Laboratory study of long, low current power frequency arcs: initial results

The paper describes the quenching behaviour of physically long, low current, medium voltage (1-20 kV) 50 Hz arcs. The circuit devised to generate the arcs is described, together with the parameters of the multi-tap reactor used to limit the prospective short-circuit currents. The results presented include examples of the voltage-time waveforms and the dynamic volt-current characteristics. The latter characteristics are compared with those reported by Cobine. Initial criteria are proposed for predicting arc stability or quenching; these are based on the excursions of the volt-time characteristic towards the static load line. The need for further analysis of the Eskom data is stressed.