Circuit breaker device and method

Abstract

The invention relates to a circuit breaker device (SG) for protection of an electrical multi-phase low-voltage AC circuit, having: - series circuits composed of a mechanical phase contact (K1, K2, K3) and an electronic switch (S1, S2, S3), wherein each series circuit electrically connects a grid-side phase connection (LG1, LG2, LG3) to a load-side phase connection (LL1, LL2, LL3), - the mechanical phase contacts (K1, K2, K3) can be opened together in order to prevent a flow of current or can be closed together for a flow of current, - the electronic switches (S1, S2, S3) can be switched by means of semiconductor-based switching elements to a high-impedance state of the switching elements in order to prevent a flow of current or to a low-impedance state of the switching elements for the flow of current, the electronic switches can be switched to a high-impedance or to a low-impedance state independently of one another in order to prevent or to enable a flow of current which is dependent on the phase conductor.

Description

[0001] Description

[0002] Protective switching device and procedure

[0003] The invention relates to the technical field of a protective switching device for a low-voltage circuit with electronic switches and a method for a protective switching device for a low-voltage circuit with electronic switches.

[0004] Low voltage refers to voltages of up to 1000 volts AC or up to 1500 volts DC. Low voltage refers in particular to voltages greater than extra-low voltage, with values ​​of 50 volts AC or 120 volts DC.

[0005] The term low-voltage circuit, network or system refers to circuits with nominal or rated currents of up to 125 amperes, more specifically up to 63 amperes. The term low-voltage circuit particularly refers to circuits with nominal or rated currents of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values ​​mentioned refer in particular to nominal, rated and / or breaking currents, i.e. the maximum current that is normally carried through the circuit or at which the electrical circuit is usually interrupted, for example by a protective device such as a protective switching device, circuit breaker or circuit breaker. The rated currents can be further staggered, from 0.5 A to 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.

[0006] Circuit breakers are long-established overcurrent protection devices used in low-voltage electrical circuits. They protect cables from damage caused by overheating due to excessive current and / or short circuits. A circuit breaker can automatically disconnect the circuit in the event of an overload and / or short circuit. A circuit breaker is a non-self-resetting fuse element.

[0007] Unlike miniature circuit breakers, circuit breakers are designed for currents greater than 125 A, and in some cases even as low as 63 A. Miniature circuit breakers are therefore simpler and more delicate in design. Miniature circuit breakers typically have a mounting option for mounting on a so-called top-hat rail (support rail, DIN rail, TH35).

[0008] Miniature circuit breakers are electromechanical in design. They contain a mechanical switching contact or shunt release in a housing to interrupt (trip) the electrical current. A bimetallic protective element or bimetallic element is usually used to trip (interrupt) the circuit in the event of a prolonged overcurrent (overcurrent protection) or thermal overload (overload protection). An electromagnetic release with a coil is used for brief 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 for arc quenching are provided. There are also connection elements for conductors of the electrical circuit to be protected.

[0009] Protective switching devices with an electronic interruption unit or an electronic switch are relatively new developments. These have a semiconductor-based electronic interruption unit / switch. This means that the electrical current flow in the low-voltage circuit is guided via semiconductor components or semiconductor switches, which interrupt the electrical current flow or can be switched to conduction. Protective switching devices with an electronic interruption unit / switch also often have a mechanical isolating contact unit, in particular with isolating properties in accordance with the relevant standards for low-voltage circuits, with the contacts of the mechanical isolating contact unit being connected in series to the electronic interruption unit / electronic switches, i.e.The current of the low-voltage circuit to be protected is conducted via both the mechanical isolating contact unit and the electronic interruption unit.

[0010] The present invention relates in particular to low-voltage alternating current circuits with an alternating voltage, usually with a time-dependent sinusoidal alternating voltage with the frequency f. The time dependence of the instantaneous voltage value u(t) of the alternating voltage is described by the equation: u(t) = U * sin (2n * f * t). Where: u(t) = instantaneous voltage value at time t

[0011] U = amplitude of the voltage

[0012] A harmonic alternating voltage can be represented by the rotation of a pointer whose length corresponds to the amplitude (U) of the voltage. The instantaneous deflection is the projection of the pointer onto a coordinate system. One oscillation period corresponds to one full rotation of the pointer, and its full angle is 2n (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 2n times its frequency, i.e.: w = 2n*f = 2n / T = angular frequency of the alternating voltage (T = period of the oscillation)

[0013] Often, the specification of the angular frequency (w) is preferred over the frequency (f), since many formulas of oscillation theory can be represented more compactly using the angular frequency due to the occurrence of trigonometric functions whose period is by definition 2n: u ( t ) = U * sin (wt)

[0014] In the case of angular frequencies that are not constant over time, the term instantaneous angular frequency is also used.

[0015] In the case of a sinusoidal, in particular temporally 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 referred to as the phase angle cp ( t ). This means that the phase angle cp ( t ) periodically passes through the range O...2n or 0°...360°. This means that the phase angle periodically assumes a value between 0 and 2n or 0° and 360° (cp = n* (0...2n) or cp = n* ( 0 °...360 ° ) , due to periodicity; in short: cp = O...2n or cp = 0°...360° ).

[0016] The instantaneous voltage value u(t) is therefore the instantaneous voltage value at time t, i.e., for a sinusoidal (periodic) alternating voltage, this refers to the voltage value at the phase angle cp (cp = 0...2n or cp = 0°...360°, of the respective period). The same applies to instantaneous current values ​​i(t), etc.

[0017] The object of the present invention is to improve a protective switching device of the type mentioned above, in particular to demonstrate a new concept for a multi-phase protective switching device and to enable greater flexibility for a multi-phase protective switching device.

[0018] This object is achieved by a protective switching device having the features of patent claim 1, as well as by a method according to patent claim 17.

[0019] According to the invention, a protective switching device for protecting an electrical multi-phase low-voltage alternating current circuit, in particular a three-phase alternating current circuit, is proposed, comprising:

[0020] - a housing with mains-side phase terminals and load-side phase terminals for phase conductors of the low-voltage alternating current circuit (for connecting external conductors to the terminals of the housing),

[0021] - Series circuits of a mechanical phase contact and an electronic switch, each of which electrically connects one of the mains-side phase connections to one of the load-side phase connections,

[0022] - that the mechanical phase contacts can be switched jointly to open in order to avoid a current flow or jointly to close in order to avoid a current flow, in particular the mechanical contacts are connected to each other via a mechanical coupling,

[0023] - that the electronic switches can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow or into a low-resistance state of the switching elements to allow current flow,

[0024] - that the electronic switches can be switched independently of one another into a high-impedance or low-impedance state. This has the advantage that the phase conductors can be switched independently of one another into a high-impedance or low-impedance state. Previous protective switching devices, in particular the widely used classic electromechanical protective switching devices (circuit breakers, power circuit breakers, residual current devices), do not offer this option, since the mechanical isolating contact unit opens or closes all contacts simultaneously (multi-pole devices).

[0025] This enables greater flexibility of a protective switching device and more flexible switching behavior.

[0026] Further advantageous embodiments of the invention are specified in the subclaims and in the exemplary embodiment.

[0027] In an advantageous embodiment of the invention, a current sensor unit is provided for each series circuit to determine the current level of the respective phase conductor. In particular, instantaneous current values ​​are determined and available.

[0028] In an advantageous further development, a control unit is provided which is connected to the current sensor units, the mechanical phase contacts, and the electronic switches. If at least one current threshold value in a conductor is exceeded, the relevant electronic switch initiates the prevention of current flow in the relevant conductor, in particular for a first period of time.

[0029] This has the particular advantage that when a specified current threshold or a current-time threshold is exceeded (i.e., the current threshold is exceeded for a defined period of time), a selective interruption occurs only in the affected conductor(s). Current flow is still permitted in the other conductors (unaffected conductors) in a multi-phase low-voltage AC circuit.

[0030] By avoiding this for an initial period, the device can be switched on again or become low-impedance after the initial period, thus ensuring continued security of supply and allowing further testing to determine whether the current threshold has been exceeded. This can be achieved particularly advantageously by evaluating instantaneous current values.

[0031] In an advantageous embodiment of the invention, the first time period is less than 20 ms, in particular less than 10 ms.

[0032] This has the particular advantage that an interruption occurs for a half-wave or full-wave of the voltage or current in the alternating current circuit—in the example (20 ms, 10 ms) based on a mains frequency of 50 Hz—so that the electrical supply reliability is restored with the next full-wave or half-wave. In particular, after an interruption, the low-resistance can occur in the area of ​​the next zero crossing (at the zero crossing, or in the range of 1 ms before or after).

[0033] In an advantageous embodiment of the invention, the protective switching device is designed such that, upon exceeding at least one second current threshold, in particular an effective value, in at least one phase conductor (or two phase conductors, in particular in three phase conductors) for at least a first period of time, the prevention of a current flow is initiated by opening the contacts. The second current threshold can advantageously be higher in magnitude than the first current threshold.

[0034] The first time period can be less than 100ms, 20ms, especially less than 10ms.

[0035] This has the particular advantage that if one or more of the electronic switches remain faulty and the second current threshold is subsequently exceeded, the current flow in the low-voltage alternating current circuit is prevented and the safety in the circuit is thus increased.

[0036] In an advantageous embodiment of the invention, the mechanical phase contacts are part of a mechanical isolating contact unit that opens or closes the phase contacts together. In particular, the mechanical isolating contact unit has a handle accessible on the protective switching device for manually opening or closing the phase contacts (of the mechanical isolating contact unit).

[0037] This has the particular advantage of achieving complete galvanic isolation of all phase conductors simultaneously, in contrast to phase-specific high-resistance electronic switches that prevent current flow. This operation enables compatible behavior with conventional electromechanical protective switching devices.

[0038] In an advantageous embodiment of the invention, the protective switching device is designed such that the mechanical isolating contact unit can be opened by the control unit, but not closed. In particular, the mechanical isolating contact unit can only be closed by the handle after it has been released by the control unit.

[0039] This has the particular advantage of increasing the safety of the protective switching device, as the control unit cannot accidentally (faultily) close the contacts.

[0040] In an advantageous embodiment of the invention, the electronic switches are part of an electronic interruption unit, wherein the electronic switches can be switched independently of one another.

[0041] This has the particular advantage of providing a compact electronic interruption unit that combines the electronic switches, enabling a space-saving design and allowing synergy effects of components to be utilized.

[0042] In an advantageous embodiment of the invention, the electronic interruption unit / electronic switches have bidirectional dielectric strength. In particular, overvoltage protection is provided for the semiconductor-based switching elements.

[0043] This has the particular advantage of being robust against overvoltages and of being able to switch off an inductive line circuit.

[0044] In an advantageous embodiment of the invention, the mechanical phase contacts are assigned to the load-side phase connections and the electronic switches are assigned to the mains-side phase connections.

[0045] This has the particular advantage of providing a convenient design that supports phase-related switching of the electronic switches and enables a self-test (in particular a self-test of the electronic switches or the electronic interruption unit), even when the contacts are open. Furthermore, a power supply to the protective switching device is ensured, even when the contacts are open.

[0046] In an advantageous embodiment of the invention, the protective switching device has at least the following switching states:

[0047] -all mechanical phase contacts open, all electronic switches high resistance,

[0048] - all mechanical phase contacts closed, all electronic switches low resistance,

[0049] - all mechanical phase contacts closed, all electronic switches high resistance,

[0050] - all mechanical phase contacts closed, one of the electronic switches low resistance, the other electronic switches high resistance,

[0051] - all mechanical phase contacts closed, one electronic switch high resistance, the other electronic switches low resistance.

[0052] In a further advantageous embodiment of the invention, the protective switching device has at least the following switching state:

[0053] - all mechanical phase contacts closed, some of the electronic switches are low-resistance, the other part of the electronic switches are high-resistance.

[0054] In a further advantageous embodiment of the invention, the protective switching device has at least the following switching state:

[0055] - all mechanical phase contacts are open, one part of the electronic switches is low-resistance, the other part of the electronic switches is high-resistance, in particular two electronic switches are low-resistance and the other electronic switch is high-resistance. Alternatively or additionally, the protective switching device has the following switching state:

[0056] - all mechanical phase contacts open, all electronic switches low-resistance. This switching state is particularly achieved when measuring resistors R12, R13, and R23 are provided between the phase conductors. For this purpose, measuring resistors are provided between LI and L2, between L2 and L3, and between LI and L3.

[0057] These switching states are advantageous for testing the ability of the electronic switches to be switched on or off. This means that the electronic switches are briefly switched on or off with the mechanical phase contacts open in order to test their functionality (regarding their ability to be switched on or off). A measuring current flows through the respective measuring resistors.

[0058] In an advantageous embodiment of the invention, in which the multi-phase low-voltage alternating current circuit is a three-phase low-voltage alternating current circuit, i.e. in which a first, second and third electronic switch is provided, which advantageously provides a solution for a classic three-phase network, the protective switching device has at least the following switching states: -all mechanical phase contacts open, all electronic switches high-resistance,

[0059] - all mechanical phase contacts closed, all electronic switches low resistance,

[0060] - all mechanical phase contacts closed, all electronic switches high resistance,

[0061] - all mechanical phase contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance,

[0062] - all mechanical phase contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance,

[0063] - all mechanical phase contacts closed, the third electronic switch low-resistance, the first and second electronic switches high-resistance. In a further advantageous embodiment of the invention, in which the multi-phase low-voltage AC circuit is a three-phase low-voltage AC circuit, i.e. in which a first, second and third electronic switch is provided, the protective switching device has at least the following switching states: - all mechanical phase contacts open, all electronic switches high-resistance,

[0064] - all mechanical phase contacts closed, all electronic switches low resistance,

[0065] - all mechanical phase contacts closed, all electronic switches high resistance,

[0066] - all mechanical phase contacts closed, the first and second electronic switch low resistance, the third electronic switch high resistance,

[0067] - all mechanical phase contacts closed, the first and third electronic switches low resistance, the second electronic switch high resistance,

[0068] - all mechanical phase contacts closed, the second and third electronic switches low resistance, the first electronic switch high resistance.

[0069] The advantageous configurations regarding the switching states, or the combination thereof, have the particular advantage of providing new switching states for a protective switching device, allowing for individual and more flexible response to overcurrent conditions (short-circuit current conditions). This means that the response is not by disconnecting all phases, but rather can be phase-specific, thus enabling greater supply reliability in the low-voltage circuit.

[0070] In an advantageous embodiment of the invention, a mains-side neutral conductor connection and a load-side neutral conductor connection are provided for a neutral conductor of the multi-phase low-voltage alternating current circuit.

[0071] The mains-side neutral conductor connection is connected to the load-side neutral conductor connection directly or via a neutral conductor contact. This has the particular advantage of creating a multi-pole protective switching device in which the neutral conductor is also galvanically interrupted if necessary.

[0072] In an advantageous embodiment of the 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.

[0073] This has the particular advantage that the neutral conductor contact always opens and closes without current. This reduces contact wear and increases its service life. Furthermore, it prevents the occurrence of an arc when the neutral conductor contact opens.

[0074] In an advantageous embodiment of the invention, a voltage sensor unit is provided between each phase conductor and the neutral conductor to determine the voltage level between the respective phase and neutral conductors, in particular the instantaneous voltage values. The voltage sensor units are connected to the control unit.

[0075] In an advantageous further development of the embodiment, the protective switching device is designed in such a way that when the control unit initiates a low-resistance event (in particular when there is no overcurrent event, i.e. when the first or second current threshold is not exceeded; e.g. when the user initiates a low-resistance event) of the (all) electronic switches, they become low-resistance one after the other when the voltage crosses zero (or at a voltage which is less than 50V, 25V, in particular less than 10V).

[0076] This has the particular advantage that the system perturbations are reduced and the switching load in the switch is lower. In an advantageous embodiment of the invention, the protective switching device is designed such that when the control unit initiates a high-impedance event (in particular when there is no overcurrent event, i.e. when the first or second current threshold is not exceeded; e.g. when the user initiates a high-impedance event) of the (all) electronic switches, they become high-impedance one after the other when the voltage crosses zero (or when the voltage is less than 50V, 25V, in particular less than 10V).

[0077] This has the particular advantage that the network perturbations are reduced and the switching load in the switch is lower.

[0078] In an advantageous embodiment of the invention, the protective switching device is designed such that when (at least) the first current threshold value in a conductor is exceeded, the relevant electronic switch initiates a current flow prevention in the relevant conductor. At the next or subsequent zero crossing of the voltage, the electronic switch becomes low-resistance again to allow current flow. The control unit is connected to the current sensor units, the voltage sensor units, the mechanical phase contacts, and the electronic switches.

[0079] This has the particular advantage that increased robustness against false triggering is achieved and thus increased electrical supply reliability is achieved.

[0080] According to the invention, a corresponding method (method claims) for a protective switching device for a low-voltage circuit with electronic (semiconductor-based) switches / switching elements with the same and further advantages is claimed.

[0081] The method for a protective switching device (SG) for protecting an electrical multi-phase low-voltage alternating current circuit comprises: - series circuits of a mechanical phase contact (and an electronic switch), each series circuit electrically connecting a mains-side phase connection with a load-side phase connection,

[0082] - that the mechanical phase contacts can be opened together to prevent current flow or closed together to allow current flow,

[0083] - that the electronic switches can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to avoid a current flow or a low-resistance state of the switching elements to allow current flow, that the electronic switches can be switched independently of one another into a high-resistance or low-resistance state in order to (advantageously) avoid or enable a phase-conductor-dependent current flow.

[0084] Advantageously, the level of the current of the respective series circuit is determined and, if at least one current threshold value in a series circuit is exceeded, the avoidance of a current flow in the series circuit in question, in particular for a first period of time, is initiated by the electronic switch in question.

[0085] All embodiments, both in dependent form referring back to patent claim 1 or 17, and also referring back only to individual features or combinations of features of patent claims, in particular also a reference of the pending arrangement claims to the independent method claim, bring about an improvement of a protective switching device, in particular an increase in the flexibility of a protective switching device and an increase in the supply reliability of the electrical circuit, and provide a new concept for a protective switching device.

[0086] The described properties, features and advantages of this invention as well as the manner in which these are achieved will become clearer and more clearly understandable in connection with the following description of the embodiments, which are explained in more detail in connection with the drawing.

[0087] The drawing shows:

[0088] Figure 1 shows a first representation of a protective switching device,

[0089] Figure 2 shows a second representation of a protective switching device, Figure 3 shows a third representation of a protective switching device.

[0090] Figure 1 shows an exemplary representation of a 3-pole, e.g. for 3-phase conductors, protective switching device SG for protecting an electrical multi-phase low-voltage alternating current circuit, in the example according to Figure 1 a three-phase low-voltage alternating current circuit, comprising:

[0091] - a housing GEH with a first, second, and third mains-side phase connection LG1, LG2, LG3 and a first, second, and third load-side phase connection LL1, LL2, LL3 for the first, second, and third phase conductors LI, L2, L3 of the low-voltage alternating current circuit. A power source is usually connected to the Grid side, and a consumer is usually connected to the Load side. In the housing GEH:

[0092] - a first series circuit SS1 of a first mechanical phase contact K1 and a first electronic switch S1, a second series circuit SS2 of a second mechanical phase contact K2 and a second electronic switch S2, a third series circuit SS3 of a third mechanical phase contact K3 and a third electronic switch S3, wherein: the first series circuit SS1 electrically connects the first mains-side phase connection LG1 to the first load-side phase connection LL1, the second series circuit SS2 electrically connects the second mains-side phase connection LG2 to the second load-side phase connection LL2, and the third series circuit SS3 electrically connects the third mains-side phase connection LG3 to the third load-side phase connection LL3,

[0093] - the mechanical phase contacts Kl, K2, K3 can be switched together, ie they are opened together to prevent a current flow or closed together to allow a current flow, ie the mechanical contacts are connected to each other via mechanical coupling (e.g. switching shaft),

[0094] - the electronic switches SI, S2, S3 can be switched by means of semiconductor-based switching elements into 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.

[0095] According to the invention, the first, second, and third electronic switches can be switched independently of one another into a high-impedance or low-impedance state. This means that the first, second, and third electronic switches are switched independently of one another into a high-impedance or low-impedance state. This is particularly useful in order to prevent or enable a phase-conductor-dependent current flow.

[0096] According to Figure 1, a first, second and third current sensor unit S1, S2, S3 are provided. The first current sensor unit S1 is in the first series circuit S1, the second current sensor unit S12 is in the second series circuit SS2 and the third current sensor unit S13 is provided or arranged in the third series circuit SS3, for respectively determining the level of the current of the first, second and third phase conductors L1, L2, L3, in particular so that instantaneous current values ​​are present. The first mechanical phase contact K1, the second mechanical phase contact K2 and the third mechanical phase contact K3 are, according to Figure 1, part of a mechanical isolating contact unit MK, which opens or closes the phase contacts K1, K2, K3 together. The mechanical isolating contact unit MK can have a handle HH accessible on the protective switching device for manually (operated by a person) opening or closing the phase contacts.The mechanical isolating contact unit MK corresponds, for example, to a classic unit as is known from electromechanical protective switching devices (circuit breakers, power switches) (although according to the invention without elements for overcurrent or short-circuit detection, such as bimetallic releases, etc.).

[0097] The protective switching device is in particular designed in such a way that the mechanical isolating contact unit MK can be opened but not closed by a control unit SE. In particular, the mechanical isolating contact unit MK can only be closed by the handle HH after release by the control unit SE. A release unit LC can be provided for this purpose. This means that the contacts can only be closed by the handle HH when release or a release signal (from the control unit) is present. Without release or the release signal, the handle HH can be operated, but the contacts cannot be closed ("continuous slipping").

[0098] The release unit LC can further be designed in such a way that the contacts Kl, K2, K3 of the mechanical isolating contact unit MK can be opened by a control signal from the control unit SE, as indicated in Figure 1 by an arrow from the control unit SE to the release unit LC.

[0099] According to Figure 1, the mechanical phase contacts K1, K2, K3 are assigned to the load-side phase connections (Load), and the electronic switches S1, S2, S3 are assigned to the grid-side phase connections (Grid). 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, whereby the electronic switches S1, S2, S3 can be switched independently of one another.

[0100] The electronic interruption unit / electronic switches can have bidirectional dielectric strength. Overvoltage protection is specifically provided for the semiconductor-based switching elements to limit the voltages and thus protect the semiconductor-based switching elements.

[0101] A control unit SE is provided (as already partially mentioned) which is connected to the current sensor units Sil, SI2, SI3, the mechanical phase contacts (Kl, K2, K3) or the mechanical isolating contact unit MK (as shown in Figure 1) and the electronic switches SI, S2, S3.

[0102] The current sensor units Sil, SI2, SI3 each determine the current level of their respective conductor, so that instantaneous current values ​​are available.

[0103] If at least a first current threshold value in a conductor is exceeded, the current flow in the respective conductor is prevented by the electronic switch becoming highly resistive.

[0104] This high-impedance condition can occur, in particular, for an initial period of time. After this period, the electronic switch in question can return to low-impedance.

[0105] The low-resistance condition can occur, in particular, at the next zero crossing, or before or after the zero crossing of the voltage. (All three options: at the zero crossing, before the zero crossing, or after the zero crossing - are possible, or when the voltage falls below a certain threshold, in particular 50V, 25V, or 10V).

[0106] The first time period can be less than 20 ms, especially less than 10 ms. A residual current sensor unit ZCT can be provided, as shown in Figure 1, for detecting residual currents in the low-voltage AC circuit, such as those known from residual current circuit breakers. The residual current sensor unit ZCT is connected to the control unit SE.

[0107] In the example shown in Figure 1, the current sensor units Sil, SI2, SI3 are arranged between the mains-side terminals LG1, LG2, LG3 of the series circuit of the electronic switches SI, S2, S3 and the mechanical phase contacts Kl, K2, K3. Specifically, between the mains-side terminals LG1, LG2, LG3 and the electronic switches SI, S2, S3. The current sensor units Sil, SI2, SI3 can also be arranged differently, for example, between the electronic switches SI, S2, S3 and the mechanical phase contacts Kl, K2, K3.

[0108] Figure 2 shows a representation according to Figure 1, with the following differences.

[0109] A mains-side neutral conductor connection NG and a load-side neutral conductor connection NL are provided for a neutral conductor N of the multi-phase low-voltage AC circuit, in the example shown in Figure 2, a three-phase low-voltage AC circuit with a neutral conductor. According to Figure 2, the mains-side neutral conductor connection NG is connected to the load-side neutral conductor connection NL via a neutral conductor contact KN.

[0110] Alternatively, the mains-side neutral conductor connection NG can also be connected directly (i.e. without a switchable contact) to the load-side neutral conductor connection NL.

[0111] In this example, an electronic switch is not provided in the neutral conductor path in the protective switch housing. This means that the neutral conductor connection between the mains-side neutral conductor connection NG and the load-side neutral conductor connection NL is free of electronic switches (electronic switch-free). Advantageously, the mechanical neutral conductor contact KN can be switched together with the phase contacts Kl, K2, K3. This means that the mechanical neutral conductor contact KN can be opened or closed together with the phase contacts Kl, K2, K3, as described above for the contacts Kl, K2, K3.

[0112] Specifically, the mechanical isolating contact unit MK can be designed such that the neutral conductor contact KN is closed before the phase contacts Kl, K2, K3 are closed. Similarly, the neutral conductor contact KN can be opened after the phase contacts Kl, K2, K3 are opened.

[0113] Furthermore, a power supply NT is provided, such as a power supply unit, for supplying power to the protective switching device SG, in particular the control unit SE.

[0114] In this example, the NT power supply is connected to the phase conductors LI, L2, L3, and (if applicable) the neutral conductor N. It can also be connected to only some of the conductors (at least two) for the power supply. In this example, the NT power supply is also connected to the control unit SE.

[0115] On the other hand, the control unit SE is combined with the electronic switches SI, S2, S3 and the current sensor units Sil, SI2, SI3, as shown in Figure 2.

[0116] Furthermore, a voltage sensor unit is provided between each phase conductor and the neutral conductor. A first voltage sensor unit SUI is provided between the first phase conductor LI 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. These units are used to determine the voltage level between the respective phase and neutral conductors, in particular to provide instantaneous voltage values.

[0117] SUI, SU2, SU3 are connected to the control unit SE.

[0118] In the case of a low-resistance switch initiated by the control unit SE, the electronic switches SI, S2, S3, for example:

[0119] - become low-resistance in the case of a user-initiated or

[0120] - in the event of a low-resistance event initiated by the protective switching device, especially in the absence of an overcurrent event (i.e. if the first or second current threshold is not exceeded), e.g. if an internal checking function (for internal checking) of the protective switching device initiates a low-resistance event,

[0121] => the electronic switches can advantageously become low-resistance one after the other when the voltage crosses zero.

[0122] In the case of a high-impedance signal initiated by the control unit SE, the electronic switches SI, S2, S3, for example:

[0123] - become high-impedance when initiated by the user or

[0124] - in the event of a high-resistance event initiated by the protective switching device, especially in the absence of an overcurrent event (i.e. if the first or second current threshold is not exceeded), e.g. if an internal checking function (for internal checking) of the protective switching device initiates a high-resistance event,

[0125] => the electronic switches can advantageously become high-impedance one after the other when the voltage passes through zero.

[0126] For this purpose, the voltage sensor units SUI, SU2, SU3 are, as already mentioned, connected to the control unit SE, which is further connected to the current sensor units S1, SI2, SI3, the mechanical phase contacts K1, K2, K3 (or mechanical isolating contact unit MK) and the electronic switches (S1, S2, S3). The protective switching device can also advantageously be designed such that when at least a first current threshold value (specifically the instantaneous current value) in a conductor is exceeded, the relevant electronic switch initiates the prevention of current flow in the relevant conductor. At the next or next but one zero crossing of the voltage, the electronic switch becomes low-resistance again to allow current flow.

[0127] This can be done several times until a certain number of repetitions is exceeded. Then: a) all electronic switches become high-impedance, or (and) b) the contacts open (galvanic isolation).

[0128] Any combinations (intermediate combinations) from the representations of the exemplary protective switching devices according to Figures 1 and 2 are possible (e.g. power supply NT from Figure 2 in Figure 1, etc.).

[0129] Figure 3 shows a diagram similar to Figure 2, with the difference that measuring resistors R12, R13, R23 are provided between the phase conductors within the protective switching device. For this purpose, in one embodiment, a first measuring resistor is provided between the first phase conductor LI and the second phase conductor L2.

[0130] (or measuring impedance) R12, between the second phase conductor L2 and the third phase conductor L3 a second measuring resistor (or measuring impedance) R23 and between the first phase conductor LI and the third phase conductor L3 a third measuring resistor (or measuring impedance) R13.

[0131] In particular, when there is no neutral conductor (3-pole protective switching device), the switching behavior of the electronic switches SI, S2, S3 can be checked using the measuring resistors (which can also be designed as measuring impedances, e.g. as resistance / capacitance and / or inductance combinations), for example by briefly switching on (ps, ms or small seconds range) the electronic switches with the contacts open, whereby a measuring current corresponding to the measuring resistance (the measuring impedance) is provided and can be checked (at the respective instantaneous values ​​of the voltage).

[0132] The (optional) differential current sensor unit ZCT is not provided in this example (but could also be provided).

[0133] High-resistance refers to a state in which only a negligible current flows. In particular, high-resistance refers to resistance values ​​greater than 1 kiloohm, preferably greater than 10 kiloohms, 100 kiloohms, 1 megaohm, 10 megaohms, 100 megaohms, 1 gigaohm, or greater.

[0134] Low-resistance refers to a condition in which the current value specified on the protective device could flow. Specifically, low-resistance refers to resistance values ​​less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm, or less.

[0135] The electronic switches SI, S2, S3, or the electronic interrupt unit EU can contain semiconductor components such as bipolar transistors, field-effect transistors (FETs), isolated-gate bipolar transistors (IGBTs), metal-oxide-layer field-effect transistors (MOSFETs), or other (self-commutated) power semiconductors. IGBTs and MOSFETs in particular are particularly well-suited for electronic switches (as semiconductor-based switching elements) due to their low forward resistance, high junction resistance, and good switching behavior.

[0136] The protective switching device according to the invention thus contains electronic and mechanical components. The sensible arrangement of all required components for safe operation is one aspect. Furthermore, several switching combinations are possible by combining the electronic switch and mechanical contacts.

[0137] In this example, the protective switching device has three mains-side and three load-side connections, or four mains-side and four load-side connections. The device contains a 3- or 4-pole mechanical isolating contact system. The contacts are mechanically coupled and can only be opened or closed together.

[0138] An electronic switch is located in series with the mechanical contact in the phase conductors. Unlike the mechanical contacts, these switches are switched on or off independently of each other. Furthermore, a current sensor unit is provided in the phase conductors (not in the neutral conductor N).

[0139] A conventional three-pole or four-pole protective device today (essentially) has only two switching states: On or Off.

[0140] According to the invention, in the example for a three-pole (for e.g. 3-phase conductor) or four-pole (for e.g. 3-phase conductor and a neutral conductor) protective switching device, further switching states are proposed, see the following table.

[0141]

[0142] In addition to the switching states known today, Off (OFF) and On (ON), there are other states such as Standby, Hybrid 1, 2, 3, Hybrid 12, 13, 23. Furthermore, test states are

[0143] 5 stands (Test 1, Test 2, Test 3, Test 4) are provided for the electronic switches.

[0144] Generalizations for two-phase or four-phase / multi-phase devices are possible.

[0145] 10 Thanks to the new hybrid switching states, the protective switching device can react differently to specific load or fault conditions than before. It can therefore be advantageous to switch only one or two of the included electronic switches to the high-impedance (off) state in a specific fault situation. When switching loads on and off, it can also be advantageous to perform a switching sequence in which only one or two of the included electronic switches are switched on at times.

[0146] Switching on can be achieved, for example, by switching the electronic switches on one after the other at the zero crossing of the voltage (i.e. not at the same time, but at the respective zero crossing of the voltage of the respective phase / phase conductor).

[0147] A switch-off process could also occur in an analogous manner.

[0148] This allows reduced network perturbations and the switching load in the switching device (especially in the electronic switch) to be reduced.

[0149] Overcurrent events (current threshold exceeded) can be handled per phase / phase conductor. This also protects the electronic switches from overload.

[0150] Likewise, phases can be switched off briefly (high impedance), for example for testing purposes.

[0151] The number of hybrid states or hybrid states occurring in a unit of time can be counted and if a limit is exceeded, all electronic switches can become high-resistance (or / and the mechanical contacts can be opened).

[0152] For single-phase consumers, a higher level of availability can be provided (fault only on one phase, switching off only one phase, continuing operation of the other phases).

[0153] The protective switching device therefore has, as an example, in one variant (3- or 4-pole), at least the following switching states: -(1) all mechanical phase contacts open, all electronic switches high resistance,

[0154] -(2) all mechanical phase contacts closed, all electronic switches low resistance,

[0155] -(3) all mechanical phase contacts closed, all electronic switches high resistance,

[0156] -(4) all mechanical phase contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance,

[0157] -(5) all mechanical phase contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance,

[0158] -(6) all mechanical phase contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance.

[0159] As an example, the protective switching device in another variant (3- or 4-pole) has at least the following switching states:

[0160] -(1) all mechanical phase contacts open, all electronic switches high resistance,

[0161] -(2) all mechanical phase contacts closed, all electronic switches low resistance,

[0162] -(3) all mechanical phase contacts closed, all electronic switches high resistance,

[0163] -(7) all mechanical phase contacts closed, the first and second electronic switch low resistance, the third electronic switch high resistance,

[0164] -(8) all mechanical phase contacts closed, the first and third electronic switch low resistance, the second electronic switch high resistance,

[0165] -(9) all mechanical phase contacts closed, the second and third electronic switch low resistance, the first electronic switch high resistance.

[0166] The protective switching device therefore has, as an example, in another variant (3- or 4-pole), the following switching states: -(1) all mechanical phase contacts open, all electronic switches high resistance,

[0167] -(2) all mechanical phase contacts closed, all electronic switches low resistance,

[0168] -(3) all mechanical phase contacts closed, all electronic switches high resistance,

[0169] -(4) all mechanical phase contacts closed, the first electronic switch low resistance, the second and third electronic switches high resistance,

[0170] -(5) all mechanical phase contacts closed, the second electronic switch low resistance, the first and third electronic switches high resistance,

[0171] -(6) all mechanical phase contacts closed, the third electronic switch low resistance, the first and second electronic switches high resistance,

[0172] -(7) all mechanical phase contacts closed, the first and second electronic switch low resistance, the third electronic switch high resistance,

[0173] -(8) all mechanical phase contacts closed, the first and third electronic switch low resistance, the second electronic switch high resistance,

[0174] -(9) all mechanical phase contacts closed, the second and third electronic switch low resistance, the first electronic switch high resistance.

[0175] The protective switching device therefore has, as an example in one variant (in particular 3-pole), at least one, the first three (10, 11, 12) or all of the following switching states: -(10) all mechanical phase contacts open, the first electronic switch and the second electronic switch have low resistance, the third electronic switch has high resistance, -(11) all mechanical phase contacts open, the second electronic switch and the third electronic switch have low resistance, the first electronic switch has high resistance, -(12) all mechanical phase contacts open, the first electronic switch and the third electronic switch have low resistance, the second electronic switch has high resistance, - (13) all mechanical phase contacts open, the first, second and third electronic switches have low resistance.

[0176] This means that, in general terms, the protective switching device has at least the following switching states:

[0177] -all mechanical contacts open, all electronic switches high resistance,

[0178] - all mechanical contacts closed, all electronic switches low resistance,

[0179] - all mechanical contacts closed, all electronic switches high resistance,

[0180] - all mechanical contacts closed, one of the electronic switches low resistance, the other electronic switches high resistance,

[0181] - all mechanical contacts closed, one electronic switch high resistance, the other electronic switches low resistance,

[0182] - all mechanical phase contacts open, some of the electronic switches are low-resistance, the other part of the electronic switches is high-resistance,

[0183] ( in particular that two electronic switches are low-impedance and the other electronic switch is high-impedance ) ,

[0184] - all mechanical phase contacts open, all electronic switches low resistance.

[0185] In general, the protective switching device is characterized, for example, by at least the following new switching state: - all mechanical (phase) contacts closed, some of the electronic switches are low-resistance, the other part of the electronic switches are high-resistance.

[0186] Mechanical contacts or mechanical isolating contact units MK refer in particular to a (standard-compliant) isolating function, implemented by the isolating contact unit MK. The isolating function includes the following points: -Minimum air gap according to the standard (minimum distance between contacts), -Contact position indicator of the contacts of the mechanical isolating contact unit,

[0187] -Operation / interruption of the contacts of the mechanical isolating contact unit (by the control unit) is always possible (no (permanent) blocking of the contacts in the closed state by the handle is possible).

[0188] The minimum clearance between the contacts of the isolating contact unit is essentially voltage-dependent. Other parameters include the degree of contamination, the type of field (homogeneous, inhomogeneous), and the air pressure or altitude above sea level.

[0189] There are corresponding regulations or standards for these minimum clearances or creepage distances. For example, these regulations specify the minimum clearance for an inhomogeneous and a homogeneous (ideal) electric field for air, depending on the degree of contamination, for surge voltage resistance. Surge voltage resistance is the resistance when a corresponding surge voltage is applied. Only if this minimum length (minimum distance) is present does the isolating contact unit or protective switching device exhibit an isolating function (isolating property).

[0190] For the purposes of the invention, the DIN EN 60947 and IEC 60947 series of standards are relevant for the isolating function and its properties, to which reference is made here.

[0191] The isolating contact unit is advantageously characterized by a minimum clearance between the open isolating contacts in the open position (open position, open contacts) depending on the rated impulse withstand voltage and the degree of pollution. The minimum clearance is, in particular, between 0.01 mm and 14 mm (at least). In particular, the minimum clearance 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.

[0192] Advantageously, the minimum air distance can have the following values:

[0193] E DIN EN 60947-1 (VDE 0660-100):2018-06

[0194] Table 13 - Minimum clearances

[0195] The pollution levels and field types correspond to those defined in the standards. This advantageously allows for a standard-compliant protective switching device dimensioned according to the rated impulse withstand voltage.

[0196] In particular, the term mechanical isolating contact unit does not refer to a relay contact.

[0197] Although the invention has been illustrated and described in detail by the embodiment, the invention is not limited by the disclosed examples and other variations can be derived therefrom by a person skilled in the art without departing from the scope of the invention.

Claims

Patent claims 1. Protective switching device (SG) for protecting an electrical multi-phase low voltage alternating current circuit comprising: - a housing (GEH) with mains-side phase connections (LG1, LG2, LG3) and load-side phase connections (LL1, LL2, LL3) for phase conductors (LI, L2, L3) of the low-voltage alternating current circuit, - Series circuits (SSI, SS2, SS3) of a mechanical phase contact (Kl, K2, K3) and an electronic switch (SI, S2, S3), whereby each series circuit (SSI, SS2, SS3) electrically connects one of the mains-side phase connections (LG1, LG2, LG3) with one of the load-side phase connections (LL1, LL2, LL3), - that the mechanical phase contacts (Kl, K2, K3) can be switched together to open in order to avoid a current flow or together to close in order to avoid a current flow, - that the electronic switches (SI, S2, S3) can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to prevent a current flow or into a low-resistance state of the switching elements to allow current flow, - that the protective switching device is designed in such a way that the electronic switches (SI, S2, S3) can be switched independently of one another into a high-resistance or low-resistance state.

2. Protective switching device (SG) according to claim 1, characterized in that for each series circuit (SSI, SS2, SS3) a current sensor unit (Sil, SI2, SI3) is provided for the respective determination of the level of the current of the respective phase conductor (LI, L2, L3), in particular in such a way that instantaneous current values ​​are available.

3. Protective switching device (SG) according to claim 2, characterized in that that a control unit (SE) is provided which is connected to the current sensor units (Sil, SI2, SI3), the mechanical phase contacts (Kl, K2, K3) and the electronic switches (SI, S2, S3), that the protective switching device is designed in such a way that when at least a first current threshold value in a phase conductor is exceeded, avoidance of a current flow in the phase conductor in question, in particular for a first period of time, is initiated by the electronic switch in question.

4. 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. Protective switching device (SG) according to one of the preceding claims, characterized in that when at least one second current threshold value is exceeded in at least one phase conductor for at least a first period of time, avoidance of a current flow is initiated by opening the contacts.

6. Protective switching device (SG) according to one of the preceding claims, characterized in that the mechanical phase contacts (Kl, K2, K3) are part of a mechanical isolating contact unit (MK) which opens or closes the contacts together, in particular that the mechanical isolating contact unit (MK) has a handle (HH) accessible on the protective switching device for manually opening or closing the phase contacts.

7. Protective switching device (SG) according to claim 6, characterized in that the protective switching device is designed such that the mechanical isolating contact unit (MK) is controlled by a / the control control unit (SE) can be opened but not closed, in particular that the mechanical isolating contact unit can only be closed by the handle after release by the control unit (SE).

8. Protective switching device (SG) according to one of the preceding claims, characterized in that the mechanical phase contacts (Kl, K2, K3) are assigned to the load-side phase connections and the electronic switches (SI, S2, S3) are assigned to the mains-side phase connections.

9. Protective switching device (SG) according to one of the preceding claims, characterized in that the protective switching device has at least the following switching states: -all mechanical phase contacts open, all electronic switches high resistance, - all mechanical phase contacts closed, all electronic switches low resistance, - all mechanical phase contacts closed, all electronic switches high resistance, - all mechanical phase contacts closed, one of the electronic switches low resistance, the other electronic switches high resistance, - all mechanical phase contacts closed, one electronic switch high resistance, the other electronic switches low resistance, in particular that the protective switching device has the following switching state: - all mechanical phase contacts open, at least two electronic switches low resistance. 10 . Protective switching device (SG) according to one of the preceding claims, characterized in that the protective switching device has at least the following switching state: - all mechanical phase contacts closed, some of the electronic switches are low-resistance, the other part of the electronic switches are high-resistance.

11. Protective switching device (SG) according to one of the preceding claims, characterized in that a mains-side neutral conductor connection (NG) and a load-side neutral conductor connection (NL) are provided for a neutral conductor of the multi-phase low-voltage alternating current circuit.

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

13. 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 (Kl, K2, K3), in particular that the neutral conductor contact (KN) is closed before the phase contacts (Kl, K2, K3) are closed or that the neutral conductor contact (KN) is opened after the phase contacts (Kl, K2, K3) are opened.

14. Protective switching device (SG) according to one of the preceding claims 11 to 13, characterized in that between each phase conductor and the neutral conductor there is provided a voltage sensor unit (SUI, SU2, SU3) connected to a / the control unit (SE) for determining the level of the voltage between the respective phase conductor and the neutral conductor. Sensitive and neutral conductors, in particular the instantaneous voltage values ​​are present, so that when the control unit (SE) initiates a low-resistance switch (SI, S2, S3), these switches become low-resistance one after the other when the voltage crosses zero.

15. Protective switching device (SG) according to claim 14, characterized in that when the electronic switches (SI, S2, S3) become high-impedance initiated by the control unit, they become high-impedance one after the other at the respective zero crossing of the voltage.

16. Protective switching device (SG) according to one of the claims 14 or 14, characterized in that the control unit (SE) is connected to the current sensor units (S11, SI2, SI3), the voltage sensor units (SU1, SU2, SU3), the mechanical phase contacts (K1, K2, K3) and the electronic switches (SI, S2, S3), that the protective switching device is designed in such a way that when at least one current threshold value in a conductor is exceeded, avoidance of a current flow in the conductor in question is initiated by the electronic switch in question, that at the next or next but one zero crossing of the voltage the electronic switch becomes low-resistance again in order to enable a current flow.

17. Method for a protective switching device (SG) for protecting an electrical multi-phase low voltage alternating current circuit comprising: - Series circuits of a mechanical phase contact (Kl, K2, K3) and an electronic switch (SI, S2, S3), whereby a series circuit electrically connects a mains-side phase connection (LG1, LG2, LG3) with a load-side phase connection (LL1, LL2, LL3), - that the mechanical phase contacts (Kl, K2, K3) are can be opened together to avoid a current flow or closed together to prevent a current flow, - that the electronic switches ( SI , S2 , S3 ) can be switched by means of semiconductor-based switching elements into a high-resistance state of the switching elements to avoid a current flow or a low-resistance state of the switching elements to allow current flow, that the electronic switches can be switched independently of one another into a high-resistance or low-resistance state to avoid or allow a phase-conductor-dependent current flow.

18. Method according to claim 17, characterized in that the level of the current of the respective series circuit is determined and, if at least a first current threshold value in a series circuit is exceeded, avoidance of a current flow in the series circuit in question, in particular for a first period of time, is initiated by the electronic switch in question.

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