Patent Application
20250046535
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 of European Patent Application EP 23200440.8, filed Sep. 28, 2023; both prior applications are herewith incorporated by reference in their 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 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 in the case of 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 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, in particular with isolator properties in accordance with the applicable standards for low-voltage circuits, wherein the 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 corresponds to the amplitude (U) of the voltage. The instantaneous deflection is in this case 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:
w=2π*f=2π/T=angular frequency of the AC voltage
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.
This object is achieved by a circuit breaker device having the features of the independent circuit breaker patent claim, and by a method according to the independent method patent 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 electronic switches/specifically the semiconductor-based switching elements, remains within its (their) 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 the electronic switches, is prevented. This can prevent thermal overload or thermal destruction. By preventing the flow of current, heating of the circuit breaker device/the respective electronic switch is prevented and a safe state is established.
Further advantageous configurations of the invention are specified in the subclaims and in the exemplary embodiment.
In one advantageous configuration of the invention, when a first temperature threshold value of a temperature sensor of a series circuit is exceeded, all of the electronic switches are switched to a high-impedance state to prevent a flow of current in order to prevent overheating.
This has the particular advantage that a behavior for conventional miniature circuit breakers is provided and, in particular, all of the phase conductors are switched to prevent a flow of current, which is especially advantageous 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 one advantageous configuration of the invention, in each case a current sensor unit is provided for each series circuit, for the respective determination of the level of the current of the respective phase conductor, in particular in such a way that instantaneous current values (are determined and) are present.
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 configured in such a way that a process for preventing a flow of current in a phase conductor is initiated by the electronic switch in question, in particular for a first period of time, if at least one first current threshold value is exceeded in the phase conductor in question.
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.
Prevention for a first period of time makes it advantageous to switch on again or become low-impedance after the first period of time, such that the supply reliability continues to be guaranteed or it is possible to continue testing 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 one advantageous configuration 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 one advantageous configuration 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 coming to have a high impedance in a manner based on phase and so as to prevent a flow of current. The handle enables a compatible behavior in accordance with conventional electromechanical circuit breaker devices.
In one advantageous configuration of the invention, the circuit breaker device is configured 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 release 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 one advantageous configuration 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 one advantageous configuration 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 one advantageous configuration of the invention, the mechanical phase contacts are assigned to the load-side phase connections and the electronic switches are assigned to the grid-side phase connections.
This has the particular advantage that an advantageous 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 one advantageous configuration of the invention, a grid-side neutral conductor connection and a load-side neutral conductor connection are provided for a neutral conductor of the multi-phase low-voltage AC circuit.
The grid-side neutral conductor connection is connected directly or via a mechanical neutral conductor contact to the load-side neutral conductor connection.
This has the particular advantage that a multi-pole circuit breaker device in which the neutral conductor may also be galvanically interrupted is provided.
In one advantageous configuration 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 one advantageous configuration of the invention, the mechanical contacts are opened in the case of an initiated high-impedance state of the electronic switch in order to prevent 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. 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 prevents the circuit breaker device from being destroyed.
In one advantageous configuration 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 in order to prevent 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, in particular the electronic switch, has cooled down. This means that the circuit breaker device is always in a safe operating state.
In one advantageous configuration 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 in order to prevent overheating and when a first time period since the high-impedance state of the electronic switch started (to prevent overheating) has expired.
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, in particular the electronic switch, has cooled down.
In one advantageous configuration of the invention, the mechanical contacts are opened within a first-time frame in the event of a change to the high-impedance state in order to prevent overheating (and back to the low-impedance state), the change exceeding a first number.
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.
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), further safety measures are 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 one advantageous configuration 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 a (central) temperature monitoring process of one or more circuit breaker devices can be carried out, so that appropriate measures can be taken as temperatures rise.
In one advantageous configuration of the invention, a display unit is provided, which is connected to the control unit and which has visible display means on the circuit breaker device for indicating the exceeding of temperature limits (first or/and second or/and third or/and fourth) or (and) the level of the temperature. As an alternative or in addition, 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 one advantageous configuration 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 one advantageous configuration 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 that a high level of safety and a circuit breaker device for low-voltage circuits that in particular is in line with standards are provided. The flow of current can be interrupted galvanically at any time by opening the contacts.
In one advantageous continuation of the configuration, 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.
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 (SG) 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 of the electronic switches are switched to a high-impedance state to prevent a flow of current in order to prevent overheating.
Advantageously, the level of the current of the respective series circuit is determined and a process for preventing a flow of current in a series circuit is initiated by the electronic switch in question, in particular for a first period of time, when at least one current threshold value is exceeded in the series circuit in question.
Advantageously, the mechanical contacts are opened in the case of an initiated high-impedance state of an electronic switch in order to prevent overheating and when a higher second temperature threshold value is exceeded.
Advantageously, the electronic switch is switched to a low-impedance state in the case of a high-impedance state of an electronic switch in order to prevent overheating and when a third temperature threshold value is undershot. The third temperature threshold value is lower than the first temperature threshold value.
Advantageously, the electronic switch is switched to the low-impedance state in order to prevent overheating in the case of a high-impedance state of an electronic switch in order to prevent overheating and when a first time period since the high-impedance state started has expired.
Advantageously, the mechanical contacts are opened within a first-time frame in the event of a change to the high-impedance state in order to prevent overheating, the change exceeding a first number.
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 configurations, both in dependent form referring back to independent patent claims, respectively, and referring back only to individual features or combinations of features of patent claims, in particular also the dependent assembly claims referring back to the independent method claim, 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.
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
a housing GEH having a first, second and third grid-side phase connection LG1, LG2, LG3 and a first, second and third load-side phase connection LL1, LL2, LL3, for a first, second and third phase conductor L1, L2, L3 of the low-voltage AC circuit, an energy source is usually connected to the grid side Grid, and a consumer is usually connected to the load side Load.
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 release 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 the 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 designed 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.
A control unit SE is provided (as already partially mentioned), which is connected to the current sensor units S11, S12, S13, the mechanical phase contacts or the mechanical isolating contact unit MK (as shown in
The current sensor units S11, S12, S13 each determine the level of the current of their respective conductor, 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 value 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, as shown in
The current sensor units S11, S12, S13 are arranged in the example according to
According to the invention, in each case at least one temperature sensor TS1, TS2, TS3 is provided for each series circuit SS1, SS2, SS3.
The first temperature sensor TS1 is provided in the first series circuit SS1, the second temperature sensor TS2 is provided in the second series circuit SS2, and the third temperature sensor TS3 is provided in the third series circuit SS3. This means that each series circuit has in each case at least one temperature sensor.
In the example according to
The first, second and third temperature sensors TS1, TS2, TS3 are each connected to the control unit SE.
The temperature sensors TS1, TS2, TS3 are used, in particular, for determining in each case the temperature level of the respective electronic switch, in particular the semiconductor-based switching element.
This means that the first temperature sensor TS1 determines, for example, the level of the temperature of the first electronic switch S1, in particular the semiconductor-based switching element/semiconductor-based switching elements.
The second temperature sensor TS2 determines, for example, the level of the temperature of the second electronic switch S2, in particular the semiconductor-based switching element/semiconductor-based switching elements.
The third temperature sensor TS3 determines, for example, the level of the temperature of the third electronic switch S3, in particular the semiconductor-based switching element/semiconductor-based switching elements.
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 in order to prevent a flow of current in order to prevent overheating.
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 electronic switches are switched to a high-impedance state to prevent a flow of current in order to prevent overheating.
A grid-side neutral conductor connection NG and a load-side neutral conductor connection NL are provided for a neutral conductor N of the multi-phase low-voltage AC circuit, in the example according to
As an alternative, the grid-side neutral conductor connection NG can also be connected directly (that is to say without a switchable contact) to the load-side neutral conductor connection NL.
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 designed 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 provided 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 only be connected 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, the temperature sensors TS1, TS2, TS3 and the current sensor units S11, S12, S13.
Furthermore, in each case 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 provide 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 conductors, in particular determining that there are instantaneous voltage values 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 S11, S12, S13, 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 a process for preventing a flow of current in a phase conductor is initiated by the electronic switch in question if at least one first current threshold value (specifically instantaneous value of the current) is exceeded in the phase conductor 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 to the electronic switches (as semiconductor-based switching elements) on account of low forward resistances, high junction resistances and 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 when a corresponding impulse voltage is applied. 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 sense of the invention, the DIN EN 60947 or IEC 60947 series of standards, to which reference is made here, is relevant in this case 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, some of the temperature sensors or all of 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.
The profile of the temperature TTS of the temperature sensor is shown as a function of the level of the current I of the phase conductor of the low-voltage circuit.
It is assumed that the heating in the circuit breaker device, specifically in the electronic switch, specifically the semiconductor-based switching elements thereof, is dependent on the level of the current I of the respective (relevant) phase conductor of the low-voltage circuit through the circuit breaker device (the circuit breaker device is to protect the low-voltage circuit). As the level of the current I in the phase conductor increases, the temperature of the temperature sensor of the electronic switch in question and, as a result, the circuit breaker device, specifically the semiconductor-based switching elements thereof, rises. Thus, the temperature TTS determined by the temperature sensor increases. The temperature increases in a monotonically rising manner with the level of the current. (In addition to the level of the current, the ambient temperature also has an influence on the heating in the circuit breaker device. 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 (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) in order to prevent a flow of current, 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 since the high-impedance state of the switching elements started to elapse. After a first period of time since the high-impedance state of the electronic switch started has elapsed, the electronic switch is switched to the low-impedance state (not shown).
If the change between the high-impedance state to prevent 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 within a first time frame in the event of a change (toggle) between the high-impedance state in order to prevent overheating and back to the low-impedance state, said change exceeding a first number.
The fourth graph in the lowest region of
Furthermore, the upper region of
For example, a (constant) current I of a first level 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.
The time offset (time delay) tv is in the range from one second, . . . 5 seconds, . . . 10 seconds, . . . 1 minute.
Individual monitoring of the temperature of the respective electronic switch can advantageously be carried out for each phase conductor and the current of 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.
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). Novel electronic protection and switching devices use electronic switching elements (power semiconductors) in the main current path, which also cause increased ohmic losses in the subdistribution system. This will exacerbate the problem of the thermal design of a subdistribution system.
The existing load current (through the device) significantly influences the temperature of the circuit breaker device and thus also the temperature increase. When a critical temperature is reached, a high-impedance state is initiated. This means that current can no longer flow on the conductor in question (through the circuit breaker device) and cool the device (and the subdistribution system).
An appropriate warning message can also be issued.
Since no current flows on the conductor in question, the electronic switch/the circuit breaker device cools down again. After a certain temperature has been undershot, the electronic switch 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.
The present invention describes a solution that simplifies the thermal design, avoids overdimensioning and prevents a dangerous state in the subdistribution system due to overheating.
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 |
| 23200440.8 | Sep 2023 | EP | regional |
