Siemens Aktiengesellschaft

Helmut Fornsel

Hans-Eberhard Simmel

A method for generating a tripping signal as a function of an overcurrent. Sampled measurement values are converted into digital values which are weighted and added up according to a predetermined function. If the sum value is above a predetermined reference value, the tripping signal is formed. In order to cancel the addition before the tripping signal is formed in dependence on the wave shape of the overcurrent if the overcurrent is decaying, the digital values of the respective last period of time corresponding to at least a half-period of the overcurrent are stored and a comparison of all digital values simultaneously stored with each other is made. The determined largest stored value is weighted and added up as a digital value and the addition is cancelled if a largest digital value is below the predetermined threshold.

Method for generating a tripping signal as a function of the magnitude

A method for generating a tripping signal in dependence on an overcurrent, in which sampled measurement values are converted into digital values. These values are weighted and summed in accordance with a predetermined function. A tripping signal is formed if a predetermined sum value is reached. In order to cause in such a method the delivery of a tripping signal only for true overcurrents, and in order to prevent the delivery of a tripping signal when an overcurrent is decaying and below a threshold, the summation is cancelled while the overcurrent is decaying, immediately in dependence on the waveform of the overcurrent. The digital values of the respective last period of time corresponding to at least one half-period of the overcurrent are stored and a comparison of all the then stored digital values with each other is made. At a determined highest stored value below a predetermined threshold, the summation is cancelled.

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Karlsruhe, Germany

Helmut Fornsel