BEHRUEHUNGSFREIER LEITFAEHIGKEITSFUEHLER

摘要

A cell for sensing conductivity of a fluid such as diolysate passing through it. The cell comprises a fluid flow path having an inlet 22 and an outlet 24 and two fluid paths 26, 28 between the two, thereby defining a fluid loop. An excitation transformer 14 comprises a first toroidal core having a hole through it and wire turns around it, the core ecompassing a portion of the fluid flow path means and the fluid loop therein. A sensing transformer 16 comprises a second toroidal core having a hole through it and wire turns around it, the core encompassing a portion of the fluid flow path means and the fluid loop. The two cores are coplanar to thereby reduce leakage between the transformers. The excitation transformer is driven by a square wave excitation signal provided by a digital timer and a flip-flop, and the sensing transformer is connected to a synchronous detector.