EXPERIMENTAL STUDY OF THE BREAKDOWN CHARACTERISTICS OF LARGE SCALE GAS-INSULATED SYSTEMS

ABSTRACT Impulse and ac breakdown characteristics are investigated using a model of 70 kV single-phase SF 6 gas-insulated substation. The formulae for the breakdown voltages and V-t curves established earlier on the basis of the Weibull statistics are found to be applicable to large scale systems. It is shown that the breakdown voltages of lightning impulse are less dependent on the system scale than those of switching impulse and ac. The slight time dependence of breakdown voltages observed in a long duration ac test conforms with the Weibull statistics which has been developed in accounting for the area effect.