Method and device for generating a classification signal classifying an electrical impedance

A method generates a classification signal classifying an electrical impedance. The time characteristic of the impedance is measured resulting in impedance values. Impedance change vectors whose direction describes the movement of the impedance in the complex impedance plane and whose length describes the amount of the respective impedance change are formed with temporally successive impedance values. A check is carried out to determine whether the impedance shows a directional, continuous impedance movement. In the event of a subsequently detected change of direction of the impedance movement, the reaching of a reversal point is inferred and the rotation of the impedance change vectors is monitored with the result of a formation of an angle of rotation measured value. A classification signal indicating a fault is generated if the impedance change vectors have rotated in the area of the reversal point through a predefined maximum angle of rotation.