Analysis of phase-phase and phase-ground air clearances of high voltage substations based on lightning and switching surges

Reducing air clearances in HV substations, which have traditionally been overspecified by the standards, can be accomplished through sound insulation coordination. Evaluation of flashover characteristics of certain electrode configurations which resemble energized parts in a substation can make this process simpler. This research conducted experiments for evaluating CFO voltage of certain electrode configurations as well as for 115 kV and 230 kV substation structures. A procedure for evaluating CFO and hence the BIL/BSL has also been described in this report. Tests were conducted under standard 1.2/50 {dollar}mu{dollar}s lightning and 250/2500 {dollar}mu{dollar}s switching impulses.