Factors affecting the choice of fault duration in transmission lines for computation of dynamic effects in EHV distribution substations

In the paper, the method of assessment of the fault duration in transmission line regard¬ing dynamic effects in the EHV distribution stations with flexible bus conductors is pre¬sented. Expected yearly frequency of exceeding the indicated dynamic forces has been assumed to be a criterion of choice of the short-circuit duration values. Results of simula¬tions carried out using Monte Carlo technique have shown the influence of parameters of the distribution substation and devices installed in it (nominal voltage, short-circuit capaci¬ty, unreliability of circuit-breakers and protections, EAZ configurations) on suggested fault duration values in the engineer-type short-circuit computations.