Impulse and dynamic flashover studies of 26-kv wood pole transmission construction

IN THIS paper is presented the results of laboratory tests with a 1,000,000-volt surge generator and 60-cycle high voltage testing equipment on 26-kv transmission poles now in use on a large system. Actual impulse curves are given for several types of straight span pole top construction. Values of impulse flashovers for the basic component parts of a pole are presented to furnish means for comparing types of construction not tested and to aid in applying protective gaps for the prevention of wood shattering. Wooden crossarm braces greatly increase the insulation on double-circuit vertical configuration construction but are of little use on singlecircuit horizontal configuration pole tops. The data given enable the more complete utilization of the wood on pole tops for insulation.