BREAKDOWN BEHAVIOUR OF GASEOUS INSULATION WITH SYNTHETIC AIR

The paper deals with basic investigation of AC breakdown behaviour of gaseous insulation with synthetic air at different level of field homogeneity and gas pressure. The measurement was performed at different gas pressure ranging from 0.1 to 0.25 MPa and gap distances from 1 to 10 cm, using two electrode test- sets. The test parameters were chosen in such a way that different field types could be realized. At slight non-uniform electrical field the measured breakdown values shows a reasonable agreement to those values based on the calculation of the streamer criterion by using a relevant approximation formula for the effective ionisation coefficient. The best fit to the measured results was reached by slightly changing the parameters of the approximation formula depending on the gas…