DE102023126536A1 - measuring system - Google Patents

Abstract

The measuring system is used to measure two (time-varying) primary (process) measured variables (x1, x2) and/or to measure a (time-varying) secondary (process) measured variable (y1) derived from at least one of the primary (process) measured variables (x1, x2). For this purpose, the measuring system comprises measuring system electronics, a sensor element (C1), a passive sensor element (R1) for detecting the primary measured variables, and electrical connecting lines (401, 402, 403, 404). The sensor element (C1) is electrically connected to the measuring system electronics via the connecting lines (401, 402), and the sensor element (R1) is electrically connected to the measuring system electronics via the connecting lines (403, 404). The sensor element (C1) is configured to generate or adjust an electrical (measurement) voltage (u1) dependent on the primary measured variable (x1). The sensor element (R1) in turn has an electrical resistance and is designed to follow a change in the primary measured variable (x2) with a change in the same resistance. The measuring system electronics, in turn, are configured to temporarily cause a voltage drop across the sensor element (R1) during a predetermined (current supply) time interval (t1) by driving a (measurement) current through the sensor element (R1) and the connecting lines (403, 404), and to refrain from driving any (measurement) current through the sensor element (R1) and connecting lines (4043, 404) during a time interval (t2) preceding the time interval (t1) and a time interval (t3) following the time interval (t1), such that the (measurement) current has rising or falling current edges at least during the (transition) time intervals (t4, t5) immediately following or preceding the time interval (t1). In addition, the measuring system electronics are configured to temporarily detect and evaluate the electrical voltage (u1). Furthermore, the measuring system electronics are designed to detect and evaluate an electrical voltage (u2) dependent on the voltage drop across the sensor element (R1) during the time interval (t1) and to suspend the detection and/or evaluation of the voltage (u1) at least during the time intervals (t4, t5).

Description

The invention relates to a measuring system for measuring two (time-varying) primary (process) measured variables of a fluid medium and/or for measuring a (time-varying) secondary (process) measured variable of the medium derived from at least one of the primary (process) measured variables.

In the US-A 2003/0061887 , the US-A 2004/0216532 , the US-A 2009/0038406 , the US-A 2022/0057240 , the WO-A 2004/023081 , the WO-A 2022/128418 or the (not pre-published) German patent application 102022127160.9 are measuring systems for measuring a time-varying primary first (process) measured variable, here namely a time-varying, in particular at least temporarily periodic, static pressure and/or a time-varying or rate of change of the same pressure, of a fluid measuring medium flowing in a (process) line and/or for measuring a (time-varying) secondary (process) measured variable derived from the same primary (process) measured variable, here namely a flow velocity and/or a volume flow of a fluid measuring medium guided in a (process) line.

Each of the measuring systems—here embodied as a vortex flowmeter (in a compact design)—includes measuring system electronics, at least one first sensor element for detecting the first primary (process) measured variable, and at least one passive second sensor element for detecting a second primary (process) measured variable that is different from the first primary (process) measured variable (serving as an auxiliary measured variable), in this case a time-varying temperature. The first and second sensor elements are each electrically connected to the respective measuring system electronics by means of electrical connecting lines (forming first and second measuring channels of the respective measuring system, respectively). In addition, the first sensor element is configured (in conjunction with the measuring system electronics) to generate or set a first electrical (measurement) voltage dependent on the first primary measured variable, and the second sensor element is configured (in conjunction with the measuring system electronics) to generate or set a second electrical (measurement) voltage dependent on the second primary measured variable.

The measuring system electronics of each of the aforementioned measuring systems is housed in an electronic (protective) housing, for example, a shock- and/or weather-resistant, and is also each configured to determine one or more (digital) measured values for the primary and/or secondary (process) measured variables based on the (time-varying) first and second electrical (measurement) voltages and to output them as qualified measured values of the measuring system. In the measuring systems shown here, the measuring system electronics are also particularly configured to determine, based on at least the first electrical (measurement) voltage, measured values for a frequency of at least temporarily periodic pressure fluctuations within the flowing medium, serving as a secondary (process) measured variable – in this case, pressure fluctuations within a Karman vortex street formed in a flow of the medium – and, based on the same (vortex) frequency and the (temperature-dependent) second electrical (measurement) voltage, measured values for a volume and/or mass flow of the medium serving as a secondary (process) measured variable. However, the measuring system electronics can also be configured, for example, to determine, based on the first and second electrical (measurement) voltages, measured values for a (static) pressure of a (flowing) fluid medium serving as a first primary (process) measured variable. Typically, measuring systems of the type in question are mostly designed as low-power measuring systems, for example, such that the respective measuring system electronics are operated at least temporarily with an electrical (nominal) power of less than 100 mW (milliwatts); this is particularly true if the measuring system electronics or the measuring system formed thereby is connected by means of a current loop interface to a (4-20 mA) 2-wire line used to transmit electrical power and measured values.

As in the US-A 2003/0061887 , the US-A 2004/0216532 , the US-A 2009/0038406 , the US-A 2022/0057240 As shown in each case, the first sensor element can be designed, for example, as a capacitive (passive) sensor element, such that the same sensor element has an electrical (sensor) capacitance and is configured to follow a change in the first primary (process) measured variable with a change in the same capacitance, and accordingly be formed by means of a (measuring) capacitor, for example with a (capacitor) electrode geometry that changes depending on the first primary measured variable. In addition, the measuring system electronics can be configured accordingly to electrically charge or keep charged the aforementioned (sensor) capacitance in order to produce the first electrical (measuring) voltage, for example by means of a corresponding charge-voltage converter (charge amplifier). In the aforementioned measuring systems, the first sensor element is formed by means of at least one (measuring) capacitor - here, for example, designed as a plate capacitor - for example with a capacitor that changes depending on a (capacitor) electrode geometry that changes depending on the first primary measured variable. The first sensor element can, for example, also be formed by a (plate) capacitor having a dielectric that changes depending on the first primary measured variable, or can, for example, also be a piezoelectric or galvanic (active) sensor element. The second sensor element, in turn, can typically be a resistive passive (temperature) sensor element, such that the same sensor element has a temperature-dependent electrical (sensor) resistance, for example a platinum measuring resistor (standardized according to EN IEC 60751), and is configured to follow a change in the second primary measured variable with a change in the same resistance. To effect the second electrical (measurement) voltage, the measuring system electronics can also be configured to energize the second sensor element, namely to drive an (impressed) electrical (measurement) current with a current intensity typically between approximately 0.05 mA and 0.5 mA through the second sensor element and connecting lines electrically connecting it to the measuring system electronics, for example in order to establish a corresponding voltage drop (proportional to the resistance) across the second sensor element.

In order to connect the first and second sensor elements or the measuring system formed thereby to the respective process or its respective measuring medium, measuring systems of the type in question typically also have a metallic (process) coupling element, formed for example by means of a membrane and/or a sleeve and/or a plate, which is designed to be contacted by the respective measuring medium (during operation of the measuring system), for example to be flowed against and/or around, in particular in such a way that the (process) coupling element has a (coupling element) temperature that is dependent on a (measured medium) temperature of the measured medium and/or that the (process) coupling element has an (elastic) expansion that is dependent on a (measured medium) pressure.

In the US-A 2003/0061887 , the US-A 2004/0216532 , the US-A 2009/0038406 , the US-A 2022/0057240 , the WO-A 2022/128418 In the measuring systems shown, the (process) coupling element is arranged partially within a (housing) connection piece which serves to hold the aforementioned electronics (protective) housing on the (process) line or a measuring tube of the measuring system integrated therein, for example, detachably connected to the electronics (protective) housing by means of a flange connection and/or is tubular, and/or is (mechanically) connected to it at a connection piece end distal to the electronics housing, and the aforementioned connecting lines are guided at least partially within the (housing) connection piece. In addition, the (process) coupling element shown here is formed by means of a membrane-like deformation body and a paddle-shaped sensor vane molded thereon and is particularly configured to be inserted at least partially into a lumen of a pipe (used to convey a fluid medium), for example, such that the (process) coupling element is inserted into the lumen through an opening in a pipe wall surrounding the lumen and is (removably) fixed to the same pipe wall. However, the coupling element can also be formed, for example, by means of a tuning fork or a vibrating rod and configured to be inserted at least partially into a lumen of a container (used to convey a fluid medium), for example, a tank or a silo.

The coupling element is further mechanically coupled to the first sensor element in such a way that the first electrical (measurement) voltage depends on an elongation of the coupling element or such that a change in an elongation of the coupling element causes a change in the first electrical (measurement) voltage, for example, by rigidly connecting at least one (movable) capacitor electrode of the (measurement) capacitor to the coupling element. Last but not least, in the aforementioned case where the first sensor element is formed by at least one (measurement) capacitor, the first sensor element can also be an (integral) component of the coupling element, for example, such that at least one (movable) capacitor electrode of the (measurement) capacitor is formed by the coupling element. Furthermore, the coupling element and the second sensor element are coupled to one another at least thermally, in particular both thermally and mechanically, in such a way that the second electrical (measurement) voltage is dependent on a (coupling element) temperature of the coupling element or that a change in a (coupling element) temperature of the coupling element causes a change in the electrical (sensor) resistance of the second sensor element.

One disadvantage of measuring systems of the type in question is that the aforementioned connecting lines, not least in the case of their at least partial installation within the connecting piece, have small distances of less than 5 mm from one another and can therefore be capacitively (signal-)coupled to a considerable extent. Due to this (signal) coupling, the (measurement) current through the second sensor element, which serves to generate the second electrical (measurement) voltage, can also affect the first electrical (measurement) voltage and thus the measuring accuracy of the measuring system as a whole. cause interference in the first measuring channel; this is particularly the case if the (measurement) current is changed abruptly, for example, when it is switched on or off. To avoid resulting measurement errors, switching operations that influence the respective measuring current are avoided in such measuring systems during the determination of the measured values, or conversely, the measuring current is kept as constant as possible for the determination of the measured values. As a result, the total electrical power required for the operation of the aforementioned first and second measuring channels alone can amount to approximately 0.5 to 2 mW, which in the case of a low-power measuring system (occasionally) amounts to more than 1% of the total available, albeit already low, electrical power (<100 mW).

Based on the aforementioned prior art, it is an object of the invention to improve the measuring system of the type in question in such a way that the electrical power required to determine the measured values can be regularly reduced from a (maximum) electrical power required overall for the operation of the first and second measuring channels to a comparatively lower (minimum) electrical power, while still maintaining a sufficiently high measurement accuracy or a sufficiently high update rate of the measured values determined thereby.

• • eine, beispielsweise mit einer maximalen elektrischen Leistung von weniger als 1 W (Watt) betriebenen und/oder an eine (4-20 mA-)2-Drahtleitung angeschlossene, Meßsystem-Elektronik,
• • wenigstens ein, beispielsweise kapazitives und/oder passives, erstes Sensorelement (C1) zum Erfassen der ersten primären (Prozeß-)Meßgröße,
• • wenigstens ein, beispielsweise resistives, passives zweites Sensorelement (R1) zum Erfassen der zweiten primären (Prozeß-)Meßgröße,
• • sowie erste, zweite, dritte und vierte, beispielsweise jeweils (zumindest) teilweise ungeschirmte und/oder nicht miteinander verdrillter, elektrische Verbindungsleitungen,
• • wobei das erste Sensorelement mittels der ersten und zweiten Verbindungsleitungen (unter Bildung eines ersten Meßkanals des Meßsystems) an die Meßsystem-Elektronik elektrisch angeschlossen ist, beispielsweise unter Zwischenschaltung einer Durchführung,
• • wobei das zweite Sensorelement mittels der dritten und vierten Verbindungsleitungen (unter Bildung eines zweiten Meßkanals des Meßsystems) an die Meßsystem-Elektronik elektrisch angeschlossen ist, beispielsweise unter Zwischenschaltung einer Durchführung,
• • und wobei wenigstens eine, beispielsweise jede, der ersten und zweiten Verbindungsleitungen mit wenigstens einer, beispielsweise jeder, der dritten und vierten Verbindungsleitungen, beispielsweise kapazitiv, (signal-)gekoppelt ist, beispielsweise indem ein kleinster Abstand zwischen wenigstens einer der ersten und zweiten Verbindungsleitungen und wenigstens einer der dritten und vierten Verbindungsleitungen weniger als 5 mm beträgt,
• • wobei das erste Sensorelement eingerichtet ist, beispielsweise im Verbund mit der Meßsystem-Elektronik, eine von der ersten primären (Prozeß-)Meßgröße abhängige erste elektrische (Meß-)Spannung zu generieren und/oder einzustellen,
• • und wobei das zweite Sensorelement einen, beispielsweise bei einer Temperatur von 20°C nicht weniger als 90 Ω und/oder nicht mehr als 1,1 kΩ betragenden, elektrischen (Sensor-)Widerstand aufweist und eingerichtet ist, einer Änderung der zweiten primären Meßgröße mit einer Änderung nämlichen Widerstands zu folgen,
• • wobei die Meßsystem-Elektronik eingerichtet ist, die erste elektrische (Meß-)Spannung zeitweise zu erfassen und auszuwerten, beispielsweise nämlich zu digitalisieren und/oder die (Meß-)Spannung repräsentierende (digitale) erste (Spannungs-)Meßwerte zu ermitteln,
• • wobei die Meßsystem-Elektronik eingerichtet ist,
• • zum vorübergehenden Bewirken eines Spannungsfalls über dem zweiten Sensorelement das zweite Sensorelement zeitweise zu bestromen, nämlich während eines vorgegebenen, beispielsweise nicht weniger als 10ms andauernden, ersten (Bestromungs-)Zeitintervalls t1 ein, beispielsweise eingeprägten und/oder konstanten und/oder eine maximale Stromstärke von nicht weniger als 0,1 mA aufweisenden und/oder im zweiten Sensorelement eine maximale elektrische Leistung von nicht weniger als 0,4 mW umsetzenden, elektrischen (Meß-)Strom durch das zweite Sensorelement sowie die dritten und vierten Verbindungsleitungen zu treiben und während eines dem ersten Zeitintervall zeitlich vorausgehenden zweiten Zeitintervalls t2 wie auch eines dem ersten (Bestromungs-)Zeitintervalls zeitlich nachfolgenden dritten Zeitintervalls t3 das zweite Sensorelement nicht zu bestromen bzw. keinen (Meß-)Strom durch das zweite Sensorelement und die dritten und vierten Verbindungsleitungen zu treiben, derart, daß der (Meß-)Strom zumindest während eines dem zweiten Zeitintervall zeitlich (unmittelbar) nachfolgenden und dem ersten (Bestromungs-)Zeitintervall zeitlich (unmittelbar) vorausgehenden, beispielsweise nicht weniger als 1µs (Mikrosekunde) andauernden, vierten (Übergangs-)Zeitintervalls eine (steigende) erste Stromflanke, beispielsweise mit einer zumindest zeitweise und/oder im zeitlichen (arithmetischen) Mittel nicht weniger als 0,1 mA/µs betragenden Stromanstiegsgeschwindigkeit, aufweist und daß der (Meß-)Strom zumindest während eines dem ersten (Bestromungs-)Zeitintervall zeitlich (unmittelbar) nachfolgenden und dem dritten Zeitintervall zeitlich (unmittelbar) vorausgehenden, beispielsweise nicht weniger als 1µs (Mikrosekunde) andauernden, fünften (Übergangs-)Zeitintervalls eine (fallende) zweite Stromflanke, beispielsweise mit einer zumindest zeitweise und/oder im zeitlichen (arithmetischen) Mittel nicht weniger als 0,1 mA/µs betragenden Stromabfallgeschwindigkeit, aufweist,
• • und wobei die Meßsystem-Elektronik eingerichtet ist, während des ersten (Bestromungs-)Zeitintervalls t1 eine vom Spannungsfall über dem zweiten Sensorelement abhängige zweite elektrischen (Meß-)Spannung zu erfassen und auszuwerten, beispielsweise nämlich zu digitalisieren und/oder die (Meß-)Spannung repräsentierende (digitale) zweite (Spannungs-)Meßwerte zu ermitteln;
• • wobei die Meßsystem-Elektronik eingerichtet ist, basierend auf zumindest der ersten elektrischen (Meß-)Spannung, beispielsweise basierend auf sowohl der ersten elektrischen (Meß-)Spannung als auch zweiten elektrischen (Meß-)Spannung, einen oder mehrere (digitale) Meßwerte für die erste primäre (Prozeß-)Meßgröße und/oder einen oder mehrere (digitale) Meßwerte für die sekundäre (Prozeß-)Meßgröße zu ermitteln, beispielsweise nämlich zu ermitteln und als qualifizierte Meßwerte des Meßsystems auszugeben,
• • und wobei die Meßsystem-Elektronik, beispielsweise zum Vermeiden von durch (Signal-)Einkopplung von den dritten und/oder vierten Verbindungsleitungen in die ersten und/oder zweiten Verbindungsleitungen verursachten Meßfehlern bei für die erste Meßgröße ermittelten Meßwerten, eingerichtet ist:
  • keinen basierend auf der während der vierten und fünften (Übergangs-)Zeitintervalle erfassten ersten (Meß-)Spannung ermittelten (qualifizierten) Meßwert für die erste primäre (Prozeß-)Meßgröße auszugeben,
  • und/oder keinen Meßwert für die erste primäre (Prozeß-)Meßgröße basierend auf der während der vierten und fünften (Übergangs-)Zeitintervalle anliegenden ersten elektrischen (Meß-)Spannung zu ermitteln,
  • und/oder keinen basierend auf der während der vierten und fünften (Übergangs-)Zeitintervalle erfassten ersten (Meß-)Spannung ermittelten (qualifizierten) Meßwert für die sekundäre (Prozeß-)Meßgröße auszugeben,
  • und/oder keinen Meßwert für die sekundäre (Prozeß-)Meßgröße basierend auf der während der vierten und fünften (Übergangs-)Zeitintervalle anliegenden ersten elektrischen (Meß-)Spannung zu ermitteln,
  • und/oder während des vierten (Übergangs-)Zeitintervalls (qualifizierte) Meßwerte für die erste primäre (Prozeß-)Meßgröße und/oder für die sekundäre (Prozeß-)Meßgröße basierend auf einer zuvor während des zweiten Zeitintervalls erfassten ersten (Meß-)Spannung zu ermitteln,
  und/oder während des fünften (Übergangs-)Zeitintervalls (qualifizierte) Meßwerte für die erste primäre (Prozeß-)Meßgröße und/oder für die sekundäre (Prozeß-)Meßgröße basierend auf einer zuvor während des ersten Zeitintervalls erfassten ersten (Meß-)Spannung zu ermitteln.

To achieve this object, the invention consists in a measuring system for measuring a (time-varying) first primary (process) measured variable, for example a (static) pressure of a fluid medium (conducted in a line and/or held in a container) and/or a temporal change in the same pressure, as well as a (time-varying) second primary (process) measured variable different from the first primary (process) measured variable, for example a temperature of a fluid medium (conducted in a line), and/or for measuring a (time-varying) secondary (process) measured variable derived from at least one of the first and second primary (process) measured variables, for example a mass flow of a fluid medium conveyed in a line or a fill level of a fluid medium held in a container, which measuring system comprises:

• • a measuring system electronics, for example, operated with a maximum electrical power of less than 1 W (watt) and/or connected to a (4-20 mA) 2-wire line,
• • at least one, for example capacitive and/or passive, first sensor element (C1) for detecting the first primary (process) measured variable,
• • at least one, for example resistive, passive second sensor element (R1) for detecting the second primary (process) measurement variable,
• • as well as first, second, third and fourth, for example (at least) partially unshielded and/or not twisted together, electrical connecting lines,
• • wherein the first sensor element is electrically connected to the measuring system electronics by means of the first and second connecting lines (forming a first measuring channel of the measuring system), for example with the interposition of a feedthrough,
• • wherein the second sensor element is electrically connected to the measuring system electronics by means of the third and fourth connecting lines (forming a second measuring channel of the measuring system), for example with the interposition of a feedthrough,
• • and wherein at least one, for example each, of the first and second connecting lines is (signal-)coupled to at least one, for example each, of the third and fourth connecting lines, for example capacitively, for example by a smallest distance between at least one of the first and second connecting lines and at least one of the third and fourth connecting lines being less than 5 mm,
• • wherein the first sensor element is configured, for example in conjunction with the measuring system electronics, to generate and/or adjust a first electrical (measurement) voltage dependent on the first primary (process) measurement variable,
• • and wherein the second sensor element has an electrical (sensor) resistance, for example at a temperature of 20°C not less than 90 Ω and/or not more than 1.1 kΩ, and is configured to follow a change in the second primary measured variable with a change in the same resistance,
• • wherein the measuring system electronics are configured to temporarily record and evaluate the first electrical (measurement) voltage, for example, to digitize it and/or to determine (digital) first (voltage) measured values representing the (measurement) voltage,
• • the measuring system electronics are set up,
• • to temporarily cause a voltage drop across the second sensor element, to temporarily energise the second sensor element, namely during a predetermined time, for example not less than 10 ms to drive an electrical (measuring) current through the second sensor element and the third and fourth connecting lines during a first (energizing) time interval t1, for example an impressed and/or constant and/or having a maximum current of not less than 0.1 mA and/or converting a maximum electrical power of not less than 0.4 mW in the second sensor element, and to not energize the second sensor element or to drive no (measuring) current through the second sensor element and the third and fourth connecting lines during a second time interval t2 preceding the first time interval and a third time interval t3 following the first (energizing) time interval, such that the (measuring) current is maintained at least during a fourth time interval (immediately) following the second time interval and (immediately) preceding the first (energizing) time interval, for example lasting not less than 1 µs (microsecond). (Transition) time interval has a (rising) first current edge, for example with a current rise rate that is at least temporarily and/or on average (arithmetic) time, not less than 0.1 mA/µs, and that the (measurement) current has a (falling) second current edge, for example with a current fall rate that is at least temporarily and/or on average (arithmetic) time, not less than 0.1 mA/µs, at least during a fifth (transition) time interval that (immediately) follows the first (current supply) time interval and (immediately) precedes the third time interval, for example lasting not less than 1µs (microsecond),
• • and wherein the measuring system electronics are configured to detect and evaluate a second electrical (measurement) voltage dependent on the voltage drop across the second sensor element during the first (energization) time interval t1, for example to digitize it and/or to determine (digital) second (voltage) measured values representing the (measurement) voltage;
• • wherein the measuring system electronics are configured to determine, based on at least the first electrical (measurement) voltage, for example based on both the first electrical (measurement) voltage and the second electrical (measurement) voltage, one or more (digital) measured values for the first primary (process) measured variable and/or one or more (digital) measured values for the secondary (process) measured variable, for example to determine them and output them as qualified measured values of the measuring system,
• • and wherein the measuring system electronics are configured, for example, to avoid measurement errors caused by (signal) coupling from the third and/or fourth connecting lines into the first and/or second connecting lines in measured values determined for the first measured variable:
  • not to output a (qualified) measured value for the first primary (process) measured variable based on the first (measurement) voltage recorded during the fourth and fifth (transition) time intervals,
  • and/or not to determine a measured value for the first primary (process) measured variable based on the first electrical (measurement) voltage applied during the fourth and fifth (transition) time intervals,
  • and/or not to output a (qualified) measured value for the secondary (process) measured variable based on the first (measurement) voltage recorded during the fourth and fifth (transition) time intervals,
  • and/or not to determine a measured value for the secondary (process) measured variable based on the first electrical (measurement) voltage applied during the fourth and fifth (transition) time intervals,
  • and/or during the fourth (transition) time interval, to determine (qualified) measured values for the first primary (process) measured variable and/or for the secondary (process) measured variable based on a first (measurement) voltage previously recorded during the second time interval,
  and/or during the fifth (transition) time interval to determine (qualified) measured values for the first primary (process) measured variable and/or for the secondary (process) measured variable based on a first (measurement) voltage previously recorded during the first time interval.

Furthermore, the invention also consists in using such a measuring system for measuring both a first primary (process) measured variable, for example a time-varying (static) pressure, and a second primary (process) measured variable (different from the first measured variable), for example a time-varying temperature, of a fluid medium (conducted in a line or held in a container).

• keinen basierend auf der während des (Bestromungs-)Zeitintervalls erfassten ersten (Meß-)Spannung ermittelten (qualifizierten) Meßwert für die erste primäre (Prozeß-)Meßgröße auszugeben,
• und/oder keinen Meßwert für die erste primäre (Prozeß-)Meßgröße basierend auf der während des (Bestromungs-)Zeitintervalls anliegenden ersten elektrischen (Meß-)Spannung zu ermitteln,
• und/oder keinen basierend auf der während des (Bestromungs-)Zeitintervalls erfassten ersten (Meß-)Spannung ermittelten (qualifizierten) Meßwert für die sekundäre (Prozeß-)Meßgröße auszugeben,
• und/oder keinen Meßwert für die sekundäre (Prozeß-)Meßgröße basierend auf der während des (Bestromungs-)Zeitintervalls anliegenden ersten elektrischen (Meß-)Spannung zu ermitteln. Diese Ausgestaltung der Erfindung weiterbildend ist die Meßsystem-Elektronik ferner eingerichtet, (qualifizierte) Meßwerte für die erste primäre (Prozeß-)Meßgröße und/oder für die sekundäre (Prozeß-)Meßgröße basierend auf einer während des ersten Zeitintervalls erfassten ersten (Meß-)Spannung zu ermitteln, und/oder basierend auf einer während des (Bestromungs-)Zeitintervalls erfassten ersten (Meß-)Spannung ermittelte (qualifizierte) Meßwerte für die erste primäre (Prozeß-)Meßgröße und/oder für die sekundäre (Prozeß-)Meßgröße auszugeben.

According to a first embodiment of the measuring system of the invention, it is further provided that the measuring system electronics are set up:

• not to output a (qualified) measured value for the first primary (process) measured variable based on the first (measurement) voltage recorded during the (current supply) time interval,
• and/or not to determine a measured value for the first primary (process) measured variable based on the first electrical (measurement) voltage applied during the (energization) time interval,
• and/or not to output a (qualified) measured value for the secondary (process) measured variable based on the first (measurement) voltage recorded during the (current supply) time interval,
• and/or not to determine a measured value for the secondary (process) measured variable based on the first electrical (measurement) voltage present during the (energization) time interval. Further developing this embodiment of the invention, the measuring system electronics is further configured to determine (qualified) measured values for the first primary (process) measured variable and/or for the secondary (process) measured variable based on a first (measurement) voltage detected during the first time interval, and/or to output (qualified) measured values for the first primary (process) measured variable and/or for the secondary (process) measured variable determined based on a first (measurement) voltage detected during the (energization) time interval.

According to a second embodiment of the measuring system of the invention, it is further provided that the first sensor element has an electrical (sensor) capacitance, for example, at a temperature of 20°C, of not less than 10 pF and/or not more than 100 pF, and is configured to follow a change in the first primary (process) measured variable with a change in the same (sensor) capacitance, and that the measuring system electronics are configured to electrically charge or keep charged the capacitance of the first sensor element, for example, at least during the second and third time intervals, in order to effect the first electrical (measurement) voltage. Further developing this embodiment of the invention, the measuring system electronics are further configured such that the first electrical (measurement) voltage is (substantially) proportional to an electrical charge of the (sensor) capacitance of the first sensor element.

According to a third embodiment of the measuring system of the invention, it is further provided that the measuring system electronics are configured to determine (voltage) measured values representing the first (measurement) voltage, for example, to determine them and store them in a (volatile) digital data memory. Further developing this embodiment of the invention, the measuring system electronics are further configured to determine one or more measured values for the second primary (process) measured variable using one or more (voltage) measured values representing the first (measurement) voltage.

According to a fourth embodiment of the measuring system of the invention, it is further provided that the measuring system electronics are configured to determine (voltage) measured values representing the second (measurement) voltage, for example, to determine them and store them in a (volatile) digital data memory. Further developing this embodiment of the invention, the measuring system electronics are further configured to determine one or more measured values for the first primary (process) measured variable using one or more (voltage) measured values representing the second (measurement) voltage and/or to determine one or more measured values for the first secondary (process) measured variable using one or more (voltage) measured values representing the second (measurement) voltage and/or to determine one or more measured values for the second primary (process) measured variable using one or more (voltage) measured values representing the second (measurement) voltage.

According to a fifth embodiment of the measuring system of the invention, it is further provided that the measuring system electronics are configured to determine, based on the second electrical (measurement) voltage, one or more (digital) measured values for the second primary (process) measured variable, for example, for determining at least one measured value for the first primary (process) measured variable and/or the secondary (process) measured variable, each serving as an auxiliary measured value, for example, to determine them and store them in a (volatile) digital data memory. Further developing this embodiment of the invention, the measuring system electronics are further configured to determine one or more measured values for the first primary (process) measured variable using one or more measured values for the second primary (process) measured variable.

According to a sixth embodiment of the measuring system of the invention, it is further provided that the measuring system electronics are set up based on at least the second electrical (measurement) voltage, for example based on both the second electrical (measurement) voltage as well as first electrical (measurement) voltage, to determine one or more (digital) measured values for the second primary (process) measured variable, for example to determine them and output them as qualified measured values of the measuring system.

According to a seventh embodiment of the measuring system of the invention, it is further provided that each of the first and second connecting lines is at least partially, for example completely, unshielded.

According to an eighth embodiment of the measuring system of the invention, it is further provided that each of the third and fourth connecting lines is at least partially, for example completely, unshielded.

According to a ninth embodiment of the invention, it is further provided that each of the first and second connecting lines is formed at least partially by means of a conductor track arranged on a (flexible) printed circuit board.

According to a tenth embodiment of the measuring system of the invention, it is further provided that each of the third and fourth connecting lines is formed at least partially by means of a conductor track arranged on a (flexible) printed circuit board.

According to an eleventh embodiment of the measuring system of the invention, it is further provided that each of the first, second, third and fourth connecting lines is formed at least partially by means of a respective conductor track arranged on one and the same (flexible) printed circuit board.

According to a twelfth embodiment of the measuring system of the invention, it is further provided that the first and second connecting lines run parallel to each other at least in sections.

According to a thirteenth embodiment of the measuring system of the invention, it is further provided that the third and fourth connecting lines run parallel to each other at least in sections.

According to a fourteenth embodiment of the measuring system of the invention, it is further provided that the first and third connecting lines run parallel to each other at least in sections.

According to a fifteenth embodiment of the measuring system of the invention, it is further provided that the first and fourth connecting lines run parallel to each other at least in sections.

According to a sixteenth embodiment of the measuring system of the invention, it is further provided that the first, second, third and fourth connecting lines run parallel to one another at least in sections.

According to a seventeenth embodiment of the measuring system of the invention, the measuring system electronics comprises at least one operational amplifier, for example, an FET or a CMOS operational amplifier, wherein the first sensor element is electrically connected to a (high-impedance) (voltage) input of the operational amplifier by means of the first and second connecting lines, for example, forming a charge-to-voltage converter of the measuring system electronics, and wherein the operational amplifier is configured to supply the first electrical (measurement) voltage at a (voltage) output (when the measuring system electronics is operating in the first operating mode). Further developing this embodiment of the invention, the operational amplifier comprises a (feedback) capacitor (Cf) that feeds back its (voltage) output to its (voltage) input, for example, a switched (feedback) capacitor. Advantageously, the (feedback) capacitor (Cf) may have a (feedback) capacitance which is not less than 0.1 pF and/or not more than 100 pF.

According to an eighteenth embodiment of the measuring system of the invention, it is further provided that the measuring system electronics has at least one, for example switchable, (electronic) current source, wherein the second sensor element is electrically connected to a (current) output of the current source by means of the third and fourth connecting lines and wherein the current source is configured to supply the (measurement) current.

According to a nineteenth embodiment of the measuring system of the invention, it is further provided that the measuring system electronics has at least one, for example switchable, (electronic) voltage source, wherein the second sensor element is electrically connected to an output of the voltage source by means of the third and fourth connecting lines and wherein the voltage source is configured to drive the (measurement) current.

According to a twentieth embodiment of the measuring system of the invention, it is further provided that the measuring system electronics are configured to determine the sensor resistance of the second sensor element based on the second (measurement) voltage.

According to a twenty-first embodiment of the invention, it is further provided that the measuring system electronics have at least one, for example, at a temperature of 20°C not a (reference) resistance element having an electrical (reference) resistance of less than 90 Ω and/or not more than 1.1 kΩ, which is electrically connected to the second sensor element, for example, electrically connected in series with the second sensor element. Further developing this embodiment of the invention, the measuring system electronics are configured to detect and evaluate, for example, digitize and/or determine (digital) third voltage measurement values representing the reference voltage, an electrical third (reference) voltage that is dependent on a voltage drop across the (reference) resistance element during the first (current supply) time interval. Advantageously, the measuring system electronics can also be configured to determine the (sensor) resistance of the second sensor element based on the third (reference) voltage, for example, based on the second and third voltages as well as the (reference) resistance and/or ratiometrically.

According to a twenty-second embodiment of the invention, it is further provided that the measuring system electronics are configured to determine, based on at least the first electrical (measurement) voltage, measured values for a frequency (serving as a secondary measured variable) of at least temporarily periodic pressure fluctuations within a fluid measuring medium, for example of pressure fluctuations within a Karman vortex street formed in a flow of the measuring medium.

According to a twenty-third embodiment of the invention, it is further provided that the measuring system electronics are configured to determine measured values for a (measuring substance) temperature (serving as a second primary measured variable) of a, for example, flowing, fluid measuring substance based on at least the second electrical (measuring) voltage.

According to a twenty-fourth embodiment of the invention, it is further provided that the measuring system electronics are configured to determine measured values for a (static) pressure of a (flowing) fluid medium (serving as the first primary measured variable) based on the first and second electrical (measurement) voltages.

According to a twenty-fifth embodiment of the invention, it is further provided that the measuring system electronics are configured to determine measured values for a volume flow of a flowing (fluid) medium (serving as a secondary measured variable) based on the first and second electrical (measurement) voltages.

According to a twenty-sixth embodiment of the invention, it is further provided that the measuring system electronics are configured to determine measured values for a mass flow of a flowing (fluid) medium (serving as a secondary measured variable) based on the first and second electrical (measurement) voltages.

According to a twenty-seventh embodiment of the invention, it is further provided that the first sensor element is formed by means of at least one (measuring) capacitor, for example designed as a plate capacitor, for example with a (capacitor) electrode geometry changing as a function of the first primary measured variable and/or with a dielectric changing as a function of the first primary measured variable.

According to a twenty-eighth embodiment of the invention, it is further provided that the second sensor element (R1) is formed by means of at least one platinum measuring resistor, for example a Pt100 and/or a Pt1000.

According to a first development of the invention, the measuring system further comprises at least one (electrical) feedthrough, for example explosion-pressure-resistant (Ex-d) and/or compliant with the international standard IEC 60079-1:2014.

According to a first embodiment of the first further development of the invention, it is provided that the first, second, third and fourth connecting lines are guided in sections within the bushing.

According to a second embodiment of the first development of the invention, it is provided that the feedthrough is electrically connected to the first, second, third and fourth connecting lines, for example by means of unshielded (connecting) pins.

According to a third embodiment of the first further development of the invention, it is provided that the bushing is interposed between the first, second, third and fourth connecting lines.

According to a second development of the invention, the measuring system further comprises an electronics (protective) housing for the measuring system electronics, for example one that is explosion-pressure-resistant (Ex-d) and/or conforms to the international standard IEC 60079-1:2014.

According to a third development of the invention, the measuring system further comprises a (housing) connection piece, which is detachably connected to the electronics (protective) housing, for example by means of a flange connection, and/or is tubular. Advantageously, the first, second, third, and fourth connecting lines can also be at least be guided proportionately within the (housing) connection piece, for example in such a way that they run parallel to each other at least in sections.

According to a fourth development of the invention, the measuring system further comprises a (process) coupling element, formed for example by means of a membrane and/or a sleeve and/or a plate, which is designed to be contacted by a fluid medium (during operation of the measuring system), for example to be flowed against and/or around, for example in such a way that the (process) coupling element has a (coupling element) temperature dependent on a (measured medium) temperature of the measured medium and/or that the (process) coupling element has an (elastic) expansion dependent on a (measured medium) pressure.

According to a first embodiment of the fourth development of the invention, it is provided that the coupling element is configured to react to a change in a (measuring substance) temperature of the measuring substance with a change in a (coupling element) temperature, for example in such a way that the (coupling element) temperature of the coupling element deviates stationary from a stationary (measuring substance) temperature of the measuring substance by less than 2 K (Kelvin).

According to a second embodiment of the fourth development of the invention, it is provided that the coupling element is designed to react to a change in a (measuring medium) pressure of the measuring medium with an, for example, biaxial and/or elastic, expansion.

According to a third embodiment of the fourth development of the invention, it is provided that the coupling element is designed to be inserted at least partially into a lumen of a tube (serving to guide a fluid measuring substance), for example, namely through an opening in a tube wall enclosing the lumen into the lumen and to be fixed (removably) to the same tube wall.

According to a fourth embodiment of the fourth development of the invention, it is provided that the coupling element is designed to be inserted at least partially into a lumen of a container (serving to guide a fluid measuring substance), for example a tank, for example through an opening in a container wall enclosing the lumen into the lumen and to be fixed (removably) to the same container wall.

According to a fifth embodiment of the fourth development of the invention, it is provided that the coupling element consists at least partially, for example completely, of metal, for example a (stainless) steel and/or a nickel-based alloy.

According to a sixth embodiment of the fourth development of the invention, it is provided that the coupling element and the first sensor element are at least mechanically coupled to one another, for example in such a way that the first electrical (measurement) voltage is dependent on the strain of the coupling element or that a change in the strain of the coupling element causes a change in the first electrical (measurement) voltage.

According to a seventh embodiment of the fourth development of the invention, it is provided that the first sensor element is an (integral) component of the coupling element, for example in such a way that the first electrical (measurement) voltage is dependent on the strain of the coupling element or that a change in the strain of the coupling element causes a change in the first electrical (measurement) voltage.

According to an eighth embodiment of the fourth development of the invention, it is further provided that the coupling element is arranged partially within a (housing) connecting piece of the measuring system, which is detachably connected, for example, by means of a flange connection to an electronics (protective) housing of the measuring system and/or is tubular, for example, namely (mechanically) connected (at a nozzle end distal to the electronics housing) to the connecting piece.

According to a ninth embodiment of the fourth development of the invention, it is further provided that the first sensor element is formed by means of at least one (measuring) capacitor, for example designed as a plate capacitor, for example with a (capacitor) electrode geometry that changes depending on the first primary measured variable and/or with a dielectric that changes depending on the first primary measured variable, wherein at least one, for example movable, (capacitor) electrode of the (measuring) capacitor is mechanically connected to the coupling element or is formed by means of the coupling element and/or wherein the coupling element and the second sensor element are at least thermally coupled to one another, for example both thermally and mechanically, for example in such a way that the second electrical (measuring) voltage is dependent on a (coupling element) temperature of the coupling element or that a change in a (coupling element) temperature of the coupling element causes a change in the electrical (sensor) resistance of the second sensor element causes.

According to a fifth development of the invention, the measuring system further comprises an electronics (protective) housing for the measuring system electronics, for example one that is explosion-pressure-resistant (Ex-d) and/or conforms to the international standard IEC 60079-1:2014.

An advantage of the invention is that the measuring current required for determining the second primary measured variable can be switched on or off in a manner optimized for the operation of the measuring system electronics, without impairing the measuring accuracy of the measuring system or its (measured value) update rate.

The invention and advantageous embodiments thereof are explained in more detail below using exemplary embodiments illustrated in the figures of the drawing. Identical or equivalent 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 have been 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.

• 1 in einer perspektivischen Seitenansicht ein Ausführungsbeispiel für ein erfindungsgemäßes Meßsystem;
• 2 schematisch in einer teilweise geschnitten Seitenansicht ein Meßsystem gemäß 1;
• 3 schematisch ein Ausführungsbeispiel für eine für ein Meßsystem gemäß 1 geeignete Meßsystem-Elektronik;
• 4 und in einem Zeitdiagramm Verläufe von Meßspannungen bzw. -strömen in einer Meßsystem-Elektronik gemäß 3.

In detail:

• 1 in a perspective side view an embodiment of a measuring system according to the invention;
• 2 schematically in a partially sectioned side view a measuring system according to 1 ;
• 3 schematically an embodiment of a measuring system according to 1 suitable measuring system electronics;
• 4 and in a time diagram, curves of measuring voltages or currents in a measuring system electronics according to 3 .

In 1 , 2 and 3 is an embodiment of a measuring system for measuring a (time-varying) first primary (process) measured variable, in particular a (static) pressure of a fluid medium (conducted in a line and/or held in a container) and/or a temporal change in the same pressure, as well as a (time-varying) second primary (process) measured variable x2 different from the first primary (process) measured variable x1, in particular a (measured medium) temperature of a fluid medium (conducted in a line), and/or for measuring a (time-varying) secondary (process) measured variable y1 derived from at least one of the first and second primary (process) measured variables, in particular a volume or mass flow of a fluid medium conducted in a line or a fill level of a fluid medium held in a container, for example a gas, a liquid or a Dispersion, shown schematically. The aforementioned line and/or the aforementioned container can, for example, each be designed as a system component of a heat supply network or a turbine cycle, thus the medium can be, for example, steam, in particular saturated steam or superheated steam, or, for example, condensate discharged from a steam line. However, the medium can also be, for example, (compressed) natural gas or biogas or, for example, (drinking) water, thus the pipeline and/or the container can, for example, also be a component of a natural gas or biogas plant or a gas supply network or a water supply network. According to the 1 or 2 In the exemplary embodiment shown, the measuring system can, for example, comprise a (measuring) tube 3 which can be inserted in the course of the aforementioned line, for example also designed as a (rigid) pipeline, with a lumen 3' surrounded by a (metallic) wall 3* of the tube, wherein the tube 3 or its lumen extends from an inlet end 3+ to an outlet end 3# and is designed to guide the measuring medium flowing (in the connected line) during operation of the measuring system or to be flowed through by the same measuring medium in the direction of a main flow direction of the measuring system. In 1 or 2 In the embodiment shown, a flange is provided at the inlet end 3+ as well as at the outlet end 3#, each serving to establish a leak-free flange connection with a corresponding flange on an inlet-side or outlet-side line segment of the line. Furthermore, the pipe 3, as shown in 1 or 2 shown, be essentially straight, for example as a hollow cylinder with at least partially circular cross-section, such that the tube 3 has an imaginary straight longitudinal axis L imaginarily connecting the inlet end 3+ and the outlet end 3#. 1 or 2 The measuring system shown as an example is designed in particular as a (vortex counting) vortex flow meter and accordingly further comprises a bluff body 4 - for example prismatic or cylindrical - arranged within the lumen 3', which is designed to swirl the flowing medium in such a way that vortices with a vortex or shedding frequency fv (fv ∼ u) dependent on a current flow velocity u of the same medium are generated in the medium flowing past it, or a Karman vortex street is formed in the medium flowing downstream of the bluff body 4.

The measuring system according to the invention comprises at least one measuring system electronics 2, which can be operated or is operated, for example, with an energy flow of less than 360 Ws/h and/or with a maximum electrical power of less than 1 W (watt), in particular less than 0.1 W, at least one, for example capacitive and/or passive, first sensor element C1 for detecting the first primary (process) measured variable, at least one, for example resistive, passive second sensor element R1 for detecting the second primary (process) measured variable. Not least for the aforementioned case that the measuring system is designed as a vortex flow meter, the first and second sensor elements can, for example, be provided or set up to detect the first or second primary (process) measured variables of the medium (during operation of the measuring system) downstream of the aforementioned bluff body or from a Karman vortex street formed there, for example in such a way that the first primary (process) measured variable x1 is a (static) pressure fluctuating with a (vortex) shedding rate or frequency (f _V ), in particular proportional to a flow velocity u of the medium, or its change over time and/or the second primary (process) measured variable y1 is a (measured medium) temperature θ of the (swirled) medium.

The measuring system electronics 2 - which can be programmed, for example - can have an interface circuit, particularly designed as a TTY interface, for both wired power supply and wired signal or measurement data transmission, by means of which the measuring system (forming a current loop 2L) can be electrically connected to higher-level evaluation and supply electronics that provide the electrical energy required by the measuring system during operation. For example, the measuring system electronics 2 can be configured to draw electrical power from the aforementioned current loop 2L and to transmit (measurement) data to the evaluation and supply electronics by means of (load) modulation of an electrical (loop) current in the current loop 2L driven by the evaluation and supply electronics, carried out by the interface circuit, for example in the form of a (4-20 mA) standard signal compliant with DIN IEC 60381-1:1985-11. For temporarily storing digital (measurement) data, the measuring system electronics 2 may further comprise, for example, at least one (volatile) digital data memory (RAM).

For electrically connecting the first and second sensor elements C1, R1 to the measuring system electronics 2, which is also formed, for example, by means of at least one microprocessor (µC), the measuring system according to the invention further comprises first, second, third and fourth, in particular non-twisted, electrical connecting lines 401, 402, 403, 404. According to a further embodiment of the invention, each of the first and second connecting lines 401, 402 and/or each of the third and fourth connecting lines 403, 404 is at least partially, for example completely, unshielded, not least for cost reasons, and/or the connecting lines 401, 402, 403, 404 are arranged, not least for space reasons, such that a smallest distance between at least one of the first and second connecting lines 401, 402 and at least one of the third and fourth connecting lines 403, 404 is less than 5 mm. The first and second connecting lines 401, 402 and/or the third and fourth connecting lines 403, 404 can, for example, also be formed at least partially by means of a conductor track arranged on a (flexible) printed circuit board. According to a further embodiment of the invention, the first and second

Connecting lines 401, 402 and/or the third and fourth connecting lines 403, 404 and/or the first and third connecting lines 401, 403 and/or the first and fourth connecting lines 401, 404 run parallel to one another at least in sections, in particular in such a way that the first, second, third and fourth connecting lines 401, 402, 403, 404 run parallel to one another at least in sections.

According to a further embodiment of the invention, the measuring system comprises an electronics (protective) housing 20, for example one that is explosion-proof (Ex-d) and/or conforms to the international standard IEC 60079-1:2014, for accommodating the measuring system electronics 2. A mechanical connection of the electronics (protective) housing to the aforementioned cable or the aforementioned container or also to a sensor (protective) housing of the measuring system can be established, for example, by means of a (housing) connection piece 30 of the measuring system, which itself is detachably connected to the electronics (protective) housing 20 by means of a flange connection and/or is tubular. In this case, the first, second, third and fourth connecting lines 401, 402, 403, 404 can also be routed at least partially within the (housing) connecting piece 30, for example in such a way that they run parallel to one another at least in sections within the (housing) connecting piece 30 and/or adjacent connecting lines 401, 402, 403, 404 have at least in sections only a small distance of less than 5 mm. Not least for the aforementioned case that the measuring system is housed in the aforementioned electronics (protective) housing 20 and/or that the first, second, third and fourth connecting lines are at least partially guided within the (housing) connection piece 30 connected to the same electronics (protective) housing 20, the measuring system according to a further embodiment of the invention further comprises at least one (electrical) bushing 50, for example explosion-pressure-resistant (Ex-d) and/or compliant with the international standard IEC 60079-1:2014. Advantageously, the first, second, third and fourth connecting lines can be guided in sections within the bushing 50 and/or the bushing 50 can be interposed between the first, second, third and fourth connecting lines 401, 402, 403, 404. According to a further embodiment of the invention, the feedthrough 50 has, for example, unshielded, (connection) pins and the feedthrough 50 is electrically connected to the first, second, third and fourth connecting lines 401, 402, 403, 404 by means of one of the (connection) pins each.

As in the 2 or schematically shown in Figure 3, the first sensor element C1 is electrically connected to the measuring system electronics 2 by means of the first and second connecting lines 401, 402 (forming a first measuring channel of the measuring system) and the second sensor element R1 is electrically connected to the measuring system electronics 2 by means of the first and second connecting lines 403, 404 (forming a second measuring channel of the measuring system), for example also (in each case) with the interposition of the possibly required (housing) feedthrough 50. In addition, the first sensor element C1 of the measuring system according to the invention is in particular configured (in conjunction with the measuring system electronics) to generate and/or adjust a first electrical (measurement) voltage u1 dependent on the first primary (process) measured variable x1, and the measuring system electronics 2 is configured to temporarily detect and evaluate said first electrical (measurement) voltage u1, for example, namely to digitize it and/or to generate a (digital) to determine first (voltage) measured values Xu1. Not least for the aforementioned case in which the measuring system is designed as a vortex flow meter, the measuring system electronics 2 can also be configured, for example, to determine, based on at least the first electrical (measurement) voltage u1, measured values for a frequency (f _V ) (serving as a secondary measured variable) of at least temporarily periodic pressure fluctuations within the fluid medium, in particular pressure fluctuations within the aforementioned Karman vortex street. According to a further embodiment of the invention, the first sensor element C1 is designed for this purpose as a capacitive sensor element (having at least one measuring capacitor). In particular, the first sensor element C1 has an electrical (sensor) capacitance, particularly at a temperature of 20°C, of not less than 10 pF (picofarads) and/or not more than 100 pF and/or composed of two or more partial capacitances, and the first sensor element is further configured to follow a change in the first primary (process) measured variable x1 with a change in the same (sensor) capacitance. Accordingly, the first sensor element C1 can, for example, also be formed by at least one plate capacitor, particularly with a (capacitor) electrode geometry that changes depending on the first primary measured variable x1 and/or with a dielectric that changes depending on the first primary measured variable x1. To generate the first electrical (measurement) voltage u1, the measuring system electronics are further configured to at least temporarily charge or maintain the same capacitance of the first sensor element C1 charged; This is also done, for example, in such a way that the first electrical (measurement) voltage u1 is (essentially) proportional to an electrical charge of the (sensor) capacitance of the first sensor element C1. The second sensor element R1, in turn, has an electrical (sensor) resistance of not less than 90 Ω and/or not more than 1.1 kΩ, in particular at a temperature of 20°C, and is also designed to follow a change in the second primary measured variable x2 with a change in the same (sensor) resistance. According to a further embodiment of the invention, the second sensor element R1 is formed by means of at least one platinum measuring resistor, for example a Pt100 and/or a Pt1000.

In the measuring system according to the invention, the measuring system electronics 2 is further configured to temporarily energize the second sensor element R1 in order to temporarily cause a voltage drop across the second sensor element R1, namely, as also in 4 shown, during a predetermined first (energization) time interval t1, for example, lasting not less than 100 ms (milliseconds), to drive an electrical (measurement) current through the second sensor element R1 and the third and fourth connecting lines 403, 404, in particular an impressed and/or constant current and/or having a maximum current of not less than 0.1 mA (milliampere) and/or converting a maximum electrical power of not less than 0.4 mW (milliwatt) in the second sensor element R1, and during a second time interval t2 preceding the first time interval t1 and a third time interval t3 following the first (energization) time interval t1, not to energize the second sensor element R1, in particular to save electrical power or energy, or to drive no (measurement) current through the second sensor element R1 and the third and fourth connecting lines 403, 404 to drive; This is particularly true in that the (measurement) current i2, as in 4 schematically shown, at least during a fourth (transition) time interval t4, which (immediately) follows the second time interval t2 and (immediately) precedes the first (current supply) time interval t1, for example, lasting not less than 1 µs (microsecond), a (rising) first current edge, for example with a current rise rate that is at least temporarily and/or on average (arithmetic time) not less than 0.1 mA/µs (milliamperes per microsecond), and that the (measurement) current i2, at least during a fifth (transition) time interval t5, which (immediately) follows the first (current supply) time interval t1 and (immediately) precedes the third time interval t3, for example, lasting not less than 1 µs (microsecond), a (falling) second current edge, for example with a and/or a current drop rate which, on an (arithmetic) average over time, is not less than 0.1 mA/µs. Furthermore, the measuring system electronics 2 are configured to detect and evaluate, at least during the first (current supply) time interval t1, a second electrical (measurement) voltage u2 which is dependent on the voltage drop across the second sensor element R1, for example, to digitize it and/or to determine (digital) second (voltage) measured values Xu2 representing the second (measurement) voltage u2. In addition, the measuring system electronics 2 is further configured to determine, based on at least the first electrical (measurement) voltage u1, for example also based on both the first electrical (measurement) voltage u1 and the second electrical (measurement) voltage u2, one or more (digital) measured values for the first primary (process) measured variable x1 and/or one or more (digital) measured values for the secondary (process) measured variable y1, in particular to determine them and output them as (qualified) measured values X _M of the measuring system. According to a further embodiment of the invention, the measuring system electronics 2 is in particular also configured to electrically charge or maintain the capacitance of the first sensor element C1 at least during the second and third time intervals in order to generate the first electrical (measurement) voltage u1, and/or the measuring system electronics 2 is configured to determine the sensor resistance of the second sensor element R1 based on the second (measurement) voltage u2. Advantageously, the measuring system electronics 2 can also be configured to (temporarily) store (voltage) measured values Xu1 representing the first (measurement) voltage u1, for example, to (temporarily) store the same (voltage) measured values u1 in the aforementioned (volatile) digital data memory and/or to determine one or more measured values for the second primary (process) measured variable x2 using one or more of the same (voltage) measured values. Alternatively or in addition, the measuring system electronics 2 can also be configured to determine (voltage) measured values Xu2 representing the second (measurement) voltage u2, for example in order to (temporarily) store the same (voltage) measured values Xu2 in the aforementioned (volatile) digital data memory and/or to determine one or more measured values for the first and/or second primary (process) measured variables x2 and/or for the secondary (process) measured variable y1 using one or more of the same (voltage) measured values Xu2.

According to a further embodiment of the invention, the measuring system electronics 2 is also configured to determine one or more (digital) measured values for the second primary (process) measured variable x2 based on the second electrical (measurement) voltage u2, for example, to store the same measured values in the aforementioned (volatile) digital data memory and/or to serve as an auxiliary measured value for determining at least one measured value for the secondary and/or first primary (process) measured variables. Alternatively or additionally, the measuring system electronics 2 can advantageously also be configured to determine one or more measured values for the first primary (process) measured variable x1 using one or more measured values for the second primary (process) measured variable x2. Not least for the aforementioned case that the measuring system is designed as a vortex flow meter, the measuring system electronics 2 can, for example, be set up to determine measured values for a (measuring medium) temperature θ of a (flowing) fluid measuring medium, which serves as a second primary measured variable x2, based on at least the second electrical (measuring) voltage u2 and/or the measuring system electronics 2 can be set up to determine measured values for a volume flow v (serving as a secondary measured variable) and/or a mass flow m (serving as a secondary measured variable) of a flowing (fluid) measuring medium and/or measured values for a (static) pressure p (serving as a first primary measured variable x1) of a (flowing) fluid measuring medium, based on the first and second electrical (measuring) voltages.

To provide the first electrical (measurement) voltage u1, the measuring system electronics 2, according to a further embodiment of the invention, has at least one operational amplifier OP, for example, a FET or a CMOS operational amplifier. Furthermore, the first sensor element C1 is electrically connected to a (high-impedance) (voltage) input of the operational amplifier OP by means of the first and second connecting lines 401, 402, in particular forming a charge-voltage converter of the measuring system electronics 2, and the operational amplifier is a directed (with the measuring system electronics operating in the first operating mode) to supply the first electrical (measurement) voltage u1 at a (voltage) output. For this purpose, the operational amplifier OP can, for example, also have a (feedback) capacitor Cf that feeds back its (voltage) output to its (voltage) input, in particular a switched (feedback) capacitor, for example with a (feedback) capacitance that is not less than 0.1 pF and/or not more than 100 pF.

To provide the second electrical (measurement) voltage u2, the measuring system electronics 2, according to a further embodiment of the invention, has at least one, for example also switchable, (electronic) current source. In addition, the second sensor element R1 is electrically connected to a (current) output of the current source by means of the third and fourth connecting lines 403, 404, and the current source is configured to supply the (measurement) current i2, in particular such that the (measurement) current is an impressed current or is regulated to a setpoint value. Instead of the aforementioned current source, the measuring system electronics 2 can, for example, also have at least one, possibly also switchable (electronic) voltage source VREF, which - as also in 3 schematically shown - with an output and by means of the third and fourth connecting lines 403, 404 is electrically connected to the second sensor element R1 and configured to drive the (measurement) current i2 or to supply an (impressed) voltage driving the (measurement) current i2. Alternatively or additionally, the measuring system electronics 2 can further comprise at least one (reference) resistance element R2 having an electrical (reference) resistance, in particular at a temperature of 20°C not less than 1000 Ω and/or not more than 10 kΩ, which is electrically connected to the second sensor element R1, in particular electrically connected in series with the second sensor element R1. In addition, the measuring system electronics 2 can be configured to detect and evaluate, in particular, a third electrical (reference) voltage u3 dependent on a voltage drop across the (reference) resistance element R2 during the first (current supply) time interval, and/or to digitize it and/or determine (digital) third voltage measurement values representing the reference voltage u3. Furthermore, the measuring system electronics can advantageously be configured to determine the (sensor) resistance of the second sensor element R1 based on the third (reference) voltage u3, for example, based on the second and third voltages u2, u3 and the (reference) resistance and/or ratiometrically.

Not least for the aforementioned case that the connecting lines 401, 402, 403, 404 are at least partially unshielded and a smallest distance between at least one of the first and second connecting lines and at least one of the third and fourth connecting lines is less than 5 mm, at least one, in particular each, of the first and second connecting lines 401, 402 is (signal-)coupled to at least one, in particular each, of the third and fourth connecting lines 403, 404; this in particular capacitively and/or in such a way that the aforementioned (measurement) current i2 flowing, among other things, through the third and fourth connecting lines 403, 404, or its temporal changes can cause or cause (voltage) disturbances in the first and second measuring lines 401, 402, and thus in the first electrical (measurement) voltage u1. In order to minimize or avoid any interference voltages caused by such (signal) coupling from the third and/or fourth connecting lines 403, 404 into the first and/or second connecting lines 401, 402, in particular but also any associated measurement errors in measured values determined for the first measured variable x1, the measuring system electronics 2 in the measuring system according to the invention is further configured not to output a (qualified) measured value X _M for the secondary and/or first primary (process) measured variables determined on the basis of the first (measurement) voltage detected during the fourth and fifth (transition) time intervals, or not to determine a measured value for the secondary and/or first primary (process) measured variables based on the first electrical (measurement) voltage present during the fourth and fifth (transition) time intervals. Alternatively or additionally, the measuring system electronics in the measuring system according to the invention can also be configured to determine (qualified) measured values for the secondary and/or first primary (process) measured variables during the fourth (transition) time interval based on a first (measurement) voltage u1 previously acquired during the second time interval and/or to determine (qualified) measured values for the secondary and/or first primary (process) measured variables during the fifth (transition) time interval based on a first (measurement) voltage u1 previously acquired during the first time interval t1. According to a further embodiment of the invention, the measuring system electronics 2 is also configured to determine, in particular to determine and output, (qualified) measured values X _M for the secondary and/or first primary (process) measured variables based on a first (measurement) voltage u1 previously acquired during the (energization) time interval t1. Alternatively, if necessary, for example to reduce the converted electrical power and/or to avoid measurement errors, the measuring system electronics 2 can also be set up, for example, not to use a (qualified) measured value for the secondary and/or first primary (process) measured variable x1 based on the first (measurement) voltage u1 recorded during the (current supply) time interval t1. to output and/or not to determine any measured value for the secondary and/or first primary (process) measured variables based on the first electrical (measurement) voltage u1 present during the (current supply) time interval. Furthermore, the measuring system electronics 2 can advantageously also be configured to determine one or more (digital) measured values for the second primary (process) measured variable x2 based on at least the second electrical (measurement) voltage u2, in particular based on both the second electrical (measurement) voltage u2 and the first electrical (measurement) voltage u1 determined in the manner described above, in particular also to output them as qualified measured values of the measuring system 2.

For the (leakage-free or fluid-tight) connection of the measuring system to a process containing or conducting the medium, in particular in such a way that an operative relationship (resulting in measuring effects) between the (fluid) medium and at least the first and second sensor elements can be established or is established during operation of the measuring system, the measuring system according to a further embodiment of the invention further comprises a (process) coupling element 11, formed for example by means of a membrane and/or a sleeve and/or a plate. According to a further embodiment of the invention, the coupling element consists at least partially, for example completely, of metal, in particular a (stainless) steel and/or a nickel-based alloy. The coupling element 11 is particularly designed to be contacted by the aforementioned medium (during operation of the measuring system), for example to be flowed against and/or around; This is particularly the case in such a way that the (process) coupling element 11 has a (coupling element) temperature dependent on a (measuring medium) temperature of the measuring medium and/or an (elastic) expansion dependent on a (measuring medium) pressure. Accordingly, according to a further embodiment, the aforementioned coupling element is also particularly configured to react to a change in a (measuring medium) pressure of the measuring medium with an expansion, for example, also biaxial and/or elastic, and to a change in a (measuring medium) temperature of the measuring medium with a change in a (coupling element) temperature, for example also in such a way that the (coupling element) temperature of the coupling element deviates from a stationary (measuring medium) temperature of the measuring medium by less than 2 K (Kelvin). For example, the coupling element 11 can be configured to be inserted at least partially into a lumen (3') of a tube (3) (serving to guide a fluid measuring substance), in particular through an opening (3a) in a tube wall (3*) surrounding the lumen into the lumen and to be fixed (removably) to the same tube wall. Not least for the aforementioned case in which the measuring system is designed as a vortex flow meter, the coupling element 11, as also in 2 schematically shown, for example, as a sensor flag projecting into the lumen 3' of the aforementioned tube 3. Alternatively, the coupling element 11 can, for example, also be configured to be inserted at least partially into a lumen of a container (used to guide a fluid measuring substance), in particular a tank, in particular through an opening in a container wall enclosing the lumen into the lumen and to be fixed (removably) to the same container wall. For the aforementioned case in which the measuring system has a connecting piece 30, the coupling element 11 can, for example, also be arranged partially within the connecting piece and/or be (mechanically) connected to the connecting piece, for example at a piece end distal to the aforementioned electronics housing 20. According to a further embodiment of the invention, the coupling element 11 and the first sensor element C1 are at least mechanically coupled to one another, or the first sensor element C1 is designed as an (integral) component of the coupling element 11; this is particularly the case in such a way that (during operation of the measuring system) the first electrical (measurement) voltage u1 is dependent at least on the strain of the coupling element 11, or that a change in the strain of the coupling element 11 causes a change in the first electrical (measurement) voltage u1. For the aforementioned case in which the first sensor element 11 is formed by means of at least one (measurement) capacitor designed as a plate capacitor, at least one (capacitor) electrode of the (measurement) capacitor, for example a movable (capacitor) electrode, can be mechanically connected to the coupling element or formed by means of the coupling element. According to a further advantageous embodiment of the invention, the coupling element 11 and the second sensor element R1 can also be coupled to one another at least thermally, in particular both thermally and mechanically; this in particular also in such a way that the second electrical (measurement) voltage u2 is dependent at least on a (coupling element) temperature of the coupling element or that a change in a (coupling element) temperature of the coupling element causes a change in the electrical (sensor) resistance of the second sensor element R1.

QUOTES CONTAINED IN THE DESCRIPTION

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

• US-A 2003/0061887 [0002, 0005, 0007]
• US-A 2004/0216532 [0002, 0005, 0007]
• US-A 2009/0038406 [0002, 0005, 0007]
• US-A 2022/0057240 [0002, 0005, 0007]
• WO-A 2004/023081 [0002]
• WO-A 2022/128418 [0002, 0007]
• DE 102022127160.9 [0002]

Claims (38)

Measuring system for measuring a (time-varying) first primary (process) measured variable (x1), in particular a (static) pressure of a fluid medium (conducted in a line and/or held in a container) and/or a temporal change in the same pressure, as well as a (time-varying) second primary (process) measured variable (x2) different from the first primary (process) measured variable, in particular a temperature of a fluid medium (conducted in a line), and/or for measuring a (time-varying) secondary (process) measured variable (y1) derived from at least one of the first and second primary (process) measured variables, in particular a mass flow of a fluid medium conveyed in a line or a fill level of a fluid medium held in a container, which measuring system comprises: - a, in particular with a maximum electrical power of less than 1 W (watt) operated and/or measuring system electronics (2) connected to a (4-20 mA) 2-wire line; - at least one, in particular capacitive and/or passive, first sensor element (C1) for detecting the first primary (process) measured variable; - at least one, in particular resistive, passive second sensor element (R1) for detecting the second primary (process) measured variable; - as well as first, second, third and fourth, in particular each (at least) partially unshielded and/or not twisted together, electrical connecting lines (401, 402, 403, 404); - wherein the first sensor element is electrically connected to the measuring system electronics (2) by means of the first and second connecting lines (forming a first measuring channel of the measuring system), in particular with the interposition of a feedthrough (50); - wherein the second sensor element is electrically connected to the measuring system electronics by means of the third and fourth connecting lines (forming a second measuring channel of the measuring system), in particular with the interposition of a feedthrough (50), - and wherein at least one, in particular each, of the first and second connecting lines (401, 402) is (signal-)coupled to at least one, in particular each, of the third and fourth connecting lines (403, 404), in particular capacitively, in particular in that a smallest distance between at least one of the first and second connecting lines and at least one of the third and fourth connecting lines is less than 5 mm; - wherein the first sensor element (C1) is configured, in particular in conjunction with the measuring system electronics, to generate and/or adjust a first electrical (measurement) voltage (u1) dependent on the first primary (process) measured variable (x1), - and wherein the second sensor element (R1) has an electrical (sensor) resistance, in particular at a temperature of 20°C, of not less than 90 Ω and/or not more than 1.1 kΩ, and is configured to follow a change in the second primary measured variable (x2) with a change in the same resistance; - wherein the measuring system electronics is configured to temporarily detect and evaluate the first electrical (measurement) voltage (u1), in particular to digitize it and/or to determine (digital) first (voltage) measured values (Xu1) representing the (measurement) voltage; - wherein the measuring system electronics are configured to temporarily energize the second sensor element to temporarily cause a voltage drop across the second sensor element, namely, during a predetermined first (energization) time interval (t1), in particular lasting no less than 10 ms, to drive an electrical (measurement) current (i2), in particular an impressed and/or constant current and/or having a maximum current of no less than 0.1 mA and/or converting a maximum electrical power of no less than 0.4 mW in the second sensor element, through the second sensor element and the third and fourth connecting lines, and not to energize the second sensor element or to drive no (measurement) current through the second sensor element and the third and fourth connecting lines during a second time interval (t2) preceding the first (energization) time interval and a third time interval (t3) following the first (energization) time interval, such that the (measurement) current has a (rising) first current edge, in particular with a current rise rate that is at least temporarily and/or on an (arithmetic) average over time not less than 0.1 mA/µs, at least during a fourth (transition) time interval (t4) that (immediately) follows the second time interval and (immediately) precedes the first (energization) time interval, in particular lasting not less than 1 µs (microsecond), and that the (measurement) current has a (falling) second current edge, in particular with a current rise rate that is at least temporarily and/or on an (arithmetic) average over time not less than 0.1 mA/µs, at least during a fifth (transition) time interval (t5) that (immediately) follows the first (energization) time interval and (immediately) precedes the third time interval, in particular lasting not less than 1 µs (microsecond), (arithmetic) mean current drop rate of not less than 0.1 mA/µs, -- and wherein the measuring system electronics are set up to detect and evaluate a second electrical (measurement) voltage (u2) dependent on the voltage drop across the second sensor element during the first (current supply) time interval (t1), in particular namely to digitize and/or to determine (digital) second (voltage) measured values (Xu2) representing the (measurement) voltage; - wherein the measuring system electronics are configured, based on at least the first electrical (measurement) voltage (u1), in particular based on both the first electrical (measurement) voltage and the second electrical (measurement) voltage (u2), to determine one or more (digital) measured values for the first primary (process) measured variable (x1) and/or one or more (digital) measured values for the secondary (process) measured variable, in particular to determine them and output them as qualified measured values (X _M ) of the measuring system, - and wherein the measuring system electronics are configured, in particular to avoid measurement errors in measured values determined for the first measured variable (x1) caused by (signal) coupling from the third and/or fourth connecting lines into the first and/or second connecting lines: -- no (digital) measured values determined based on the first (measurement) voltage (u1) detected during the fourth and fifth (transition) time intervals to output a (qualified) measured value for the first primary (process) measured variable, -- and/or not to determine a measured value for the first primary (process) measured variable (x1) based on the first electrical (measurement) voltage (u1) present during the fourth and fifth (transition) time intervals, -- and/or not to output a (qualified) measured value for the secondary (process) measured variable (y1) determined based on the first (measurement) voltage (u1) recorded during the fourth and fifth (transition) time intervals, -- and/or not to determine a measured value for the secondary (process) measured variable (y1) based on the first electrical (measurement) voltage (u1) present during the fourth and fifth (transition) time intervals, -- and/or during the fourth (transition) time interval (qualified) measured values (X _M ) for the first primary (Process) measured variable (x1) and/or for the secondary (process) measured variable (y1) based on a first (measurement) voltage previously recorded during the second time interval, -- and/or during the fifth (transition) time interval (qualified) measured values (X _M ) for the first primary (process) measured variable (x1) and/or for the secondary (process) measured variable (y1) based on a first (measurement) voltage (u1) previously recorded during the first time interval (t1). Measuring system according to Claim 1 , wherein the measuring system electronics are set up: -- not to output a (qualified) measured value for the first primary (process) measured variable determined on the basis of the first (measurement) voltage detected during the (current supply) time interval, -- and/or not to determine a measured value for the first primary (process) measured variable based on the first electrical (measurement) voltage present during the (current supply) time interval, -- and/or not to output a (qualified) measured value for the secondary (process) measured variable determined on the basis of the first (measurement) voltage detected during the (current supply) time interval, -- and/or not to determine a measured value for the secondary (process) measured variable based on the first electrical (measurement) voltage present during the (current supply) time interval. Measuring system according to Claim 1 , wherein the measuring system electronics are set up: -- to determine (qualified) measured values for the first primary (process) measured variable and/or for the secondary (process) measured variable based on a first (measurement) voltage detected during the first time interval; -- and/or to output (qualified) measured values for the first primary (process) measured variable and/or for the secondary (process) measured variable determined based on a first (measurement) voltage detected during the (current supply) time interval. Measuring system according to one of the preceding claims, - wherein the first sensor element has an electrical (sensor) capacitance, in particular at a temperature of 20°C, of not less than 10 pF and/or not more than 100 pF, and is configured to follow a change in the first primary (process) measured variable with a change in the same (sensor) capacitance, - and wherein the measuring system electronics are configured to electrically charge or maintain the capacitance of the first sensor element, in particular at least during the second and third time intervals, in order to generate the first electrical (measurement) voltage. Measuring system according to the preceding claim, wherein the first electrical (measurement) voltage is (substantially) proportional to an electrical charge of the (sensor) capacitance of the first sensor element. Measuring system according to one of the preceding claims, wherein the measuring system electronics are configured to determine (voltage) measured values representing the first (measurement) voltage, in particular to determine them and to store them in a (volatile) digital data memory. Measuring system according to the preceding claim, wherein the measuring system electronics are configured to determine one or more measured values for the second primary (process) measured variable using one or more (voltage) measured values representing the first (measurement) voltage. Measuring system according to one of the preceding claims, wherein the measuring system electronics are configured to determine (voltage) measured values representing the second (measurement) voltage, in particular to determine them and to store them in a (volatile) digital data memory. Measuring system according to the preceding claim, - wherein the measuring system electronics are configured to determine one or more measured values for the first primary (process) measured variable using one or more (voltage) measured values representing the second (measurement) voltage; and/or - wherein the measuring system electronics are configured to determine one or more measured values for the first secondary (process) measured variable using one or more (voltage) measured values representing the second (measurement) voltage; and/or - wherein the measuring system electronics are configured to determine one or more measured values for the second primary (process) measured variable using one or more (voltage) measured values representing the second (measurement) voltage. Measuring system according to one of the preceding claims, wherein the measuring system electronics are configured, based on the second electrical (measurement) voltage, to determine one or more (digital) measured values for the second primary (process) measured variable, in particular for determining at least one measured value for the first primary (process) measured variable and/or the secondary (process) measured variable, each serving as an auxiliary measured value, in particular to determine them and to store them in a (volatile) digital data memory. Measuring system according to the preceding claim, wherein the measuring system electronics are configured to determine one or more measured values for the first primary (process) measured variable using one or more measured values for the second primary (process) measured variable. Measuring system according to one of the preceding claims, wherein the measuring system electronics are configured to determine, based on at least the second electrical (measurement) voltage, in particular based on both the second electrical (measurement) voltage and the first electrical (measurement) voltage, one or more (digital) measured values for the second primary (process) measured variable, in particular to determine them and output them as qualified measured values of the measuring system. Measuring system according to one of the preceding claims, - wherein each of the first and second connecting lines is at least partially, in particular completely, unshielded; and/or - wherein each of the third and fourth connecting lines is at least partially, in particular completely, unshielded; and/or - wherein each of the first and second connecting lines is at least partially formed by a conductor track arranged on a (flexible) printed circuit board; and/or - wherein each of the third and fourth connecting lines is at least partially formed by a conductor track arranged on a (flexible) printed circuit board; and/or - wherein each of the first, second, third, and fourth connecting lines is at least partially formed by a conductor track arranged on one and the same (flexible) printed circuit board; and/or - wherein the first and second connecting lines run parallel to one another at least in sections; and/or - wherein the third and fourth connecting lines run parallel to one another at least in sections; and/or - wherein the first and third connecting lines run parallel to one another at least in sections; and/or - wherein the first and fourth connecting lines run parallel to one another at least in sections; and/or - wherein the first, second, third, and fourth connecting lines run parallel to one another at least in sections. Measuring system according to one of the preceding claims, - wherein the measuring system electronics comprises at least one operational amplifier, in particular a FET or CMOS operational amplifier; - wherein the first sensor element is electrically connected to a (high-impedance) (voltage) input of the operational amplifier by means of the first and second connecting lines, in particular forming a charge-to-voltage converter of the measuring system electronics; - and wherein the operational amplifier is configured to supply the first electrical (measurement) voltage at a (voltage) output (when the measuring system electronics is operating in the first operating mode). Measuring system according to the preceding claim, wherein the operational amplifier has a (feedback) capacitor (Cf) which feeds back its (voltage) output to its (voltage) input, in particular a switched (feedback) capacitor. Measuring system according to the preceding claim, wherein the (feedback) capacitor (Cf) has a (feedback) capacitance which is not less than 0.1 pF and/or not more than 100 pF. Measuring system according to one of the Claims 1 until 16 , - wherein the measuring system electronics comprises at least one, in particular switchable, (electronic) current source; - wherein the second sensor element is electrically connected to a (current) output of the current source by means of the third and fourth connecting lines; - and wherein the current source is configured to supply the (measurement) current. Measuring system according to one of the Claims 1 until 16 , - wherein the measuring system electronics comprises at least one, in particular switchable, (electronic) voltage source; - wherein the second sensor element is electrically connected to an output of the voltage source by means of the third and fourth connecting lines; - and wherein the voltage source is configured to drive the (measurement) current. Measuring system according to one of the preceding claims, wherein the measuring system electronics are configured to determine the sensor resistance of the second sensor element based on the second (measurement) voltage. Measuring system according to one of the preceding claims, wherein the measuring system electronics comprises at least one (reference) resistance element having an electrical (reference) resistance, in particular at a temperature of 20°C (degrees Celsius) not less than 90 Ω (ohms) and/or not more than 1.1 kΩ (kiloohms), which is electrically connected to the second sensor element, in particular electrically connected in series with the second sensor element. Measuring system according to the preceding claim, wherein the measuring system electronics are configured to detect and evaluate, in particular to digitize and/or to determine (digital) third voltage measurement values representing the reference voltage, an electrical third (reference) voltage dependent on a voltage drop across the (reference) resistance element during the first (current supply) time interval. Measuring system according to the preceding claim, wherein the measuring system electronics are configured to determine the (sensor) resistance of the second sensor element based on the third (reference) voltage, in particular based on the second and third voltages as well as the (reference) resistance and/or ratiometrically. Measuring system according to one of the preceding claims, further comprising: at least one (electrical) feedthrough (50), in particular explosion-pressure-resistant (Ex-d) and/or compliant with the international standard IEC 60079-1:2014. Measuring system according to the preceding claim, - wherein the first, second, third, and fourth connecting lines are routed in sections within the feedthrough (50); and/or - wherein the feedthrough is electrically connected to the first, second, third, and fourth connecting lines, in particular by means of unshielded (connecting) pins; and/or - wherein the feedthrough is interposed between the first, second, third, and fourth connecting lines. Measuring system according to one of the preceding claims, further comprising: an electronics (protective) housing (20) for the measuring system electronics (2), in particular an electronics housing that is explosion-proof (Ex-d) and/or conforms to the international standard IEC 60079-1:2014. Measuring system according to the preceding claim, further comprising: a (housing) connection piece (30), in particular detachably connected to the electronics (protective) housing by means of a flange connection and/or tubular. Measuring system according to the preceding claim, wherein the first, second, third and fourth connecting lines are guided at least partially within the (housing) connection piece, in particular running parallel to one another at least in sections. Measuring system according to one of the preceding claims, further comprising: a (process) coupling element (11), in particular formed by means of a membrane and/or a sleeve and/or a plate, which is designed to be contacted by a fluid measuring substance (during operation of the measuring system), in particular to be flowed against and/or around, in particular in such a way that the (process) coupling element (11) has a (coupling element) temperature dependent on a (measuring substance) temperature of the measuring substance and/or that the (process) coupling element has an (elastic) expansion dependent on a (measuring substance) pressure. Measuring system according to the preceding claim, - wherein the coupling element is configured to react to a change in a (measuring substance) temperature of the measuring substance with a change in a (coupling element) temperature, in particular such that the (coupling element) temperature of the coupling element deviates stationary from a stationary (measuring substance) temperature of the measuring substance by less than 2 K (Kelvin); and/or - wherein the coupling element is configured to react to a to react to a change in the (measuring medium) pressure of the measuring medium with a, in particular biaxial and/or elastic, expansion; and/or - wherein the coupling element is designed to be inserted at least partially into a lumen of a tube (used to guide a fluid measuring medium), in particular namely through an opening in a tube wall surrounding the lumen into the lumen and to be (releasably) fixed to the same tube wall; and/or - wherein the coupling element is designed to be inserted at least partially into a lumen of a container (used to guide a fluid measuring medium), in particular a tank, in particular namely through an opening in a container wall surrounding the lumen into the lumen and to be (releasably) fixed to the same container wall; and/or - wherein the coupling element consists at least partially, in particular completely, of metal, in particular a (stainless) steel and/or a nickel-based alloy. Measuring system according to Claim 28 or 29 , wherein the coupling element and the first sensor element are at least mechanically coupled to one another, in particular in such a way that the first electrical (measurement) voltage is dependent on the strain of the coupling element or that a change in the strain of the coupling element causes a change in the first electrical (measurement) voltage. Measuring system according to Claim 28 or 29 , wherein the first sensor element is an (integral) component of the coupling element, in particular such that the first electrical (measurement) voltage is dependent on the strain of the coupling element or that a change in the strain of the coupling element causes a change in the first electrical (measurement) voltage. Measuring system according to Claim 26 in connection with one of the Claims 28 until 31 - wherein the coupling element is (mechanically) connected to the connecting piece, in particular at a piece end distal to the electronics housing; and/or - wherein the coupling element (11) is arranged partially within the connecting piece (30). Measuring system according to one of the preceding claims, wherein the first sensor element (C1) is formed by means of at least one (measuring) capacitor, in particular designed as a plate capacitor, in particular with a (capacitor) electrode geometry changing as a function of the first primary measured variable and/or with a dielectric changing as a function of the first primary measured variable. Measuring system according to Claim 33 in conjunction with one of the Claims 28 until 32 , wherein at least one, in particular movable, (capacitor) electrode of the (measuring) capacitor is mechanically connected to the coupling element or is formed by means of the coupling element. Measuring system according to one of the Claims 28 until 33 , wherein the coupling element (11) and the second sensor element (R1) are coupled to one another at least thermally, in particular both thermally and mechanically, in particular in such a way that the second electrical (measurement) voltage is dependent on a (coupling element) temperature of the coupling element or that a change in a (coupling element) temperature of the coupling element causes a change in the electrical (sensor) resistance of the second sensor element. Measuring system according to one of the preceding claims, wherein the second sensor element (R1) is formed by means of at least one platinum measuring resistor, in particular a Pt100 and/or a Pt1000. Measuring system according to one of the preceding claims, - wherein the measuring system electronics are configured to determine, based on at least the first electrical (measurement) voltage, measured values for a frequency (serving as a secondary measured variable) of at least temporarily periodic pressure fluctuations within a fluid medium, in particular pressure fluctuations within a Karman vortex street formed in a flow of the medium; and/or - wherein the measuring system electronics are configured to determine, based on at least the second electrical (measurement) voltage, measured values for a (measurement) temperature of a, in particular a flowing, fluid medium (serving as a second primary measured variable); and/or - wherein the measuring system electronics are configured to determine, based on the first and second electrical (measurement) voltages, measured values for a (static) pressure of a (flowing) fluid medium (serving as a first primary measured variable); and/or - wherein the measuring system electronics are configured to determine measured values for a volume flow of a flowing (fluid) medium (serving as a secondary measured variable) based on the first and second electrical (measurement) voltages; and/or - wherein the measuring system electronics are configured to determine measured values for a mass flow of a flowing (fluid) medium (serving as a secondary measured variable) based on the first and second electrical (measurement) voltages. Use of a measuring system according to one of the preceding claims for measuring both a first primary (process) measured variable, in particular a time-varying (static) pressure, and a second primary (process) measured variable (different from the first measured variable), in particular a time-varying temperature, of a fluid measuring substance (conducted in a line or held in a container).

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