Supply isolator, field device and system consisting of the supply isolator and the field device

Abstract

The invention discloses a supply isolator (1) for supplying energy to a field device (10) for process automation. A control unit (4) takes control information received via a signal input (3) as a basis for acting on the supply isolator (1) in regard to the output of energy via the energy output (2). The invention also discloses a field device (10) in which a computing unit (14) determines an actual value for energy available at an energy input (12) and a requirement value for an energy requirement of the field device (10), generates control information therefrom, and outputs said control information via a signal output (13). The invention also relates to a system (100) consisting of the supply isolator (1) and the field device (10).

Description

[0001] Power isolator, field device and system consisting of power isolator and field device

[0002] The invention relates to a power isolator for supplying power to at least one field device in process automation. Furthermore, the invention relates to a field device in process automation and a system with at least one power isolator.

[0003] Several prior art publications (cf. DE 100 34 685 A1, DE 10 2008 062 815 B4, DE 10 2019 118 839 A1, DE 102021 114686 A1, DE 10 2021 134 390 A1, or WO 00 / 75904 A1) address energy management within a field device. Energy management is particularly important for devices powered by a current loop, as the available energy depends on the output value of the field device. For example, if a field device in a 4...20 mA current loop requires 40 mW of energy, the minimum voltage at the energy input—usually a connection terminal—must be at least 10 V (fault conditions are neglected for the sake of simplicity). Voltage drops can occur between a power supply that supplies the field device and the field device itself. Therefore, such a power supply must provide more than 10 V to the field device at its output due to the voltage drops.If the field device temporarily requires more energy, or, for example, if additional functional modules of the field device are to be activated depending on the available energy, some form of energy management within the field device is required. As already mentioned, several approaches exist in the state of the art for this.

[0004] For safety reasons, which are intended to ensure the functionality of the field device, the power supplies usually provide a higher voltage than the field device requires. The resulting excess energy must be dissipated within the field device. There are approaches to operating additional functions of the field device or, for example, storing the energy. Typically, however, the excess energy is converted into heat within the field device. Since the energy is in the mW range, this is not really detrimental to the individual field device. However, from today's perspective, this is no longer sustainable for all field devices.

[0005] The invention is based on the object of improving the energy supply of field devices in the field of process automation in terms of sustainability.

[0006] The invention solves the problem with a power isolator, an associated field device and with a system which has a power isolator and a suitable field device.

[0007] The invention solves the problem according to a first teaching by means of a power supply isolator for supplying energy to at least one field device of process automation, wherein the power supply isolator has an energy output, wherein the energy output is configured such that the power supply isolator outputs electrical energy to supply energy to the field device via the energy output, wherein the power supply isolator has a signal input, wherein the signal input is configured such that the power supply isolator receives control information via the signal input, wherein the power supply isolator has a control unit, wherein the control unit is configured such that the control unit, based on control information received via the signal input, acts on the power supply isolator with regard to the output of electrical energy via the energy output.

[0008] The power supply isolator according to the invention receives control information via a signal input, which a control unit uses to control which power the power supply isolator outputs via the power output. The signal input is preferably designed for communication with a field device, so that the field device directly or indirectly connected to the power output can communicate which power it requires. In one embodiment, the power output and the signal input coincide.

[0009] One embodiment of the power supply isolator provides that the control unit is configured such that the control unit extracts an actual value for the energy available to the field device and a requirement value for the energy requirement of the field device from the received control information, that the control unit is configured such that the control unit determines a controlled variable from the actual value and the requirement value, and that the control unit influences the power supply isolator such that the energy output by the power supply isolator via the energy output depends on the controlled variable. In this embodiment, the power supply isolator receives an actual value regarding the amount of energy arriving at the affected field device and a requirement value regarding the amount of energy required by the field device from the received control information. The control unit determines a controlled variable from these two pieces of data in order to regulate the output of energy via the energy output.Alternatively, the control information already includes the controlled variable that has been generated by the field device.

[0010] A supplementary design of the supply isolator includes that the controlled variable refers to a voltage value of the energy output at the energy output.

[0011] The invention solves the problem according to a second teaching by a field device for process automation, wherein the field device has an energy input, wherein the energy input is designed such that the field device receives electrical energy via the energy input, wherein the field device has a signal output, wherein the signal output is designed such that the field device outputs control information via the signal output, wherein the field device has a calculation unit, and wherein the calculation unit is designed to determine an actual value for energy available at the energy input, to determine a requirement value for an energy requirement of the field device, to generate control information from the actual value and the requirement value, and to output the control information via the signal output.

[0012] The field device according to the invention determines the amount of energy available at the energy input. This is the actual value. In addition, the field device, and in particular the calculation unit of the field device, determines a required value for the amount of energy the field device requires for safe operation. Actual can therefore also be understood as a target value. From both values, the calculation unit generates control information, which is output via the signal output to which the power supply isolator, to which the field device is connected and which supplies the field device with energy, is connected. The field device according to the invention thus communicates a statement about the amount of energy supplied to it by the power supply to the power supply, so that the amount of energy can be adapted to the needs of the field device.

[0013] One embodiment of the field device provides that the field device has a sensor unit, and that the sensor unit is configured such that the field device determines and / or monitors a process variable via the sensor unit. In this embodiment, the field device is a measuring device and thus not, for example, an actuator.

[0014] One embodiment of the field device includes the calculation unit being configured to generate control information from the actual value and the required value such that the control information comprises a controlled variable to optimize, in particular minimize, the energy available at the energy input. In this embodiment, the calculation unit calculates the actual value and the required value to produce a controlled variable that allows the connected power supply to adapt the amount of energy provided to the needs of the field device and, in particular, to reduce or minimize it. In an alternative embodiment, the actual value and the required value are output as control information so that the power supply can determine the controlled variable.

[0015] One design of the field device provides that the actual value refers to the electrical voltage applied at the energy input.

[0016] One configuration of the field device involves the calculation unit determining the demand value as a fixed expected value. This configuration assumes that the energy demand of the field device will not change, so a fixed value can be set and output as the demand value.

[0017] One embodiment of the field device provides for the calculation unit to dynamically determine the demand value in relation to current application conditions. In this embodiment, the energy demand of the field device can change dynamically, for example, by activating additional functions. This is taken into account in this embodiment in that the calculation unit determines the current demand value, e.g., based on an activation signal for additional functionalities, and then transmits it as control information to the field device so that the energy supply can be adjusted. This refers to increasing or decreasing the amount of energy, depending on the case.

[0018] One embodiment of the field device includes the calculation unit being designed such that the calculation unit monitors whether there is a future energy requirement of the field device that is greater than a current actual value for the energy available at the energy input or a determined requirement value output in the form of control information via the signal output, and that, in the event that the future energy requirement is greater, the calculation unit outputs updated control information via the signal output and blocks an increase in the current energy requirement of the field device until the actual value of the energy available at the energy input is at least equal to the future energy requirement. In this embodiment, the calculation unit determines whether an energy requirement of the field device exceeds the amount of energy made available to the field device.The calculation unit therefore influences the field device in such a way that it blocks an increase in energy demand. This occurs, for example, by not activating an additional function of the field device selected by the user or by deactivating other functions to compensate. This blocking occurs until the amount of energy present at the energy input covers the increased demand. The calculation unit can monitor this by regularly determining the actual value at the energy input.

[0019] One embodiment of the field device provides for the power input and signal output to be designed as a single unit. In this embodiment, the field device outputs the control information via the interface through which it receives the power. One embodiment of the field device includes a loop-powered field device that outputs signals in 4...20 mA format via the signal output.

[0020] According to a third teaching, the invention achieves the object by means of a system with at least one power isolator according to one of the preceding or following embodiments and with at least one field device according to one of the embodiments described above or below. The statements therefore also apply accordingly to the system.

[0021] The core of the invention lies in the coordination of energy management between a field device as an energy sink and the power supply isolator as an energy source. In particular, the field device is only provided with as much energy as it actually needs, for example, for the measurement task or, if necessary, for other modules. This offers the advantage that such a controlled interaction between the power supply isolator and the field device allows an energy-optimized operating point to be achieved.

[0022] Possible types of communication between the field device and the power supply can be, for example, digital communication using HART signals, fieldbus or Ethernet protocols or wireless connections.

[0023] The invention is explained in more detail with reference to the figure. It shows:

[0024] Fig. 1 shows a schematic of a system with a supply isolator and a field device.

[0025] Fig. 1 shows a schematic diagram of a system 100 as it can be used in a process plant.

[0026] The system 100 comprises a power supply 1 that supplies a field device 10, which in this case is, for example, a measuring device, with electrical energy. The field device 10 is assumed to be a loop-powered measuring device that outputs measurement signals using the so-called 4...20 mA standard. This means that based on a correlation between the current intensity and the measurement signal, the resistance value of the energy input 12 is appropriately adjusted, so that the measurement signal can in turn be derived from the current value on the receiving side. For the measurements, the field device 10 has a sensor unit 11 that, in this case, uses the radar principle, for example, to determine and / or monitor the fill level of a medium (not shown here).

[0027] The calculation unit 14 records the energy present at the energy input 12 as an actual value and determines the energy requirement value required by the field device 10 for its tasks. From these two values ​​(actual value and required value), the calculation unit 14 determines control information and outputs it to the power supply isolator 1 via the signal output 13.

[0028] The power supply 1 receives the control information via signal input 3. The control unit 4 extracts the actual value and the required value from this and regulates the energy output 2 so that the energy provided to the field device 1 is optimal and preferably reduced. This is, for example, the voltage value. When setting the energy, the distance between the power supply 1 and the field device 10, i.e., the loss via the cable, must also be considered.

[0029] List of reference symbols

[0030] Power supply isolator Energy output Signal input Control unit

[0031] field device

[0032] Sensor unit

[0033] Energy input Signal output Calculation unit System

Claims

Patent claims 1. Power supply isolator (1) for supplying energy to at least one field device (10) of the process automation, wherein the power supply isolator (1) has a power output (2), wherein the power output (2) is set up such that the power supply isolator (1) outputs electrical energy to supply energy to the field device (10) via the power output (2), wherein the power supply isolator (1) has a signal input (3), wherein the signal input (3) is set up such that the power supply isolator (1) receives control information via the signal input (3), wherein the power supply isolator (1) has a control unit (4), wherein the control unit (4) is set up such that the control unit (4), based on control information received via the signal input (3), acts on the power supply isolator (1) with regard to the output of electrical energy via the power output (2).

2. Power supply isolator (1) according to claim 1, wherein the control unit (4) is set up in such a way that the control unit (4) extracts an actual value for an energy available to the field device (10) and a requirement value for an energy requirement of the field device (10) from the received control information, wherein the control unit (4) is set up in such a way that the control unit (4) determines a controlled variable from the actual value and the requirement value, and wherein the control unit (4) acts on the power supply isolator (1) in such a way that the energy output by the power supply isolator (1) via the energy output (2) depends on the controlled variable.

3. Power supply isolator (1) according to claim 2, wherein the controlled variable relates to a voltage value of the energy output at the energy output (2).

4. Field device (10) of process automation, wherein the field device (10) has an energy input (12), wherein the energy input (12) is designed such that the field device (10) receives electrical energy via the energy input (12), wherein the field device (10) has a signal output (13), wherein the signal output (13) is designed such that the field device (10) outputs control information via the signal output (13), wherein the field device (10) has a calculation unit (14), and wherein the calculation unit (14) is designed such that it determines an actual value for energy available at the energy input (12), determines a requirement value for an energy requirement of the field device (10), generates control information from the actual value and the requirement value, and outputs the control information via the signal output (13).

5. Field device (10) according to claim 4, wherein the field device (10) has a sensor unit (11), and wherein the sensor unit (11) is designed such that the field device (10) determines and / or monitors a process variable via the sensor unit (11).

6. Field device (10) according to claim 4 or 5, wherein the calculation unit (14) is designed to generate the control information from the actual value and the required value in such a way that the control information comprises a controlled variable in order to optimize, in particular to minimize, the energy available at the energy input (12).

7. Field device (10) according to one of claims 4 to 6, wherein the actual value refers to the electrical voltage applied to the energy input (12).

8. Field device (10) according to one of claims 4 to 7, wherein the calculation unit (14) determines the required value as a fixed expected value.

9. Field device (10) according to one of claims 4 to 7, wherein the calculation unit (14) determines the demand value dynamically with respect to current application conditions.

10. Field device (10) according to one of claims 4 to 9, wherein the calculation unit (14) is designed such that the calculation unit (14) monitors whether there is a future energy requirement of the field device (10) which is greater than a current actual value for the energy available at the energy input (12) or a requirement value determined and output in the form of control information via the signal output (13), and that in the event that the future energy requirement is greater, the calculation unit (14) outputs updated control information via the signal output (13) and blocks an increase in the current energy requirement of the field device (10) until the actual value of the energy available at the energy input (12) is at least equal to the future energy requirement.

11. Field device (10) according to one of claims 4 to 10, wherein the energy input (12) and the signal output (13) are designed as a single piece.

12. Field device (10) according to one of claims 4 to 11, wherein the field device (10) is a loop-powered field device (10) which outputs signals in 4...20 mA format via the signal output (13).

13. Process automation system (100) with at least one power isolator (1) according to one of claims 1 to 3 and with at least one field device (10) according to claim 4 or 12.

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