Abstract: The method described here makes it possible to determine the impedance of a line (1) by measuring the voltage (u) applied across the line and the time derivative of the current (i) flowing through the line. The measured values of the differentiated current are not integrated in this case, but rather are substituted directly, together with the measured voltage values, into an equation system from which the values of the inductance (L) and the resistance (R) of the line (1) can be estimated. In this way, integration of the values of the differentiated current is obviated.

Abstract: Current and voltage values (uk, ik) are measured for protection of an electrical power line (1). An adaptive estimator is used to analyze all the values within a measurement window, and to convert them to impedance values (Z). The line (1) is switched off if the impedance values (Z) assume unacceptable values. In order to shorten the reaction time, a warning signal (W) is produced if powerful radio-frequency signals are detected on the line (1). When the warning signal (W) occurs, the respective measurement window is located such that its start matches the time of the warning signal (W), and/or the respective measurement window is shortened.

Abstract: A method and a sensor (1) for oil-in-water measurement, in particular for the oil industry. In an electric measuring cell (7, 12) a capacitance is measured as a measure of an oil concentration in the water flowing through or in the accumulation filter (16, 16a, 16b). In order to reduce the maintenance requirement, the measuring cell (7, 12) is automatically calibrated at recurring time intervals with clean water (FIG. 1) and/or flushed with water, possibly oil-contaminated, in the back-flushing direction (FIG. 2). Advantages of the invention are reduced signal drift, improved long-term reliability and a long service life without monitoring or filter exchange.

Abstract: The method described here makes it possible to determine the impedance of a line (1) by measuring the voltage (u) applied across the line and the time derivative of the current (i) flowing through the line. The measured values of the differentiated current are not integrated in this case, but rather are substituted directly, together with the measured voltage values, into an equation system from which the values of the inductance (L) and the resistance (R) of the line (1) can be estimated. In this way, integration of the values of the differentiated current is obviated.

Abstract: Current and voltage values (uk, ik) are measured for protection of an electrical power line (1). An adaptive estimator is used to analyze all the values within a measurement window, and to convert them to impedance values (Z). The line (1) is switched off if the impedance values (Z) assume unacceptable values. In order to shorten the reaction time, a warning signal (W) is produced if powerful radio-frequency signals are detected on the line (1). When the warning signal (W) occurs, the respective measurement window is located such that its start matches the time of the warning signal (W), and/or the respective measurement window is shortened.

Abstract: An apparatus for capacitively determining a position of a counter wheel (1) in a wheel counter mechanism has fixed electrodes (3, 3′) at a distance from the counter wheel (1). Extending over the circumference of the counter wheel (1) are a sequence of measurement electrodes (12, 12′, 12″), and electrically nonconductive sections (13, 13′) arranged between said measurement electrodes. This means that it is possible to detect either a high or a low capacitance value, that is to say a binary value of either 0 or 1, for each position of the counter wheel and for each fixed electrode. According to the number of fixed electrodes for each counter wheel, these binary values can be combined to form a binary representation of any desired number characterizing the current position of the counter wheel (1).