Protection switch device and method

Abstract

The invention relates to a protective switching device for protecting a multi-phase low-voltage AC circuit, comprising: a housing having a grid-side phase connection and a load-side phase connection for phase conductors of the low-voltage circuit; a series circuit of mechanical phase contacts and electronic switches, the series circuit respectively connecting the phase connection terminals on the power grid side and the load side; the mechanical phase contacts can be jointly opened in order to avoid current flow or jointly closed in order to avoid current flow; the electronic switches can be switched to a high-resistance state to avoid current flow or to a low-resistance state for current flow by means of the semiconductor-based switching element, the electronic switches can be switched to the high-resistance state or the low-resistance state independently of each other; a temperature sensor is arranged for each series circuit and is used for correspondingly determining the temperature of the connecting terminal of the corresponding series circuit; when a first temperature threshold is exceeded, the electronic switch of the series circuit is switched into a high resistance state to avoid current flow, thereby avoiding overheating.

Description

[0001] It does not concern the grammatical gender of a particular term and includes people with either masculine or feminine identities. Technical Field

[0002] The invention relates to the technical field of a protective switching device for a low-voltage circuit having an electronic switch and a method for a protective switching device for a low-voltage circuit having an electronic switch. Background Art

[0003] Low voltage refers to voltages up to 1000 V AC or 1500 V DC. Low voltage specifically refers to voltages greater than minimum voltage, which is 50 V AC or 120 V DC.

[0004] A low-voltage circuit or a low-voltage network or a low-voltage system is a circuit with a rated or nominal current of up to 125 amperes, more particularly up to 63 amperes. A low-voltage circuit is particularly a circuit with a rated or nominal current of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values ​​mentioned are particularly the rated current, the nominal current and / or the cut-off current, i.e. the maximum current conducted through the circuit under normal circumstances, or the current which is usually interrupted by the circuit, for example by a protective device, such as a protective switchgear or a line protection switch or a circuit breaker. The rated current can be further graded 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.

[0005] Circuit breakers are overcurrent protection devices that have been known for a long time and are used in low-voltage circuits in electrical installation technology. Circuit breakers protect circuits from damage caused by overcurrent and / or short circuits. Circuit breakers can automatically switch off the circuit in the event of an overload and / or short circuit. Circuit breakers are non-automatically resettable fuse elements.

[0006] Unlike line circuit breakers, circuit breakers are designed for currents greater than 125 amperes, in some cases also starting at 63 amperes. The line circuit breaker is therefore simpler and more compact in design. Line circuit breakers usually have the option of being mounted on a so-called top hat rail (support rail, DIN rail, TH35).

[0007] Line protection switches are electromechanical in structure. In the housing, they have mechanical switch contacts or working current triggers for interrupting (triggering) the current. Usually, bimetallic protection elements or bimetallic elements are used to trigger (interrupt) in the case of long-term overcurrent (overcurrent protection) or thermal overload (overload protection). Electromagnetic triggers with coils are used to trigger for a short time when the overcurrent limit value is exceeded or a short circuit occurs (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.

[0008] Protection switchgear with electronic interruption units or electronic switches is a relatively recent development. The protection switchgear has a semiconductor-based electronic interruption unit / electronic switch. That is, the current of the low-voltage circuit is conducted through a semiconductor device or a semiconductor switch, which can interrupt the current or switch to conduction. In addition, the protection switchgear with an electronic interruption unit / electronic switch usually has a mechanical separation contact unit with contacts, which has separation characteristics in particular according to the relevant standards for low-voltage circuits, wherein the contacts of the mechanical separation contact unit are connected in series to the electronic interruption unit / electronic switch, that is, the current of the low-voltage circuit to be protected is conducted both through the mechanical separation contact unit / mechanical contacts and through the electronic interruption unit / electronic switch.

[0009] The invention relates in particular to a low-voltage AC circuit having an AC voltage, which is usually a time-dependent sinusoidal AC voltage with a frequency f. The time dependence of the instantaneous voltage value u(t) of the AC voltage is described by the following equation:

[0010] u(t)=U*sin(2π*f*t)

[0011] in:

[0012] u(t) = instantaneous voltage value at time t

[0013] U = voltage amplitude

[0014] A harmonic AC voltage can be represented by the rotation of a pointer, the length of which corresponds to the amplitude of the voltage (U). 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:

[0015] ω = 2π*f = 2π / T = angular frequency of the AC voltage (T = duration of the oscillation cycle)

[0016] The specification of angular frequency (ω) is usually preferred to frequency (f) because many vibration theory formulas can be expressed more compactly in terms of angular frequency due to the presence of trigonometric functions, which by definition have a period of 2π:

[0017] u(t)=U*sin(ωt)

[0018] In the case of an angular frequency that is not constant over time, the term instantaneous angular frequency is also used.

[0019] In the case of a sinusoidal, in particular temporally constant, alternating voltage, the time-dependent value corresponding to the angular velocity ω and the time t corresponds to the time-dependent angle This angle is also called the phase angle

[0020] 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° ( (0...2π) or (0°...360°), due to periodicity; abbreviated as: or ...360°).

[0021] Therefore, the instantaneous voltage value u(t) refers to the instantaneous value of the voltage at the time point t, that is, in the case of a sinusoidal (periodic) alternating voltage, it refers to the phase angle The voltage value ( or ...360° for the corresponding period). The same applies to the instantaneous current value i(t) etc. Summary of the invention

[0022] The object of the present invention is to improve a circuit breaker of the type mentioned at the outset, in particular to avoid destruction, damage or inadmissible operating states (in particular inadmissible operating temperatures) of the polyphase circuit breaker, in particular its connecting terminals.

[0023] The above-mentioned technical problem is solved by a protection switching device having the features according to the invention and by a method according to the invention.

[0024] According to the present invention, a protective switch device for protecting a multi-phase low-voltage AC circuit, in particular a three-phase AC circuit, is provided, wherein the protective switch device comprises:

[0025] a housing having line-side and load-side phase connection terminals for phase conductors of a low-voltage AC circuit,

[0026] (Connection terminals are used to connect the external conductor of the low-voltage circuit to be protected to the protective switchgear.)

[0027] - a series circuit of mechanical phase contacts and electronic switches,

[0028] The series circuits respectively connect one of the phase connections on the grid side to one of the phase connections on the load side (electrically),

[0029] - Mechanical phase contacts can be switched open together to prevent current flow or can be switched together to be closed for the flow of current, in particular the mechanical contacts are connected to one another via a mechanical coupling,

[0030] - the electronic switch can be switched by means of a semiconductor-based switching element to a high-resistance state of the switching element to prevent a current flow or to a low-resistance state of the switching element for a current flow,

[0031] - electronic switches can be switched to a high-resistance state or a low-resistance state independently of each other,

[0032] - at least one temperature sensor is provided for each series circuit (so that each series circuit has at least one temperature sensor),

[0033] for correspondingly determining the magnitude of the temperature of at least one connecting terminal of the respective series circuit,

[0034] (in particular, at least one temperature sensor of the series circuit is arranged at a connection terminal (for example at the connection terminal or in the region of the connection terminal)),

[0035] (in particular, not only the grid-side phase connection of the series circuit has a grid-side temperature sensor, but also the load-side phase connection of the series circuit has a load-side temperature sensor),

[0036] The protective switching device is designed to switch the electronic switch of the series circuit to a high-impedance state to prevent a current flow and thus to prevent overheating of the connection terminal or (usually) the protective switching device when a first temperature threshold of a temperature sensor of the series circuit is exceeded.

[0037] Avoiding overheating means that the protective switching device, in particular the connecting terminals, are kept within their (their) permissible thermal limits or permissible (device) temperature.

[0038] The temperature sensor can be connected to a control unit which in turn is connected to mechanical contacts and electronic switches which switch together.

[0039] This has the advantage that overheating of the protective switchgear, in particular one or selected or all connecting terminals, is avoided. Thermal overload or thermal destruction can thus be avoided, thereby preventing, for example, cables of connected conductors from burning. By preventing a current flow, heating of the protective switchgear / the corresponding connecting terminals is avoided and a safe state is established.

[0040] Other advantageous embodiments of the present invention are given in the exemplary embodiments.

[0041] In an advantageous embodiment of the invention, when a first temperature threshold value of the temperature sensor of the series circuit is exceeded, all electronic switches (of the series circuit) are switched to a high-resistance state in order to prevent a current flow and thus to prevent overheating.

[0042] This has the particular advantage that it provides properties similar to conventional line circuit breakers and in particular all phase conductors are switched to prevent current flow, which is particularly advantageous for three-phase loads. In addition, the circuit breaker device can cool more quickly due to the lack of current flow in the other series circuits.

[0043] In an advantageous embodiment of the invention, a current sensor unit is provided for each series circuit in order to determine the magnitude of the current in the corresponding phase conductor in each case, in particular to (determine and make available) the instantaneous current value.

[0044] A control unit is provided, which is connected to the current sensor unit, the temperature sensor, the (jointly switched) mechanical phase contacts and the electronic switch. The protective switchgear is designed such that when at least one first current threshold value in the phase conductor is exceeded, the avoidance of the current flow in the relevant phase conductor is initiated by the relevant electronic switch, in particular the avoidance of the current flow lasts for a first duration.

[0045] This has the particular advantage that, when a defined current threshold or current-time threshold is exceeded (i.e., the current threshold is exceeded within a defined time limit), only a selective interruption of the conductor involved (or of the conductors involved) occurs. In addition, a current flow can be achieved in other conductors (not involved) in the polyphase low-voltage AC circuit.

[0046] By avoiding the first duration, it is advantageous to switch on again or to change to low resistance after the first duration, thereby further ensuring the power supply safety or further checking whether a current threshold value is exceeded. This can be advantageously performed in particular by evaluating the instantaneous value of the current magnitude.

[0047] In an advantageous embodiment of the present invention, the first time period is shorter than 20 ms, in particular shorter than 10 ms.

[0048] This has the particular advantage that, for a half-wave or full-wave of the voltage or current in the AC circuit, in this example (20ms, 10ms) relative to the grid frequency of 50Hz, an interruption is performed, thereby providing power supply security again with the next full-wave or half-wave. In particular, it is possible to become a low impedance in the region of the next zero crossing (in the zero crossing, or in the region 1ms before or after it) after the interruption.

[0049] In an advantageous embodiment of the invention, the mechanical phase contact is part of a mechanical disconnecting contact unit, which jointly opens or closes the phase contacts. In particular, the mechanical disconnecting contact unit has a handle accessible on the protective switchgear for manually opening or closing the phase contacts (of the mechanical disconnecting contact unit).

[0050] This has the particular advantage that, in contrast to the phase-dependent high impedance of the electronic switch which prevents current flow, complete galvanic isolation of all phase conductors is simultaneously achieved. Compatible behavior with conventional electromechanical protective switchgear can be achieved by the handle.

[0051] In an advantageous design of the present invention, the protection switch device is designed so that the mechanically disconnecting contact unit can be opened by the control unit but cannot be closed. In particular, the mechanically disconnecting contact unit can only be closed by the handle after being released by the control unit.

[0052] This has the particular advantage that an increased safety of the protective switching device is provided, since the control unit cannot inadvertently (erroneously) close the contacts.

[0053] 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.

[0054] This has the particular advantage that a compact electronic interruption unit is provided which combines the electronic switches, so that a space-saving design can be achieved and synergistic effects of the components can be utilized.

[0055] In an advantageous embodiment of the present invention, the electronic interruption unit / electronic switch has a bidirectional voltage resistance. In particular, an overvoltage protection is provided for the semiconductor-based switching element.

[0056] This has the particular advantage that robustness against overvoltages is provided and inductive line loops can be disconnected.

[0057] In an advantageous embodiment of the invention, the mechanical phase contacts are associated with the load-side phase terminals and the electronic switches are associated with the grid-side phase terminals.

[0058] This has the particular advantage that an advantageous protection switchgear design is provided which supports phase-dependent switching of the electronic switch and enables self-testing (in particular self-testing of the electronic switch or the electronic interruption unit) even when the contacts are open. Furthermore, the energy supply of the protection switchgear is ensured even when the contacts are open. Thus, a structure for a protection switchgear is provided, in which the functionality of the protection switchgear is provided even when the contacts are open.

[0059] In an advantageous embodiment of the present invention, a grid-side neutral conductor connection terminal and a load-side neutral conductor connection terminal are provided for the neutral conductor of a multi-phase low-voltage AC circuit, in particular a three-phase low-voltage AC circuit.

[0060] The neutral conductor connection terminal on the grid side is (electrically) connected to the neutral conductor connection terminal on the load side directly or via a mechanical neutral conductor contact.

[0061] At least one temperature sensor is provided for the neutral conductor connection terminal to determine the magnitude of the temperature of at least one neutral conductor connection terminal. In particular, the grid-side temperature sensor is provided for the grid-side neutral conductor connection terminal, and the load-side temperature sensor is provided for the load-side neutral conductor connection terminal, so that the magnitude of the temperature of the grid-side neutral conductor connection terminal and the magnitude of the temperature of the load-side neutral conductor connection terminal can be determined.

[0062] When a first temperature threshold value (1.SW) of at least one temperature sensor of the neutral conductor connection terminal is exceeded, the electronic switch of the series circuit is switched to a high-resistance state to prevent current flow and thus overheating. That is, when the neutral conductor connection terminal temperature is too high, all phase conductors become high-resistance.

[0063] Alternatively, all mechanical contacts may be opened.

[0064] This has the particular advantage that a multi-pole circuit breaker device is provided in which at least one neutral conductor connection terminal is also monitored and the current flow is interrupted, if necessary (in particular galvanically).

[0065] In an advantageous embodiment of the invention, the mechanical neutral conductor contact can be opened or closed (switched) together with the phase contacts. The mechanical neutral conductor contact is switched together with the mechanical 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.

[0066] This has the particular advantage that the neutral conductor contact always opens and closes without current. This reduces the wear on the contacts and increases their service life. In addition, this prevents arcs from occurring when the neutral conductor contact opens.

[0067] In an advantageous embodiment of the invention, the mechanical contact is opened in the activated high-resistance state of the electronic switch to avoid overheating and when a higher second temperature threshold is exceeded (ie the second temperature threshold is higher than the first temperature threshold).

[0068] This has the particular advantage that an additional safety feature is provided in the protective switchgear. If, despite the activation of the high-resistance electronic switch, there is still an increased heating, this may be due to the fact that the electronic switch is not high-resistance or not high enough, and the (faulty) current flow leads to further heating of the protective switchgear / connecting terminal. In this case, the contacts open in order to achieve galvanic isolation and thus completely prevent the current flow. Damage to the protective switchgear / connecting terminal is avoided by this additional safety feature.

[0069] In an advantageous embodiment of the present invention, the electronic switch is switched to a low resistance state (for current flow in the low voltage circuit) when the electronic switch is in a high resistance state to avoid overheating and below a third temperature threshold. The third temperature threshold is lower than the first temperature threshold.

[0070] This has the particular advantage that, after the circuit breaker device / connecting terminal has cooled, current can flow again, so that the circuit breaker device is always in a safe operating state.

[0071] In an advantageous design of the present invention, alternatively, in a high-resistance state of the electronic switch to avoid overheating, and after a first time period has passed since the high-resistance state of the electronic switch (to avoid overheating) occurred, the electronic switch can be switched to a low-resistance state (for current flow in a low-voltage circuit).

[0072] The first time period may be, for example, in the order of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes.

[0073] This has the particular advantage that a fixed cooling time (first time period) is achieved. After the protective switching device / connecting terminal has cooled, current flow is achieved again.

[0074] In an advantageous embodiment of the invention, the mechanical contact is opened within a first time frame if a first number of changes to the high-resistance state to avoid overheating (and back to the low-resistance state) is exceeded.

[0075] The first time frame can be, for example, one hour, several hours, such as 3 hours, 5 hours, 6 hours, 10 hours, 12 hours, 18 hours, 24 hours (a day), several days, a week. For example, the number of changes can be changed from 2, 3, 4, ..., 10, ... 20 times.

[0076] This has the particular advantage that in the case of frequent temperature-induced changes to the high-resistance state (from the low-resistance state to the high-resistance state), additional safety is achieved and the contacts are opened in order to perform galvanic isolation and completely avoid the flow of heat-generating currents. Thus, further changes of the electronic switch(es) to the high-resistance state (to the high-resistance state and back to the low-resistance state) are avoided and safety is established in the low-voltage circuit.

[0077] In an advantageous embodiment of the present invention, a communication unit (connected to the control unit) is provided. When a fourth temperature threshold is exceeded, a warning is issued by means of the communication unit. The fourth temperature threshold is lower than the first temperature threshold.

[0078] The fourth temperature threshold may be, for example, 10, ..., 20, ..., 30, ..., 40 Kelvin less than the first temperature threshold.

[0079] This has the particular advantage that a notification is given when a temperature threshold value is reached, so that, for example or advantageously, a cause determination can be carried out before a shutdown due to overtemperature occurs.

[0080] Alternatively or additionally, the magnitude (or an equivalent value) of the temperature of the temperature sensor may be output (communicated) by means of the communication unit.

[0081] This has the particular advantage that (central) temperature monitoring of one or more protective switching devices is possible, so that corresponding measures can be taken in the event of a temperature increase.

[0082] In an advantageous embodiment of the invention, a display unit connected to the control unit is provided, which has a display device visible on the protective switchgear for displaying the magnitude of the temperature limit value (first and / or second and / or third and / or fourth) or (and) the temperature exceeded, in particular the temperature limit value or (and) the temperature associated with the conductor (phase conductor, neutral conductor) as an alternative or in addition to the high-resistance or low-resistance state of the electronic switch.

[0083] This has the particular advantage that a visualization of the temperature status is provided.

[0084] In an advantageous embodiment of the invention, the mechanical contacts can be opened by the control unit, but cannot be closed by the control unit.

[0085] This has the particular advantage that the circuit breaker device has a high degree of safety, since contacts within the circuit breaker device cannot be closed erroneously.

[0086] In an advantageous embodiment of the invention, the mechanical contact has a release function. This can be a release function provided according to a standard. In particular, it is possible to open the contact by the control unit even when the mechanical handle is locked, that is to say, for example, when the handle is locked in a closed contact state.

[0087] This has the particular advantage that a high level of safety and a particularly standard-compliant protective switchgear for low-voltage circuits is provided.By opening the contacts, the current flow can be interrupted at any time by the current.

[0088] In an advantageous improvement of this design, the protective switch device is designed so that when it is initiated by the control unit to become low resistance, for example when it is below a third temperature threshold, the electronic switch becomes low resistance at the corresponding zero crossing of the voltage (or at a voltage less than 50V, 25V, and in particular less than 10V).

[0089] This has the particular advantage that the grid reaction is reduced and the load in the switch is lower.

[0090] In an advantageous embodiment of the invention, the protective switchgear is designed such that when (at least) a first current threshold is exceeded in the conductor, the prevention of the current flow of the relevant conductor is initiated by the relevant electronic switch. At the next or the next zero crossing of the voltage, the electronic switch changes to a low resistance again in order to enable the current flow. The control unit is connected to the current sensor unit, the temperature sensor, the voltage sensor unit(s), the mechanical contacts and the electronic switch.

[0091] This has the particular advantage that an increased robustness against erroneous triggering and thus an increased power supply reliability is achieved.

[0092] According to the invention, a corresponding method is claimed for a protective switchgear for a multi-phase low-voltage AC circuit having electronic (semiconductor-based) switches / switching elements, which method has the same and other advantages.

[0093] A method for a protective switchgear (SG) for protecting a multi-phase low-voltage AC circuit has:

[0094] a housing having line-side and load-side phase connection terminals for phase conductors of the low-voltage circuit,

[0095] (Connection terminals are used to connect the external conductor of the low-voltage circuit to be protected to the protective switchgear.)

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

[0097] The series circuit respectively connects the phase connection terminals on the grid side with the phase connection terminals on the load side (electrically).

[0098] - mechanical phase contacts can be opened together to prevent current flow or closed together to allow current flow,

[0099] - the electronic switch is capable of switching by means of a semiconductor-based switching element to a high-resistance state of the switching element to prevent a current flow or to a low-resistance state of the switching element for a current flow,

[0100] the electronic switches can be switched independently of one another into a high-resistance or low-resistance state in order to (advantageously) prevent or enable a current flow associated with the phase conductors,

[0101] - at least one temperature sensor is provided for each series circuit in order to respectively determine the magnitude of the temperature of at least one connecting terminal of the respective series circuit (in particular two temperature sensors are provided, one for determining the magnitude of the temperature of the connecting terminal on the grid side and one for determining the magnitude of the temperature of the connecting terminal on the load side),

[0102] When a first temperature threshold value of the temperature sensor of the series circuit is exceeded, the electronic switch of the series circuit is switched to a high-resistance state to prevent a current flow and thus to prevent overheating (of the protective switching device / connecting terminal).

[0103] Advantageously, when a first temperature threshold of the temperature sensor of the series circuit is exceeded, all electronic switches (of the series circuit) are switched to a high-resistance state in order to avoid a current flow and thus to avoid overheating.

[0104] Advantageously, the magnitude of the current of 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 respective series circuit is initiated by the respective electronic switch, in particular for a first duration.

[0105] Advantageously, in the case of an activated high-impedance state of the electronic switch to avoid overheating, and when a second, higher temperature threshold is exceeded, the mechanical contacts are opened.

[0106] Advantageously, in the case of the high resistance state of the electronic switch to avoid overheating, and below a third temperature threshold, the electronic switch is switched to a low resistance state. The third temperature threshold is lower than the first temperature threshold.

[0107] Advantageously, in the case of a high-resistance state of the electronic switch for avoiding overheating and after a first period of time has elapsed since the occurrence of the high-resistance state for avoiding overheating, the electronic switch is switched to a low-resistance state.

[0108] Advantageously, the mechanical contacts are opened within a first time frame in the event that a first number of changes to the high resistance state to avoid overheating are exceeded.

[0109] Advantageously, a warning is issued when a fourth temperature threshold is exceeded.

[0110] Advantageously, the magnitude or an equivalent value of the temperature of at least one temperature sensor is output.

[0111] All embodiments, whether individual features or combinations of features, allow an improvement of the protective switching device, in particular avoiding destruction, damage or inadmissible operating states (in particular inadmissible operating temperatures) of the protective switching device, in particular the connecting terminals. BRIEF DESCRIPTION OF THE DRAWINGS

[0112] The described characteristics, features and advantages of the present invention and the manner in which these characteristics, features and advantages are achieved will become clearer and more easily understood with reference to the following description of embodiments, which are explained in detail with reference to the accompanying drawings.

[0113] Here, in the accompanying drawings:

[0114] Figure 1 A first diagram showing a protective switchgear,

[0115] Figure 2 A second diagram showing a protective switchgear,

[0116] Figure 3 A first illustration of a graph is shown,

[0117] Figure 4 A second illustration of the diagram shows,

[0118] Figure 5 A third illustration of a diagram shows,

[0119] Figure 6 A fourth diagram of a graph is shown,

[0120] Figure 7 A fifth illustration of a diagram is shown. DETAILED DESCRIPTION

[0121] Figure 1 A method for protecting a multiphase low voltage AC circuit (according to Figure 1 An exemplary illustration of a 3-pole protection switchgear SG for a three-phase conductor, for example, in the example of a three-phase low-voltage AC circuit, the protection switchgear having:

[0122] a housing GEH having a first, second and third phase connection terminal LG1, LG2, LG3 on the grid side and a first, second and third phase connection terminal LL1, LL2, LL3 on the load side for a first, second and third phase conductor L1, L2, L3 of a low-voltage AC circuit,

[0123] The grid is usually connected to an energy source.

[0124] The load side Load is usually connected to electrical consumers.

[0125] In case of GEH:

[0126] a first series circuit SS1 of a first mechanical phase contact K1 and a first electronic switch S1,

[0127] a second series connection SS2 of a second mechanical phase contact K2 and a second electronic switch S2,

[0128] a third series circuit SS3 of a third mechanical phase contact K3 and a third electronic switch S3,

[0129] in:

[0130] The first series circuit SS1 (electrically connects) a first phase connection terminal LG1 on the grid side to a first phase connection terminal LL1 on the load side.

[0131] The second series circuit SS2 (electrically connects) the second phase connection terminal LG2 on the grid side to the second phase connection terminal LL2 on the load side, and

[0132] The third series circuit SS3 (electrically connects) the third phase connecting terminal LG3 on the grid side to the third phase connecting terminal LL3 on the load side.

[0133] the mechanical phase contacts K1 , K2 , K3 can be switched jointly, ie opened jointly to prevent a current flow or closed jointly for a current flow, ie the mechanical contacts are connected to one another via a mechanical coupling (eg a switching shaft),

[0134] 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 prevent a current flow or into a low-resistance state of the switching element for a current flow.

[0135] According to the invention, the first, second and third electronic switches can be switched to a high-resistance state or a low-resistance state independently of one another. That is, the first, second and third electronic switches can be switched to a high-resistance state or a low-resistance state independently of one another. In particular, in order to avoid or enable a current flow associated with a phase conductor.

[0136] according to Figure 1, a first, a second and a third current sensor unit SI1, SI2, SI3 are provided. 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 current magnitude of the first, second and third phase conductors L1, L2, L3, in particular, there are instantaneous current values.

[0137] 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 disconnecting contact unit MK, which jointly opens or closes the phase contacts K1, K2, K3. The mechanical disconnecting 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 disconnecting contact unit MK corresponds, for example, to a conventional unit, as is known from an electromechanical protective switching device (circuit protection switch, circuit breaker) (however, according to the invention, it does not have an element for overcurrent or short-circuit detection, such as a bimetallic release or the like).

[0138] In particular, the protective switch device is designed so that the mechanical disconnecting contact unit MK can be opened by the control unit SE, but cannot be closed. In particular, the mechanical disconnecting 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. That is, the contacts can only be closed by the handle HH when there is a release or release signal (from the control unit). In the absence of a release or release signal, the handle HH can be operated, but the contacts cannot be closed ("continuous slip (Dauerrutscher)").

[0139] Furthermore, the release unit LC can be designed so that the contacts K1, K2, K3 of the mechanical separation contact unit MK can be opened by a control signal of the control unit SE, as in Figure 1 This is indicated by an arrow from the control unit SE to the release unit LC.

[0140] according to Figure 1 , the mechanical phase contacts K1 , K2 , K3 are associated with the phase connectors on the load side / load side Load, and the electronic switches S1 , S2 , S3 are associated with the phase connectors on the grid side / grid side Grid.

[0141] The first electronic switch S1 , the second electronic switch S2 and the third electronic switch S3 may be part of an electronic interruption unit EU, wherein the electronic switches S1 , S2 , S3 are switchable independently of one another.

[0142] The electronic interruption unit / electronic switch can have a bidirectional voltage withstand strength. In particular, an overvoltage protection for the semiconductor-based switching element is provided in order to limit the voltage and thus provide protection for the semiconductor-based switching element.

[0143] A control unit SE is provided (as already mentioned in part), which is connected to the current sensor units SI1, SI2, SI3, the mechanical phase contacts (K1, K2, K3) or the mechanical disconnecting contact unit MK (as in Figure 1 As shown in FIG. 1 ) and connected to electronic switches S1, S2, and S3.

[0144] The current sensor units SI1 , SI2 , SI3 each determine the magnitude of the current in their respective conductor, so that in particular the instantaneous value of the current is present.

[0145] When at least one first current threshold in a conductor is exceeded, the prevention of a current flow in the conductor concerned is initiated by the electronic switch becoming high-impedance.

[0146] The high resistance can in particular last for a first duration. After the duration, the associated electronic switch can again be changed to a low resistance.

[0147] The change to low resistance can be carried out in particular at the next zero crossing of the voltage 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 in absolute terms below a voltage threshold, in particular 50V, 25V or 10V).

[0148] In particular, the first time period can be less than 20 ms, in particular less than 10 ms.

[0149] A differential current sensor unit ZCT can be provided (in Figure 1 The differential current sensor unit ZCT is connected to the control unit SE.

[0150] The current sensor units SI1, SI2, SI3 are based on Figure 1 In the example of FIG. 1 , the current sensor units SI1, SI2, SI3 are arranged between the connection terminals LG1, LG2, LG3 on the grid side of the series circuit of the electronic switches S1, S2, S3 and the mechanical phase contacts K1, K2, K3. Specifically, between the connection terminals LG1, LG2, LG3 on the grid side and the electronic switches S1, S2, S3. The current sensor units SI1, SI2, SI3 may also be arranged in other ways. For example, between the electronic switches S1, S2, S3 and the mechanical phase contacts K1, K2, K3.

[0151] According to the present invention, at least one temperature sensor is provided for each series circuit SS1, SS2, SS3. Figure 1 In the example of FIG. 1 , two temperature sensors are provided for each series circuit.

[0152] In the first series circuit SS1 , a first grid-side temperature sensor TLG1 is provided for a first grid-side phase connection LG1 of the first phase conductor L1 .

[0153] In the first series circuit SS1 , a load-side first temperature sensor TLL1 is provided for a load-side first phase connection LL1 of the first phase conductor L1 .

[0154] In the second series circuit SS2 , a second grid-side temperature sensor TLG2 is provided for a second grid-side phase connection LG2 of the second phase conductor L2 .

[0155] In the second series circuit SS2 , a load-side second temperature sensor TLL2 is provided for a load-side second phase connection LL2 of the second phase conductor L2 .

[0156] In the third series circuit SS3 , a third grid-side temperature sensor TLG3 is provided for a third grid-side phase connection LG3 of the third phase conductor L3 .

[0157] In the third series circuit SS3 , a load-side third temperature sensor TLL3 is provided for a load-side third phase connection LL3 of the third phase conductor L3 .

[0158] The temperature sensors are respectively arranged at the connection terminals or in the region of the connection terminals. The temperature sensors are used in particular to respectively determine the magnitude of the temperature of the respective connection terminal or the region of the connection terminal.

[0159] The temperature sensors are respectively connected to the control unit SE so that the control unit obtains the magnitude (or equivalent value) of the temperature.

[0160] That is to say, each series circuit has at least one temperature sensor.

[0161] The protective switching device is designed such that, when a first temperature threshold value 1.SW of a temperature sensor of the series circuit is exceeded, the electronic switch of the series circuit is switched to a high-resistance state to prevent a current flow and thus to prevent overheating (of the connection terminals).

[0162] Alternatively or additionally (e.g. configurably), when a first temperature threshold of a temperature sensor of the series circuit is exceeded, all electronic switches (of the series circuit in a protective switchgear for a conductor of a low-voltage circuit) are switched to a high-resistance state to avoid current flow and thereby avoid overheating.

[0163] Figure 2 Shown according to Figure 1 , with the following differences.

[0164] A neutral conductor connection terminal NG on the grid side and a neutral conductor connection terminal NL on the load side are provided for the neutral conductor N of the multi-phase low-voltage AC circuit. Figure 2 The example in is a three-phase low-voltage AC circuit with a neutral conductor. Figure 2 , the neutral conductor connection terminal NG on the grid side is connected to the neutral conductor connection terminal NL on the load side through the neutral conductor contact KN.

[0165] Alternatively, the grid-side neutral conductor connection terminal NG can also be connected directly (ie without switchable contacts) to the load-side neutral conductor connection terminal NL.

[0166] At least one temperature sensor is provided for the neutral conductor connection terminal to determine the temperature of at least one neutral conductor connection terminal. Figure 2 A temperature sensor is provided for each neutral conductor connection terminal. A grid-side temperature sensor TNG for the neutral conductor connection terminal NG on the grid side and a load-side temperature sensor TNL for the neutral conductor connection terminal NL on the load side are provided, so that the magnitude of the temperature of the neutral conductor connection terminal NG on the grid side and the magnitude of the temperature of the neutral conductor connection terminal NL on the load side can be determined.

[0167] A grid-side temperature sensor TNG on the neutral conductor side and a load-side temperature sensor TNL on the neutral conductor side are connected to the control unit SE.

[0168] In this example, no electronic switch is provided in the neutral conductor path in the housing of the protective switchgear, that is, the neutral conductor connection between the neutral conductor connection NG on the grid side and the neutral conductor connection NL on the load side has no electronic switch (no electronic switch).

[0169] Advantageously, the mechanical neutral conductor contact KN can be switched jointly with the phase contacts K1 , K2 , K3 . That is, the mechanical neutral conductor contact KN can be opened or closed jointly with the phase contacts K1 , K2 , K3 , as described above with respect to the contacts K1 , K2 , K3 .

[0170] In particular, the mechanical separation contact unit MK can be designed such that the neutral conductor contact KN is closed before the phase contacts K1, K2, K3 are closed. Similarly, the neutral conductor contact KN can be opened after the phase contacts K1, K2, K3 are opened.

[0171] Furthermore, a power supply device NT is provided, for example a power supply unit, for supplying energy to the protection switching device SG, in particular to the control unit SE.

[0172] 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 some (at least two) of the conductors for supplying energy. In this example, the energy supply device NT is also connected to the control unit SE.

[0173] On the other hand, a control unit SE is shown in combination with electronic switches S1 , S2 , S3 and current sensor units SI1 , SI2 , SI3 .

[0174] Furthermore, a voltage sensor unit is arranged between each phase conductor and the neutral conductor. A first voltage sensor unit SU1 is arranged between the first phase conductor L1 and the neutral conductor N, a second voltage sensor unit SU2 is arranged between the second phase conductor L2 and the neutral conductor N, and a third voltage sensor unit SU3 is arranged between the third phase conductor L3 and the neutral conductor N for determining the magnitude of the voltage between the corresponding phase conductor and the neutral conductor, in particular the instantaneous voltage value. The voltage sensor units SU1, SU2, SU3 are connected to the control unit SE.

[0175] In the case of low resistance activation by the control unit SE, the electronic switches S1, S2, S3, for example:

[0176] - becomes low impedance in case of user-side startup, or

[0177] - in the event of actuation by the protective switching device, in particular below a third temperature threshold 3.SW, becomes low-resistance,

[0178] =>, the electronic switch concerned can become low-resistance at the corresponding zero crossing of the voltage (in the region, see above).

[0179] For this purpose, the voltage sensor units SU1, SU2, SU3 are connected, as already mentioned, to the control unit SE, which is further connected to the current sensor units SI1, SI2, SI3, the temperature sensors TS1, TS2, TS3, the mechanical phase contacts K1, K2, K3 (or the mechanical disconnecting contact units MK) and the electronic switches (S1, S2, S3). Furthermore, the protective switch device can advantageously be designed such that when at least one first current threshold value (in particular the instantaneous value of the current) in the conductor is exceeded, the prevention of the current flow of the relevant conductor is initiated by the relevant electronic switch. At the next or the next zero crossing of the voltage, the electronic switch changes to a low resistance again in order to enable the current flow.

[0180] This can be done multiple times until the first number of repetitions is exceeded. Then:

[0181] a) All electronic switches become high resistance, or ( / and)

[0182] b) Open contacts (galvanic isolation).

[0183] according to Figure 1 and Figure 2 Any combination (intermediate combination) of the exemplary protective switchgear shown in the figure is possible (for example Figure 1 The basis of Figure 2 energy supply device NT, etc.).

[0184] High resistance refers to a state in which only a negligible current still flows. High resistance refers in particular to resistance values ​​greater than 1 kOhm, preferably greater than 10 kOhm, 100 kOhm, 1 MOhm, 10 MOhm, 100 MOhm, 1 kOhm or more.

[0185] Low resistance refers to a state in which a given current value can flow in the protective switching device. Low resistance refers in particular to resistance values ​​less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less.

[0186] The electronic switches S1, S2, S3 or the electronic interruption unit EU may have semiconductor devices such as bipolar transistors, field effect transistors (FETs), insulated gate bipolar transistors (IGBTs), metal oxide field effect transistors (MOSFETs) or other (self-conducting) power semiconductors. In particular, IGBTs and MOSFETs are particularly well suited for electronic switches (as semiconductor-based switching elements) due to their low on-resistance, high junction resistance and good switching characteristics.

[0187] Mechanical contacts or mechanical disconnecting contact units MK are particularly understood to mean the (standard-compliant) disconnecting function implemented by the disconnecting contact unit MK. The disconnecting function is understood to mean the following:

[0188] - According to the standard minimum air distance (minimum distance of contacts),

[0189] - contact position indication of the contacts of a mechanically separated contact unit,

[0190] - Operation / opening of the contacts of a mechanically separated contact unit is always possible (via the control unit) (it is not possible to (permanently) lock the contacts in the closed state by means of a handle).

[0191] As regards the minimum air distance between the contacts of the separating contact system, this minimum air distance depends essentially on the voltage. Other parameters are the degree of contamination, the type of field (homogeneous, inhomogeneous) and the air pressure or the height above the standard zero point.

[0192] There are corresponding regulations or standards for this minimum air distance or creepage distance. These regulations, for example, stipulate the minimum air distance in air for the impulse withstand voltage, which is used for inhomogeneous and uniform (ideal) electric fields depending on the degree of pollution. The impulse withstand voltage 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 switch device have a separating function (separator characteristic).

[0193] In this context, for the function of the separator and its characteristics, the standard series DIN EN 60947 or IEC 60947 are relevant within the meaning of the present invention and are hereby incorporated by reference.

[0194] The disconnect contact system is advantageously characterized by a minimum air distance of the disconnected contacts in the off position (open position, open contacts), depending on the rated impulse withstand voltage and the degree of contamination. The minimum air distance is in particular between (minimum) 0.01 mm and 14 mm.

[0195] Particularly advantageously, the minimum air distance is between 0.01 mm at 0.33 kV and 14 mm at 12 kV, in particular for pollution degree 1 and in particular for inhomogeneous fields.

[0196] Advantageously, the minimum air distance may have the following values:

[0197] E DIN EN 60947-1 (VDE 0660-100): 2018-06

[0198] Table 13 - Minimum air distances

[0199]

[0200] The degree of pollution and the field type correspond to the degree of pollution and the field type defined in the standard. This advantageously makes it possible to achieve a standard-compliant circuit breaker device that is dimensioned according to the rated surge voltage resistance.

[0201] Mechanically isolating contact units do not in particular refer to relay contacts.

[0202] The control unit SE can have a microcontroller (microcontroller unit).

[0203] The circuit breaker device can have a (in particular wireless / cordless) communication unit COM which is connected to the control unit SE or is part of the control unit SE.

[0204] When the fourth temperature threshold is exceeded, a warning can be issued by means of the communication unit COM. Alternatively or additionally, the magnitude of the temperature (or its equivalent) of at least one temperature sensor, a portion of the temperature sensors or all the temperature sensors can be output (communicated) by means of the communication unit COM.

[0205] In addition, a display unit AE can be provided. The display unit AE can be designed as a combined display and input unit. The display unit AE (display and input unit) is connected to the control unit SE or is part of the control unit SE. The display unit has a display device visible on the protective switch device, in particular for displaying the high resistance or low resistance state of the electronic switch. As a replacement or supplement for displaying the size of the temperature exceeding the temperature limit value (first or / and second or / and third or / and fourth) or (and) at least one temperature sensor, a part of the temperature sensors or all temperature sensors.

[0206] When a first temperature threshold 1.SW of at least one temperature sensor of the neutral conductor connection is exceeded, the electronic switch of the series circuit is switched to a high-resistance state to prevent current flow and thus overheating. That is, when the neutral conductor connection temperature is too high, all phase conductors become high-resistance.

[0207] Alternatively, all mechanical contacts may be opened.

[0208] Figure 3 A diagram of a first diagram or coordinate system is shown, wherein the magnitude of the current I of a phase conductor (such as L1, L2 or L3) of a low-voltage AC circuit is plotted on the horizontal axis (abscissa) and the temperature T of a temperature sensor (such as TLL1, TLL2, TLL3, TLG1, TLG2 or TLG3) associated with the selected phase conductor current is plotted on the vertical axis (ordinate). TS The size (for example, the current I of L2=> the temperature T of TLL2 or TLG2 TS size).

[0209] Shows the temperature of the temperature sensor T TS Curve that changes with the magnitude of the current I in the phase conductor of a low-voltage circuit.

[0210] It is assumed here that the heating in the protective switchgear, more particularly at the (selected) connecting terminal (in the event of a fault), depends on the magnitude of the current I through the corresponding (relevant) phase conductor of the low-voltage circuit of the protective switchgear (the protective switchgear is to protect the low-voltage circuit). As the magnitude of the current I in the (selected) phase conductor increases, the temperature of the temperature sensor of the relevant connecting terminal (usually in part of the protective switchgear) increases. The temperature T determined by the temperature sensor is therefore TSThe temperature increases monotonically with the current. (In addition to the current, the ambient temperature also affects the heat generation. To simplify the diagram, Figure 3 Not shown.)

[0211] according to Figure 3 , different temperature thresholds are shown: a first temperature threshold 1.SW (100°C in the example), a second temperature threshold 2.SW (110°C in the example), and a third temperature threshold 3.SW (80°C in the example).

[0212] Figure 4 Shown according to Figure 3 , except that three interrelated diagrams are shown, in which the time t is plotted on the horizontal axis (abscissa).

[0213] exist Figure 4 In the upper region of the graph, the temperature T of the (selected) temperature sensor TS is plotted. TS The magnitude of t varies with time t. The first temperature threshold 1.SW and the third temperature threshold 3.SW are plotted.

[0214] exist Figure 4 In the middle region of , the magnitude of the current I is plotted versus time t.

[0215] exist Figure 4 In the lower region of the diagram, the switching state SZ of the associated electronic switch is plotted over time t. The low-resistance state of the electronic switch is indicated by on. The high-resistance state of the electronic switch is indicated by off.

[0216] For example, a (constant) current I or a current I having a constant effective value of a first magnitude flows for a certain time ( Figure 4 Center). Corresponding heating occurs at the (faulty) connection terminal. Temperature at the connection terminal / determined temperature T of the temperature sensor TS The magnitude of increases until it reaches the first temperature threshold 1.SW( Figure 4 upper part).

[0217] When a first temperature threshold value 1.SW (in the example 100° C.) is reached or exceeded, the associated electronic switch is switched to the high-resistance state (of the switching element) off to prevent a current flow in the associated phase conductor of the connection terminal, at a first time t1 ( Figure 4 Thus, further heating and overheating of the connection terminals (and damage associated therewith) are avoided.

[0218] The protection switch device can cool down. At the second time point t2, the third temperature threshold 3.SW is reached or falls below, in the example 80°C. When the third temperature threshold 3.SW is reached or falls below, the electronic switch (again) (at the second time point t2) switches to the low-resistance state on (for current flow in the low-voltage circuit) ( Figure 4 The current I can flow again (from the second time point t2) ( Figure 4 middle). Possibly, the temperature can be raised again ( Figure 4 upper part).

[0219] The third temperature threshold is lower than the first temperature threshold.

[0220] Alternatively or additionally, instead of the third temperature threshold 3.SW, a first time period may be waited for from the occurrence of the high impedance state of the switching element. After the first time period has elapsed from the occurrence of the high impedance state of the electronic switch, the electronic switch is switched to the low impedance state (not shown).

[0221] If the changeover between the high resistance state for avoiding overheating and the return to the low resistance state is too frequent, the mechanical contact (of the possible mechanically disconnectable contact unit MK) is opened. That is, the contact is opened within a first time frame if the changeover (switching) between the high resistance state for avoiding overheating and the return to the low resistance state exceeds a first number.

[0222] Figure 5 Shown according to Figure 4 , except that a fourth graph is shown, which is associated with the three above graphs.

[0223] The fourth chart is Figure 5 The change in the switching state of the mechanical contact SZK over time t is shown in the lowermost area of ​​. The closed state of the contact is marked as closed. The open state of the contact is marked as open.

[0224] In addition, Figure 5 A first temperature threshold value 1.SW and a second temperature threshold value 2.SW are shown in the upper region of FIG.

[0225] For example, a (constant) current I of a first magnitude flows for a certain period of time ( Figure 5 Center). Corresponding heating occurs at the (faulty) connection terminal. Temperature / determined temperature T of the temperature sensor TS The magnitude of increases until it reaches the first temperature threshold 1.SW( Figure 5 upper part).

[0226] When a first temperature threshold 1.SW (in the example 100°C) is reached or exceeded, the electronic switch is switched to a high-resistance state off (of the switching element) to prevent current flow, at a first time point t1 ( Figure 5 lower part).

[0227] Current decreases ( Figure 5 middle).

[0228] If the temperature continues to rise despite the electronic switch being switched to high resistance, for example because the electronic switch is defective (i.e. the high resistance state is activated but, for example, does not function or does not function completely) and a (lower) current flows, then the contacts open when the second temperature threshold 2.SW (in the example 110° C.) is reached or exceeded. Figure 5 bottom), at a third time point t3.

[0229] The second temperature threshold 2.SW is higher than the first temperature threshold 1.SW.

[0230] Figure 6 Shown according to Figure 4 The difference is that in Figure 6 The output of a warning Warn. as a function of time t is shown in the middle region of .

[0231] also, Figure 6 The upper area of ​​shows a first temperature threshold 1.SW and a fourth temperature threshold 4.SW. When the fourth temperature threshold is exceeded at a fourth time point t4, a warning Warn. is issued by means of the communication unit COM (wirelessly / wiredly). For example, it is output to a superior management system. Alternatively or additionally, the warning can be displayed, for example, using a display unit AE. The fourth temperature threshold is less than the first temperature threshold.

[0232] The electronic switch remains in the low resistance on state.

[0233] Alternatively or additionally, the magnitude of the temperature can be output (wirelessly / wiredly) by means of the communication unit COM. For example, to a higher-level management system. Alternatively or additionally, the magnitude of the temperature can be displayed, for example, using a display unit AE.

[0234] Figure 7 Shown according to Figure 6 The difference is that the time offset (time delay) t V That is, when the fourth temperature threshold 4.SW is exceeded at the fourth time point t4, no warning Warn. is issued, but Figure 7As shown, the warning Warn. is issued only at the fifth time point t5. Thus, for example, a warning based on a short-term heating caused by a short-term increase in starting current or switching current can be avoided. TS If the temperature drops below the fourth temperature threshold 4.SW again, no warning Warn. is issued.

[0235] Time offset (time delay) t V In the range of 1 second, ..., 5 seconds, ...10 seconds, ...1 minute.

[0236] Advantageously, the temperature of at least one or two connecting terminals can be monitored individually for each phase conductor and the current of the phase conductor can be reduced individually. The circuit is interrupted (mechanically / galvanically) only in the event of a persistent heating which can indicate a malfunction of the electronic switch.

[0237] In particular, the reaching of a first temperature threshold value 1 .SW, a second temperature threshold value 2 .SW, a third temperature threshold value 3 .SW or / and a fourth temperature threshold value 4 .SW of the relevant phase conductor can also be communicated or displayed.

[0238] Hereinafter, in other words, the present invention is explained again.

[0239] In electrical (sub)distribution systems there are a number of different protection and switching devices which are interconnected via corresponding lines. When designing such subdistribution systems, thermal considerations and calculations must also be carried out, since losses occur in the subdistribution systems due to ohmic losses in the conductors and electrical operating devices. The subdistribution systems thus heat up. Currently, thermal overload is prevented by corresponding (over)dimensioning (according to standards, guidelines or regulations).

[0240] In addition to the thermal design of the electrical sub-distribution system mentioned above, electrical connection points (connection terminals) are often the cause of thermal overloads and fires. This can be due to faulty commissioning or due to aging (corrosion).

[0241] Today, both installation companies and insurance companies stipulate that a visual inspection by a qualified electrician is carried out. However, here, not every faulty terminal point may be found.

[0242] According to the invention, temperature measurements are performed at (selected / multiple) connecting terminals of the protective switchgear. The temperature measuring device and other device components are connected to a control unit so that a corresponding algorithm can shut down the device before dangerous temperatures are generated at the connection points / connecting terminals, in order to protect the device / sub-distribution system from dangerous fires.

[0243] New electronic protection devices and switchgear use electronic switching elements (power semiconductors) in the main current path. If a critical temperature is reached, a high-resistance state is initiated. As a result, current can no longer flow through the protection switchgear and the connection terminals (and the sub-distribution system) cool down.

[0244] Furthermore, a corresponding message for warning can be issued.

[0245] Since no current flows through the device any more, the device cools down again. After falling below a certain temperature, the device can automatically switch to a low-resistance state for current flow (hysteresis).

[0246] Depending on the device configuration, instead of the low-resistance state, opening of the contacts of the mechanically separated contact unit can also be initiated. Automatic reclosing after cooling is then not possible. Manual reclosing of the contacts is required.

[0247] Although the present invention has been illustrated and described in detail through embodiments, the present invention is not limited to the disclosed examples and those skilled in the art may derive other variations therefrom without departing from the protection scope of the present invention.

Claims

1. A protection switchgear (SG) for protecting a multi-phase low voltage AC circuit, comprising: a housing (GEH) having grid-side phase connection terminals (LG1, LG2, LG3) and load-side phase connection terminals (LL1, LL2, LL3) for phase conductors (L1, L2, L3) of the low-voltage AC circuit, - a series circuit (SS1, SS2, SS3) of mechanical phase contacts (K1, K2, K3) and electronic switches (S1, S2, S3), The series circuits (SS1, SS2, SS3) respectively connect one of the phase connection terminals (LG1, LG2, LG3) on the grid side to one of the phase connection terminals (LL1, LL2, LL3) on the load side, the mechanical phase contacts (K1, K2, K3) can be switched together to open in order to prevent a current flow or to close in order to allow a current flow, the electronic switch (S1, S2, S3) can be switched by means of a semiconductor-based switching element to a high-resistance state of the switching element to prevent a current flow or to a low-resistance state of the switching element for a current flow, - the protective switch device is designed so that the electronic switches (S1, S2, S3) can be switched to a high-resistance state or a low-resistance state independently of each other, - at least one temperature sensor is provided for each series circuit (SS1, SS2, SS3) for respectively determining the magnitude of the temperature of at least one connecting terminal of the respective series circuit, The protective switching device is designed to switch the electronic switch of the series circuit into a high-resistance state to prevent a current flow and thus to prevent overheating when a first temperature threshold value (1.SW) of a temperature sensor of the series circuit is exceeded.

2. The protective switchgear (SG) according to claim 1, It is characterized in that A current sensor unit (SI1, SI2, SI3) is provided for each series circuit (SS1, SS2, SS3) for correspondingly determining the current magnitude of the corresponding phase conductor (L1, L2, L3), - providing a control unit (SE), which is connected to the current sensor unit (SI1, SI2, SI3), the temperature sensor (TS1, TS2, TS3), the mechanical phase contacts (K1, K2, K3) and the electronic switch (S1, S2, S3), The protective switching device is designed such that, when at least one first current threshold value in a phase conductor is exceeded, an avoidance of a current flow in the respective phase conductor is initiated by the respective electronic switch, in particular the avoidance of a current flow lasts for a first time period.

3. The protective switchgear (SG) according to claim 1 or 2, It is characterized in that The mechanical phase contacts (K1, K2, K3) are associated with the load-side connecting terminals (LL1, LL2, LL3), and the electronic switches (S1, S2, S3) are associated with the grid-side connecting terminals (LG1, LG2, LG3).

4. The protective switchgear (SG) according to claim 1 or 2, It is characterized in that Set the neutral conductor connection terminal (NG) on the grid side and the neutral conductor connection terminal (NL) on the load side. At least one temperature sensor is provided for the neutral conductor connection terminal to determine the temperature of at least one neutral conductor connection terminal. A mechanical neutral conductor contact (KN) is provided, wherein the mechanical neutral conductor contact connects the neutral conductor connection terminal (NG) on the grid side with the neutral conductor connection terminal (NL) on the load side, The mechanical neutral conductor contact (KN) switches jointly with the mechanical phase contacts (K1, K2, K3), The protective switchgear is designed to switch the electronic switch of the series circuit to a high-resistance state to prevent a current flow and thus overheating when a first temperature threshold (1.SW) of at least one temperature sensor of the neutral conductor connection terminal is exceeded.

5. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that In the case of an activated high-resistance state of the electronic switch to avoid overheating, and when a second, higher temperature threshold (2.SW) is exceeded, the mechanical contacts are opened.

6. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that In the case of a high resistance state of the electronic switch to avoid overheating, and below a third temperature threshold (3.SW), the electronic switch switches to a low resistance state, in particular, the third temperature threshold is lower than the first temperature threshold.

7. A protective switchgear (SG) according to any one of claims 1 to 5, It is characterized in that In the case of a high resistance state of the electronic switch to avoid overheating, and after a first period of time has passed since the high resistance state to avoid overheating occurred, the electronic switch is switched to a low resistance state.

8. A protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The temperature sensors are each arranged at or in the region of the connecting terminals.

9. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The mechanical contacts are opened within a first time frame when the transition to the high resistance state to avoid overheating exceeds a first number of transitions.

10. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that A communication unit (COM) is provided which is connected to the control unit (SE).

11. The protective switchgear (SG) according to claim 10, It is characterized in that When a fourth temperature threshold value (4.SW) of the temperature sensor is exceeded, a warning is output by means of the communication unit (COM).

12. Protection switchgear (SG) according to claim 10 or 11, It is characterized in that The temperature (T TS ) or equivalent.

13. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The mechanical contacts can be opened by the control unit (SE), but cannot be closed.

14. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that The mechanical contacts can be operated by a mechanical handle (HH) to switch the opening of the mechanical contacts or the closing of the mechanical contacts.

15. Protection switchgear (SG) according to claim 14, It is characterized in that The mechanical contact has a release function so that the mechanical contact can be opened by the control unit (SE) even if the mechanical handle (HH) is locked.

16. The protective switchgear (SG) according to any one of the preceding claims, It is characterized in that When a first temperature threshold (1.SW) of the temperature sensor of the series circuit is exceeded, all electronic switches are switched to a high-resistance state to prevent current flow and thus overheating.

17. A method for a protective switchgear (SG) for protecting a multi-phase low voltage AC circuit, comprising: a housing (GEH) having grid-side phase terminals (LG1, LG2, LG3) and load-side phase terminals (LL1, LL2, LL3) for phase conductors (L1, L2, L3) of the low-voltage circuit, - a series circuit of mechanical phase contacts (K1, K2, K3) and electronic switches (S1, S2, S3), The series circuit respectively connects the phase connection terminals (LG1, LG2, LG3) on the grid side to the phase connection terminals (LL1, LL2, LL3) on the load side. the mechanical phase contacts (K1, K2, K3) can be opened together to prevent a current flow or closed together to allow a current flow, the electronic switch (S1, S2, S3) can be switched by means of a semiconductor-based switching element to a high-resistance state of the switching element to prevent a current flow or to a low-resistance state of the switching element for a current flow, the electronic switches can be switched independently of one another into a high-resistance state or a low-resistance state in order to prevent or enable a current flow associated with the phase conductors, - at least one temperature sensor is provided for each series circuit (SS1, SS2, SS3) for respectively determining the magnitude of the temperature of at least one connecting terminal of the respective series circuit, When a first temperature threshold (1.SW) of a temperature sensor of the series circuit is exceeded, the electronic switch of the series circuit is switched to a high-resistance state in order to prevent a current flow and thus to prevent overheating.

18. The method according to claim 17, It is characterized in that The magnitude of the current of the respective series circuit is determined and, when at least one first current threshold in the series circuit is exceeded, the avoidance of the current flow in the respective series circuit is initiated by the respective electronic switch, in particular for a first duration.

19. The method according to claim 17 or 18, It is characterized in that In the case of an activated high-resistance state of the electronic switch to avoid overheating, and when a second, higher temperature threshold (2.SW) is exceeded, the mechanical contacts are opened.

20. The method according to claim 17, 18 or 19, It is characterized in that In the case of a high resistance state of the electronic switch to avoid overheating, and below a third temperature threshold (3.SW), switching the electronic switch to a low resistance state, In particular, the third temperature threshold (3.SW) is smaller than the first temperature threshold (1.SW).

21. The method according to claim 17, 18, 19 or 20, It is characterized in that In the case of a high-resistance state of the electronic switch to avoid overheating and after a first period of time has elapsed since the occurrence of the high-resistance state to avoid overheating, the electronic switch is switched to a low-resistance state.

22. The method according to claim 17, 18, 19, 20 or 21, It is characterized in that The mechanical contacts are opened within a first time frame when the transition to the high resistance state to avoid overheating exceeds a first number of transitions.

23. The method of claim 17, 18, 19, 20, 21 or 22, It is characterized in that When the fourth temperature threshold (4.SW) is exceeded, a warning (Warn.) is issued.

24. The method of claim 17, 18, 19, 20, 21, 22 or 23, It is characterized in that Output the temperature of at least one temperature sensor (T TS ) or equivalent.

25. The method of claim 17, 18, 19, 20, 21, 22, 23 or 24, It is characterized in that A grid-side temperature sensor (TLG1, TLG2, TLG3) and a load-side temperature sensor (TLL1, TLL2, TLL3) are provided for each series circuit (SS1, SS2, SS3) to respectively determine the temperatures of the grid-side connecting terminals (LG1, LG2, LG3) and the load-side connecting terminals (LL1, LL2, LL3) of the corresponding series circuit (SS1, SS2, SS3).

26. The method of claim 17, 18, 19, 20, 21, 22, 23, 24 or 25, It is characterized in that When a first temperature threshold value (1.SW) of the temperature sensor of the series circuit is exceeded, all electronic switches are switched into a high-resistance state in order to prevent a current flow and thus to prevent overheating.

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