Abstract: A protective device for an electrical power distribution network has: means for processing measured values from measurement appliances for the power distribution network, means for initiating switching commands by means of primary appliances for the power distribution network, as well as a programmable protective function which, when it is carried out, determines the switching commands on the basis of the measured values. In this case, the protective device has programmable logic, which can be programmed in order to carry out the protective function.

Abstract: For measuring an electric voltage in an electro-optic voltage converter, polarized light of two wavelengths is sent through a medium. At the output side, the light is led through a polarizer and the remaining signal is measured. For compensating a temperature dependence of the electro-optic coefficients, the measured results at both wavelengths are compared, and the voltage value consistant with both measurements is used.

Abstract: A protective device (1) for an electrical power distribution network has: means for processing measured values (14) from measurement appliances (3,4) for the power distribution network, means for initiating switching commands (16) by means of primary appliances (2) for the power distribution network, as well as a programmable protective function which, when it is carried out, determines the switching commands on the basis of the measured values. In this case, the protective device (1) has programmable logic (13), which can be programmed in order to carry out the protective function.

Abstract: In order to measure an electrical voltage in an electrooptical voltage converter, polarized light at two wavelengths is sent through the medium (1). On the output side, the light is passed through a polarizer (10) and the remaining signal is measured. In order to compensate for the temperature dependency of the electrooptical coefficients, the measurement results at the two wavelengths are compared with one another, and that voltage value which is consistent with both measurements is used.

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: 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.