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1. (WO2018041968) METHOD FOR CHECKING THE OPERABILITY OF MEASURING TRANSDUCERS

Pub. No.:    WO/2018/041968    International Application No.:    PCT/EP2017/071903
Publication Date: Fri Mar 09 00:59:59 CET 2018 International Filing Date: Fri Sep 01 01:59:59 CEST 2017
IPC: G01D 18/00
G05B 19/042
Applicants: ABB SCHWEIZ AG
Inventors: SCHWANZER, Horst
MERLIN, Tilo
Title: METHOD FOR CHECKING THE OPERABILITY OF MEASURING TRANSDUCERS
Abstract:
The invention relates to a method for checking the operability of two-wire measuring transducers in automation technology which output a measurement signal as an impressed loop direct current (IS) via a two-wire line and the active assemblies of which are supplied with electrical energy via the same two-wire line, wherein the loop direct current (IS) and the input voltage (UE) of the measuring transducer (100) are measured, wherein the loop direct current (IS) is increased in the range from the minimum value to the maximum value (ISM) independently of the measured values and the input voltage (UE) of the measuring transducer (100) is measured in the process. It is proposed to store the measured values of the input voltage (UE) at the selected measuring points of the loop direct current (IS) as an individual signature of the measuring transducer (100). During ongoing operation, the input voltage (UE) at the connection terminals of the two-wire line is measured via the internal resistance of the measuring transducer (100) with a prevailing loop direct current (IS) and is recursively compared with the signature for the same loop direct current (IS). As soon as the input voltage (UE) at the connection terminals of the two-wire line (200) leaves a predefined tolerance via the internal resistance of the measuring transducer (100) with a prevailing loop direct current (IS), a predefined reaction of the measuring transducer (100) is triggered.