Experimental investigation of the current-voltage characteristics in corona discharges in SF6-N2 gas mixtures have been carried out in a point to plane configuration. Empirical formulae have been used to determine the corona onset voltages (V0) in both polarities at higher pressure. The results show that for low concentrations of SF6 the increase of the onset voltage is relatively substantial, whereas, for amounts over 10 % of SF6 the increase is slowed down. This can be an advantage for the substitution of SF6. The results obtained with the empirical models are compared with the measures values. Calculated values overestimate V0 for low SF6 ratio (≤ 5 % SF6) and underestimate V0 for high pressures (≥ 50 % SF6).

Keywords: Corona discharge, Gas dielectric, High voltage, Sulphur hexafluoride