Method for determining a physical and/or chemical, temperature dependent, process variable

A technology for determining process and process variables, applied in the field of process variables, to solve problems such as unpredictable drift

Active Publication Date: 2015-03-25
ENDRESS HAUSER CONDUCTA GESELLSCHAFT FUER MESS UND REGELTECHNIK MBH CO KG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Drift is usually unpredictable

Method used

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  • Method for determining a physical and/or chemical, temperature dependent, process variable
  • Method for determining a physical and/or chemical, temperature dependent, process variable
  • Method for determining a physical and/or chemical, temperature dependent, process variable

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Embodiment Construction

[0037] The following will be based on figure 1 The conductivity sensor 1 shown is used to explain the invention. However, the basic idea is equally applicable to other types of sensors for measuring physical or chemical process variables. These sensors are mainly used in the field of process automation. A wide variety of sensors are therefore available for measuring various parameters of the medium 5 , these parameters being generally temperature-dependent. In this regard, the sensor is positioned, or partially positioned, in the medium 5 to be measured or at least in contact with the medium 5 to be measured. Traditional sensors include, in this case, pH-, oxidation-, turbidity-, amino-, chloride- and conductivity sensors, among others. The basic principles of conductivity sensors are known. The measurement of conductivity is highly temperature dependent, therefore, each conductivity sensor also includes a resistance thermometer R Pt1000 Used to determine the temperature ...

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Abstract

A method for determining a physical and / or chemical, temperature dependent, process variable of process automation technology utilizing a resistance thermometer, wherein the resistance thermometer is installed in an electrical circuit, comprising the steps of: measuring a first voltage across at least a first precision resistor; measuring a second voltage across at least a second precision resistor; measuring a third voltage across at least a third precision resistor, wherein cyclically or continuously a constant electrical current is sent through the at least first precision resistor, the at least second precision resistor or the at least third precision resistor; determining temperature coefficients characteristic for the electrical circuit by means of the first voltage, the second voltage and the third voltage; sending the constant electrical current through the resistance thermometer and measuring a voltage across the resistance thermometer; and determining the temperature by means of the temperature coefficients and the measured voltage. An electrical circuit and a sensor of process automation technology, especially a conductivity sensor, comprising such an electrical circuit are also discussed.

Description

technical field [0001] The invention relates to a method for determining a physical and / or chemical temperature-dependent process variable in process automation technology using a resistance thermometer. The invention further relates to an electrical circuit and to a sensor of process automation technology, in particular a conductivity sensor comprising such an electrical circuit. Background technique [0002] Pure metals show a larger change in resistance than alloys and have a relatively constant temperature coefficient of resistance. For precise temperature measurement by means of resistance thermometers, noble metals are generally used, more generally platinum or nickel, since these in particular show little aging and because resistance thermometers can be manufactured with narrow tolerances. Temperature-sensitive sensors can also be fabricated from ceramics (sintered metal oxides) or semiconductor materials (silicon), thus achieving higher temperature coefficients than...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01D3/028
CPCG01N27/07G01K7/18G01N27/028
Inventor 斯特凡·保罗斯特凡·布施纳科斯基
Owner ENDRESS HAUSER CONDUCTA GESELLSCHAFT FUER MESS UND REGELTECHNIK MBH CO KG
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