phase contacts are closed, the first and third electronic switches are of low resistance, and the second electronic switch is of high resistance.

[0080] - All mechanical phase contacts are closed, the second and third electronic switches are of low resistance, and the first electronic switch is of high resistance.

[0081] Advantageous design solutions regarding the switch states or their combinations have the particular advantage that a new switch state for protecting the switching device is provided, so as to react to overcurrent conditions (short-circuit current conditions) separately and more flexibly. Thus, it does not react to the interruption of all phases, but can act in a phase-related manner, thereby achieving higher power supply security in low-voltage circuits.

[0082] In an advantageous design solution of the present invention, a grid-side neutral conductor connection and a load-side neutral conductor connection are provided for the neutral conductor of a multi-phase low-voltage AC circuit.

[0083] The grid-side neutral conductor connection is directly or connected to the load-side neutral conductor connection through a neutral contact.

[0084] This has the particular advantage that a multi-pole protection switching device is provided, in which the neutral conductor can also be interrupted by current.

[0085] In an advantageous design solution of the present invention, the mechanical neutral conductor contact can be opened or closed together with the phase contacts. In particular, the neutral conductor contact is closed before the phase contacts are closed, or the neutral conductor contact is opened after the phase contacts are opened.

[0086] This has the particular advantage that the neutral conductor contact is always opened and closed without current. This reduces the wear of the contacts and extends the service life. In addition, this can avoid the occurrence of arcs when the neutral conductor contact is opened.

[0087] In an advantageous design solution of the present invention, voltage sensor units are respectively arranged between each phase conductor and the neutral conductor for determining the magnitude of the voltage between the corresponding phase conductor and the neutral conductor, especially the instantaneous voltage value. The voltage sensor units are connected to a control unit.

[0088] In an advantageous expansion of this implementation design solution, the protection switching device is designed such that in the case of being switched to low resistance by the control unit (especially in the absence of an overcurrent event, that is, if the first or second current threshold is not exceeded; for example, when being switched to low resistance at the user side, (all) the electronic switches are switched to low resistance in sequence for the corresponding zero-crossing of the voltage (or when the voltage is less than 50V, 25V, especially less than 10V).

[0089] This has the particular advantage that the influence of grid feedback is reduced and the turn-off load in the switch is lower.

[0090] In an advantageous embodiment of the invention, the protective switching device is designed such that, when switching to the high-impedance state is initiated by the control unit (in particular in the absence of an overcurrent event, i.e. if the first or second current threshold is not exceeded; for example, when switching to the high-impedance state is initiated on the user side), all the electronic switches sequentially switch to the high-impedance state at the corresponding zero-crossing of the voltage (or at a voltage below 50 V, 25 V, in particular below 10 V).

[0091] This has the particular advantage that the grid feedback effect is reduced and the switching-off load in the switches is lower.

[0092] In an advantageous embodiment of the invention, the protective switching device is designed such that, when at least the first current threshold in the conductor is exceeded, the current flow in the conductor concerned is prevented by the electronic switch concerned. When the voltage crosses zero for the next or subsequent time, the electronic switch switches back to the low-impedance state to enable current flow. The control unit is connected here to a current sensor unit, a voltage sensor unit, mechanical phase contacts and the electronic switches.

[0093] This has the particular advantage that enhanced robustness against false triggering is achieved and thus enhanced power supply security is achieved.

[0094] According to the invention, a corresponding method (method claim) for a protective switching device for low-voltage circuits having electronic (semiconductor-based) switches / switching elements is claimed, which has the same and other advantages.

[0095] The method for a protective switching device (SG) for protecting a multi-phase low-voltage AC circuit has:

[0096] - a series circuit of mechanical phase contacts and electronic switches,

[0097] wherein each series circuit electrically connects a grid-side phase connection to a load-side phase connection respectively,

[0098] - the mechanical phase contacts can be switched together to open to prevent current flow or switched together to close for current flow,

[0099] - the electronic switches can be switched by means of semiconductor-based switching elements into the high-impedance state of the switching elements to prevent current flow, or into the low-impedance state of the switching elements for current flow,

[0100] The electronic switches can be switched into the high-impedance state or the low-impedance state independently of one another in order to advantageously prevent or enable current flow depending on the phase conductors.

[0101] Advantageously, the magnitude of the current in the respective series circuit is determined, and when at least one current threshold in the series circuit is exceeded, the avoidance of the current flow in the involved series circuit, in particular the avoidance of the current flow for a first time period, is initiated by the involved electronic switch.

[0102] All embodiments, not only in the form of dependent claims referring to claim 1 or 17, but also referring to the individual features or combinations of features of the claims, in particular the reference of the device claims to be processed to the independent method claims, have achieved improvements in protecting switchgear, in particular an increase in the flexibility of protecting switchgear and an increase in the power supply safety of the circuit, and have provided a new solution for protecting switchgear. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] The characteristics, features and advantages of the described invention and the implementation thereof will become clearer and easier to understand in conjunction with the following description of the embodiments, and the embodiments will be described in detail with reference to the drawings.

[0104] Here, in the drawings:

[0105] Figure 1 A first illustration of a protective switchgear is shown,

[0106] Figure 2 A second illustration of a protective switchgear is shown,

[0107] Figure 3 A third illustration of a protective switchgear is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0108] Figure 1 An exemplary illustration of a 3-pole (for example, for three-phase conductors) protective switchgear SG for protecting a polyphase low-voltage AC circuit (a three-phase low-voltage AC circuit in the example according to Figure 1 is shown, and the protective switchgear SG has:

[0109] - A housing GEH, having first, second, and third grid-side phase connections LG1, LG2, LG3 and first, second, and third load-side phase connections LL1, LL2, LL3 for the first, second, and third phase conductors L1, L2, L3 of the low-voltage AC circuit,

[0110] An energy source is usually connected on the grid side Grid,

[0111] An electrical consumer is usually connected on the load side Load.

[0112] In the housing GEH:

[0113] - A first series circuit SS1 of a first mechanical phase contact K1 and a first electronic switch S1,

[0114] The second series circuit SS2 of the second mechanical phase contact K2 and the second electronic switch S2

[0115] The third series circuit SS3 of the third mechanical phase contact K3 and the third electronic switch S3

[0116] Wherein:

[0117] The first series circuit SS1 electrically connects the first grid-side phase connection LG1 to the first load-side phase connection LL1,

[0118] The second series circuit SS2 electrically connects the second grid-side phase connection LG2 to the second load-side phase connection LL2, and

[0119] The third series circuit SS3 electrically connects the third grid-side phase connection LG3 to the third load-side phase connection LL3,

[0120] - The mechanical phase contacts K1, K2, K3 can be switched together, i.e., they open together to avoid current flow or close together for current flow, i.e., the mechanical contacts are connected to each other by mechanical coupling (e.g., a switch shaft).

[0121] - The electronic switches S1, S2, S3 can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching element to avoid current flow or into a low-resistance state of the switching element for current flow.

[0122] According to the invention, the first, second and third electronic switches can be switched into a high-resistance state or a low-resistance state independently of each other. This means that the first, second and third electronic switches are switched into a high-resistance state or a low-resistance state independently of each other. In particular, current flow depending on the phase conductors can be avoided or achieved.

[0123] According to Figure 1 , there are provided first, second and third current sensor units SI1, SI2, SI3. The first current sensor unit SI1 is provided or arranged in the first series circuit SS1, the second current sensor unit SI2 is provided or arranged in the second series circuit SS2, and the third current sensor unit SI3 is provided or arranged in the third series circuit SS3 for respectively determining the magnitudes of the currents in the first, second and third phase conductors L1, L2, L3, in particular the instantaneous current values.

[0124] According to Figure 1, the first mechanical phase contact K1, the second mechanical phase contact K2, and the third mechanical phase contact K3 are part of a mechanical disconnect contact unit MK, which disconnects or closes the phase contacts K1, K2, and K3 together. The mechanical disconnect contact unit MK may have a handle HH that is accessible on the protective switchgear for manually (operated by a person) disconnecting or closing the phase contacts. The mechanical disconnect contact unit MK corresponds to a classical unit known, for example, from electromechanical protective switchgear (line protective switches, circuit breakers), (however, according to the present invention, there are no elements for overcurrent or short-circuit recognition, such as bimetal trip units, etc.).

[0125] The protective switchgear is designed in particular such that the mechanical disconnect contact unit MK can be disconnected but not closed by the control unit SE. In particular, the mechanical disconnect contact unit MK can only be closed by the handle HH after being released by the control unit SE. For this purpose, a release unit LC can be provided. This means that the handle HH can only close the contacts when a release signal (from the control unit) is present or released. In the absence of a release or release signal, the handle HH can be operated, but the contacts cannot be closed ("Dauerrutscher, continuous slip").

[0126] The release unit LC can also be designed such that the contacts K1, K2, K3 of the mechanical disconnect contact unit MK can be disconnected by a control signal from the control unit SE, as Figure 1 shown by the arrow from the control unit SE to the release unit LC in

[0127] According to Figure 1 , the mechanical phase contacts K1, K2, K3 are associated with the load-side phase connection / load-side Load, and the electronic switches S1, S2, S3 are associated with the grid-side phase connection / grid-side Grid.

[0128] The first electronic switch S1, the second electronic switch S2, and the third electronic switch S3 can be part of an electronic interruption unit EU, where the electronic switches S1, S2, S3 can be switched independently of each other.

[0129] The electronic interruption unit / electronic switch can have a bidirectional voltage withstand strength. In particular, overvoltage protection is provided for semiconductor-based switching elements to limit the voltage and thus protect the semiconductor-based switching elements.

[0130] A control unit SE is provided (as already partially mentioned), which is connected to the current sensor units SI1, SI2, SI3, the mechanical phase contacts (K1, K2, K3) or the mechanical disconnect contact unit MK (as Figure 1 shown) and the electronic switches S1, S2, S3.

[0131] Current sensor units SI1, SI2, SI3 respectively determine the magnitude of the current in their respective conductors such that in particular the instantaneous value of the current exists.

[0132] When at least one first current threshold in the conductor is exceeded, the avoidance of the current flow in the involved conductor is initiated by making the electronic switch become high-impedance.

[0133] The high impedance can in particular persist for a first time period. After this time period, the involved electronic switch can become low-impedance again.

[0134] Becoming low-impedance can in particular occur at the next zero-crossing of the voltage or before or after the zero-crossing. (All 3 options: at the zero-crossing, before the zero-crossing or after the zero-crossing are possible, or when numerically below a voltage threshold, in particular 50 V, 25 V or 10 V).

[0135] The first time period can in particular be less than 20 ms, especially less than 10 ms.

[0136] As Figure 1 shown, a differential current sensor unit ZCT can be provided for collecting the differential current of a low-voltage AC circuit, such as known from a fault current protection switch. The differential current sensor unit ZCT is connected to the control unit SE.

[0137] In the example according to Figure 1 the current sensor units SI1, SI2, SI3 are arranged between the grid-side connectors LG1, LG2, LG3 of the series circuit of the electronic switches S1, S2, S3 and the mechanical phase contacts K1, K2, K3. Specifically, they are arranged between the grid-side connectors LG1, LG2, LG3 and the electronic switches S1, S2, S3. The current sensor units SI1, SI2, SI3 can also be arranged in other ways. For example, between the electronic switches S1, S2, S3 and the mechanical phase contacts K1, K2, K3.

[0138] Figure 2 Shows a diagram according to Figure 1 with the following differences.

[0139] For the neutral conductor N of a polyphase low-voltage AC circuit, a grid-side neutral conductor connector NG and a load-side neutral conductor connector NL are provided. The polyphase low-voltage AC circuit is a three-phase low-voltage AC circuit with a neutral conductor in the example according to Figure 2 According to Figure 2 the grid-side neutral conductor connector NG is connected to the load-side neutral conductor connector NL through the neutral conductor contact KN.

[0140] Alternatively, the grid-side neutral conductor connector NG can also be directly (i.e., without a switchable contact) connected to the load-side neutral conductor connector NL.

[0141] In this example, no electronic switch is provided in the neutral conductor path within the housing of the protective switching device. This means that there is no electronic switch (no electronic switch) in the neutral conductor connection between the grid-side neutral conductor connection NG and the load-side neutral conductor connection NL.

[0142] The mechanical neutral conductor contact KN can advantageously be switched together with the phase contacts K1, K2, K3. This means that the mechanical neutral conductor contact KN can be opened or closed together with the phase contacts K1, K2, K3, as implemented above for the contacts K1, K2, K3.

[0143] In particular, the mechanical disconnecting contact unit MK can be designed such that the neutral conductor contact KN closes before the phase contacts K1, K2, K3 close. Similarly, the neutral conductor contact KN can open after the phase contacts K1, K2, K3 open.

[0144] Furthermore, an energy supply device NT, such as a power supply, is provided for supplying energy to the protective switching device SG, in particular to the control unit SE.

[0145] In this example, the energy supply device NT is connected on the one hand to the phase conductors L1, L2, L3 and (if necessary) to the neutral conductor N. It can also be connected to only a part of the conductors (at least two) to supply energy. In this example, the energy supply device NT is connected on the other hand to the control unit SE.

[0146] On the other hand, the control unit SE is combined with the electronic switches S1, S2, S3 and the current sensor units SI1, SI2, SI3, as Figure 2 shown.

[0147] In addition, voltage sensor units are respectively provided between each phase conductor and the neutral conductor. A first voltage sensor unit SU1 is provided between the first phase conductor L1 and the neutral conductor N, a second voltage sensor unit SU2 is provided between the second phase conductor L2 and the neutral conductor N, and a third voltage sensor unit SU3 is provided between the third phase conductor L3 and the neutral conductor N for determining the magnitude of the voltage between the respective phase conductor and the neutral conductor, in particular the presence of an instantaneous voltage value. The voltage sensor units SU1, SU2, SU3 are connected to the control unit SE.

[0148] In the case of activation to low resistance by the control unit SE, the electronic switches S1, S2, S3, for example:

[0149] - when activated to low resistance on the user side, or

[0150] - In the case of activation to low resistance via the protective switching device, especially in the absence of an overcurrent event (i.e., if neither the first nor the second current threshold is exceeded), for example if the internal inspection function (for internal inspection) of the protective switching device activates to low resistance,

[0151] => The electronic switches can advantageously become low resistance in sequence at the corresponding zero crossings of the voltage.

[0152] In the case of activation to high resistance via the control unit SE, the electronic switches S1, S2, S3, for example:

[0153] - When activation to high resistance is initiated on the user side, or

[0154] - In the case of activation to high resistance via the protective switching device, especially in the absence of an overcurrent event (i.e., if neither the first nor the second current threshold is exceeded), for example if the internal inspection function (for internal inspection) of the protective switching device activates to high resistance,

[0155] => The electronic switches can advantageously become high resistance in sequence at the corresponding zero crossings of the voltage.

[0156] For this purpose, as already mentioned, the voltage sensor units SU1, SU2, SU3 are connected to the control unit SE, which is also connected to the current sensor units SI1, SI2, SI3, the mechanical phase contacts K1, K2, K3 (or the mechanical disconnection contact unit MK) and the electronic switches (S1, S2, S3). The protective switching device can also advantageously be designed such that, when at least the first current threshold (especially the instantaneous value of the current) in the conductor is exceeded, the flow of current in the involved conductor is avoided by activating the involved electronic switches. When the voltage crosses zero the next or subsequent time, the electronic switches become low resistance again so that current flow can be achieved.

[0157] This can be done multiple times until the first repetition count is exceeded. Then it is possible to:

[0158] a) All the electronic switches become high resistance, or ( / and)

[0159] b) The contacts are opened (current isolation).

[0160] According to Figure 1 and Figure 2 Any combination (intermediate combination) of the illustrations of the exemplary protective switching device is possible (e.g., Figure 1 the energy supply device NT from Figure 2 etc.).

[0161] Figure 3 Shows according to Figure 2Illustration, except that the measuring resistors R12, R13, R23 are arranged between the phase conductors within the protective switching device. For this purpose, in one design, a first measuring resistor (or measuring impedance) R12 is arranged between the first phase conductor L1 and the second phase conductor L2, a second measuring resistor (or measuring impedance) R23 is arranged between the second phase conductor L2 and the third phase conductor L3, and a third measuring resistor (or measuring impedance) R13 is arranged between the first phase conductor L1 and the third phase conductor L3.

[0162] Especially in the case of the absence of a neutral conductor (3-pole protective switching device), the switching characteristics of the electronic switches S1, S2, S3 can be checked by means of measuring resistors (which can also be designed as measuring impedances, i.e., can be implemented as a combination of resistors / capacitors and / or inductors, for example), for example by briefly closing (in the μs, ms or smaller second range) the electronic switches in the case of open contacts, where a measuring current corresponding to the measuring resistor (measuring impedance) is provided and can be checked (at the corresponding instantaneous value of the voltage).

[0163] In this example, no (optional) differential current sensor unit ZCT is provided (but it can also be provided).

[0164] High resistance refers to a state in which only a negligibly small current still flows. High resistance especially refers to a resistance value greater than 1 kΩ, preferably greater than 10 kΩ, 100 kΩ, 1 MΩ, 10 MΩ, 100 MΩ, 1 kΩ or greater.

[0165] Low resistance refers to a state in which the current values present on the protective switching device can flow. Low resistance especially refers to a resistance value less than 10 Ω, preferably less than 1 Ω, 100 mΩ, 10 mΩ, 1 mΩ or smaller.

[0166] The electronic switches S1, S2, S3 or the electronic interruption unit EU can have semiconductor devices such as bipolar transistors, field effect transistors (FETs), insulated gate bipolar transistors (IGBTs), metal oxide layer field effect transistors (MOSFETs) or other (self-commutating) power semiconductors. Especially IGBTs and MOSFETs are particularly well-suited for electronic switches (as semiconductor-based switching elements) due to their low on-resistance, high breakdown resistance and good switching characteristics.

[0167] Thus, the protection switch device according to the present invention includes electronic and mechanical components. The reasonable arrangement of all components required for safe operation is a key point. In addition, various switching combinations can be achieved through the combination of electronic switches and mechanical contacts.

[0168] In this example, the protection switch device has three grid-side connectors and three load-side connectors / four grid-side connectors and four load-side connectors respectively. In this example, a 3-pole or 4-pole mechanical disconnecting contact system is included in the device. The contacts are mechanically coupled to each other and can only be opened or closed together.

[0169] There are electronic switches in series with the mechanical contacts in the phase conductors. Different from the mechanical contacts, these electronic switches are switched on or off independently of each other. In addition, a current sensor unit is provided in the phase conductors (not in the neutral conductor N).

[0170] Traditional protection devices, such as 3-pole or 4-pole ones, nowadays (basically) only have two switching states: on or off.

[0171] According to the present invention, additional switching states are proposed in the example of a 3-pole (for example, for three-phase conductors) or 4-pole (for example, for three-phase conductors and a neutral conductor) protection switch device, as shown in the following table.

[0172]

[0173] In addition to the currently known switching states off (OFF), on (ON), there are other states, such as standby, hybrid 1, 2, 3, hybrid 12, 13, 23. In addition, test states (test 1, test 2, test 3, test 4) are provided for the electronic switches.

[0174] Thus, a summary of two-phase or four-phase / multi-phase devices can be achieved.

[0175] Through the new hybrid switching states, the protection switch device can respond to special load conditions or fault conditions in a different way from before. Therefore, the advantage is that in a specific fault condition, only one or two of the included electronic switches are brought into a high impedance (off) state. Even when switching on and off the load, it is also beneficial to perform the following switching sequence, in which only one or two of the included electronic switches are switched on twice.

[0176] Switching on can be carried out, for example, in such a way that the electronic switches are switched on in sequence at the voltage zero crossings (i.e., not at the same time point, but at the corresponding zero crossings of the voltage of the corresponding phase / corresponding phase conductor).

[0177] The switching-off process can be carried out similarly.

[0178] This makes it possible to reduce the grid feedback effect and the turn-off load in switching devices, especially electronic switches.

[0179] Overcurrent events (exceeding the current threshold) can be processed per phase / phase conductor. This can also protect the electronic switches from overload.

[0180] The phase can also be briefly turned off (become high impedance), for example for testing purposes.

[0181] The number of hybrid states or the number of hybrid states occurring per unit time can be counted, and if the limit number is exceeded, all electronic switches can become high impedance (or / and the mechanical contacts can be opened).

[0182] For single-phase consumers, higher availability can be provided (only a fault on one phase, only this phase is turned off, and the other phases continue to operate).

[0183] Thus, as an example of a variant (3-pole or 4-pole), the protective switching device has at least the following switching states:

[0184] -(1) All mechanical phase contacts are open, and all electronic switches are high impedance,

[0185] -(2) All mechanical phase contacts are closed, and all electronic switches are low impedance,

[0186] -(3) All mechanical phase contacts are closed, and all electronic switches are high impedance,

[0187] -(4) All mechanical phase contacts are closed, the first electronic switch is low impedance, and the second and third electronic switches are high impedance,

[0188] -(5) All mechanical phase contacts are closed, the second electronic switch is low impedance, and the first and third electronic switches are high impedance,

[0189] -(6) All mechanical phase contacts are closed, the third electronic switch is low impedance, and the first and second electronic switches are high impedance.

[0190] Thus, as an example of another variant (3-pole or 4-pole), the protective switching device has at least the following switching states:

[0191] -(1) All mechanical phase contacts are open, and all electronic switches are high impedance,

[0192] -(2) All mechanical phase contacts are closed, and all electronic switches are low impedance,

[0193] -(3) All mechanical phase contacts are closed, and all electronic switches are high impedance,

[0194] -(7) All mechanical phase contacts are closed, the first and second electronic switches are low impedance, and the third electronic switch is high impedance,

[0195] -(8) All mechanical phase contacts are closed, the first and third electronic switches are of low resistance, and the second electronic switch is of high resistance.

[0196] -(9) All mechanical phase contacts are closed, the second and third electronic switches are of low resistance, and the first electronic switch is of high resistance.

[0197] Therefore, as an example of another variant (3 - pole or 4 - pole), the protective switching device has the following switching states:

[0198] -(1) All mechanical phase contacts are open, and all electronic switches are of high resistance.

[0199] -(2) All mechanical phase contacts are closed, and all electronic switches are of low resistance.

[0200] -(3) All mechanical phase contacts are closed, and all electronic switches are of high resistance.

[0201] -(4) All mechanical phase contacts are closed, the first electronic switch is of low resistance, and the second and third electronic switches are of high resistance.

[0202] -(5) All mechanical phase contacts are closed, the second electronic switch is of low resistance, and the first and third electronic switches are of high resistance.

[0203] -(6) All mechanical phase contacts are closed, the third electronic switch is of low resistance, and the first and second electronic switches are of high resistance.

[0204] -(7) All mechanical phase contacts are closed, the first and second electronic switches are of low resistance, and the third electronic switch is of high resistance.

[0205] -(8) All mechanical phase contacts are closed, the first and third electronic switches are of low resistance, and the second electronic switch is of high resistance.

[0206] -(9) All mechanical phase contacts are closed, the second and third electronic switches are of low resistance, and the first electronic switch is of high resistance.

[0207] Therefore, as an example, in one variant (especially 3 - pole), the protective switching device further has at least one of the following switching states, the first three (10, 11, 12), or all:

[0208] -(10) All mechanical phase contacts are open, the first and second electronic switches are of low resistance, and the third electronic switch is of high resistance.

[0209] -(11) All mechanical phase contacts are open, the second and third electronic switches are of low resistance, and the first electronic switch is of high resistance.

[0210] -(12) All mechanical phase contacts are open, the first and third electronic switches are of low resistance, and the second electronic switch is of high resistance.

[0211] -(13) All mechanical phase contacts are open, and the first, second, and third electronic switches are of low resistance.

[0212] This means that, generally speaking, the protective switching device has at least the following switching states, for example:

[0213] - All mechanical contacts are open, and all electronic switches are of high resistance.

[0214] - All mechanical contacts are closed, and all electronic switches are of low resistance.

[0215] - All mechanical contacts are closed, and all electronic switches are of high resistance.

[0216] - All mechanical contacts are closed, one of the electronic switches is of low resistance, and the other electronic switches are of high resistance.

[0217] - All mechanical contacts are closed, one of the electronic switches is of high resistance, and the other electronic switches are of low resistance.

[0218] - All mechanical phase contacts are open, a part of the electronic switches is of low resistance, and another part of the electronic switches is of high resistance.

[0219] (In particular, two electronic switches are of low resistance, while the other (one / the other) electronic switch is of high resistance),

[0220] - All mechanical phase contacts are open, and all electronic switches are of low resistance.

[0221] Generally speaking, the protective switching device is characterized by at least the following new switching states, for example:

[0222] - All mechanical (phase) contacts are closed, a part of the electronic switches is of low resistance, and another part of the electronic switches is of high resistance.

[0223] The mechanical contact or the mechanical disconnect contact unit MK particularly refers to the (standard-compliant) disconnect function achieved through the disconnect contact unit MK. The disconnect function means the following key points:

[0224] - The minimum air distance according to the standard (the minimum distance between contacts),

[0225] - The contact position indication of the contacts of the mechanical disconnect contact unit,

[0226] - The operation / interruption of the contacts of the mechanical disconnect contact unit (by the control unit) is always possible (it is not possible to lock the contacts (continuously) in the closed state by the handle).

[0227] Regarding the minimum air distance between the contacts of a separating contact unit, this minimum air distance depends essentially on the voltage. Other parameters include the degree of contamination, the type of field (uniform, non-uniform), and the air pressure or the altitude above standard zero.

[0228] There are corresponding regulations or standards for this minimum air distance or creepage distance. These regulations stipulate, for example, the minimum air distance for impulse withstand voltage strength in air, which is used for non-uniform and uniform (ideal) electric fields depending on the degree of contamination. The impulse withstand voltage strength is the strength that can be withstood when a corresponding impulse voltage is applied. Only when this minimum length (minimum distance) exists does the separating contact unit or the protective switching device have a separating function (separator characteristic).

[0229] Here, in the sense of the present invention, the standard series DIN EN 60947 or IEC 60947 is relevant for the separator function and its characteristics, and is hereby incorporated by reference.

[0230] The separating contact unit is advantageously characterized by the minimum air distance of the open separating contacts in the off position (open position, open contacts) depending on the rated impulse withstand voltage strength and the degree of contamination. The minimum air distance is especially between (min) 0.01 mm and 14 mm. Particularly advantageously, the minimum air distance is between 0.01 mm at 0.33 kV and 14 mm at 12 kV, especially for a degree of contamination of 1 and especially for a non-uniform field.

[0231] Advantageously, the minimum air distance can have the following values:

[0232] E DIN EN 60947-1 (VDE 0660-100): 2018-06

[0233] Table 13 - Minimum air distance

[0234]

[0235] The degree of contamination and the type of field correspond to the degree of contamination and the type of field defined in the standard. Thereby, a standard-compliant protective switching device dimensioned according to the rated impulse withstand voltage strength can be advantageously achieved.

[0236] The mechanical separating contact unit especially does not refer to relay contacts.

[0237] Although the present invention has been described in detail by way of examples, the present invention is not limited to the disclosed examples and those skilled in the art can derive other variants therefrom without departing from the scope of protection of the present invention.

Claims

1. A protective switching device (SG) for protecting a polyphase low-voltage AC circuit, having: - A housing (GEH) having line-side phase connections (LG1, LG2, LG3) for the phase conductors (L1, L2, L3) of the low-voltage AC circuit and load-side phase connections (LL1, LL2, LL3), - A series circuit (SS1, SS2, SS3) of mechanical phase contacts (K1, K2, K3) and electronic switches (S1, S2, S3), wherein, each series circuit (SS1, SS2, SS3) electrically connects one of the line-side phase connections (LG1, LG2, LG3) to one of the load-side phase connections (LL1, LL2, LL3) respectively, - The mechanical phase contacts (K1, K2, K3) can be switched to open together to avoid current flow or switched to close together for current flow, - The electronic switches (S1, S2, S3) can be switched by semiconductor-based switching elements into a high-resistance state of the switching elements to avoid current flow, or switched into a low-resistance state of the switching elements for current flow, - The protective switching device is designed such that the electronic switches (S1, S2, S3) can be switched into a high-resistance state or a low-resistance state independently of each other.

2. The protective switching device (SG) according to claim 1, characterized in that, a current sensor unit (SI1, SI2, SI3) is provided for each series circuit (SS1, SS2, SS3) respectively, for correspondingly determining the current magnitude of the respective phase conductors (L1, L2, L3), in particular such that there is an instantaneous current value.

3. The protective switching device (SG) according to claim 2, characterized in that, a control unit (SE) is provided, which is connected to the current sensor units (SI1, SI2, SI3), the mechanical phase contacts (K1, K2, K3) and the electronic switches (S1, S2, S3), the protective switching device is designed such that when at least one first current threshold in the phase conductors is exceeded, the avoidance of current flow in the concerned phase conductor is initiated by the concerned electronic switch, in particular the avoidance of current flow lasts for a first time period.

4. The protective switching device (SG) according to claim 3, characterized in that, the first time period is less than 20 ms, in particular less than 10 ms.

5. The protective switching device (SG) according to any one of the above claims, characterized in that, when at least one second current threshold of at least one phase conductor is exceeded for at least a first duration, the avoidance of current flow is initiated by opening the contacts.

6. The protective switching device (SG) according to any one of the above claims, characterized in that, the mechanical phase contacts (K1, K2, K3) are part of a mechanical disconnect contact unit (MK) that opens or closes the contacts together, In particular, the mechanical disconnecting contact unit (MK) has a handle (HH) accessible on the protective switching device for manually opening or closing the phase contacts.

7. The protective switching device (SG) according to claim 6, characterized in that the protective switching device is designed such that the mechanical disconnecting contact unit (MK) can be opened by the control unit / the control unit (SE), but cannot be closed, in particular, the mechanical disconnecting contact unit can only be closed by the handle after being released by the control unit (SE).

8. The protective switching device (SG) according to any one of the above claims, characterized in that the mechanical phase contacts (K1, K2, K3) are associated with the load-side phase connections, and the electronic switches (S1, S2, S3) are associated with the grid-side phase connections.

9. The protective switching device (SG) according to any one of the above claims, characterized in that the protective switching device has at least the following switching states: - all mechanical phase contacts are open and all electronic switches are in high impedance, - all mechanical phase contacts are closed and all electronic switches are in low impedance, - all mechanical phase contacts are closed and all electronic switches are in high impedance, - all mechanical phase contacts are closed, one electronic switch is in low impedance and the other electronic switches are in high impedance, - all mechanical phase contacts are closed, one electronic switch is in high impedance and the other electronic switches are in low impedance, in particular, the protective switching device has the following switching states: - all mechanical phase contacts are open and at least two electronic switches are in low impedance.

10. The protective switching device (SG) according to any one of the above claims, characterized in that the protective switching device has at least the following switching states: - all mechanical phase contacts are closed, a part of the electronic switches are in low impedance and another part of the electronic switches are in high impedance.

11. The protective switching device (SG) according to any one of the above claims, characterized in that a grid-side neutral conductor connection (NG) and a load-side neutral conductor connection (NL) are provided for the neutral conductor of the polyphase low-voltage AC circuit.

12. The protective switching device (SG) according to claim 11, characterized in that the grid-side neutral conductor connection (NG) is connected to the load-side neutral conductor connection (NL) through a neutral conductor contact (KN).

13. The protective switching device (SG) according to claim 12, characterized in that the mechanical neutral conductor contact (KN) can be opened or closed together with the phase contacts (K1, K2, K3), in particular, the neutral conductor contact (KN) is closed before the phase contacts (K1, K2, K3) are closed, or the neutral conductor contact (KN) is opened after the phase contacts (K1, K2, K3) are opened.

14. The protective switching device (SG) according to any one of claims 11 to 13 above, characterized in that A voltage sensor unit (SU1, SU2, SU3) connected to the control unit / the control unit (SE) is respectively provided between each phase conductor and the neutral conductor for determining the magnitude of the voltage between the corresponding phase conductor and the neutral conductor, in particular the presence of an instantaneous voltage value. In the case of starting to become low-resistance by the control unit (SE), the electronic switches (S1, S2, S3) become low-resistance in sequence at the corresponding zero-crossing of the voltage.

15. The protective switching device (SG) according to claim 14, characterized in that In the case of starting to become high-resistance by the control unit (SE), the electronic switches (S1, S2, S3) become high-resistance in sequence at the corresponding zero-crossing of the voltage.

16. The protective switching device (SG) according to any one of claims 14 or 14, characterized in that The control unit (SE) is connected to the current sensor unit (SI1, SI2, SI3), the voltage sensor unit (SU1, SU2, SU3), the mechanical phase contacts (K1, K2, K3) and the electronic switches (S1, S2, S3), The protective switching device is designed such that when at least one current threshold in the conductor is exceeded, the avoidance of the current flow in the involved conductor is initiated by the involved electronic switch. When the voltage crosses zero for the next or subsequent time, the electronic switch becomes low-resistance again to enable current flow.

17. A method for a protective switching device (SG) for protecting a polyphase low-voltage AC circuit, having: - A series circuit of mechanical phase contacts (K1, K2, K3) and electronic switches (S1, S2, S3), wherein each series circuit (SS1, SS2, SS3) electrically connects the grid-side phase connection (LG1, LG2, LG3) to the load-side phase connection (LL1, LL2, LL3) respectively, - The mechanical phase contacts (K1, K2, K3) can be opened together to avoid current flow or closed together for current flow, - The electronic switches (S1, S2, S3) can be switched to the high-resistance state of the switching element by means of a semiconductor-based switching element to avoid current flow, or switched to the low-resistance state of the switching element for current flow, The electronic switches can be switched to the high-resistance state or the low-resistance state independently of each other to avoid or enable current flow depending on the phase conductor.

18. The method according to claim 17, characterized in that Determine the magnitude of the current in the corresponding series circuit, and when at least one first current threshold in the series circuit is exceeded, initiate the avoidance of the current flow in the involved series circuit by the involved electronic switch, in particular the avoidance of the current flow lasts for a first time period.

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