SENSOR FOR MEASURING THE ELECTRICAL CONDUCTIVITY OF A FLUID MEDIUM

The invention relates to an inductively operating sensor ( 1 ) for measuring the electrical conductivity of a fluid medium ( 2 ), having an excitation coil ( 3 ), to which an input signal is fed, and a receiver coil ( 4 ) coupled with the former via the fluid medium ( 2 ), which provides an output signal (I Ind ), which is a measurement for the conductivity of the fluid medium ( 2 ). To make possible the timely detection of damage to the windings of the excitation coil ( 3 ) or the receiver coil ( 4 ), or respectively a service cable for the sensor ( 1 ), which leads to leak currents or short circuits, it is proposed by the invention that the sensor ( 1 ) has means ( 5 ) for measuring a variable signal at the input of the excitation coil ( 3 ). The excitation coil ( 3 ) of the sensor is preferably fed by an input voltage (U Err ), and the means ( 5 ) for measuring the variable signal preferably measure the input current (I Err ) at the input of the excitation coil ( 3 ).