Patent US 3,970,901

A method for the detection of short circuits in electrical installations, in particular on railway contact wires, comprising: generating a signal corresponding to the derivative with respect to time of the monitored current, comparing the generated signal with at least one limit value, indicating a short circuit if the generated signal exceeds a limit value, monitoring the behavior of the monitored current for the occurrence of a criterion indicating the probability of a short circuit, triggering a replica signal corresponding to the behavior of the monitored current from the movement of occurrence onwards as a function of the probability criterion, comparing the replica signal with at least one limit value, and indicating a short circuit if the limit value is exceeded.