Transmission Lightning Arrester Application Study

Location: Johnson & Lowell, Vermont

The Transmission Lightning Arrester Application Study project was to provide an investigation into the transmission line outages caused by lightning events on certain transmission lines. The Utility requested a review of the lightning related outages to determine if the frequency of these outages was outside the norm and if design modifications could improve the performance of those lines. RLC was responsible for investigating the causes and made recommendations on potential mitigation options based on our field inspections. The intent of this investigation was to determine the most feasible mitigation alternative to reduce the number of outages caused by lightning.

Scope of Services:

  • Reviewed the Utilities’ records for outage rates per year caused by lightning events.
  • Developed criteria for ranking the level of importance on each line.
  • For the eight selected lines, reviewed and analyzed possible commonalities that might contribute to susceptibility (geography, structure type, shielding configuration, grounding design, arrester types and ratings, design parameters).
  • Determined the location of electrical faults on transmission lines from field data collected (Vaisala or Digital Fault Recorder (DFR)).
  • Conducted on-site investigation by performing field walk-down in area where fault occurred.
  • Documented results of field investigations and any findings in a summary report.
  • Developed and summarized mitigation options that were recommended for each line and type.