Device for a low-voltage circuit

Abstract

Device (D) for a low-voltage circuit in an enclosure (ICU), comprising exclusively: - a four-pole input terminal for a three-phase alternating current circuit with neutral (N), with a first, second and third input phase terminal (E1, E2, E3) and an input neutral terminal (EN), - a four-pole output terminal with a first, second and third output phase terminal (AP1, AP2, AP3) and an output neutral terminal (AN), - a first connection (VN1) between the input neutral terminal (EN) and the output neutral terminal (AN), - a first, second and third electronic switching unit (SE1, SE2, SE3) performing a semiconductor-based opening and closing of an electrical connection, wherein the first electronic switching unit (SE1) is connected on the input side to the first input phase terminal (E1),the second electronic switching unit (SE2) is connected on the input side to the second input phase pole (E2) and the third electronic switching unit (SE3) is connected on the input side to the third input phase pole (E3); the first, second and third electronic switching units (SE1, SE2, SE3) are connected on the output side to the first output phase pole (AP1); a tenth electronic switching unit (SEA) that performs a semiconductor-based closing and opening of an electrical connection, wherein the tenth electronic switching unit (SEA) is connected on the input side to the second input phase pole (E2) and on the output side to the second output phase pole (AP2); an eleventh electronic switching unit (SEB) that performs a semiconductor-based closing and opening of an electrical connection, wherein the eleventh electronic switching unit (SEB) is connected on the input side to the third input phase pole (E3) and on the output side to the third output phase pole (AP3);a communication interface (KS) for a communication signal and a voltage sensor (A1) for determining the voltage level of the first, second, and third input phase terminals (E1, E2, E3), and an external current sensor (C) arranged outside the housing (GEH) for determining the current level of the first, second, and third power source-side phase conductors (L1, L2, L3) of the low-voltage circuit, which are connected to the first, second, and third input phase terminals (E1, E2, E3), - a control unit (A4) which is connected to the communication interface (KS) and the voltage sensor (A1) and the external current sensor (C), - that the control unit (A4) is further connected to the first, second, third, tenth, and eleventh electronic switching units (SE1, SE2, SE3, SEA, SEB) and is designed such that, in the case of a three-phase load (B), the first, second, and third output phase terminals (AP1, AP2, AP3) the first,The tenth and eleventh electronic switching units (SE1, SEA, SEB) are activated, such that the first input phase pole (E1) is connected to the first output phase pole (AP1), the second input phase pole (E2) to the second output phase pole (AP2), the third input phase pole (E3) to the third output phase pole (AP3), and an internal current sensor (A3) for determining the magnitude of the current of the first output phase pole (AP1), which is connected to the control unit (A4).

Description

The invention relates to a device for a low voltage circuit, a method for a three-phase low voltage circuit with neutral and three phase conductors and a system for a three-phase low voltage circuit with neutral and three phase conductors.By low voltage is meant voltages up to 1000 volts AC or 1500 volts DC. By low voltage is more specifically meant in particular voltages which are greater than the low voltage, with values of 50 volts AC voltage or 120 volts DC voltage.By low voltage circuit is meant circuits, by the voltages mentioned, for currents of 10 to 6300 amperes. The stated currents are understood in particular to mean rated currents or regular maximum currents of the circuit.Three-phase low-voltage circuits are consequently, for example, 400 volts (phase phase) / 230 volts (phase neutral) circuits or power grids, having three phase conductors and one neutral, as are usually the case in Europe.The three-phase power grid is generally asymmetrically charged with single-phase energy sinks or consumers, such as operating means, storage devices and / or generators. In the most recent years, a particularly unbalanced load due to powerful chargers for or the electric vehicles occurs, which will increase in the future, and increasingly leads to oblique loads (unbalanced load) in the circuit or (power) network. Even the uniform distribution of single-phase charging connections to individual phases does not lead to compensation by the statistical distribution of the charging processes. A similar problem exists in battery storage systems, for example in private homes, which are usually operated only in one phase, or in photovoltaic systems (in the case of a generator). Three-phase alternating current circuits are usually designed for a (approximately) symmetrical load. Unbalanced loads lead to strong balancing currents in neutral conductors (or neutral conductors) which are intended to be avoided. To this end, DE 10 2015 105 152 A1 discloses an arrangement and a method for reducing a skew load in a three-phase distribution network. DE 10 2011 078 047 A1 discloses a device for controlling the loading of the phases of a three-phase power grid. Finally, DE 10 2015 000 076 A1 discloses a method for operating an electrical load or generator on a subscriber network and also a device and a switching matrix.It is an object of the present invention to provide a device for improving the symmetry of a three-phase alternating current mains with neutral, which device operates particularly rapidly.This object is achieved by a device having the features of the patent claim. 1.According to the invention, a device is proposed which enables a phase change of a load to a less loaded phase or allocates the phases of a load to the phases of the low-voltage circuit in such a way that the phases (phase conductors) are loaded as uniformly as possible. According to the invention, this is carried out by electronic switching units. According to the invention, an electronic switching unit means a unit which performs a semiconductor-based closing and opening of an electrical connection. Electromechanical switching units, i.e. with mechanical contacts, are not meant.According to the invention, the criterion for switching a load to a phase can be, on the one hand, the magnitude of the voltage. The phase with the highest voltage (root mean square of the voltage) is often the least stressed phase. That is to say that the load is assigned to the phase with the highest voltage.The criterion for switching a load to a phase can, on the other hand, be the magnitude of the current. The phase with the lowest current (root mean square of the current) is the least loaded phase. That is, the load is assigned to the phase with the lowest current.In an alternative embodiment, the assignment can be effected by a superordinate management system. That is to say that the device has a communication interface with which the assignment of a load to a phase (or the assignment of the load-side phases (phase conductors) to the energy-source-side phases (phase conductors)) can be established, for example by means of a communication signal.This has the particular advantage that more uniform loading of a three-phase alternating current network is made possible, wherein a particularly fast (in the micro- or one-digit milli-second range) and, for example, power-free switching can take place with electronic switching units, wherein the number of switching cycles is almost unlimited in the case of a power-free switching.Advantageous embodiments are specified in the dependent claims.In an advantageous embodiment of the invention, the device is arranged in a housing.This has the particular advantage that a compact device is available which can be interposed in a branch for the connection of a load in order to achieve an approximately symmetrical load.In an advantageous embodiment of the invention, depending on the embodiment, an (internal) current sensor is provided for determining the magnitude of the current of the first output phase pole and / or a voltage sensor is provided for determining the magnitude of the voltage of the first, second and third input phase pole. This is / are connected to the control unit. This has the particular advantage that, in addition to the criterion of the voltage or the current, a further criterion (additionally current or voltage) is available for phase selection. Thus, even better phase selection can be achieved.In an advantageous embodiment of the invention, the electronic switching units are designed as semiconductor switches, in particular they comprise power semiconductors based on silicon, silicon carbide, silicon carbon, gallium, gallium nitride or gallium nitrogen. This has the particular advantage that a simple realization of the semiconductor switches or electronic switching units is possible, which enable low losses and high switching powers.In an advantageous embodiment of the invention, the device has a frequency sensor for determining the frequency of the electric current of the first, second and third input phase pole, which is connected to the control unit. In one configuration, the frequency, of the voltage of the respective input phase pole can also be determined. This has the particular advantage that, for example, a phase change can take place at the zero crossing of the current or ( / and) of the voltage. In addition, a very fast phase change can take place with the electronic switching units, so that this takes place virtually unnoticed. As a result, on the one hand, a power-free switch can be made, on the other hand, a smooth transition during the phase change can be achieved.An ancillary advantageous method and a system for phase change is also claimed.All embodiments, both dependent on claim 1, 3, 4, 6, 7, 9 or 10, and dependent only on individual features or combinations of features of claims, bring about an improvement in the symmetrical load of a three-phase alternating current circuit.The described properties, features and advantages of this invention and the manner in which these are achieved become clearer and more clearly comprehensible in conjunction with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawing.The accompanying drawing shows: FIGS. 1, 2, 3, 4, 5, 6, 7, 8 to 9 show circuits for explaining the invention.FIG. 1 shows a circuit for explaining the invention, having a first phase conductor L 1, a second phase conductor L 2, a third phase conductor L 3 and a neutral conductor N of a three-phase low-voltage circuit. This circuit has a branch, wherein a first load V 1 (energy sink) is connected to the first phase conductor L 1 and the neutral conductor N, a second load V 2 is connected to the second phase conductor L 2 and the neutral conductor N, a third load V 3 is connected to the third phase conductor L 3 and the neutral conductor N. The connection of the three loads V 1, V 2, V 3 to the phase conductors L 1, L 2, L 3 has a three-phase switch S 1. If the resistances of the first, second and third loads are of the same magnitude, the same power is converted in the loads V 1, V 2, V 3, i.e. the first power P 1 of the first load V 1, the second power P 2 of the second load V 2 and the third power P 3 of the third load V 3 are of the same magnitude; P 1=P 2=P 3. The first current I1 of the first load V1, the second current I2 of the second load V2 and the third current I3 of the third load V3 are thus of the same magnitude (meaning the phase conductor current, the first current I1 flows in the branch of the first phase conductor L1 to the first load V1, the second current I2 flows in the branch of the second phase conductor L2 to the second load V2, the third current I3 flows in the branch of the third phase conductor L3 to the load V3), I1=I2=13. There is a balanced load on the three-phase alternating current circuit.FIG. 2 shows a circuit according to FIG. 1, with the difference that the resistances of the first, second and third loads V 1, V 2, V 3 are different. Thus, different first, second and third powers P 1, P 2, P 3 of the consumers are also present, P 1≠P 2≠P 3. Thus, the first to third currents I 1, I 2, I 3 are also different--lich, I 1≠I 2≠I 3. A compensation current thus flows in the neutral conductor N, In≠0. There is unbalanced load on the three-phase AC circuit.FIG. 3 shows a circuit according to FIG. 1 or FIG. 2, with the difference that only the first load V 1 is connected to the three-phase alternating current circuit. This has only one, single-phase switch S 2. Here, the first current I 1 of the branch to the first load V 1 is equal to the current in the neutral conductor N, I 1=IN. That is, the three-phase alternating current circuit is asymmetrically loaded by a single-phase load. There is unbalanced load on the three-phase AC circuit.FIG. 4 shows a circuit according to FIG. 3, with the difference that instead of the first load V 1, a socket Wallbox 1 is connected as a branch to the first phase conductor L 1 and the neutral conductor N. A second socket Wallbox 2 is connected as a branch to the second phase conductor L 2 and the neutral conductor N. A third socket Wallbox 3 is connected as a branch to the third phase conductor L 3 and the neutral conductor N. In an analogous manner, further sockets Wallbox 4... Wallbox N can be connected in the form of a branch to the phase conductors. The electrical cars Car 1, Car 2, Car 3, Car 4, Car N can be connected to the power outlets as consumers, for example.FIG. 5 shows a circuit according to the preceding figures, with the difference that the sockets are designed in 3-phase fashion, so that the sockets are connected as a branch to the three phase conductors, L 1, L 2, L 3 and the neutral conductor N.FIG. 6 shows a circuit according to the preceding figures, with the difference that a device EA according to the invention is provided. This has:a quadrupole input terminal, for a three-phase alternating current circuit with neutral, having a first, second and third input phase pole E 1, E 2, E 3 and an input neutral pole EN;a two-pole output terminal having a first output phase pole AP1 and an output neutral pole AN;a first connection VN1 between input neutral terminal EN and output neutral terminal AN;a first, second and third electronic switching unit SE 1, SE 2, SE 3 which performs a semiconductor-based closing and opening of an electrical connection, wherein the first electronic switching unit SE 1 is connected on the input side to the first input phase pole E 1, the second electronic switching unit SE 2 is connected on the input side to the second input phase pole E 2 and the third electronic switching unit SE 3 is connected on the input side to the third input phase pole E 3;the first, second and third electronic switching units SE1, SE2, SE3 are connected on the output side to the first output phase pole AP1;a voltage sensor A1 or U for determining the magnitude of the voltage of the first, second and third input phase poles E1, E2, E3, that is to say of three individual voltages;a control unit A4, which is connected to the voltage sensor A1, the first, second and third electronic switching units SE1, SE2, SE3 and which is designed such that, as a function of the level of the voltage of the first, second and third input phase poles, the first, second or third input phase pole E1, E2, E3 is connected by means of the respective electronic switching unit to the first output phase pole AP1, wherein the first output phase pole AP1 is in each case connected to the input phase pole which has the highest voltage.To determine the magnitude of the voltage, the voltage sensor A 1 can be connected to the neutral conductor / input neutral conductor pole EN.That is to say, for example, the first input phase pole E1 has a voltage of 228 volts, the second input phase pole E2 has a voltage of 230 volts and the third input phase pole E3 has a voltage of 232 volts, then the third input phase pole E3 is connected to the first output phase pole AP1 by means of the third electronic switching unit.SE3.During operation, the assignment can be changed periodically, at certain time intervals, depending on how the voltage level changes. The following are also included. Voltage is meant to be the root mean square of the voltage. That is to say, a change in the assignment takes place, for example, minimally after a plurality of passes of the sinusoidal oscillation of the alternating voltage. For example, after a minimum of 10' sine oscillations, an assignment change can take place provided that the voltage level changes. This makes it possible to prevent the device from swinging and to prevent a constant change in allocation, so that a stable state can occur.The device EA is arranged, for example, in a housing GEH.The device EA also has an internal current sensor A3 or I, i.e. for example within the housing GEH, for determining the magnitude of the current of the first output phase pole AP1, which is connected to the control unit A4.The electronic switching units SE 1, SE 2, SE 3 can be embodied as semiconductor switches, in particular e.g. with power semiconductors, e.g. based on silicon, silicon carbide, silicon carbon, gallium, gallium nitride or gallium nitrogen.The device EA can have a frequency sensor A2 or f for determining the frequency of the electric current and / or the electric voltage of the first, second and third input phase pole E1, E2, E3, which is connected to the control unit A4. A phase change can thus be carried out, for example, in a zero crossing.In an alternative configuration, which can be combined as desired with the aforementioned configuration, an external current sensor C arranged outside, for example outside, the housing GEH is provided for determining the magnitude of the current of the first, second and third phase conductors L 1, L 2, L 3 on the energy source side and, if appropriate, of the neutral conductor N of the low-voltage circuit. These phase conductors L 1, L 2, L 3 and the neutral conductor N are connected via a branch to the first, second and third input phase poles E 1, E 2, E 3, EN.Further branches with consumers are usually connected to the phase conductors L 1, L 2, L 3 and the neutral conductor N (not illustrated in FIG. 6 ).In this configuration, the control unit A 4 is connected, for example, to the external current sensor C, the first, second and third electronic switching units SE 1, SE 2, SE 3 and is configured in such a way that, depending on the level of the current of the first, second and third phase conductors L 1, L 2, L 3 on the energy source side, the first, second or third input phase pole E 1, E 2, E 3 is connected to the first output phase pole AP 1 by means of the respective electronic switching unit SE 1, SE 2, SE 3, wherein the first output phase pole AP.1 is connected in each case to the input phase pole E 1, E 2, E 3 whose phase conductor L 1, L 2, L 3 on the energy source side has the lowest current level.That is, for example, the first phase conductor L 1 has a current of 70 amperes, the second phase conductor L 2 has a current of 40 amperes, the third phase conductor L 3 has a current of 60 amperes; then, the second input phase pole E 2 is connected to the first output phase pole AP 1 by means of the second electronic switching unit SE 2.In the example according to the figures, an energy source (not shown) is located at the left end of the phase conductors L 1, L 2, L 3 or of the neutral conductor N, where the reference symbols L 1, L 2, L 3 or N are drawn in.In one configuration, which can be combined as desired with the aforementioned configuration, a communication interface KS is provided, for example on the housing GEH, for a communication signal which can be communicated via it. The control unit A 4, which is connected to the communication unit, the first, second and third electronic switching units, can be designed in this case such that, as a function of the communication signal, the first, second or third input phase pole E 1, E 2, E 3 is connected to the first output phase pole AP 1 by means of the respective electronic switching unit SE 1, SE 2, SE 3.FIG. 6 shows according to the invention the device EA with all these configurations, which can be used individually or optionally or together. In the example according to FIG. 6, a management system D, for example, is connected to the communication interface KS.A load or an energy sink B, such as an electric car Car 1,..., Car N, is connected, for example, to the first output phase pole AP 1 and output neutral pole AN.FIG. 7 shows an arrangement according to FIG. 6, with the difference that a four-pole output connection is provided with a first, second and third output phase pole AP 1, AP 2, AP 3 and an output neutral pole AN.A tenth electronic switching unit SEA is also provided, which is connected on the input side to the second input phase pole E 2 and on the output side to the second output phase pole AP 2. Furthermore, an eleventh electronic switching unit SEB is provided, which is connected on the input side to the third input phase pole E 3 and on the output side to the third output phase pole AP 3.In this configuration, only one output phase pole, in the example the first output phase pole AP 1, can carry out a phase change. This is advantageous in particular for electrical outlets of electric vehicles, since either single-phase or three-phase charging is effected. Thus, with approximately symmetrical three-phase loading / charging by an electric vehicle, no phase change needs to be carried out; with only single-phase loading, a phase change can be carried out.FIG. 8 shows a variant of a section of the circuit according to FIG. 7, with the difference that:fourth, fifth and sixth electronic switching units SE 4, SE 5, SE 6 are provided, wherein the fourth electronic switching unit SE 4 is connected on the input side to the first input phase pole E 1, the fifth electronic switching unit SE 5 is connected on the input side to the second input phase pole E 2 and the sixth electronic switching unit SE 6 is connected on the input side to the third input phase pole E 3, the fourth, fifth and sixth electronic switching units SE 4, SE 5, SE 6 are connected on the output side to the second output phase pole AP 2,seventh, eighth and ninth electronic switching units SE 7, SE 8, SE 9 are provided, wherein the seventh electronic switching unit SE 7 is connected on the input side to the first input phase pole E 1, the eighth electronic switching unit SE 8 is connected on the input side to the second input phase pole E 2 and the ninth electronic switching unit SE 9 is connected on the input side to the third input phase pole E 3, the seventh, eighth and ninth electronic switching units SE 7, SE 8, SE 9 are connected on the output side to the third output phase pole AP 3.In an embodiment according to FIG. 8 (referred back to FIG. 7 ), which can be combined with the other embodiments, the voltage sensor A 1 is provided for determining the magnitude of the voltage of the first, second and third input phase poles E 1; E 2, E 3. Furthermore, the internal current sensor A 3 for determining the magnitude of the current of the first, second and third output phase poles AP 1, AP 2, AP 3. The control unit A 4 is connected to the voltage sensor A 1, the internal current sensor A 3, the first to ninth electronic switching units SE 1 to SE 9 and is configured such that, depending on the magnitude of the voltage of the first, second and third input phase poles and depending on the magnitude of the current of the first, second and third output phase poles, an input phase pole is connected to an output phase pole by means of the respective electronic switching unit, wherein:the output phase pole having the highest current with the input phase pole having the highest voltage,the output phase pole having the second highest current having the input phase pole having the second highest voltage,connecting the output phase pole having the third highest current to the input phase pole having the third highest voltage.For example, if the voltage of the first input phase pole 228 is volts, that of the second input phase pole 230 is volts, that of the third input phase pole 232 is volts; the currents of the first output phase pole 42 is amperes, the second output phase pole 44 is amperes, and the third output phase pole 38 is amperes; then the second output phase pole is connected to the third input phase pole, the first output phase pole is connected to the second input phase pole, and the third output phase pole is connected to the first input phase pole.In another configuration according to FIG. 8 (referring back to FIG. 7 ), which can be combined with the other configurations, the external current sensor C arranged outside, for example outside, the housing GEH is provided for determining the magnitude of the current IP 1, IP 2, IP 3, INN of the first, second and third phase conductors L 1, L 2, L 3 on the energy source side and of the neutral conductor N of the low-voltage circuit (which are connected to the first, second and third input phase poles in the form of a branch). Furthermore, the internal current sensor A 3 for determining the magnitude of the current of the first, second and third output phase poles AP 1, AP 2, AP 3.The control unit A 4 is connected to the external and internal current sensors C, A 3 of the first to ninth electronic switching units SE 1 to SE 9 and is configured such that depending on the magnitude of the current IP 1, IP 2, IP 3 and, if appropriate, it is also possible. INN of the first, second and third power source side phase conductor (if necessary. The neutral conductor N) and, depending on the magnitude of the current of the first, second and third output phase poles (AP1, AP2, AP3), an input phase pole is connected to an output phase pole by means of the respective electronic switching unit SE1 to SE9. Wherein:the output phase pole having the highest current is connected to the input phase pole whose power source side phase conductor has the lowest current level,the output phase pole having the second highest current is connected to the input phase pole whose phase conductor on the power source side has the second lowest current level,the output phase pole having the third highest current is connected to the input phase pole whose power source side phase conductor has the third lowest current level.That is, for example, the current IP 1 of the first phase conductor L 1 is 500 amperes, the current IP 2 of the second phase conductor L 2 is 400 amperes, the current IP 3 of the third phase conductor L 3 is 250 amperes; the currents of the first output phase pole are 42 amperes, the second output phase pole is 44 amperes, and the third output phase pole is 38 amperes; then, the second output phase pole is connected to the third input phase pole, the first output phase pole is connected to the second input phase pole, and the third output phase pole is connected to the first input phase pole.In an embodiment according to FIG. 8 (referred back to FIG. 7 ), which can be combined with the other embodiments, only the communication interface KS for a communication signal is provided. The control unit, which is connected to the communication interface KS and the first to ninth electronic switching units SE 1 to SE 9, is configured such that, depending on the communication signal, at least one input phase pole is connected to an output phase pole by means of the respective electronic switching unit. in particular, two input phase poles are connected to two output phase poles by means of the respective electronic switching unit or three input phase poles are connected to three output phase poles by means of the respective electronic switching unit. In each case one phase is switched through from an input phase pole to an output phase pole, so that two different phases are never connected to one another.FIG. 9 shows a circuit according to FIG. 5, with the difference that a device EA according to the invention according to FIG. 6, 7 or 8 is provided in the at least one or all sockets wallbox 1 to wallbox N.In the following, the invention, including its advantages, will be explained again in other words.On the basis of power arresters (silicon, silicon carbide / SiC or GaIumNitride / GaN), the phase selection can be effected without mechanical switching elements. An already integrated measuring and regulating technique of an electronic switching unit, for example, can automatically identify to which phase the power is to be switched, for example, by means of determined current and / or voltage values. This can be done before or continuously during operation. These can be adapted or switched over before or during operation. The selection and control of the electronic switching units can also be effected by external systems D, such as e.g. network control technology or (charging) management systems.This has the advantage that:electronic switching units that open and close a semiconductor-based electrical connection, i.e. switching, are not subject to mechanical wear and can thus perform a much higher number of circuits.The selection of the phase can be changed during operation without problems and largely without interruptions (commutation).The use of wide bandgap power semiconductors (SiC-based, GaN-based) eliminates unnecessary power losses due to coils and drives for electromechanical switching elements.external / superimposed systems can offer further services from supplied data and information, and can act "from the outside" on the electronic switching units (semiconductor-based).For controlling the electronic switching units, measured values are available in real time by sensors.the semiconductor-based electronic switching units can change between two phases in the time range of less than one millisecond and thus commute the power.the semiconductor-based electronic switching units can perform several million switching cycles and are thus also capable of performing operational switching, in contrast to electromechanical switching devices.the series on-resistance of electronic switching units in the on-state is approximately equal to the contact resistance of mechanical contacts. Thus, power losses in coils of contactors and thermal losses in bimetallic elements of thermal tripers are eliminated.IP-based communication can be carried out with superimposed systems using a communication interface, for example by means of TCP-IP, Modbus, etc.Although the invention has been illustrated and described in more detail by the exemplary embodiment, the invention is not restricted by the disclosed examples and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

Claims

Device (EA) for a low-voltage circuit in a housing (GEH), exclusively having: - a quadrupole input connection for a three-phase alternating circuit with neutral (N), having a first, second and third input phase pole (E1, E2, E3) and an input neutral pole (EN), - a quadrupole output connection having a first, second and third output phase pole (AP1, AP2, AP3) and an output neutral pole (AN), - a first connection (VN1) between input neutral pole (EN) and output neutral pole (AN), - a first, second and third electronic switching unit (SE1, SE2, SE3) which performs a semiconductor-based closing and opening of an electrical connection, wherein the first electronic switching unit (SE1) is connected on the input side to the first input phase pole (E1), the second electronic switching unit (SE2) is connected on the input side to the second input phase pole (E2) and the third electronic switching unit (SE3) is connected on the input side to the third input phase pole (E3), the first, second and third electronic switching units (SE1, SE2, SE3) are connected on the output side to the first output phase pole (AP1), - a tenth electronic switching unit (SEA) which performs a semiconductor-based closing and opening of an electrical connection, wherein the tenth electronic switching unit (SEA) is connected on the input side to the second input phase pole (E2) and on the output side to the second output phase pole (AP2), - an eleventh electronic switching unit (SEB), which performs a semiconductor-based closing and opening of an electrical connection, wherein the eleventh electronic switching unit (SEB) is connected on the input side to the third input phase pole (E3) and on the output side to the third output phase pole (AP3), a communication interface (KS) for a communication signal and a voltage sensor (A1) for determining the magnitude of the voltage of the first, second and third input phase poles (E1, E2, E3), and an external current sensor (C) arranged outside the housing (GEH) for determining the magnitude of the current of first, second and third power-source-side phase conductors (L1, L2, L3) of the low-voltage circuit which are connected to the first, second and third input phase poles (E1, E2, E3), a control unit (A4) which is connected to the communication interface (KS) and to the voltage sensor (A1) and to the external current sensor (C), - in that the control unit (A4) is furthermore connected to the first, second, third, tenth and eleventh electronic switching units (SE1, SE2, SE3, SEA, SEB) and is designed in such a way that, in the case of a three-phase load (B) at the first, second and third output phase poles (AP1, AP2, AP3), the first, tenth and eleventh electronic switching units (SE1, SEA, SEB) are activated, such that the first input phase pole (E1) is connected to the first output phase pole (AP1), the second input phase pole (E2) is connected to the second output phase pole (AP2), the third input phase pole (E3), to which the third output phase pole (AP3) is connected, and an internal current sensor (A3) for determining the magnitude of the current of the first output phase pole (AP1), which is connected to the control unit (A4).Device (EA) according to claim 1, characterised in that depending on the communication signal two input phase poles are connected to two output phase poles by means of the respective electronic switching unit (SE1,..., SE9).Device (EA) according to claim 1 or 2, characterised in that, depending on the communication signal, three input phase poles are connected to three output phase poles by means of the respective electronic switching unit (SE1,..., SE9).Device (EA) according to one of the preceding patent claims, characterized in that the electronic switching units (SE1,..., SE9) are designed as semiconductor switches, in particular comprise power semiconductors based on silicon, silicon carbide, silicon carbon, gallium, gallium nitride or gallium nitrogen.Device (EA) according to one of the preceding patent claims, characterized in that a frequency sensor (A2) for determining the frequency of the electrical current of the first, second and third input phase pole (E1, E2, E3) is provided, which is connected to the control unit (A4), such that in particular a phase change can be carried out at a zero crossing of the electrical current.

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