Managing Overhead Transmission Lines
Dr. Andrew Phillips is director of Transmission and Substation Research at the Electric Power Research Institute. Phillips earned bachelor’s, master’s, and doctoral degrees in electrical engineering at the University of the Witwatersrand in Johannesburg, South Africa.
Managing the more than 160,000 miles of U.S. high-voltage overhead transmission lines-including towers, conductors, and insulators, as well as corridors-is a costly and challenging proposition. Utilities' stringent standards for reliability, vegetation management and worker safety often require circuits to be located in remote and rugged environments. While Unmanned Aerial Systems or drones show promise as an option for transmission line inspection, there is still much work to do in order to ensure their safety and operational effectiveness near live lines.
The North American Electric Reliability Council (NERC) mandates that transmission system owners and operators maintain adequate clearances between overhead circuits and vegetation along right-of-ways, and that they take additional measures to minimize or prevent vegetation-related outages. For many utilities, the current practice involves dispatching inspection workers to conduct fast-flyby to assess the condition of lines in remote or inaccessible areas, employing limited helicopter hovering.
Ground inspections of components also are performed in some instances, while certain components can only be examined by climbing towers. Some equipment cannot be inspected at all due to hazardous conditions or access restrictions.