The effect of temperature on the impulse voltage strength of SF6 in inhomogeneous electrode gaps

The effect of gas temperature on the impulse voltage strength of a rod-plane electrode gap in SF₆ was studied with positive standard lightning impulses. Two hemispherically capped rods, the radii of which were 2 mm and 5 mm, were used. The electrode distance was either 20 mm or 30 mm. The temperature was varied from -30°C up to +60°C, and the gas pressure was 1.5 bar or 2.0 bar. The breakdown strength was observed to decrease with increasing gas temperature, although the differences were small. The effect was strongest with the electrode gap having the most nonuniform electric field and with the lower pressure