must be separated from the charging circuit by the aforementioned semiconductor switches s 1 s 4 in order to prevent the quenching thyristors from remaining conducting after successful current degradation by the charging current this would in fact prevent a further charging process resulting in overloading of the charging resistors r 1 r 4 as soon as the condensers c 2 and c 2 are sufficiently charged once more a new quenching process can take place however with the frequency of repetition of quenching processes or the number of quenching processes within a specific period of time being determined by the dimensioning of the circuit in particular of the charging resistors and the voltage limiter control of the circuit as a whole which is not the direct subject matter of the present invention can be effected by means of an analog circuit with microprocessor support for communication with the converter the triggering criteria for activation of the quenching thyristors are determined by the software on the basis of measured voltages and currents and or times even if as stated the invention does not relate to this some examples of faulty operating statuses are provided which can be rectified by the inventive quenching device in the case of lightning strikes in high or medium voltage facilities spark gaps or gas filled overvoltage protective elements are fired they then bum until the next current zero crossing this results in a low impedance mains voltage drop lasting between 3 and 20 ms however it is also possible for a longer mains voltage drop to arise in which one or more transformers or other loads keep the network to low impedance at zero in the case of a short circuit affecting a parallel electrical circuit in the same network a mains.