Practical experience of using additional earthing of the faulty phase during a ground fault

The paper is focused on the operational experience with an automatic system for suppression of a fault current during a ground fault by the additional earthing of the faulted phase in a supply substation. Such system was experimentally installed in the Brno-Medlánky 110/22 kV substation. To verify the benefits of the system as well as to assess its possible failings, twenty-four experimental measurements based on a theoretical study were performed. During those experiments, low-resistance and arc ground faults were monitored in the urban and suburban part of the compensated network with a capacitive current of 300 A and 800 A. The results of the crucial experiments and the evaluation of the system functioning are summed up in the final part of the paper.