Impulse voltage breakdown of argon+SF6 mixtures under non-uniform electric fields

This experimental study addresses the behavior of binary mixtures of argon and sulfur hexafluoride in a rod-plane electrode configuration when subjected to impulse voltages. Positive-polarity, standard lightning impulse voltages (1.2-μs/50-μs) with different magnitudes were employed throughout the experiments. The percentage of SF₆ in Ar was varied from 1% to 90% at a total gas pressure of 50 kPa and 100 kPa. The breakdown voltage of each gas mixture was recorded at 50% breakdown probability. Similar to our theoretical as well as experimental studies under static electric fields it is observed that the breakdown strength of Ar has increased dramatically when mixed with a small percentage of SF₆. However, the breakdown voltages did increase monotonically but not dramatically for higher SF₆ percentages.