SLF 合成回路条件における油中しゃ断再起電圧

Abstract

The interruption of current in liquid oil under very short-line fault (SLF) conditions within a distance of 1km long has been performed using 10 sections of π-type artificial line. It has been found that, under the suitable number of used sections between 4 and 8,the ideal triangular shape of the transient recovery voltage (TRV) can also be obtained even for the moment of current interruption in oil as is usually the case with air-blast circuit-breakers. Reducing the value of line capacitance, to obtain the higher value of the surge impednace of the line, will reproduce the triangular waveform at a wide range of used sections. The sudden change of arc voltage, or the deformation of current before its zero (current chopping is also included here) affects the shape of the triangular voltage oscillation after interruption. The deformation in current was considerably reduced, compared with the formerly reported breaker-terminal fault conditions, by the insertion of the artificial line into the test circuit. But the amount of damping of the lineside TRV may vary from test to test, and occasionally these oscillations disappear completely, which characterizes the interrupting phenomena in oil.