Short-circuit currents and recovery voltages

FIELD tests were made on a 7,200/12,470Y-volt multigrounded rural distribution system to check fault current calculations and to investigate transient recovery voltages experienced as a consequence of clearing fault currents. Tests were also made using a miniature circuit representation of a rural distribution system in order to investigate the effect of variations in circuit conditions incident to the fault. The use of the miniature system or transient analyzer made possible a determination of the order of magnitude of crest voltages and rates of rise that may be expected under most severe conditions. The work is expected to be of considerable value in the preparation of standards for the testing of such devices as expulsion lightning arresters and distribution fuse cutouts. In so far as the authors are aware, this is the first published information on transient recovery voltage tests on rural distribution systems and the correlation therewith of transient analyzer results.