Influence of Air Density on Electrical Strength of Transmission Line Insulation

Flashover tests were conducted at the Leadville EHV Test Facility of the Public Service Company of Colorado and Project EHV at Pittsfield, Mass., to obtain comparative data to evaluate the influence of air density on switching surge and impulse flashover strength of transmission line insulation. The tests showed that negative polarity flashover voltages are greater than those of positive polarity. Therefore, positive polarity will be the critical requirement for transmission line design for switching surge duty.