Abstract
The behaviors of metal oxide surge arresters installed at substation terminal, generally without spark gaps are well-known by the excellent performances of automatic fault clearance and of reliable overvoltage protection of substation apparatus. As the result of four-year research experiences on the 77kV operating power systems including observed substations T and F halfway between the protection terminals, authors have proved the characterized discharge current of those arresters can be divided into three types of waveforms such as instantaneous heavy pulse, low level lingering continuance and medium continued damping oscillation. The negative lightning discharge with subsequent multiple strokes against de-energized power lines may be the distinct and frequent causes of damping current oscillation of surge arresters. Moreover, the negative discharge current on the sound phase has been encountered not a little in the case of related double-line-to-ground fault. In this paper, the combination of those parameters is clearly expressed through several representing figures of arrester current waveforms together with those of corresponding voltage of surge fronts and 60Hz voltage transients if available.
