The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 25, 2011
Filed:
Mar. 14, 2008
Heinz Rufer, Dornach, CH;
Wolfgang Drahm, Freising, DE;
Frank Schmalzried, Freising, DE;
Endress + Hauser Flowtec AG, Reinach, CH;
Abstract
A method for predictive maintenance for a magneto-inductive flow-measuring device and/or to a method for determining electrical conductivity of a medium flowing through a magneto-inductive flow-measuring device, wherein the magneto-inductive flow-measuring device includes a magnet system, which produces a magnetic field passing through the measuring tube essentially transversely to a measuring tube axis; at least two measuring electrodes coupled with the medium, having a defined rest potential and being arranged in a region of the measuring tube lying essentially perpendicularly to the magnetic field; and a control/evaluation unit, which delivers information concerning volume- or mass-flow of the medium on the basis of measurement voltage induced in the measuring electrodes. A first exciting signal with a first frequency (f) and at least a second exciting signal with a second frequency (f), or an exciting signal containing at least two frequencies (f, f) are/is applied to the measuring electrode in such a manner that the average value of the exciting signals or exciting signal coincides, at least approximately, with the average value of the electrode potential of the measuring electrode. On the basis of at least one impedance value measured between measuring electrode and reference potential, conductivity of the medium and/or change on the surface of the measuring electrode are/is detected.