Patent ID: 8228103

Claim:
A method for detecting aperiodic, substantially step-like changes in amplitude of at least one electric parameter, especially the current and/or the voltage, in an electric network, comprising the steps of: measuring a temporal progression of the at least one electric parameter and forming a first parameter signal faithfully representing the temporal progression; assigning for a duration of the first parameter signal a predetermined constant positive first value to each positive component of the first parameter signal and assigning a predetermined constant negative second value to each negative component of the first parameter signal, and forming a first rectangular signal; detecting rising or falling flanks of the first rectangular signal and assigning a predetermined constant third value unequal zero to regions between two consecutive rising flanks or two consecutive falling flanks, and assigning a value of zero to regions disposed between a rising flank and a falling flank, forming a second rectangular signal; determining a first pulse-duty factor of the second rectangular signal; comparing the first pulse-duty factor with a pulse-duty factor of 1:1; and signaling detection of an aperiodic, substantially step-like change in the amplitude of the at least one electric parameter if the first pulse-duty factor is different from the pulse-duty factor of 1:1.