METHOD AND DEVICE FOR DETECTING FAILURES IN INDUCTIVE CONDUCTIVITY MEASUREMENTS OF A FLUID MEDIUM

摘要

The present invention discloses a method and device for detecting open-circuit and short-circuit failure in an electromagnetic (inductive) measurement of the conductivity of liquids. An electromagnetic measurement of the conductivity of a liquid is performed by immersing a sensor into the liquid, wherein the sensor includes at least 2 toroidal cores, one of them carrying an excitation coil and the other carrying an induction coil. When an AC excitation voltage is applied to the excitation coil, an induced current or voltage can be measured in the induction coil which is proportional to the conductivity of the measured liquid. The present invention discloses a method and device for detecting open-circuit and short-circuit failure on the sensor and cable wiring. Its concept is to add a very small DC current at the terminal of the excitation coil or induction coil in order to detect an open-circuit failure of the device, and to monitor the output swing of the excitation-driving circuit in order to detect a short-circuit failure of the device. The purpose is to improve the reliability of the measurement result.