Patent Application
20250046536
This application claims the priority, under 35 U.S.C. § 119, of German Patent Application DE 10 2023 207 405.2, filed Aug. 2, 2023, and European Patent Application EP 23200428.3 filed Sep. 28, 2023; both prior applications are herewith incorporated by reference in its entirety.
Irrespective of the grammatical gender of a specific term, persons with male, female or other gender identity are also included.
The invention relates to the technical field of a circuit breaker device for a low-voltage circuit having electronic switches and to a method for a circuit breaker device for a low-voltage circuit having electronic switches.
Low voltage is understood to mean voltages of up to 1,000 volts AC or up to 1,500 volts DC. Low voltage is understood in particular to mean voltages that are greater than extra-low voltage, with values of 50 volts AC or 120 volts DC.
A low-voltage circuit or grid or installation is understood to mean circuits with nominal currents or rated currents of up to 125 amperes, more specifically up to 63 amperes. A low-voltage circuit is understood to mean in particular circuits with nominal currents or rated currents of up to 50 amperes, 40 amperes, 32 amperes, 25 amperes, 16 amperes or 10 amperes. The current values are understood to mean in particular nominal, rated or/and shutdown currents, that is to say the maximum current that is normally carried through the circuit or at which the electrical circuit is usually interrupted, for example by a protection device, such as a circuit breaker device, miniature circuit breaker or power circuit breaker. The nominal currents may be gradated further, 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.
Miniature circuit breakers are overcurrent protection devices that have long been known and that are used in low-voltage circuits in electrical installation engineering. They protect lines against damage caused by heating due to excessively high current and/or a short circuit. A miniature circuit breaker may automatically shut down the circuit in the event of an overload and/or short circuit. A miniature circuit breaker is not a fuse element that resets automatically.
In contrast to miniature circuit breakers, power circuit breakers are intended for currents greater than 125 A, in some cases also starting from 63 amperes. Miniature circuit breakers therefore have a simpler and more delicate design. Miniature circuit breakers usually have a fastening option for fastening to a so-called top-hat rail (carrier rail, DIN rail, TH35).
Miniature circuit breakers have an electromechanical design. In a housing, they have a mechanical switching contact or shunt opening release for interrupting (tripping) the electrical current. A bimetallic protection element or bimetallic element is usually used for tripping (interruption) in the case of a longer-lasting overcurrent (overcurrent protection) or in the event of a thermal overload (overload protection). An electromagnetic release with a coil is used for brief tripping if an overcurrent limit value is exceeded or in the event of a short circuit (short-circuit protection). One or more arc quenching chamber(s) or arc quenching devices are provided. Connection elements for conductors of the electrical circuit to be protected are also provided.
Circuit breaker devices having an electronic interruption unit or an electronic switch are relatively recent developments. They have a semiconductor-based electronic interruption unit/switch. In other words, the flow of electric current in the low-voltage circuit is guided via semiconductor components or semiconductor switches that are able to interrupt the flow of electric current or are able to be switched to the on state. Circuit breaker devices having an electronic interruption unit/switch often also have a mechanical isolating contact unit having contacts, in particular with isolator properties in accordance with the applicable standards for low-voltage circuits, which contacts of the mechanical isolating contact unit are connected in series with the electronic interruption unit/electronic switches, that is to say the current of the low-voltage circuit that is to be protected is guided both through the mechanical isolating contact unit/the mechanical contact and through the electronic interruption unit/the electronic switch.
The present invention relates in particular to low-voltage AC circuits having an AC voltage, usually having a time-dependent sinusoidal AC voltage of the frequency f. The temporal dependence of the instantaneous voltage value u(t) of the AC voltage is described by the equation:
A harmonic AC voltage can be represented by the rotation of a phasor, the length of which equals the amplitude (U) of the voltage. The instantaneous deflection is the projection of the phasor onto a coordinate system. An oscillation period corresponds to a full revolution of the phasor and its full angle is 2π (2pi) or 360°. The angular frequency is the rate of change of the phase angle of this rotating phasor. The angular frequency of a harmonic oscillation is always 2π times its frequency, that is to say:
It is often preferred to give the angular frequency (w) rather than the frequency (f), since many formulae in oscillation theory can be represented more compactly using the angular frequency due to the occurrence of trigonometric functions, the period of which is by definition 2π:
In the case of angular frequencies that are not constant over time, the term instantaneous angular frequency is also used.
In the case of a sinusoidal AC voltage, in particular an AC voltage that is constant over time, the time-dependent value formed from the angular velocity ω and the time t corresponds to the time-dependent angle φ(t) which is also referred to as the phase angle φ(t).
That is to say, the phase angle φ(t) periodically passes through the range 0 . . . 2π or 0° . . . 360°. That is to say, the phase angle periodically assumes a value of between 0 and 2π or 0° and 360° (φ=n*(0 . . . 2π) or φ=n*(0° . . . 360°) on account of periodicity; in abbreviated form: φ=0 . . . 2π or φ=0° . . . 360°).
The instantaneous voltage value u(t) is therefore used to mean the instantaneous value of the voltage at the time t, that is to say, in the case of a sinusoidal (periodic) AC voltage, the value of the voltage at the phase angle φ (φ=0 . . . 2π or φ=0° . . . 360°, of the respective period). The same applies with respect to instantaneous current values i(t) etc.
The object of the present invention is to improve a circuit breaker device of the type mentioned at the outset, in particular to avoid destruction, damage or an impermissible operating state (in particular an impermissible operating temperature) of a multi-phase circuit breaker device, in particular of the connection terminals thereof.
This object is achieved by a circuit breaker device having the features of the independent circuit breaker device claim, and by a method as claimed in the independent method claim.
According to the invention, a circuit breaker device for protecting an electrical multi-phase low-voltage AC circuit, in particular a three-phase AC circuit, is proposed, containing:
Preventing overheating means that the circuit breaker device, in particular the connection terminal, remains within its permissible thermal limits or permissible (device) temperatures.
The temperature sensors can be connected to a control unit, which in turn is connected to the jointly switched mechanical contacts and the electronic switches.
This has the advantage that overheating of the circuit breaker device, in particular of one or selected or all connection terminal(s), is prevented. This can avert thermal overload or thermal destruction, thereby preventing, for example, a cable fire of the connected conductors. By preventing the flow of current, heating of the circuit breaker device/the associated connection terminal is prevented and a safe state is established.
Further advantageous embodiments of the invention are specified in the subclaims and in the exemplary embodiment.
In an advantageous embodiment of the invention, when a first temperature threshold value of a temperature sensor of a series circuit is exceeded, all the electronic switches (in the series circuit) are switched to a high-impedance state for preventing a flow of current in order to prevent overheating.
This has the particular advantage that a behavior similar to conventional miniature circuit breakers is provided and, in particular, all of the phase conductors are switched to prevent a flow of current, which is advantageous especially for 3-phase consumers. In addition, the circuit breaker device can cool down faster due to the lack of current flow from the other series circuits.
In an advantageous embodiment of the invention, a current sensor unit is provided for each series circuit, for determining the level of the current in the respective phase conductors, in particular in such a way that instantaneous current values (are determined and) are available.
A control unit that is connected to the current sensor units, the temperature sensors, the (jointly switched) mechanical phase contacts and the electronic switches is provided. The circuit breaker device is designed in such a way that when at least one first current threshold value is exceeded in a phase conductor, a process for preventing a flow of current in the phase conductor in question is initiated by the electronic switch in question, in particular for a first period of time.
This has the particular advantage that, when a specified current threshold or a current/time threshold is exceeded (that is to say the current threshold value is exceeded for a defined time limit), only the conductor in question (or the conductors in question) is selectively interrupted. A flow of current is still enabled in the other conductors (non-affected conductors) in a multi-phase low-voltage AC circuit.
The prevention for a first period of time means that switching-on again or becoming low-impedance takes place advantageously after the first period of time, so that the reliability of supply continues to be guaranteed or it is possible to continue checking for the presence of the exceeding of the current threshold. This can be carried out advantageously, in particular, by evaluating instantaneous values of the level of the current.
In an advantageous embodiment of the invention, the first period of time is less than 20 ms, in particular less than 10 ms.
This has the particular advantage that for a half wave or full wave of the voltage or the current in the AC circuit, in the example (20 ms, 10 ms) based on a grid frequency of 50 Hz, an interruption occurs, so that electrical supply reliability is restored with the next full or half wave. In particular, after an interruption, the change to low-impedance can occur in the region of the next zero crossing (in the zero crossing or in the range of 1 ms before or after said zero crossing).
In an advantageous embodiment of the invention, the mechanical phase contacts are part of a mechanical isolating contact unit, which opens or closes the phase contacts together. In particular, the mechanical isolating contact unit has an accessible handle on the circuit breaker device, for manually opening or closing the phase contacts (of the mechanical isolating contact unit).
This has the particular advantage that complete galvanic isolation of all of the phase conductors is carried out simultaneously, in contrast to the electronic switches changing to high impedance in a manner based on phase and so as to prevent a flow of current. The handle enables compatible behavior in accordance with conventional electromechanical circuit breaker devices.
In an advantageous embodiment of the invention, the circuit breaker device is designed in such a way that the mechanical isolating contact unit can be opened, but not closed, by way of the control unit. In particular, closing of the mechanical isolating contact unit by way of the handle is only possible after an enable by way of the control unit.
This has the particular advantage that the safety of the circuit breaker device is increased, as the control unit cannot accidentally (incorrectly) close the contacts.
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.
This has the particular advantage that a compact electronic interruption unit that combines the electronic switches is provided, such that a space-saving design is made possible and synergy effects of components can be utilized.
In an advantageous embodiment of the invention, the electronic interruption unit/the electronic switches has/have a bidirectional dielectric strength. In particular, overvoltage protection is provided for the semiconductor-based switching elements.
This has the particular advantage that it is robust against overvoltages and that it is possible to switch off an inductive line circuit.
In an advantageous embodiment of the invention, the mechanical phase contacts are assigned to the load-side phase connection terminals, and the electronic switches are assigned to the grid-side phase connection terminals.
This has the particular advantage that an advantageous circuit breaker device design is provided, which supports phase-related switching of the electronic switches, and allows a self-test (in particular a self-test of the electronic switches or the electronic interruption unit), even when the contacts are open. In addition, a power supply to the circuit breaker device is ensured, even when the contacts are open. This provides a structure for a circuit breaker device in which the circuit breaker device can function even when the contacts are open.
In an advantageous embodiment of the invention, a grid-side neutral-conductor connection terminal and a load-side neutral-conductor connection terminal are provided for a neutral conductor of the multi-phase low-voltage AC circuit, in particular three-phase low-voltage AC circuit.
The grid-side neutral-conductor connection terminal is (electrically) connected directly or via a mechanical neutral-conductor contact to the load-side neutral-conductor connection terminal.
For the neutral-conductor connection terminals is provided at least one temperature sensor for determining the level of the temperature of at least one neutral-conductor connection terminal. In particular, a grid-side temperature sensor is provided for the grid-side neutral-conductor connection terminal, and a load-side temperature sensor is provided for the load-side neutral-conductor connection terminal, so that it is possible to determine the level of the temperature of the grid-side neutral-conductor connection terminal and the level of the temperature of the load-side neutral-conductor connection terminal.
When a first temperature threshold value (1.SW) of the at least one temperature sensor of the neutral-conductor connection terminals is exceeded, the electronic switches of the series circuits are switched to a high-impedance state for preventing a flow of current in order to prevent overheating. That is to say, when a neutral-conductor connection terminal temperature is too high, all the phase conductors change to high impedance.
Alternatively, all the mechanical contacts can be opened.
This has the particular advantage that a multi-pole circuit breaker device is provided in which also at least one neutral-conductor connection terminal is monitored, and the flow of current is interrupted (in particular galvanically) if applicable.
In an advantageous embodiment of the invention, the mechanical neutral-conductor contact can be opened or closed (can be 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.
This has the particular advantage that the neutral-conductor contact always opens and closes with no current flowing. This reduces the wear of the contact and increases the service life. Furthermore, this prevents an arc from arising when the neutral-conductor contact is opened.
In an advantageous embodiment of the invention, the mechanical contacts are opened in the case of an initiated high-impedance state of the electronic switch for preventing overheating and when a higher second temperature threshold value is exceeded (that is to say the second temperature threshold value is higher than the first temperature threshold value).
This has the particular advantage that an additional degree of safety is provided in the circuit breaker device. If there is increased heating despite initiated high-impedance electronic switches, this could be due to the fact that the electronic switch is not or not sufficiently high-impedance and a (faulty) flow of current leads to further heating of the circuit breaker device/connection terminal. In this case, the contacts are opened in order to achieve galvanic isolation and thus completely prevent the flow of current. This additional safety measure avoids destruction of the circuit breaker device/connection terminals.
In an advantageous embodiment of the invention, the electronic switch is switched to a low-impedance state (for allowing a flow of current in the low-voltage circuit) in the case of a high-impedance state of the electronic switch for preventing overheating and when a third temperature threshold value is undershot. The third temperature threshold value is lower than the first temperature threshold value.
This has the particular advantage that a flow of current is enabled again after the circuit breaker device/connection terminal has cooled down. This means that the circuit breaker device is always in a safe operating state.
In an advantageous embodiment of the invention, alternatively, the electronic switch is switched to the low-impedance state (for allowing a flow of current in the low-voltage circuit) in the case of a high-impedance state of the electronic switch for preventing overheating and when a first time period has elapsed since the start of the high-impedance state of the electronic switch (to prevent overheating).
For example, the first time period may be in the order of magnitude of 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.
This has the particular advantage that a fixed cooling time (first time period) is implemented. A flow of current is enabled again after the circuit breaker device/connection terminal has cooled down.
In an advantageous embodiment of the invention, the mechanical contacts are opened in the event of a change to the high-impedance state for preventing overheating (and back to the low-impedance state), the change exceeding a first number, within a first-time frame.
For example, the first-time frame may be one hour, several hours, such as 3 hours, 5 hours, 6 hours, 10 hours, 12 hours, 18 hours, 24 hours (one day), several days, one week. For example, the number of changes can start from 2, 3, 4, . . . , 10, . . . 20 changes.
This has the particular advantage that, in the event of a frequent temperature-related change to the high-impedance state (from the low-impedance to the high-impedance state), additional safety is implemented, and the contacts are opened to perform galvanic isolation and completely prevent a heating flow of current. This prevents a further change to the high-impedance state (to the high-impedance state and back to the low-impedance state) of the electronic switch(es) and ensures safety in the low-voltage circuit.
In an advantageous embodiment of the invention, a communication unit (which is connected to the control unit) is provided. A warning is issued by means of the communication unit when a fourth temperature threshold value is exceeded. The fourth temperature threshold value is lower than the first temperature threshold value.
For example, the fourth temperature threshold value may be 10, . . . , 20, . . . , 30, . . . , 40 Kelvin lower than the first temperature threshold value.
This has the particular advantage that an indication is communicated when a temperature threshold value is reached, so that, for example or advantageously, a cause determination process can be carried out before a shutdown due to an overtemperature occurs.
As an alternative or in addition, the level of the temperature (or an equivalent) of the temperature sensor can be issued (communicated) by means of the communication unit.
This has the particular advantage that (central) temperature monitoring of one or more circuit breaker devices can be carried out, so that appropriate measures can be taken as temperatures rise.
In an advantageous embodiment of the invention, a display unit is provided on the circuit breaker device, which display unit is connected to the control unit and has visible display means for displaying the exceeding of temperature limits (first or/and second or/and third or/and fourth) or (and) the level of the temperature, in particular with reference to a conductor (phase conductor, neutral conductor); alternatively or additionally, for indicating a high-impedance or low-impedance state of the electronic switches.
This has the particular advantage that a visualization of the temperature state is provided.
In an advantageous embodiment of the invention, the mechanical contacts can be opened by way of the control unit, but cannot be closed by way of the control unit.
This has the particular advantage that the safety of the circuit breaker device is high, as the contacts cannot be incorrectly closed within the circuit breaker device.
In an advantageous embodiment of the invention, the mechanical contacts have a release functionality. This may be a release functionality that is provided in accordance with current standards; in particular in such a way that the contacts can be opened by the control unit, even if the mechanical handle is blocked, that is to say, for example, if the handle becomes/is blocked for the state in which the contacts are closed.
This has the particular advantage of providing a high level of safety and a circuit breaker device for low-voltage circuits that in particular is in line with standards. The flow of current can be interrupted galvanically at any time by opening the contacts.
In an advantageous continuation of the embodiment, the circuit breaker device is configured in such a way that, when the control unit is used to initiate a change to the low-impedance state, for example when the third temperature threshold value is undershot, the electronic switch comes to have a low impedance at the respective zero crossing of the voltage (or at a voltage that is less than 50 V, 25 V, in particular less than 10 V).
This has the particular advantage that the instances of grid interference are reduced and the load in the switch is lower.
In an advantageous embodiment of the invention, the circuit breaker device is configured in such a way that when (at least) the first current threshold value in a conductor is undershot, a process for preventing a flow of current in the conductor in question is initiated by the electronic switch in question. At the next or next-but-one zero crossing of the voltage, the electronic switch comes to have a low impedance again to allow a flow of current. The control unit is in this case connected to the current sensor units, the temperature sensors, (the) voltage sensor units, the mechanical contacts and the electronic switches.
This has the particular advantage of achieving increased robustness to faulty tripping, and hence achieving increased reliability of electrical supply.
According to the invention, a corresponding method (method claims) for a circuit breaker device for a multi-phase low-voltage AC circuit with electronic (semiconductor-based) switches/switching elements with the same and further advantages is claimed.
The method for a circuit breaker device for protecting an electrical multi-phase low-voltage AC circuit contains:
Advantageously, when a first temperature threshold value of a temperature sensor of a series circuit is exceeded, all the electronic switches (in the series circuit) are switched to a high-impedance state for preventing a flow of current in order to prevent overheating.
Advantageously, the level of the current in the respective series circuits is determined, and when at least one current threshold value is exceeded in a series circuit, a process for preventing a flow of current in the series circuit in question is initiated by the electronic switch in question, in particular for a first period of time.
Advantageously, the mechanical contacts are opened in the case of an initiated high-impedance state of an electronic switch for preventing overheating and when a higher second temperature threshold value is exceeded.
Advantageously, in the case of a high-impedance state of an electronic switch for preventing overheating and when a third temperature threshold value is undershot, the electronic switch is switched to a low-impedance state. The third temperature threshold value is lower than the first temperature threshold value.
Advantageously, in the case of a high-impedance state of an electronic switch for preventing overheating and when a first time period has elapsed since the start of the high-impedance state for preventing overheating, the electronic switch is switched to the low-impedance state.
Advantageously, the mechanical contacts are opened in the event of a change to the high-impedance state for preventing overheating, the change exceeding a first number, within a first-time frame.
Advantageously, a warning is issued when a fourth temperature threshold value is exceeded.
Advantageously, the level of the temperature of at least one temperature sensor or an equivalent is issued.
All embodiments, both in dependent form referring back to the independent claims, and referring back only to individual features or combinations of features of claims, in particular also the dependent assembly claims referring back to the independent method claim, and vice versa, improve a circuit breaker device, in particular prevent destruction, damage or an impermissible operating state (in particular an impermissible operating temperature) of a circuit breaker device, specifically of the connection terminals.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a circuit breaker device and a method, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Referring now to the figures of the drawings in detail and first, particularly to
In the housing GEH:
According to the invention, the first, second and third electronic switches can be switched to a high-impedance or low-impedance state independently of one another. That is to say that the first, second and third electronic switches are switched to a high-impedance or low-impedance state independently of one another. In particular, in order to prevent or to enable a phase-conductor-dependent flow of current.
According to
According to
The circuit breaker device is configured, in particular, in such a way that the mechanical isolating contact unit MK can be opened, but not closed, by way of a control unit SE. In particular, closing of the mechanical isolating contact unit MK by way of the handle HH is only possible after an enable by way of the control unit SE. A release unit LC can be provided for this purpose. That is to say, the contacts can be closed by way of the handle HH only when the enable or an enable signal (from the control unit) is present. Without the enable or the enable signal, although the handle HH can be actuated, the contacts cannot be closed (“permanent slider contacts”).
The release unit LC may also be configured such that it is possible to open the contacts K1, K2, K3 of the mechanical isolating contact unit MK by way of a control signal from the control unit SE, as indicated in
According to
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 can be switched independently of one another.
The electronic interruption unit/the electronic switches may have a bidirectional dielectric strength. Specifically, overvoltage protection is provided for the semiconductor-based switching elements in order to limit the voltages and thus have protection for the semiconductor-based switching elements.
The control unit SE is provided (as already partially mentioned), which is connected to the current sensor units SI1, SI2, SI3, the mechanical phase contacts K1, K2, K3 or the mechanical isolating contact unit MK (as shown in
The current sensor units SI1, SI2, SI3 each determine the level of the current in their respective conductors, so that, in particular, instantaneous values of the current are available.
When at least one first current threshold value in a conductor is exceeded, a process for preventing the flow of current in the conductor in question is initiated by way of the electronic switch coming to have a high impedance.
The high impedance can be achieved, in particular, for a first period of time. After the period of time, the electronic switch in question can come to have a low impedance again.
Coming to have a low impedance can occur, in particular, in the next zero crossing or before or after the zero crossing of the voltage. (All 3 options—in the zero crossing, before the zero crossing or after the zero crossing—are possible, or if the magnitude falls below a voltage threshold, in particular 50 V, 25 V or 10 V).
In particular, the first time period may be less than 20 ms, especially less than 10 ms.
A differential current sensor unit ZCT may be provided (not shown in
The current sensor units SI1, SI2, SI3 are arranged in the example of
According to the invention, at least one temperature sensor TS1, TS2, TS3 is provided for each series circuit SS1, SS2, SS3. In the example of
In the first series circuit SS1 is provided a first grid-side temperature sensor TLG1 for the first grid-side phase connection terminal LG1 for the first phase conductor L1.
In the first series circuit SS1 is provided a first load-side temperature sensor TLL1 for the first load-side phase connection terminal LL1 for the first phase conductor L1.
In the second series circuit SS2 is provided a second grid-side temperature sensor TLG2 for the second grid-side phase connection terminal LG2 for the second phase conductor L2.
In the second series circuit SS2 is provided a second load-side temperature sensor TLL2 for the second load-side phase connection terminal LL2 for the second phase conductor L2.
In the third series circuit SS3 is provided a third grid-side temperature sensor TLG3 for the third grid-side phase connection terminal LG3 for the third phase conductor L3.
In the third series circuit SS3 is provided a third load-side temperature sensor TLL3 for the third load-side phase connection terminal LL3 for the third phase conductor L3.
The temperature sensors are each provided at, or in the region of, a connection terminal. The temperature sensors serve in particular to determine the level of the temperature of the respective connection terminals or in the region of the respective connection terminals.
The temperature sensors are each connected to the control unit SE, so that the control unit receives the level of the temperature (or an equivalent).
This means that each series circuit has at least one temperature sensor.
The circuit breaker device is designed in such a way that, if a first temperature threshold value 1.SW of a temperature sensor of a series circuit is exceeded, the electronic switch of the series circuit is switched to a high-impedance state for preventing a flow of current in order to prevent overheating (of the connection terminal).
As an alternative or in addition (for example in a configurable manner), if a first temperature threshold value of a temperature sensor of a series circuit is exceeded, all the electronic switches (of the series circuits in the circuit breaker device for the conductors of the low-voltage circuit) are switched to a high-impedance state for preventing a flow of current in order to prevent overheating.
A grid-side neutral conductor connection terminal NG and a load-side neutral conductor connection terminal NL are provided for a neutral conductor N of the multi-phase low-voltage AC circuit, in the example according to
As an alternative, the grid-side neutral conductor connection terminal NG can also be connected directly (that is to say without a switchable contact) to the load-side neutral conductor connection terminal NL.
For the neutral-conductor connection terminals is provided at least one temperature sensor for determining the level of the temperature of at least one neutral-conductor connection terminal. In
The neutral-conductor-side grid-side temperature sensor TNG and the neutral-conductor-side load-side temperature sensor TNL are connected to the control unit SE.
In this example, an electronic switch is not provided in the neutral conductor path in the housing of the circuit breaker device. This means that the neutral conductor connection between the grid-side neutral conductor connection NG and the load-side neutral conductor connection NL is free of electronic switches (electronic switch-free).
The mechanical neutral-conductor contact KN can advantageously be connected together with the phase contacts K1, K2, K3. This means that the mechanical neutral-conductor contact KN can be opened or closed together with the phase contacts K1, K2, K3, as described further above in relation to the contacts K1, K2, K3.
Specifically, the mechanical isolating contact unit MK can be configured in such a way 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 have been opened.
Furthermore, an energy supply NT is provided, such as a power supply unit, for the supply of energy to the circuit breaker device SG, in particular to the control unit SE.
In the example, the energy supply NT is connected on one side to the phase conductors L1, L2, L3 and (if necessary) to the neutral conductor N. It can also be connected only to some of the conductors (at least two) for the purpose of supplying energy. In the example, the energy supply NT is connected on the other side to the control unit SE.
On the other hand, the control unit SE is illustrated combined with the electronic switches S1, S2, S3 and the current sensor units SI1, SI2, SI3.
Furthermore, a voltage sensor unit is provided between each phase conductor and the neutral conductor. A first voltage sensor unit SU1 is provided between the first phase conductor L1 and the neutral conductor N, a second voltage sensor unit SU2 is provided between the second phase conductor L2 and the neutral conductor N, and a third voltage sensor unit SU3 is provided between the third phase conductor L3 and the neutral conductor N for determining the level of the voltage between the respective phase conductors and neutral conductor, in particular so that instantaneous voltage values are available. The voltage sensor units SU1, SU2, SU3 are connected to the control unit SE.
In the case of the electronic switches S1, S2, S3 coming to have a low impedance, which is initiated by way of the control unit SE, for example:
As already mentioned, the voltage sensor units SU1, SU2, SU3 are to this end connected to the control unit SE, which is also connected to the current sensor units SI1, SI2, SI3, the temperature sensors TS1, TS2, TS3, the mechanical phase contacts K1, K2, K3 (or mechanical isolating contact unit MK) and the electronic switches. The circuit breaker device can also advantageously be designed in such a way that when at least one first current threshold value (specifically instantaneous value of the current) is exceeded in a phase conductor, a process for preventing a flow of current in the phase conductor in question is initiated by the electronic switch in question. At the next or next-but-one zero crossing of the voltage, the electronic switch comes to have a low impedance again to allow a flow of current.
This can be done several times until a first number of repetitions are exceeded. Then:
Any combinations (intermediate combinations) from the illustrations of the exemplary circuit breaker devices according to
High impedance is used to mean a state in which only a current of a negligible magnitude flows. In particular, high impedance is used to mean resistance values of greater than 1 kilohm, preferably greater than 10 kilohms, 100 kilohms, 1 megaohm, 10 megaohms, 100 megaohms, 1 gigaohm or greater.
Low impedance is used to mean a state in which the current value indicated on the circuit breaker device could flow.
In particular, low impedance is used to mean resistance values of less than 10 ohms, preferably less than 1 ohm, 100 milliohms, 10 milliohms, 1 milliohm or less.
The electronic switches S1, S2, S3 and the electronic interruption unit EU may have semiconductor components such as bipolar transistors, field-effect transistors (FET), isolated gate bipolar transistors (IGBT), metal oxide layer field-effect transistors (MOSFET) or other (self-commutated) power semiconductors. In particular, IGBTs and MOSFETs are particularly well suited for the electronic switches (as semiconductor-based switching elements) on account of low forward resistances, high junction resistances and a good switching behavior.
Mechanical contacts or a mechanical isolating contact unit MK is used to mean, in particular, a (standards-compliant) isolating function implemented by the isolating contact unit MK. An isolating function is used to mean the following points:
The minimum clearance in air between the contacts of the isolating contact system is substantially voltage-dependent. Further parameters are the pollution degree, the type of field (homogeneous, inhomogeneous) and the barometric pressure and the height above sea level.
There are corresponding rules or standards for these minimum clearances in air or creepage distances. These rules specify, for example in air for an impulse withstand voltage, the minimum clearance in air for an inhomogeneous and a homogeneous (ideal) electrical field on the basis of the pollution degree. The impulse withstand voltage is the strength to withstand an applied corresponding impulse voltage. The isolating contact system or circuit breaker device has an isolating function (isolator property) only when this minimum length (minimum distance) is present.
In the context of the invention, the DIN EN 60947 and IEC 60947 series of standards, to which reference is made here, are relevant to the isolator function and its properties.
The isolating contact system is advantageously characterized by a minimum clearance in air of the open isolating contacts in the OFF position (open position, open contacts) on the basis of the rated impulse withstand voltage and the pollution degree. The minimum clearance in air is, in particular, between (a minimum of) 0.01 mm and 14 mm.
In particular, the minimum clearance in air is advantageously 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.
The minimum clearance in air can advantageously have the following values:
The pollution degrees and types of field correspond to those defined in the standards. This advantageously allows a standards-compliant circuit breaker device dimensioned according to the rated impulse withstand voltage to be achieved.
In particular, a mechanical isolating contact unit does not mean a relay contact.
The control unit SE may have a microcontroller (microcontroller unit).
The circuit breaker device may have an (in particular wireless) communication unit COM, which is connected to the control unit SE or is a part of it.
A warning can be issued by means of the communication unit COM when a fourth temperature threshold value is exceeded. As an alternative or in addition, the level of the temperature of at least one temperature sensor, of some of the temperature sensors or of all the temperature sensors can be issued (communicated) by means of the communication unit COM (or an equivalent of this).
A display unit AE can also be provided. The display unit AE can be configured as a combined display and input unit. The display unit AE (display and input unit) is connected to, or is part of, the control unit SE. The display unit has display means visible on the circuit breaker device, in particular for displaying the high-impedance or low-impedance state of the electronic switches. As an alternative or in addition, for displaying the exceeding of temperature limits (first or/and second or/and third or/and fourth) or (and) the level of the temperature of at least one temperature sensor, some of the temperature sensors, or all of the temperature sensors.
When a first temperature threshold value 1.SW of the at least one temperature sensor of the neutral-conductor connection terminals is exceeded, the electronic switches of the series circuits are switched to a high-impedance state for preventing a flow of current in order to prevent overheating. That is to say, when a neutral-conductor connection terminal temperature is too high, all the phase conductors change to high impedance.
Alternatively, all the mechanical contacts can be opened.
It shows the variation in the temperature TTS of the temperature sensor as a function of the level of the current I in the phase conductor of the low-voltage circuit.
It is assumed that the heating in the circuit breaker device, specifically at the (selected) connection terminal (in the event of a fault), is dependent on the level of the current I in the associated (relevant) phase conductor of the low-voltage circuit through the circuit breaker device (the circuit breaker device is intended to protect the low-voltage circuit). As the level of the current I in the (selected) phase conductor increases, the temperature of the temperature sensor of the connection terminal in question (and in general in parts of the circuit breaker device) rises. Thus, the temperature TTS determined by the temperature sensor increases. The temperature increases monotonically with the level of the current. In addition to the level of the current, the ambient temperature also has an influence on the heating. This is not shown in
According to
In the upper region of
In the middle region of
In the lower region of
For example, a (constant) current I or a current I with a constant root mean square value of a first level for a certain time flows (center of
When the first temperature threshold value 1.SW is reached or exceeded, in the example 100° C., the electronic switch in question is switched to a high-impedance state off (of the switching elements) to prevent a flow of current in the phase conductor in question of the connection terminal, first time t1 (bottom of
The circuit breaker device can cool down. At a second time t2, the third temperature threshold value 3.SW, in the example 80° C., is reached or undershot. When the third temperature threshold value 3.SW is reached or undershot, the electronic switch is (again) switched (at the second time t2) to a low-impedance state on (for allowing a flow of current in the low-voltage circuit) (bottom of
The third temperature threshold value is lower than the first temperature threshold value.
As an alternative or in addition, instead of the third temperature threshold value 3.SW, it is possible to wait for a first period of time to elapse after the start of the high-impedance state of the switching elements. After a first period of time has elapsed since the start of the high-impedance state of the electronic switch, the electronic switch is switched to the low-impedance state (not shown).
If the change between the high-impedance state for preventing overheating and back to the low-impedance state is too frequent, the mechanical contacts (if applicable, the mechanical isolating contact unit MK) are opened. This means that the mechanical contacts are opened in the event of a change (toggle) between the high-impedance state for preventing overheating and back to the low-impedance state, the change exceeding a first number, within a first time frame.
The fourth graph in the lowest region of
Furthermore, the upper region of
For example, a (constant) current I of a first level flows for a certain time (center of
When the first temperature threshold value 1.SW is reached or exceeded, in the example 100° C., the electronic switch is switched to a high-impedance state off (of the switching elements) in order to prevent a flow of current, first time t1 (bottom of
The current is reduced (center of
Even though the electronic switch is switched to a high impedance, if the temperature now rises further, for example because the electronic switch is defective (that is to say the high-impedance state is initiated, but for example is not or not fully effective) and a (lower) current flows, the contacts are opened when the second temperature threshold value 2.SW, in the example 110° C., is reached or exceeded (bottom of
The second temperature threshold value 2.SW is higher than the first temperature threshold value 1.SW.
Furthermore, the upper region of
The electronic switch remains in the low-impedance state on.
As an alternative or in addition, the level of the temperature can be issued (wirelessly/in wired fashion) by means of the communication unit COM, for example, to a higher-level management system. As an alternative or in addition, the level of the temperature can be displayed, for example using the display unit AE.
Individual monitoring of the temperature of at least one or both connection terminals can advantageously be carried out for each phase conductor, and the current in the phase conductor can be reduced individually. The circuit is interrupted (mechanically/electrically) only if the heating continues, which indicates a fault in the electronic switch.
It is likewise possible to communicate or display the attainment of the first temperature threshold value 1.SW, the second temperature threshold value 2.SW, the third temperature threshold value 3.SW or/and fourth temperature threshold value 4.SW, in particular of the phase conductor in question.
The invention is explained again in other words below.
An electrical (sub) distribution system contains a large number of different protective and switching devices, which are connected to one another via appropriate cables. When designing such a subdistribution system, thermal considerations and calculations must also be carried out, as losses occur in the subdistribution system due to ohmic losses on the lines and the electrical equipment. This heats up the subdistribution system. Today, thermal overload is prevented by appropriate (over) dimensioning (in accordance with standards, guidelines or regulations).
Apart from the aforementioned thermal designs of an electrical subdistribution system, the electrical connection points (connection terminals) frequently lead to thermal overloads and fires. These can arise as a result of faulty commissioning or else as a result of ageing (corrosion).
Installer regulations and insurers today stipulate visual inspections by qualified electricians. However, these inspections may not find every faulty connection point.
According to the invention, a temperature measurement is implemented at (selected/the) connection terminals of the circuit breaker device. The temperature sensors and the additional device components are connected to the control unit, so that here a suitable algorithm can switch off the device before a hazardous temperature occurs at the connection points/connection terminals, and thereby protect the device/subdistribution system from a dangerous fire.
Recent electronic protective and switching devices use electronic switching elements (power semiconductors) in the main current path. When a critical temperature is reached, a high-impedance state is initiated. This means that current can no longer flow through the circuit breaker device and allows the connection terminal (and the subdistribution system) to cool down.
An appropriate warning message can also be issued.
Since current is no longer flowing through the device, this cools down again. Once the temperature has gone below a certain temperature, the device can automatically switch back to the low-impedance state for allowing a flow of current (hysteresis).
Depending on the device configuration, an opening of the contacts of the mechanical isolating contact unit can also be initiated instead of the low-impedance state. An automatic restart after cooling is then not possible. It is necessary to manually close the contacts again.
Although the invention has been described and illustrated in more detail by way of the exemplary embodiment, the invention is not restricted by the disclosed examples and other variations may be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 207 405.2 | Aug 2023 | DE | national |
| 23200428.3 | Sep 2023 | EP | regional |
