(Universal) power supply

Abstract

The power supply comprises a supply circuit (100) for providing an internal operating voltage, a protection circuit, two selection circuits (311, 312), two energy flow monitoring circuits (321, 322) and a control circuit (400), wherein a selectively activatable first protected supply path of the power supply is formed by means of the supply circuit, the protection circuit, the selection circuit (311) and the monitoring circuit (321) and a selectively activatable second protected supply path of the power supply is formed by means of the supply circuit, the protection circuit, the selection circuit (312) and the monitoring circuit (322) and wherein the control circuit (400) is configured, among other things, to output a selection signal activating the first supply path in a first operating mode and a selection signal activating the second supply path in an (alternative) second operating mode.Each of the monitoring circuits (321, 322) is also configured to monitor a respective energy flow based on at least one respective (energy flow) parameter, namely to determine whether the at least one (energy flow) parameter has exceeded at least one respective (energy flow) threshold value and, if so, to output a fault signal indicating this to the protection circuit. The protection circuit is also configured, triggered by one or more of the fault signals, to switch from a first operating mode, in which a load input of the protection circuit is electrically connected to a load output of the supply circuit, to a second operating mode, in which the load input or the load output of the supply circuit connected to it is short-circuited, thereby interrupting each of the first and second supply paths equally.

Description

[0001] The invention relates to a power supply unit, in particular suitable for a measuring system, and to an (industrial) measuring system with such a power supply unit.

[0002] WO-A 2018 / 215215 shows a power supply unit that is particularly suitable for an industrial measuring system (operable in a potentially explosive atmosphere). The power supply unit comprises a (mains-powered) supply circuit with a load input and a load output that can be connected to a measuring system's transducer and provides an (output) voltage during operation, as well as a protective circuit that is electrically connected to the supply circuit and formed by a clamping circuit (crowbar) for providing a protective function that shuts down the power supply unit in the event of a fault.

[0003] A (crowbar) protection circuit suitable for such power supplies, as well as its use in a power supply intended to supply one or more load circuits with electrical energy, is disclosed, for example, in CA-A 982 228. The protection circuit shown in CA-A 982 228 is formed by means of a fuse and a controllable (electronic) switching element and has a load input connectable to the load output of an upstream supply circuit, a load output (each for an independent load circuit), and first and second (opto-electrical) control inputs. The load output of the protection circuit, as well as each of the control inputs, are each further provided with a (first or second) control input.second), each having a load input, a load output and an (optical) control output, such that the load output of the protective circuit (forming first and second supply paths of the power supply involving the protective circuit as well as the first and second control and monitoring circuits) is permanently electrically connected to the load input of each of the control and monitoring circuits and that the first control input is signal-coupled, in this case optically, to the control output of the first control and monitoring circuit and the second control input is signal-coupled, in this case optically, to the control output of the second control and monitoring circuit, forming first and second clamping circuits of the power supply.a configured, in a first operating mode, to keep their load input electrically connected to their load output in such a way that a current flows from the same load input to the same load output, while at the load output a DC voltage provided by the supply circuit is present, which serves as the input voltage for each of the control and monitoring circuits. Each of the control and monitoring circuits comprises a DC-DC converter and is further configured to generate a current or voltage converter when a DC (input) voltage is applied to their respective load input.to enable energy flow from their load input to their load output and to monitor this same energy flow based on a voltage level of the (output) DC voltage applied to the load output, namely to determine whether the respective (output) DC voltage has exceeded an (energy flow) threshold value specific to the respective control and monitoring circuit, namely a predetermined maximum voltage level, and if necessary to output an error signal signaling this to their control output. In addition, the protection circuit is further configured, controlled by one or more of the error signals (of the first and second control and monitoring circuits), in such a way that an error signal is applied to at least one of the first and second control inputs, to switch from the first operating mode to a second operating mode in which its load input orThe connected load output of the supply circuit is short-circuited, allowing a (short-circuit) current driven by the aforementioned supply circuit to flow through the protective circuit. The fuse, in turn, is designed to be triggered by the aforementioned short-circuit current, causing the protective circuit to (automatically) switch from the second operating mode to a third operating mode, in which its load input is (permanently) separated from its load output, and the aforementioned short-circuit current is interrupted again.

[0004] One disadvantage of the power supply shown in CA-A 982 228 is, among other things, that the overall complexity of electrical components is very high due to the large number of (independent) control and monitoring circuits and, secondly, that all control and monitoring circuits are permanently electrically connected to the supply circuit. This means that even control and monitoring circuits which are not connected to a load circuit on the output side and are therefore not actually required are nevertheless permanently energised during operation of the power supply or must be in order to maintain the protective functionality of the power supply; this is especially true if the power supply is intended to achieve a certain specified level of protection, in particular a protection level "ia", "ib" or at least "ic" in accordance with the international standard IEC 60079-11:2023-01 (Edition 7.0, Explosive atmospheres - Part 11: Equipment protection by intrinsic safety "i").the control and monitoring circuits implementing the protective functionality must not be (re-)programmable, and / or that the power supply is to be used as a universal power supply (scalable with regard to the DC voltages provided), in such a way that by means of its two or more control and monitoring circuits two or more (output) DC voltages differing from one another with regard to a respective (nominal) voltage level are provided and that during operation only a single load circuit is electrically connected to exactly one matching control and monitoring circuit (or to the one supply path formed in the power supply) and is supplied with electrical energy from there, while the remaining unused control and monitoring circuits are permanently operated in idle mode.

[0005] Based on the aforementioned prior art, one object of the invention is to provide a power supply unit that can be used in a potentially explosive atmosphere as a (universal) power supply unit ensuring a predeterminable level of protection, in particular corresponding to at least one of the protection levels "ia", "ib", or "ic" according to IEC 60079-11:2023-01. Compared to conventional (intrinsically safe) power supplies, it has an overall lower number of (components) in terms of the installed (electronic) components, while at the same time offering sufficient diversity in terms of the protection levels and, if applicable, also (nominal) voltage levels that can be provided by the power supply unit. Furthermore, the power supply unit should have a (nominal) lower proportion of idle-related power loss during operation compared to conventional universal power supplies, for example due to unused supply paths operating in idle mode.

[0006] To achieve the object, the invention consists in a power supply, for example a power supply for an (industrial) measuring system and / or a (wide-range) universal power supply, which power supply comprises: • a supply circuit, formed for example by means of one or more DC-DC converters and / or fed by means of one or more energy storage devices and / or fed from the mains and / or controllable, with a (digital) control input, with a first load output and with a second load output; • a protection circuit with a first control input, with at least one second control input, with a load input, and with a load output; • a first selection circuit with a control input, with a load input, and with a load output; • a second selection circuit, for example identical in construction to the first selection circuit, with a control input, with a load input, and with a load output; • a first (energy flow) monitoring circuit with at least one (first) control output, with a load input, and with a load output, for example for electrically connecting an electrical load (external to the power supply); • a second (energy flow) monitoring circuit with at least one (first) control output, with a load input, and with a load output, for example for electrically connecting a (power supply external) (consumer) circuit; • and a control circuit, for example comprising at least one microprocessor (µC) and / or at least one (field) programmable logic gate circuit (FPGA) and / or at least one application-specific integrated circuit (ASIC), with a first control output, with a second control output, with at least one (digital) third control output, and with a supply input; • wherein the supply circuit is electrically connected with its first load output to the supply input of the control circuit and with its second load output to the load input of the protection circuit; • wherein the first selection circuit is electrically connected with its load output to the load input of the first monitoring circuit and the second selection circuit is electrically connected with its load output to the load input of the second monitoring circuit; • wherein the protective circuit is electrically connected with its load output both to the load input of the first selection circuit (forming a first fused supply path of the power supply unit which, in addition to the supply circuit and the protective circuit, also includes the first selection circuit and the first monitoring circuit) and to the load input of the second selection circuit (forming a second fused supply path of the power supply unit which, in addition to the supply circuit and the protective circuit, also includes the second selection circuit and the second monitoring circuit); • and wherein the control circuit is coupled (signal-wise), for example electrically connected, with its first control output to the control input of the first selection circuit, with its second control output to the control input of the second selection circuit and with its third control output to the control input of the supply circuit; • wherein the supply circuit is configured to provide, in a first operating mode, both a first (DC) voltage (serving as the operating voltage of the control circuit) at the first load output and a second (DC) voltage at the second load output, such that the second (DC) voltage has a first (nominal) voltage level, for example a constant and / or not less than 1 V; • wherein the first selection circuit is configured to electrically connect or keep connected its load input to its load output in a first switching state, such that a current flow from the said load input to the said load output is enabled and, meanwhile, a voltage (serving as the output voltage of the first selection circuit) is provided at the load output, for example, depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the first selection circuit, • wherein the second selection circuit is configured to electrically connect or keep connected its load input to its load output in a first switching state, such that a current flow from the said load input to the said load output is enabled and, meanwhile, a voltage (serving as the output voltage of the second selection circuit) is provided at the load output, for example, depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the second selection circuit, • and wherein each of the first and second selection circuits is each configured to electrically separate or keep separate the respective load input and the respective load output (of the respective selection circuit) from one another in a respective second switching state, for example in such a way that even with an (input) voltage applied to the respective load input with an (over)voltage level of more than 1.5 V and less than 90 V (volts), a (leakage) current flow with a current strength of at most 100 µA (microamperes) from the respective load input to the respective load output is possible; • wherein the control circuit is configured to output, in a first operating mode, a selection signal activating the first switching state of the first selection circuit at its first control output, for example no selection signal (activating the first switching state of the second selection circuit) at the second control output, and a control signal having a first control value activating the first operating mode of the supply circuit at its third control output; • and wherein the control circuit is configured to output, in a second operating mode, at its second control output a selection signal activating the first switching state of the second selection circuit, for example no selection signal (activating the first switching state of the first selection circuit) at the first control output; • wherein the first monitoring circuit is configured to enable a current or energy flow from the load input to the load output when an (input) voltage is applied to the load input thereof, for example in a non-interruptible or continuous manner, and meanwhile to provide a voltage (serving as the output voltage of the power supply) at the load output, for example depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the first monitoring circuit, • and wherein the first monitoring circuit is configured to monitor the energy flow (through the first monitoring circuit) based on at least one (energy flow) parameter, for example a voltage level of the (input) voltage applied to the load input and / or a current strength of the (useful) current driven by the supply circuit, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the first monitoring circuit), for example a predetermined first (maximum) voltage level or a predetermined first (maximum) current strength, and if necessary to output an error signal signaling this, for example in the form of a binary (switching) signal, to its (first) control output; • wherein the second monitoring circuit is configured to enable a current or energy flow from the load input to the load output when an (input) voltage is applied to the load input thereof, for example in a non-interruptible or continuous manner, and meanwhile to provide a voltage (serving as the output voltage of the power supply) at the load output, for example depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the second monitoring circuit, • and wherein the second monitoring circuit is configured to monitor the energy flow (through the second monitoring circuit) based on the at least one (energy flow) parameter, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the second monitoring circuit), for example a predetermined second (maximum) voltage level or a predetermined second (maximum) current strength, and if necessary to output an error signal signaling this, for example in the form of a binary (switching) signal, to its (first) control output; • wherein the protective circuit is configured to electrically connect or keep connected its load input to its load output in a first operating mode, such that a current flow from said load input to said load output is enabled and, meanwhile, an (output) voltage (of the protective circuit) is provided at the load output, for example, depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the protective circuit, for example in such a way that the (DC) voltage at the load output of the supply circuit is connected to the load output of the protective circuit, • and wherein the protective circuit is configured to short-circuit the load input or the load output of the supply circuit connected thereto in a second operating mode, for example in such a way that a (short-circuit) current driven by the supply circuit is allowed to flow through the protective circuit and at the load output (of the protective circuit) there is at most a (fault) voltage of no more than 0.5 V; • wherein the protective circuit is (signal-technically) coupled, for example electrically connected, with its first control input to the control output of the first monitoring circuit, for example forming a first clamping circuit (321, 200) of the power supply unit (compliant with the international standard IEC 60079-11:2023-01), • wherein the protective circuit is (signal-technically) coupled, for example electrically connected, with its second control input to the control output of the second monitoring circuit, for example forming a second clamping circuit (322, 200) of the power supply unit (compliant with the international standard IEC 60079-11:2023-01), • and wherein the protection circuit is configured to operate in the second operating mode, for example to switch from the first operating mode to the second operating mode within less than 10 ms after the arrival of the error signal, when controlled by one or more of the error signals (of the first and second monitoring circuits) such that an error signal is present at at least one of the first and second control inputs.

[0007] Furthermore, the invention also consists in a measuring system formed by means of such a power supply, further comprising: • a measuring sensor which is designed to detect at least one, for example physical or chemical, measured variable and to convert it into at least one measuring signal (s1) representing the same measured variable; • and a (measuring transducer) circuit having, for example, at least one microprocessor (µC) and / or conforming to the international standard IEC 60079-11:2023-01, with a load input, with at least one signal input and with at least one (digital) signal output.

[0008] According to a first embodiment of the power supply unit of the invention, it is further provided that the first monitoring circuit is designed as a trigger circuit, for example, compliant with the international standard IEC 60079-11:2023-01, of a clamping circuit formed together with the protective circuit, for example, compliant with the international standard IEC 60079-11:2023-01.

[0009] According to a second embodiment of the power supply unit of the invention, it is further provided that the second monitoring circuit is designed as a trigger circuit, for example one that conforms to the international standard IEC 60079-11:2023-01, of a clamping circuit formed together with the protective circuit, for example one that conforms to the international standard IEC 60079-11:2023-01.

[0010] According to a third embodiment of the power supply unit of the invention, it is further provided that the load input of the first monitoring circuits is permanently electrically connected to their load output.

[0011] According to a fourth embodiment of the power supply of the invention, it is further provided that the load input of the second monitoring circuits is permanently electrically connected to their load output.

[0012] According to a fifth embodiment of the power supply of the invention, it is further provided that the first monitoring circuit is designed as a non-(re-)programmable and / or unchangeable hardware component (of the power supply).

[0013] According to a sixth embodiment of the power supply of the invention, it is further provided that the second monitoring circuit is designed as a non-(re-)programmable and / or unchangeable hardware component (of the power supply).

[0014] According to a seventh embodiment of the power supply unit of the invention, it is further provided that the protective circuit is set up to separate or keep separate its load input from its load output in a third operating mode, for example in such a way that even with an (input) voltage applied to its load input with an (over)voltage level of more than 1.5 V and less than 90 V (volts), at most a (leakage) current flow with a current intensity of at most 100 µA (microamperes) from the same load input to the load output is possible.

[0015] According to an eighth embodiment of the power supply of the invention, it is further provided that the supply circuit has at least one DC / DC converter.

[0016] According to a ninth embodiment of the power supply unit of the invention, it is further provided that the supply circuit has an isolation circuit, for example formed by means of a transformer and / or serving to form a galvanic decoupling within the supply circuit.

[0017] According to a tenth embodiment of the power supply of the invention, it is further provided that the protective circuit has an overcurrent protection device, for example designed as a fuse, and at least one controllable (electronic) switching element, for example formed by at least one thyristor and / or at least one symistor (triac). Further developing this embodiment of the invention, the overcurrent protection device is further configured to permanently carry at least the (useful) current (driven by the supply circuit), for example, namely at least one (fault) current driven by the supply circuit in the first operating mode with a current intensity that is higher than the (useful) current and / or more than 30 mA, at least in the first operating mode of the protective circuit.Alternatively or additionally, the overcurrent protection device can advantageously be further configured to interrupt a (short-circuit) current flowing through the overcurrent protection device in the second operating mode of the protective circuit, for example, more than 500 mA and / or less than 100 A, within a predetermined tripping time, for example such that the tripping time for a (short-circuit) current of more than 500 mA and / or less than 100 A is less than 100 ms (milliseconds).

[0018] According to an eleventh embodiment of the power supply of the invention, it is further provided that the protective circuit has at least one third control input.

[0019] According to a twelfth embodiment of the power supply of the invention, it is further provided that the supply circuit is configured, in a second operating mode, to provide the first (DC) voltage at the first load output as well as the second (DC) voltage at the second load output, such that the second (DC) voltage has a second (nominal) voltage level that differs from the first voltage level (in the first operating mode), for example by more than 0.05 V, for example constant and / or not less than 1.05 V, for example more than 0.05 V, greater than the first (nominal) voltage level. Further developing this embodiment of the invention, the supply circuit is further configured, in its second operating mode, to drive or supply a (usable) current flowing through the second load output, for example limited to a predetermined maximum (usable) current of 1 A or less.to control a (useful) energy flow passing through the second load output, for example limited to a predetermined maximum (useful) power of 30 W or less, for example in such a way that the (useful) energy flow passed in the second operating mode is limited to a second maximum (useful) power.Alternatively or additionally, the supply circuit can advantageously be configured to provide, in a third operating mode, both the first (DC) voltage at the first load output and the second (DC) voltage at the second load output, such that the second (DC) voltage has a third (nominal) voltage level which differs from the first and second voltage levels, for example by more than 0.05 V in each case, for example constant and / or not less than 1.1 V, for example namely more than 1 V greater than the first (nominal) voltage level and more than 0.05 V greater than the second (nominal) voltage level and / or the control circuit can advantageously be configured to output, in its second operating mode, at its third control output a control signal having a second control value activating the second operating mode of the supply circuit.

[0020] According to a thirteenth embodiment of the power supply of the invention, the supply circuit is configured to provide, in a second operating mode, both the first (DC) voltage at the first load output and the second (DC) voltage at the second load output, such that the second (DC) voltage has a second (nominal) voltage level that differs from the first voltage level (in the first operating mode), for example by more than 0.05 V, for example, constant and / or not less than 1.05 V, for example, namely more than 0.05 V, greater than the first (nominal) voltage level, and in a third operating mode, to provide, both the first (DC) voltage at the first load output and the second (DC) voltage at the second load output, such that the second (DC) voltage has a second (nominal) voltage level that differs from the first and second voltage levels, for example, by more than 0.05 V each, for example, constant and / or not less than 1,1 V, for example, more than 1 V, is greater than the first (nominal) voltage level and more than 0.05 V, is greater than the second (nominal) voltage level. Further developing this embodiment of the invention, the control circuit is configured to output a control signal with a third control value activating the third operating mode of the supply circuit at its third control output.

[0021] According to a fourteenth embodiment of the power supply unit of the invention, it is further provided that the supply circuit is configured to drive, in its first operating mode, a (useful) current flowing through the second load output, for example limited to a predetermined maximum (useful) current of 1 A or less, or to control a (useful) energy flow leading through the second load output, for example limited to a predetermined maximum (useful) power of 30 W or less, for example in such a way that the (useful) current flowing in the first operating mode is limited to a first maximum (useful) current and / or that the (useful) energy flow conducted in the first operating mode is limited to a first maximum (energy flow) power.

[0022] According to a fifteenth embodiment of the power supply unit of the invention, it is further provided that the supply circuit is configured to be electrically connected to an electrical energy source (external to the power supply unit) and to draw therefrom electrical (mains) power (required for the operation of the power supply unit), for example in an amount of more than 2 W (watts) and / or less than 50 W. Further developing this embodiment of the invention, the supply circuit is further configured to draw electrical (mains) power from the (connected) energy source and thus to at least partially, for example predominantly or completely, cover a respective (power) requirement (of the power supply unit) for electrical (useful) power, which can be adjusted, for example, during operation, for example, namely to drive the (useful) current (flowing through the second load output) or to effect the (useful) energy flow.

[0023] According to a sixteenth embodiment of the power supply unit of the invention, it is further provided that the supply circuit is configured to provide the first (DC) voltage at the first load output in a fourth operating mode, which is activated (automatically), for example, during commissioning, but no voltage at the second load output.

[0024] According to a seventeenth embodiment of the power supply of the invention, it is further provided that the supply circuit has a load input for a (for example, external and / or unregulated) (mains) voltage, which serves, for example, to electrically connect the supply circuit or the power supply formed thereby to an (external power supply) electrical energy source. Further developing this embodiment of the invention, the supply circuit is further configured to start automatically after the (mains) voltage is applied to the load input, for example, to start automatically in the fourth operating mode.

[0025] According to an eighteenth embodiment of the power supply of the invention, it is further provided that the first (energy flow) monitoring circuit has at least one second control output and is also configured to monitor the energy flow (through the first monitoring circuit) using a second (energy flow) parameter (different from the first energy flow parameter), namely to determine whether the second (energy flow) parameter has exceeded at least a second (energy flow) threshold value (of the first monitoring circuit), for example a predetermined (maximum) voltage level or a (maximum) current intensity, and if necessary to output an error signal signaling this to its second control output.Developing this embodiment of the invention, the protective circuit is coupled with its third control input to the second control output of the first monitoring circuit (in terms of signaling), for example electrically connected, and is also configured to operate in the second operating mode, controlled by one or more of the error signals (of the first and second monitoring circuits), such that an error signal is present at at least one of the first, second and third control inputs.

[0026] According to a first development of the invention, the power supply further comprises: a third selection circuit, for example structurally identical to the first selection circuit and / or electrically connected to the protection circuit in the same way as the first selection circuit, having a control input, a load input, and a load output; and a third (energy flow) monitoring circuit having at least one (first) control output, a load input, and a load output, for example serving for the electrical connection of an electrical load (external to the power supply).Advantageously, the third selection circuit can also be electrically connected with its load output to the load input of the third monitoring circuit, and the protection circuit can be electrically connected with its load output to the load input of the third selection circuit (forming a third fused supply path of the power supply unit, which, in addition to the supply circuit and the protection circuit, also at least partially involves the third selection circuit and the third monitoring circuit). Furthermore, the third selection circuit can advantageously be configured to electrically connect its load input to its load output in a first switching state.to keep it switched on in such a way that a current flow from the same load input to the same load output is possible and meanwhile a voltage (serving as the output voltage of the third selection circuit) is provided at the load output, for example depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the third selection circuit, and in a second switching state to electrically separate or keep separate its load input and its load output from one another, for example in such a way that even with an (input) voltage applied to its load input with an (over)voltage level of more than 1.5 V and less than 90 V (volts), a (leakage) current flow with a current intensity of at most 100 µA (microamperes) from the load input to its load output is possible.Furthermore, the third monitoring circuit can be set up to detect a current or voltage when the (input) voltage applied to its load input is non-interruptible or continuous, for example.to enable energy flow from its load input to its load output and, at the same time, to provide a voltage (serving as the output voltage of the power supply) at the load output which, for example, depends on a voltage level of an (input) voltage applied to the load input and / or a current strength of a (useful) current driven by the supply circuit through the third monitoring circuit, and to monitor the same energy flow (through the third monitoring circuit) on the basis of the at least one (energy flow) parameter, for example a voltage level of the (input) voltage applied to the load input and / or a current strength of the (useful) current driven by the supply circuit, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the third monitoring circuit), for example a predetermined (maximum) voltage level or a (maximum) current strength, and if necessaryto output an error signal signaling this at its (first) control output. In addition, the protection circuit can be (signal-wise) coupled, for example electrically connected, with its third control input to the control output of the third monitoring circuit, for example to form a third clamping circuit of the power supply (compliant with the international standard IEC 60079-11:2023-01), and can also be configured to operate in the second operating mode, for example, to switch from the first operating mode to the second operating mode within less than 10 ms of the arrival of the error signal, when controlled by one or more of the error signals (of the first, second, and third monitoring circuits) in such a way that an error signal is present at at least one of the first, second, and third control inputs.Alternatively or additionally, the control circuit in this (first) development of the invention can further comprise a fourth control output and thus be coupled (in terms of signaling) to the control input of the third selection circuit, for example, namely electrically connected, for example in order to output a selection signal activating the first switching state of the third selection circuit at its fourth control output in a third operating mode, for example, namely no selection signal at the first and second control outputs.

[0027] According to a second development of the invention, the power supply further comprises: a printed circuit board, which serves, for example, as a carrier for the supply circuit and / or the control circuit and / or the protection circuit and / or the first and second selection circuits and / or the first and second monitoring circuits. In one embodiment of the second development of the invention, the first and second selection circuits are arranged at least partially, for example entirely, on the printed circuit board and / or the first and second monitoring circuits are arranged at least partially, for example entirely, on the printed circuit board, for example also in such a way that the first and second selection circuits and the first and second monitoring circuits are arranged at least partially, for example entirely, on the printed circuit board.

[0028] According to a first embodiment of the measuring system of the invention, it is further provided that the load input of the (measuring transducer) circuit is electrically connected at least temporarily, for example permanently, to the load output of the first (energy flow) monitoring circuit, for example not to the load output of the second (energy flow) monitoring circuit, for example in such a way that when an (input) voltage is applied to the load input of the first (energy flow) monitoring circuit, for example with a voltage level of more than 1 V and / or less than 40 V, a current flow, for example with a current intensity of more than 100 mA (milliamperes) and / or less than 500 mA, from the load output of the first (energy flow) monitoring circuit to the load input of the (measuring transducer) circuit or an energy flow, for example more than 2000 Ws / h (watt-second per hour), from the power supply to the (measuring transducer) circuit is possible.Developing this embodiment of the invention further, it is further provided that (during operation of the measuring system) the first operating mode of the control circuit, thus the first operating mode of the supply circuit, the first switching state of the first selection circuit and the second switching state of the second selection circuit are activated, for example in such a way that a load circuit of the measuring system involving a current path leading from the load output of the supply circuit to the load input of the protection circuit, further via its load output to the first circuit input of the first selection circuit, further via its load output to the load input of the first (energy flow) monitoring circuit and further via its load output to the load input of the (measuring transducer) circuit is closed.

[0029] According to a second embodiment of the measuring system of the invention, it is further provided that the measuring sensor is electrically coupled to the (measuring transducer) circuit via the signal input and that the (measuring transducer) circuit is configured to receive and evaluate the at least one measuring signal, for example to determine measured values ​​quantifying the at least one measured variable on the basis of the measuring signal.

[0030] A basic idea of ​​the invention is to provide a (universal) power supply unit which can be parameterised with regard to the protection level implemented on the output side, if necessary also with regard to its (nominal) output voltage (even during final production and / or via firmware), and / or which has a protection functionality that can be flexibly adapted to different output voltage variants provided; this in particular in such a way that the protection functionality also easily ensures the intrinsic safety of the output voltage provided during operation and / or meets the intrinsic safety requirements of the international standard IEC 60079-11:2023-01, and can therefore also be used in potentially explosive atmospheres requiring one of the protection levels “ia”, “ib” or “ic” according to the aforementioned standard. This is achieved, among other things, by having a protection function in the power supply unit for each nominally provided protection level ora respective (output voltage) variant is provided with an independently protected supply path (each in compliance with the standard IEC 60079-11:2023-01), whereby the required protection functionality is an inseparable (hardware) component thereof, which is only switched on by activating the supply path actually required in each case (intrinsically, nevertheless appropriately) or, conversely, in the case of the supply paths not required in each case, remains or is deactivated solely by their non-activation.

[0031] One advantage of the invention is that the power supply can be produced cost-effectively and in large quantities (in stock) for a large number of different power supply variants (with respect to the respective output voltage to be provided). Furthermore, the power consumption can be reduced compared to the conventional (universal) power supplies mentioned above.

[0032] The invention and advantageous embodiments thereof are explained in more detail below using exemplary embodiments illustrated in the figures of the drawing. Identical or similarly acting or functioning parts are provided with the same reference numerals in all figures; where clarity requires it or it otherwise seems expedient, previously mentioned reference numerals are omitted in subsequent figures. Further advantageous embodiments or developments, in particular combinations of partial aspects of the invention initially explained only individually, will become apparent from the figures of the drawing and / or from the claims themselves.

[0033] In detail: Fig. 1 schematically shows, in the form of a block diagram, an embodiment of a (universal) power supply according to the invention; Fig. 2 schematically shows, in the form of a block diagram, another embodiment of a (universal) power supply according to the invention; and Fig. 3 a measuring system with a (universal) power supply according to the invention.

[0034] In the Fig. Figure 1 schematically shows an embodiment of a power supply according to the invention in the form of a block diagram. The power supply can, for example, be intended for use in an (industrial) measuring system, in particular in an (industrial) measuring system that complies with at least one of the protection levels "ia," "ib," or "ic" according to the international standard IEC 60079-11:2023-01 and / or is usable in a potentially explosive atmosphere, in order to supply (in addition to the power supply itself) further (sub)circuits of the same measuring system, for example, a measuring transducer circuit, with electrical energy during operation.

[0035] The power supply comprises a supply circuit 100, in particular a mains-fed and / or controllable supply circuit, having a (digital) control input 100.11, a first load output 100.41 and a second load output 100.42, as well as a control circuit 400, for example comprising at least one microprocessor (µC) and / or at least one (field-programmable) logic gate circuit (FPGA) and / or at least one application-specific integrated circuit (ASIC), with a supply input 400.31, a first control output 400.21, a second control output 400.22 and at least one (digital) third control output 400.23, for providing a control functionality (of the power supply). As in Fig. 1, the supply circuit 100 is electrically connected with its first load output 100.41 to the supply input 400.31 of the control circuit 400 in order to provide the electrical power required by the control circuit 400 during operation.

[0036] According to a further embodiment of the power supply unit of the invention, the supply circuit 100 is also provided or configured, among other things, to be electrically connected to an electrical energy source (external to the power supply unit) and to draw therefrom electrical (mains) power (required for the operation of the power supply unit), for example in an amount of more than 2 W (watts) and / or less than 50 W (watts) and / or with a time-varying or fluctuating voltage; this is particularly intended to convert the aforementioned electrical (mains) power drawn from an electrical energy source external to the power supply unit into a (useful) power internal to the power supply unit with a stabilized (useful) voltage and / or to thereby at least partially, in particular predominantly or completely, cover a respective (power) requirement (of the power supply unit) for electrical (useful) power, which can also be adapted, for example, during operation, for example, namely a load generated by the second load output 100.42 to drive the (useful) current (of the power supply) flowing through the second load output 100.42 or to effect a (useful) energy flow (of the power supply) through the second load output 100.42. Accordingly, the supply circuit 100 can advantageously further comprise a load input 100.31, which serves, for example, to electrically connect the supply circuit 100 or the power supply formed thereby to the aforementioned (power supply external) electrical energy source (NRG) and / or has electrical connection terminals for a (mains) voltage, for example an unregulated and / or (power supply) external (mains) voltage. Alternatively or additionally, the supply circuit 100 can further comprise one or more (internal) energy storage devices and / or be formed by means of one or more DC-DC converters (DC / DC converters); this can also be done, for example, in such a way that a wide mains voltage range can be used for supply, thus embodying the power supply as a wide-range power supply.According to a further embodiment of the power supply of the invention, the supply circuit 100 has an isolation circuit, for example formed by means of a transformer and / or serving to form a galvanic decoupling within the supply circuit 100.

[0037] The supply circuit 100 of the power supply according to the invention is further configured, in a first operating mode, to provide a first (DC) voltage (serving as the operating voltage of the control circuit) at its first load output 100.41 as well as a second (DC) voltage at its second load output 100.42, wherein the second (DC) voltage provided in the first operating mode has a first (nominal) voltage level, for example a constant or kept constant voltage level; this in particular in such a way that the first (nominal) voltage level is not less than 1 V.

[0038] Furthermore, according to a further embodiment of the power supply of the invention, the supply circuit is further configured to provide, in a second operating mode, both the first (DC) voltage at the first load output 100.41 and the second (DC) voltage at the second load output 100.42, such that the second (DC) voltage provided in the second operating mode has a second (nominal) voltage level that deviates from the first voltage level, for example by more than 0.05 V, in particular a constant or constant second (nominal) voltage level; this in particular also in such a way that the second (nominal) voltage level is more than 0.05 V, greater than the first (nominal) voltage level and / or not less than 1.05 V. Advantageously, the supply circuit 100 can also be configured in its aforementioned first operating mode and / or in its aforementioned second operating mode to supply a voltage flowing through the second load output, in particularto drive a (useful) current limited to a predetermined maximum (useful) current of 1 A (ampere) or less, or to control a (useful) energy flow leading through the second load output, for example limited to a predetermined maximum (useful) power of 30 W or less; this can also be done, for example, in such a way that the (useful) current flowing in the first operating mode is limited to a first maximum (useful) current and / or that the (useful) current flowing in the second operating mode is limited to a second maximum (useful) current. Alternatively or additionally, the (useful) energy flow conducted in the first operating mode can be limited to a first maximum (energy flow) power and / or the (useful) energy flow conducted in the second operating mode can be limited to a second maximum (useful) power.Alternatively or additionally, the supply circuit 100 can advantageously also be configured to start automatically after applying a voltage, for example the aforementioned mains voltage, to the aforementioned load input 100.31; this can also be done, for example, in such a way that the supply circuit 100, after applying the voltage, checks it for compliance with predetermined criteria (minimum and / or maximum permissible voltage level, stability, polarity or minimum and / or maximum permissible frequency, etc.) and only delivers the aforementioned (DC) voltage at the load output 100.41 by means of the voltage at the load input 100.31 if the criteria are met.

[0039] For the purpose of implementing a protective functionality (of the power supply), in particular one that also complies with the international standard IEC 60079-11:2023-01, the power supply according to the invention further comprises a protective circuit 200 with a load input 200.31, with a load output 200.41, with a first control input 200.11, and with at least one second control input 200.12, wherein the protective circuit 200 is electrically connected with its supply input 200.31 to the second load output 100.42 of the supply circuit 100. Furthermore, the power supply unit (serving the implementation of the protection functionality) comprises first and second, for example identical, selection circuits (311, 312), each with a load input (311.31, 312.31), each with a load output (311.41, 312.41), and each with a control input (311.11, 312.11) as well as first and second (energy flow) monitoring circuits (321, 322), each with a load input (321.31, 322.31), each with a, in particularA load output (321.41, 322.41) serving to electrically connect an electrical load (circuit) (external to the power supply) and having at least one (first) control output (321.21, 322.21), optionally also two or more control outputs. According to a further embodiment of the power supply of the invention, the load input 321.31 of the first monitoring circuits 321 is permanently electrically connected to their load output 321.41 and / or the load input 322.31 of the second monitoring circuits 322 is permanently electrically connected to their load output 322.41.Not least for the purpose of providing a (universal) power supply unit that can be used in a potentially explosive atmosphere and / or a protective functionality of the power supply unit that corresponds to one or more of the protection levels “ia”, “ib” or “ic” according to the international standard IEC 60079-11:2023-01, each of the monitoring circuits of the power supply unit is advantageously designed, according to a further embodiment of the invention, as an immutable or non-(re-)programmable hardware component of the power supply unit according to the invention.

[0040] As in Fig. 1, the first selection circuit 311 is electrically connected with its load output 311.41 to the load input 321.31 of the first monitoring circuit 321, and the second selection circuit 312 is electrically connected with its load output 312.41 to the load input 322.31 of the second monitoring circuit 322. The protection circuit 200, in turn, is further coupled (signal-wise) with its first control input 200.11 to the control output 321.21 of the first monitoring circuit 321 and with its second control input 200.12 to the control output 322.21 of the second monitoring circuit 322, for example, electrically and / or opto-electrically connected. Furthermore, the protection circuit 200 is connected with its load output 200.41 (forming a first fused supply path of the power supply unit, which in addition to the supply circuit 100 and the protection circuit 200 also includes the first selection circuit 311 and the first monitoring circuit 321, each at least partially involving) both to the load input 311.31 of the first selection circuit 311 and (forming a second fused supply path of the power supply unit, which in addition to the supply circuit 100 and the protection circuit 200 also includes the second selection circuit 312 and the second monitoring circuit 322, each at least partially involving) to the load input 312.31 of the second selection circuit 312. In addition, the control circuit 400 is connected with its first control output 400.21 to the control input 311.11 of the first selection circuit 311, with its second control output 400.22 to the control input 312.11 of the second selection circuit 312 and with its third control output 400.23 to the control input 100.11 of the supply circuit 100 (signal-wise), in particular, electrically connected. In addition to the aforementioned first and second control inputs, the protection circuit 200 may also have additional control inputs, for example, to connect any additional control outputs of the first and / or second monitoring circuits and / or any additional monitoring circuits (of the power supply).

[0041] The protective circuit 200 of the power supply according to the invention is further configured, in a first operating mode, to electrically connect or keep connected its load input 200.31 to its load output 200.41, such that a current flow from said load input 200.31 to said load output 200.41 is enabled, and meanwhile, at the load output 200.41, an (output) voltage (of the protective circuit) is provided, in particular depending on a voltage level of an (input) voltage applied to the load input 200.31 - here namely the aforementioned second (DC) voltage - and / or a current intensity of a (useful) current driven by the supply circuit 100 through the protective circuit 200, for example by applying the aforementioned second (DC) voltage at the load output 100.42 of the supply circuit 100 (directly) to the Load output 200.41 of the protection circuit is switched through.

[0042] Not least for the purpose of implementing the aforementioned protective functionality, the protective circuit 200 of the power supply according to the invention is further configured to short-circuit the load input 200.31 or the load output 100.42 of the supply circuit 100 connected thereto in a second operating mode (alternative to the aforementioned first operating mode); this is done in particular in such a way that a (short-circuit) current driven by the supply circuit 100 is allowed to flow through the protective circuit 200 and at most an (error) voltage of less than 0.5 V is present at the load output 200.41 (of the protective circuit 200).

[0043] In addition, each of the first and second selection circuits (311, 321) of the power supply according to the invention, which are electrically connected to the protective circuit 200 in the manner described above, is in turn configured to electrically connect or keep connected the respective load input (311.31, 312.31) to the respective associated load output (311.41, 312.41) in a respective first switching state, such that a current flow from the said load input (311.31, 312.31) to the said load output (311.41, 312.41) is enabled and, meanwhile, at the respective load output (311.41, 312.41), in particular of a voltage level of an (input) voltage applied to the respective load input (311.31, 312.31) - here namely the aforementioned (output) voltage of the protective circuit - and / or a current intensity of a (useful) current driven by the supply circuit through the respective selection circuit dependent output voltage is provided.Furthermore, each of the first and second selection circuits (311, 312) of the power supply according to the invention is each configured to electrically separate or keep separate the respective load input and the respective load output (of the respective selection circuit) from one another in a respective second switching state; this in particular in such a way that even with an (input) voltage applied to the respective load input with an (over)voltage level of more than 1.5 V and less than 90 V (volts), at most a (leakage) current flow with a current intensity of at most 100 µA (microamperes) from the respective load input to the respective load output is possible.

[0044] In order to enable selective activation of one of the aforementioned protected supply paths of the power supply, the control circuit 400 of the power supply according to the invention is in turn configured to output, in a first operating mode, at its first control output a selection signal activating the first switching state of the first selection circuit, in particular no selection signal (activating the first switching state of the second selection circuit) at the second control output, and to output, at its third control output, a control signal with a first control value activating the first operating mode of the supply circuit. In addition, the control circuit is further configured to output, in a second operating mode, at its second control output a selection signal activating the first switching state of the second selection circuit, in particular no selection signal (activating the first switching state of the second selection circuit).namely, not to output a selection signal (activating the first switching state of the first selection circuit) at the first control output, and to output a control signal with a second control value activating the second operating mode of the supply circuit at its third control output.

[0045] Not least for the purpose of realizing or executing the aforementioned protective functionality, each of the first and second monitoring circuits of the power supply according to the invention is further configured to enable a current or energy flow from the said load input to the respectively associated load output when an (input) voltage is applied to its respective load input, in particular an uninterruptible or continuous voltage, and to meanwhile provide a voltage at the respective load output (which voltage is dependent in particular on a voltage level of an (input) voltage applied to the associated load input and / or a current intensity of a (useful) current driven by the supply circuit through the respective monitoring circuit) (each serving as an output voltage of the power supply). Furthermore, each of the first and second monitoring circuits is configured to enable the same energy flow (through the first orsecond monitoring circuit) based on at least one (energy flow) parameter, for example a voltage level of the (input) voltage applied to the respective load input and / or a current strength of the (useful) current driven by the supply circuit, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (specific to the first monitoring circuit) first (energy flow) threshold value, in particular a predetermined (maximum) voltage level or a (maximum) current strength, and if necessary to output an error signal signaling this, for example in the form of a binary (switching) signal, at its (first) control output or to determine whether the at least one (energy flow) parameter has exceeded at least one (specific to the second monitoring circuit) second (energy flow) threshold value, in particular a predetermined (maximum) voltage level or a (maximum) current strength, and if necessaryto output an error signal signaling this, for example, embodied as a binary (switching) signal and / or of the same type as the error signal of the first monitoring circuit, to its (first) control output. Furthermore, the protection circuit is configured to operate in the second operating mode, controlled by one or more of the error signals (of the first and second monitoring circuits) such that an error signal is present at at least one of the first and second control inputs, in particular to switch from the first operating mode to the second operating mode within less than 10 ms after the arrival of the error signal.

[0046] In addition, one or more of the monitoring circuits of the power supply can also be configured to monitor the energy flow (through the respective monitoring circuit) based on at least one or more further (energy flow) parameters (different from the aforementioned energy flow parameter), namely to determine whether one of the (energy flow) parameters has exceeded at least one (energy flow) threshold value (of the respective monitoring circuit) and, if necessary, to output an error signal signaling this at a corresponding further control output (of the respective monitoring circuit). Accordingly, the protection circuit 200 can advantageously also have at least one third control input 200.13 or further suitable control inputs and can also be configured to be controlled by one or more of the aforementioned error signals (of one or more of the monitoring circuits) in such a way that at least one of the control inputs (200.11, 200.12, 200.13,...) is present, to switch from the first operating mode to the second operating mode. Alternatively or additionally, the protection circuit and / or one or more of the monitoring circuits can each be designed redundantly.

[0047] According to a further embodiment of the power supply of the invention, the protective circuit 200 together with the first monitoring circuit 321 forms a first clamping circuit (321+200) of the power supply and / or the protective circuit 200 together with the second monitoring circuit 322 forms a second clamping circuit (322+200) of the power supply; this in particular also in such a way that the first clamping circuit (321+200) and / or the second clamping circuit (322+200) conform to the aforementioned international standard IEC 60079-11:2023-01, for example, namely correspond to one or more of the protection levels "ia", "ic" or "ic" according to IEC 60079-11:2023-01. According to a further embodiment of the power supply unit of the invention, the first monitoring circuit 321 is designed as a trigger circuit of the aforementioned first clamping circuit, in particular one that conforms to the international standard IEC 60079-11:2023-01, or the second monitoring circuit 322 is designed as a trigger circuit, in particular one that conforms to the international standard IEC 60079-11:2023-01.The trigger circuit of the aforementioned second clamping circuit is also designed to comply with the international standard IEC 60079-11:2023-01. Not least for the purpose of implementing first and second clamping circuits that comply with IEC 60079-11:2023-01, the protective circuit 200 is further configured, according to a further embodiment of the power supply of the invention, to disconnect or keep disconnected its load input 200.31 from its load output 200.41 in a third operating mode (chronologically following the second operating mode). This is particularly the case in such a way that even with an (input) voltage applied to the load input 200.31 with an (over)voltage level of more than 1.5 V and less than 90 V (volts), a (leakage) current flow with a current strength of at most 100 µA (microamperes) from the load input 200.31 to the load output 200.41 is possible.For this purpose, according to a further embodiment of the power supply unit of the invention, the protective circuit 200 further comprises an overcurrent protection device, for example designed as a fuse, and at least one controllable (electronic) switching element, in particular formed by at least one thyristor and / or at least one symistor (triac). Advantageously, the overcurrent protection device is further configured to permanently carry at least the (useful) current (driven by the supply circuit), in particular namely at least one (fault) current driven by the supply circuit in the first operating mode with a current intensity that is higher than the (useful) current and / or more than 30 mA, at least in the first operating mode of the protective circuit, and / or the overcurrent protection device is further configured to permanently carry a current allowed to flow through the overcurrent protection device in the second operating mode of the protective circuit, in particularto safely interrupt a (short-circuit) current of more than 500 mA and / or less than 100 A within a specified tripping time, in particular in such a way that the tripping time for a (short-circuit) current of more than 500 mA (milliamperes) and / or less than 100 A is less than 100 ms (milliseconds).

[0048] According to a further embodiment of the power supply of the invention, the first (energy flow) monitoring circuit 321 has at least one second control output 321.22, and the first (energy flow) monitoring circuit 321 is further configured to monitor the energy flow (through the first monitoring circuit) based on a second (energy flow) parameter (different from the first energy flow parameter), namely to determine whether the second (energy flow) parameter has exceeded at least a second (energy flow) threshold value (of the first monitoring circuit), for example, a predetermined (maximum) voltage level or a (maximum) current intensity, and, if necessary, to output a (binary) error signal signaling this to its second control output. Furthermore, the protection circuit 200 can be connected to the second control output 321, for example, via its aforementioned third control input 200.13.22 of the monitoring circuit 321 (signal-wise), for example, electrically connected. Furthermore, each of the monitoring circuits of the power supply can be configured to monitor two or more (energy flow) parameters or each have two or more corresponding control outputs.

[0049] The power supply unit according to the invention can advantageously also be designed as a universal power supply unit, in particular one that conforms to the international standard IEC 60079-11:2023-01, such that it has or provides a total of three or more supply paths, each (permanently) protected, but nevertheless selectively activatable (by means of the control circuit 400), with different voltage levels.

[0050] According to a further development of the invention, the power supply comprises, as in Fig. 2 schematically shown, accordingly furthermore at least one - for example identical in construction to the first and / or second selection circuit (311, 312) - third selection circuit 313 with a load input 313.31, with a load output 313.41 and with a control input 313.11, as well as a third (energy flow) monitoring circuit 323 - for example designed as an unchangeable or non-(re-)programmable hardware component of the power supply according to the invention - with a load input 323.31, with a load output 323.41 (serving the electrical connection of an electrical load external to the power supply) and with at least one (first) control output 323.21. The third selection circuit 313 is also electrically connected with its load output 313.41 to the load input 323.31 of the third monitoring circuit 323, and the protection circuit 200 is in turn connected with its load output 200.41 to the load input 313.31 of the third selection circuit 313 (forming a third fused supply path of the power supply, which, in addition to the supply circuit and the protection circuit, also at least partially involves the third selection circuit and the third monitoring circuit). The third selection circuit 313 is also configured, in a first switching state, to electrically connect or keep connected its load input 313.31 to its load output 313.41, such that a current flow from the said load input 313.31 to the said load output 313.41 is enabled, and meanwhile, a third output voltage of the power supply is provided at the load output 313.41, in particular depending on a voltage level of an (input) voltage applied to the load input 313.31 and / or a current intensity of a (useful) current driven by the supply circuit 100 through the third selection circuit 313.in a second switching state, to electrically separate or keep separate their load input and their load output from each other, in particular in such a way that even with an (input) voltage applied to their load input 313.31 with an (over)voltage level of more than 1.5 V and less than 90 V (volts), a (leakage) current flow with a current strength of at most 100 µA (microamperes) from the load input 313.31 to their load output 313.41 is possible.

[0051] Furthermore, in this development of the power supply according to the invention, the supply circuit 100 is also configured, in a third operating mode, to provide the first (DC) voltage at the first load output 100.41 as well as the second (DC) voltage at the second load output 100.42, such that the second (DC) voltage has a third (nominal) voltage level which deviates from the first and second voltage levels, in particular by more than 0.05 V in each case, in particular is constant and / or not less than 1.1 V, in particular more than 1 V greater than the first (nominal) voltage level and more than 0.05 V greater than the second (nominal) voltage level. To control the third selection circuit 313 or to activate the third operating mode of the supply circuit 100, the control circuit 400 further has a fourth control output 400.24 and the control circuit 400 is connected to the control input 313 with the fourth control output 400.24.11 of the third selection circuit 313 (signal-wise), in particular, electrically connected. Furthermore, the control circuit 400 is configured, in a third operating mode, to output a selection signal activating the first switching state of the third selection circuit 313 at its fourth control output 400.24, in particular, no selection signal at the first and second control outputs, and a control signal with a third control value activating the third operating mode of the supply circuit 100 at its third control output 400.23.

[0052] Not least for the purpose of realizing the aforementioned protection functionality also in the Fig. In the further development of the power supply shown in Figure 2, the third monitoring circuit is also further configured to enable a current or energy flow from its load input to its load output when an (input) voltage is applied to its load input, in particular an uninterruptible or uninterrupted voltage, and to monitor the same energy flow based on at least one (energy flow) parameter, in particular a voltage level of the (input) voltage applied to the load input and / or a current intensity of the (useful) current driven by the supply circuit, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the third monitoring circuit), in particular a predetermined (maximum) voltage level or a (maximum) current intensity, and if necessary to output an error signal signaling this to its (first) control output.In addition, the protective circuit accordingly has a third control input, and the protective circuit is (signal-technically) coupled, in particular electrically connected, to the control output of the third monitoring circuit via the third control input, in particular to form a third clamping circuit of the power supply (compliant with the international standard IEC 60079-11:2023-01). Furthermore, the protective circuit is configured to operate in the second operating mode or to switch from the first operating mode to the second operating mode in the manner described above, controlled by one or more of the error signals (of the first, second, and third monitoring circuits) such that an error signal is present at at least one of the first, second, and third control inputs.

[0053] According to a further embodiment of the power supply unit of the invention, the supply circuit is further configured to provide the first (DC) voltage at the first load output in a fourth operating mode, which can be activated (automatically), for example, during commissioning, but no voltage at the second load output. The fourth operating mode of the supply circuit 100 can be activated, for example, in that the supply circuit 100, as already mentioned, is configured to start up automatically in the fourth operating mode after a (mains) voltage is applied to its aforementioned load input 100.31, and in that (during commissioning of the power supply unit) an external voltage is applied to the load input 100.31, for example, via a connecting cable electrically connected to the aforementioned load input 100.31. A later activation of one of the aforementioned first, second orThe third operating mode can then be activated, for example, by a start command transmitted to the control circuit 400 (externally) and / or program- or time-controlled by the control circuit 400 itself.

[0054] According to a further embodiment of the power supply unit of the invention, the power supply unit further comprises at least one printed circuit board, which serves in particular as a (circuit) carrier for the supply circuit and / or the control circuit and / or the protection circuit and / or the first and second selection circuits and / or the first and second monitoring circuits. Advantageously, for example, the first and second selection circuits (311, 312,...) can be arranged at least partially, in particular entirely, on the printed circuit board and / or the first and second monitoring circuits (321, 322,...) can be arranged at least partially, in particular entirely, on the printed circuit board; this is advantageously also in such a way that all of the aforementioned selection circuits (311, 312, 313,...) and all of the aforementioned monitoring circuits (321, 322, 323,...) are at least partially, in particular entirely,are arranged entirely on the circuit board, for example together with the supply circuit 100 and / or the control circuit 400 and / or the protection circuit 200.

[0055] As already mentioned, the power supply according to the invention can also be used advantageously to supply energy to an example of Fig. 3 (compliant with the international standard IEC 60079-11:2023-01). Accordingly, according to a further embodiment of the power supply of the invention, the power supply is designed as a (circuit) component of an (industrial) measuring system, in particular an industrial measuring system that corresponds to at least one of the protection levels "ia", "ib" or "ic" according to IEC 60079-11:2023-01 and / or can be used in an explosion-hazardous industrial measuring system, in particular as a (circuit) component that serves to supply further (sub-)circuits or (circuit) components of the same measuring system with electrical energy.

[0056] The Fig. The (industrial) measuring system schematically illustrated in Figure 3 comprises a measuring sensor MA and a (measuring transducer) circuit MU, for example having at least one microprocessor (µC), with a load input MU.31, with at least one signal input (s1) and with at least one (digital) signal output d1. The measuring sensor MA is designed to detect (during operation of the measuring system) at least one, for example physical or chemical, measured variable and to convert it into at least one measurement signal s1 representing the same measured variable. Furthermore, the measuring sensor MA is electrically coupled to the (measuring transducer) circuit via the signal input and the (measuring transducer) circuit MU is designed to receive and evaluate the at least one measurement signal s1, for example to determine measured values ​​quantifying the at least one measured variable based on the measurement signal s1.

[0057] In Fig.3, the load input MU.31 of the (measuring transducer) circuit MU is electrically connected at least temporarily, in particular permanently, to the load output 321.41 of the first (energy flow) monitoring circuit; this is done in particular in such a way that the load input MU.31 of the (measuring transducer) circuit is electrically connected to the load output 321.41 of the first (energy flow) monitoring circuit 321, but at the same time is not electrically connected to the load output 322.41 of the second (energy flow) monitoring circuit 322 or not to a load input of any further (energy flow) monitoring circuits of the power supply. According to a further embodiment of the power supply unit of the invention, it is further provided that when an (input) voltage is applied to the load input 321.31 of the first (energy flow) monitoring circuit 321, in particular with a voltage level of more than 1 V and / or less than 40 V, a current flow, in particularwith a current of more than 100 mA (milliamperes) and / or less than 500 mA, from the load output of the first (energy flow) monitoring circuit 321 to the load input MU.31 of the (measuring transducer) circuit, or an energy flow from the power supply to the (measuring transducer) circuit, in particular more than 2000 Ws / h (watt-second per hour), is enabled or takes place. Accordingly, according to a further embodiment of the power supply of the invention, it is provided that during (normal) operation of the power supply orof the measuring system formed thereby, the first operating mode of the control circuit 400, thus the first operating mode of the supply circuit 100 as well as the first switching state of the first selection circuit 311 and the second switching state of the second selection circuit 312 are activated; this in particular in such a way that a load circuit of the measuring system involving a current path leading from the load output of the supply circuit 100 to the load input of the protection circuit 200, further via its load output to the first circuit input of the first selection circuit 311, further via its load output to the load input of the first (energy flow) monitoring circuit 321 and further via its load output to the load input of the (measurement transducer) circuit MU is closed orthat no (further) load circuit of the measuring system is formed which involves a current path leading from the load output of the supply circuit 100 to the load input of the protection circuit 200, further via its load output to the first circuit input of the second selection circuit 312, further via its load output to the load input of the second (energy flow) monitoring circuit 322 and further via its load output to the load input of the (measuring transducer) circuit MU. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO-A 2018 / 215215

[0002] CA-A 982 228 [0003, 0004] Cited non-patent literature

[0000] international standard IEC 60079-11:2023-01

[0004]

Claims

[1] Power supply, in particular power supply for an (industrial) measuring system and / or (wide-range) universal power supply, which power supply includes: - a supply circuit (100), in particular formed by one or more DC-DC converters and / or fed by one or more energy storage devices and / or fed by the mains and / or controllable -- with a (digital) control input (100.11), -- with a first load output (100.41) -- and with a second load output (100.42); - a protective circuit (200) -- with a first control input (200.11), -- with at least one second control input (200.12), -- with one load input (200.31), -- and with a load output (200.41); - a first selection circuit (311) -- with one control input (311.11), -- with one load input (311.31), -- and with a load output (311.41); - a second selection circuit (312), in particular identical in construction to the first selection circuit -- with one control input (312.11), -- with one load input (312.31), -- and with a load output (312.41); - a first (energy flow) monitoring circuit (321) -- with at least one (first) control output (321.21), -- with one load input (321.31), -- and with a load output (321.41), particularly useful for the electrical connection of an electrical load (external to the power supply unit); - a second (energy flow) monitoring circuit (322) -- with at least one (first) control output (322.21), -- with one load input (322.31), -- and with a load output (322.41), particularly useful for the electrical connection of a (power supply external) (consumer) circuit; - and a control circuit (400), in particular comprising at least one microprocessor (µC) and / or at least one (field-programmable) logic gate circuit (FPGA) and / or at least one application-specific integrated circuit (ASIC) -- with a first control output (400.21), -- with a second control output (400.22), -- with at least one (digital) third control output (400.23), -- and with a supply input (400.31); - wherein the supply circuit (100) is electrically connected with its first load output (100.41) to the supply input (400.31) of the control circuit and with its second load output (100.42) to the load input (200.31) of the protection circuit; - wherein the first selection circuit is electrically connected with its load output (311.41) to the load input (321.31) of the first monitoring circuit and the second selection circuit is electrically connected with its load output (312.41) to the load input (322.31) of the second monitoring circuit; - wherein the protective circuit (200) is electrically connected with its load output (200.41) both to the load input (311.31) of the first selection circuit (forming a first fused supply path of the power supply unit which, in addition to the supply circuit and the protective circuit, also includes the first selection circuit and the first monitoring circuit) and to the load input (312.31) of the second selection circuit (forming a second fused supply path of the power supply unit which, in addition to the supply circuit and the protective circuit, also includes the second selection circuit and the second monitoring circuit); - and wherein the control circuit (400) is (signal-technically) coupled, in particular electrically connected, with its first control output (400.21) to the control input (311.11) of the first selection circuit, with its second control output (400.22) to the control input (312.11) of the second selection circuit, and with its third control output (400.23) to the control input (100.11) of the supply circuit; - wherein the supply circuit (100) is configured, in a first operating mode, to provide a first (DC) voltage (serving as the operating voltage of the control circuit) at the first load output (100.41) and a second (DC) voltage at the second load output (100.42), such that the second (DC) voltage has a first (nominal) voltage level, in particular a constant and / or not less than 1 V; - wherein the first selection circuit is configured to electrically connect or keep connected its load input to its load output in a first switching state, such that a current flow from the said load input to the said load output is possible and, meanwhile, a voltage (serving as the output voltage of the first selection circuit) is provided at the load output, in particular depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the first selection circuit, - wherein the second selection circuit is configured to electrically connect or keep connected its load input to its load output in a first switching state, such that a current flow from the said load input to the said load output is possible and, meanwhile, a voltage (serving as the output voltage of the second selection circuit) is provided at the load output, in particular depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the second selection circuit, - and wherein each of the first and second selection circuits is each configured to electrically separate or keep separate the respective load input and the respective load output (of the respective selection circuit) from one another in a respective second switching state, in particular in such a way that even with an (input) voltage applied to the respective load input with an (over)voltage level of more than 1.5 V and less than 90 V (volts), a (leakage) current flow with a current intensity of at most 100 µA (microamperes) from the respective load input to the respective load output is possible; - wherein the control circuit (400) is configured to operate in a first operating mode -- at its first control output a selection signal activating the first switching state of the first selection circuit, in particular no selection signal (activating the first switching state of the second selection circuit) at the second control output, -- and to output a control signal with a first control value activating the first operating mode of the supply circuit (100) at its third control output - and wherein the control circuit (400) is arranged to operate in a second operating mode -- to output a selection signal activating the first switching state of the second selection circuit at its second control output, in particular no selection signal (activating the first switching state of the first selection circuit) at the first control output; - wherein the first monitoring circuit (321) is configured to enable a current or energy flow from the load input to the load output (321.41) thereof when an (input) voltage is applied to the load input (321.31), in particular an uninterruptible or uninterrupted voltage, and meanwhile to provide a voltage (serving as the output voltage of the power supply) at the load output, in particular depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the first monitoring circuit, - and wherein the first monitoring circuit (321) is configured to monitor the energy flow (through the first monitoring circuit) based on at least one (energy flow) parameter, in particular a voltage level of the (input) voltage applied to the load input and / or a current intensity of the (useful) current driven by the supply circuit, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the first monitoring circuit), in particular a predetermined first (maximum) voltage level or a predetermined first (maximum) current intensity, and, if necessary, to output an error signal signaling this, in particular designed as a binary (switching) signal, to its (first) control output (321.21); - wherein the second monitoring circuit (322) is configured to enable a current or energy flow from the load input to the load output (322.41) thereof when an (input) voltage is applied to the load input (322.31), in particular an uninterruptible or uninterrupted voltage, and meanwhile to provide a voltage (serving as the output voltage of the power supply) at the load output, in particular depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the second monitoring circuit, - and wherein the second monitoring circuit (322) is configured to monitor the energy flow (through the second monitoring circuit) based on the at least one (energy flow) parameter, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the second monitoring circuit), in particular a predetermined second (maximum) voltage level or a predetermined second (maximum) current intensity, and, if appropriate, to output an error signal signaling this, in particular in the form of a binary (switching) signal, to its (first) control output (322.21); - wherein the protective circuit is configured, in a first operating mode, to electrically connect or keep connected its load input to its load output in such a way that a current flow from said load input to said load output is possible, and meanwhile, an (output) voltage (of the protective circuit) is provided at the load output, in particular dependent on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the protective circuit, in particular in such a way that the (DC) voltage at the load output of the supply circuit is connected to the load output of the protective circuit, - and wherein the protective circuit is configured to short-circuit the load input or the load output of the supply circuit connected thereto in a second operating mode, in particular in such a way that a (short-circuit) current driven by the supply circuit is allowed to flow through the protective circuit and at the load output (of the protective circuit) there is at most a (fault) voltage of not more than 0.5 V; - wherein the protective circuit (200) is (signal-technically) coupled, in particular electrically connected, with its first control input to the control output of the first monitoring circuit, in particular forming a first clamping circuit (321, 200) of the power supply unit (compliant with the international standard IEC 60079-11:2023-01), - wherein the protective circuit (200) is (signal-wise) coupled, in particular electrically connected, with its second control input to the control output of the second monitoring circuit, in particular forming a second clamping circuit (322, 200) of the power supply unit (compliant with the international standard IEC 60079-11:2023-01), - and wherein the protection circuit (200) is configured to operate in the second operating mode, in particular to switch from the first operating mode to the second operating mode within less than 10 ms after the arrival of the error signal, when controlled by one or more of the error signals (of the first and second monitoring circuits) such that an error signal is present at at least one of the first and second control inputs. [2] Power supply according to one of the preceding claims, - wherein the first monitoring circuit is designed as a trigger circuit, in particular one compliant with the international standard IEC 60079-11:2023-01, of a clamping circuit formed together with the protective circuit, in particular one compliant with the international standard IEC 60079-11:2023-01; and / or - wherein the second monitoring circuit is designed as a trigger circuit, in particular one compliant with the international standard IEC 60079-11:2023-01, of a clamping circuit formed together with the protective circuit, in particular one compliant with the international standard IEC 60079-11:2023-01; and / or - wherein the load input of the first monitoring circuits is permanently electrically connected to their load output; and / or - wherein the load input of the second monitoring circuits is permanently electrically connected to their load output; and / or - wherein the first monitoring circuit is designed as an unchangeable and / or non-(re-)programmable hardware component (of the power supply); and / or - wherein the second monitoring circuit is designed as an unchangeable and / or non-(re-)programmable hardware component (of the power supply). [3] Power supply according to one of the preceding claims, wherein the protective circuit is arranged to separate or keep separate its load input from its load output in a third operating mode, in particular in such a way that even with an (input) voltage applied to its load input (200.31) with an (over)voltage level of more than 1.5 V and less than 90 V (volts), at most a (leakage) current flow with a current intensity of at most 100 µA (microamperes) from the same load input (200.31) to the load output (200.41) is possible. [4] Power supply according to one of the preceding claims, - wherein the supply circuit (100) comprises at least one DC / DC converter; and / or - wherein the supply circuit (100) has an isolation circuit, in particular formed by means of a transformer and / or serving to form a galvanic decoupling within the supply circuit. [5] Power supply according to one of the preceding claims, wherein the protective circuit comprises an overcurrent protection device, in particular designed as a fuse, and at least one controllable (electronic) switching element, in particular formed by at least one thyristor and / or at least one symistor (triac). [6] Power supply according to claim 5, - wherein the overcurrent protection device is designed to permanently bear at least the (useful) current (driven by the supply circuit), in particular at least one (fault) current driven by the supply circuit in the first operating mode with a current intensity that is higher than the (useful) current and / or more than 30 mA, at least in the first operating mode of the protection circuit; and / or - wherein the overcurrent protection device is configured to interrupt a (short-circuit) current flowing through the overcurrent protection device in the second operating mode of the protective circuit, in particular a current of more than 500 mA and / or less than 100 A, within a predetermined tripping time, in particular such that the tripping time for a (short-circuit) current of more than 500 mA and / or less than 100 A is less than 100 ms (milliseconds). [7] Power supply according to one of the preceding claims, wherein the protection circuit (200) has at least one third control input (200.13). [8] Power supply according to one of the preceding claims, further comprising: - a third selection circuit (313), in particular identical in construction to the first selection circuit -- with one control input (313.11), -- with one load input (313.31), -- and with a load output (313.41); - and a third (energy flow) monitoring circuit (323) -- with at least one (first) control output (323.21), -- with one load input (323.31) -- and with a load output (323.41), particularly useful for the electrical connection of an electrical load (external to the power supply unit). [9] Power supply according to the previous claim, - wherein the third selection circuit is electrically connected with its load output (313.41) to the load input (323.31) of the third monitoring circuit, - and wherein the protective circuit is electrically connected with its load output (200.41) to the load input (313.31) of the third selection circuit (forming a third protected supply path of the power supply unit which, in addition to the supply circuit and the protective circuit, also at least partially involves the third selection circuit and the third monitoring circuit). [10] Power supply according to the previous claim, - wherein the third selection circuit is configured to electrically connect or keep connected its load input to its load output in a first switching state, such that a current flow from the said load input to the said load output is possible and, meanwhile, a voltage (serving as the output voltage of the third selection circuit) is provided at the load output, in particular depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the third selection circuit, - and wherein the third selection circuit is configured to electrically separate or keep separate its load input and its load output from one another in a second switching state, in particular in such a way that even with an (input) voltage applied to its load input with an (over)voltage level of more than 1.5 V and less than 90 V (volts), a (leakage) current flow with a current intensity of at most 100 µA (microamperes) from the load input to its load output is possible. [11] Power supply according to the previous claim, - wherein the third monitoring circuit (323) is configured to enable a current or energy flow from the load input to the load output when an (input) voltage is applied to the load input thereof, in particular a non-interruptible or uninterrupted flow, and meanwhile to provide a voltage (serving as the output voltage of the power supply) at the load output, in particular depending on a voltage level of an (input) voltage applied to the load input and / or a current intensity of a (useful) current driven by the supply circuit through the third monitoring circuit, -- and wherein the third monitoring circuit (323) is configured to monitor the said energy flow (through the third monitoring circuit) on the basis of the at least one (energy flow) parameter, in particular a voltage level of the (input) voltage applied to the load input and / or a current intensity of the (useful) current driven by the supply circuit, namely to determine whether the at least one (energy flow) parameter has exceeded at least one (energy flow) threshold value (of the third monitoring circuit), in particular a predetermined (maximum) voltage level or a (maximum) current intensity, and, if appropriate, to output an error signal signaling this to its (first) control output. [12] Power supply according to the previous claim, - wherein the protective circuit (200) is (signal-technically) coupled, in particular electrically connected, with its third control input (200.13) to the control output (323.21) of the third monitoring circuit, in particular forming a third clamping circuit (323, 200) of the power supply unit (compliant with the international standard IEC 60079-11:2023-01), - and wherein the protection circuit (200) is configured to operate in the second operating mode, in particular to switch from the first operating mode to the second operating mode within less than 10 ms after the arrival of the error signal, when controlled by one or more of the error signals (of the first, second and third monitoring circuits) such that an error signal is present at at least one of the first, second and third control inputs. [13] Power supply according to one of claims 7 to 11, - wherein the first (energy flow) monitoring circuit (321) has at least one second control output (321.22); - and wherein the first (energy flow) monitoring circuit (321) is configured to monitor the energy flow (through the first monitoring circuit) also on the basis of a second (energy flow) parameter (different from the first energy flow parameter), namely to determine whether the second (energy flow) parameter has exceeded at least a second (energy flow) threshold value (of the first monitoring circuit), in particular a predetermined (maximum) voltage level or a (maximum) current intensity, and, if appropriate, to output an error signal signaling this to its second control output. [14] Power supply according to the previous claim, - wherein the protective circuit (200) is coupled with its third control input to the second control output of the first monitoring circuit (signal-wise), in particular electrically connected, - and wherein the protection circuit (200) is configured to operate in the second operating mode, controlled by one or more of the error signals (of the first and second monitoring circuits), such that an error signal is present at at least one of the first, second and third control inputs. [15] Power supply according to one of claims 8 to 14, wherein the third monitoring circuit is designed as a non-(re-)programmable and / or unchangeable hardware component (of the power supply). [16] Power supply according to one of claims 8 to 15, wherein the control circuit (400) has a fourth control output (400.24) and is coupled (signal-wise), in particular electrically connected, to the control input (313.11) of the third selection circuit by means of its fourth control output (400.24). [17] Power supply according to the preceding claim, wherein the control circuit (400) is configured, in a third operating mode, to output at its fourth control output (400.24) a selection signal activating the first switching state of the third selection circuit (313), in particular no selection signal at the first and second control outputs. [18] Power supply according to one of the preceding claims, wherein the supply circuit (100) is configured to provide, in a second operating mode, the first (DC) voltage at the first load output (100.41) as well as the second (DC) voltage at the second load output (100.42), such that the second (DC) voltage has a second (nominal) voltage level which differs from the first voltage level (in the first operating mode), in particular by more than 0.05 V, in particular constant and / or not less than 1.05 V, in particular more than 0.05 V, greater than the first (nominal) voltage level. [19] Power supply according to the preceding claim, wherein the supply circuit (100) is configured, in its second operating mode, to drive a (useful) current flowing through the second load output, in particular limited to a predetermined maximum (useful) current of 1 A or less, or to control a (useful) energy flow leading through the second load output, in particular limited to a predetermined maximum (useful) power of 30 W or less, in particular in such a way that the (useful) energy flow guided in the second operating mode is limited to a second maximum (useful) power. [20] Power supply according to one of claims 18 to 19, wherein the control circuit (400) is arranged to output, in its second operating mode, at its third control output a control signal having a second control value activating the second operating mode of the supply circuit (100). [21] Power supply according to one of claims 18 to 20, wherein the supply circuit (100) is configured, in a third operating mode, to provide the first (DC) voltage at the first load output as well as the second (DC) voltage at the second load output, such that the second (DC) voltage has a third (nominal) voltage level which differs from the first and second voltage levels, in particular by more than 0.05 V in each case, in particular is constant and / or not less than 1.1 V, in particular is more than 0.1 V greater than the first (nominal) voltage level and more than 0.05 V greater than the second (nominal) voltage level. [22] Power supply according to claim 17 and claim 21, wherein the control circuit (400) is arranged to output, in its third operating mode, at its third control output (400.23) a control signal having a third control value activating the third operating mode of the supply circuit (100). [23] Power supply according to one of the preceding claims, wherein the supply circuit (100) is configured, in its first operating mode, to drive a (useful) current flowing through the second load output, in particular limited to a predetermined maximum (useful) current of 1 A or less, or to control a (useful) energy flow leading through the second load output, in particular limited to a predetermined maximum (useful) power of 30 W or less, in particular such that the (useful) current flowing in the first operating mode is limited to a first maximum (useful) current and / or that the (useful) current flowing in the second operating mode is limited to a second maximum (useful) current and / or that the (useful) energy flow conducted in the first operating mode is limited to a first maximum (energy flow) power. [24] Power supply according to one of the preceding claims, wherein the supply circuit is arranged to be electrically connected to an electrical energy source (external to the power supply) and to draw therefrom electrical (mains) power (required for the operation of the power supply), in particular in the amount of more than 5 W (watts) and / or less than 50 W (watts). [25] Power supply unit according to the preceding claim, wherein the supply circuit is arranged to draw electrical (mains) power from the (connected) energy source and thus to cover at least partially, in particular predominantly or completely, a respective (power) requirement (of the power supply unit) for electrical (useful) power, in particular one that can be adapted during operation, in particular to drive the (useful) current (flowing through the second load output) or to effect the (useful) energy flow. [26] Power supply according to one of the preceding claims, wherein the supply circuit (100) is configured to provide the first (DC) voltage at the first load output in a fourth operating mode, in particular one activated (automatically) during commissioning, but to provide no voltage at the second load output. [27] Power supply according to one of the preceding claims, wherein the supply circuit (100) has a load input for a, in particular external and / or unregulated, (mains) voltage, in particular for electrically connecting the supply circuit or the power supply formed thereby to an electrical energy source (external to the power supply). [28] Power supply according to the preceding claim, wherein the supply circuit (100) is arranged to start automatically after the (mains) voltage is applied to the load input. [29] Power supply according to claim 26 and 27, wherein the supply circuit (100) is arranged to start automatically in the fourth operating mode after application of a (mains) voltage to the load input. [30] Power supply according to one of the preceding claims, further comprising: a printed circuit board, in particular serving as a carrier for the supply circuit and / or the control circuit and / or the protection circuit and / or the first and second selection circuits and / or the first and second monitoring circuits. [31] Power supply according to the previous claim, - wherein the first and second selection circuits are arranged at least partially, in particular entirely, on the printed circuit board; and / or - wherein the first and second monitoring circuits are arranged at least partially, in particular entirely, on the printed circuit board. [32] Power supply according to the preceding claim, wherein the first and second selection circuits and the first and second monitoring circuits are arranged at least partially, in particular entirely, on the printed circuit board. [33] Measuring system comprising: - a measuring sensor (MA) which is designed to detect at least one, in particular physical or chemical, measured variable and to convert it into at least one measuring signal (s1) representing the same measured variable; - a (measuring transducer) circuit (MU), in particular one having at least one microprocessor and / or conforming to the international standard IEC 60079-11:2023-01 -- with a load input, -- with at least one signal input -- and with at least one (digital) signal output; - and a power supply unit (electrically connected to the measuring transducer circuit) according to one of the preceding claims. [34] Measuring system according to the preceding claim, wherein the load input of the (measuring transducer) circuit (MU) is at least temporarily, in particular permanently, electrically connected to the load output of the first (energy flow) monitoring circuit, in particular not at the same time to the load output of the second (energy flow) monitoring circuit, in particular such that when an (input) voltage is applied to the load input of the first (energy flow) monitoring circuit, in particular with a voltage level of more than 1 V and / or less than 40 V, a current flow, in particular with a current intensity of more than 100 mA (milliamperes) and / or less than 500 mA, from the load output of the first (energy flow) monitoring circuit to the load input of the (measuring transducer) circuit (MU) or a current, in particular more than 2000 Ws / h (watt-second per hour) energy flow from the power supply to the (measuring transducer) circuit (MU) is possible. [35] Measuring system according to the previous claim, - the first operating mode of the control circuit, thus - the first operating mode of the supply circuit (100), - the first switching state of the first selection circuit - and the second switching state of the second selection circuit are activated, in particular in such a way that a load circuit of the measuring system involving a current path leading from the load output of the supply circuit to the load input of the protection circuit, further via its load output to the first circuit input of the first selection circuit, further via its load output to the load input of the first (energy flow) monitoring circuit (321) and further via its load output to the load input of the (measuring transducer) circuit (MU) is closed. [36] Measuring system according to one of claims 33 to 35, -- wherein the measuring sensor (MA) is electrically coupled to the (measuring transducer) circuit (MU) via the signal input - and wherein the (measurement transducer) circuit (MU) is configured to receive and evaluate the at least one measurement signal, in particular to determine measured values ​​quantifying the at least one measurement variable on the basis of the measurement signal.

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