• A land developer had set up a temporary rock crushing operation a few hundred yards from the tie line and was producing large amounts of rock dust. At certain times of the day and night the wind was pushing this debris toward the towers.


• The second factor was
  we had had an exceptionally dry year. In late September we had gone over 170 days without any rainfall. The insulators were not being naturally cleaned and the contaminates were building up. At 5:30AM the fog rolled in off the ocean and wetted the insulators just enough to provide a path to ground.

I was asked to fly this portion of the tie line with the DayCor®II Corona camera in the Polytech gimbal. The flight information was recorded on an Avalex Digital Flight Recorder.

The system worked extremely well and I identified several structures that needed cleaning. Over the next week, with a planned outage, the insulators were hand wiped in remote areas or washed by truck where access was possible. With the line re-energized it was inspected with Corona camera. There was no Corona activity and there have been no more flashovers.


A rough estimate of the nine hour outage would be between two and four hundred thousand dollars. The helicopter time for the one-hour flight was $550.00.

The airborne system worked very well. The DayCor Camera easily identified the areas that needed attention and allowed us to put our resources to better use. It would have taken several hours to inspect all of the towers we look at from the air.

David Eaton
Transmission Engineer,
SDGE,
USA,
September 2004