Power frequency AC sparkover voltage measurements of small air gaps

This paper present results of tests conducted in the High Voltage Laboratory of the Ohio State University and deals with power frequency AC sparkover voltage measurement of small air gaps. Emphasis was placed on obtaining breakdown characteristics of electrodes and air gap separations that are representative of power lines 69 kV and below. Besides the customary rod-rod, rod-plane, and sphere-plane arrangements, other electrode configurations included various conductor sizes with conductor-rod, -plane, and -sphere arrangements and conductor-hot stick configurations with hook, puller, and wire brush accessories. It was found that the conductor size has a significant effect on the sparkover voltage. In addition, for the more practical electrode arrangement involving conductors, the sparkover voltages were greater than the rod-rod results in all but a few instances.