Patent ID: 6510393
Filing Date: 2003-01-21
Classification: H04M

Abstract:
A method for detecting transient faults in a switching device, the method comprising the steps of:counting in a fault counter by a specific first counting value, in a first counting direction, when a fault occurs; counting in the fault counter at specific times in each case, by a second counting value which is greater or less than that said first counting value, or is equal to the first counting value in a second direction, which is opposite to said first counting direction, the situation when the relevant unit has operated without any faults within a time interval provided between two such times; triggering an alarm signal when the relevant fault counter reaches or exceeds a defined counting threshold value in said first counting direction; triggering a first alarm signal on reaching or exceeding a further counting threshold value which is below said defined counting threshold value and which only signals the occurrence of faults in the relevant unit; and triggering a second alarm signal in conjunction with the respective unit being switched off, only on reaching or exceeding said counting threshold value, which is higher that the former, and in that on reaching only said further counting threshold and the faults subsequent not being evident, of if the count falls below the relevant further counting threshold value due to faults not being evident, the time interval between any two of said times at which said fault counter counts in the second counting direction is lengthened.