| 摘要 |
In the case of cutting off short-circuits in high-voltage systems, rather than, as in the past, proceeding from a fixed tripping time, which is calculated on the assumption of unfavourable conditions, for a power circuit breaker, the invention proposes that an individual tripping time (t3) be calculated in each case of a short-circuit which occurs at a time (t0) and is identified at a time (t1). For this purpose, it is proposed to sample the current behaviour (I) in an initial region (10) until a time (t2) and, using the data obtained from this, to adapt a mathematical model which is used for calculating the predicted theoretical time (t5) of the first zero crossing of an uninfluenced short-circuit current (8). Starting from the theoretical time (t5), the tripping time (t3) is calculated, taking into account the response time of the circuit breaker itself and any other influences. The actual first zero crossing occurs at a time (t4) which, if the tripping time (t3) is selected suitably, is before the theoretical time (t5). <IMAGE>
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