Last weekend, fishermen and others who braved the winds and visited O'Neill Forebay may have noticed something a bit unusual that some commuters heading over Pacheco Pass have been wondering about for the last week or two - chopper operations. For several days a helicopter has been buzzing around the high tension power transmission towers across the highway from the William R. Gianelli pumped storage hydroelectric plant and the B.F. Sisk Dam. The helicopter operations are to support a program of changing-out many of the extra-high-voltage insulators on the nearby overhead transmission towers.

Power transmission line insulators, which are also known in the business as dielectrics, have been made from materials such as porcelain, ceramics, toughened-glass, polymers, and various non-ceramic and composite materials known as NCIs. The purpose of these insulators is to support and separate high voltage lines while at the same time restricting the electrical current from passing through to the transmission towers. Besides the obvious safety considerations, proper insulation makes for a more efficient power-grid. The integrity of power transmission lines can be directly related to the mechanical and electrical quality of the insulators which are also known to be associated with a high percentage of line outages. Insulators can fail for several reasons including age, maker-defects, and vandalism. Several types of contamination can also adversely affect insulator performance.

While cleaning is sometimes enough, the insulators may have to be changed-out from time to time and that is exactly what is going on right now over near the forebay. A small staging area has been set up near the west side of the water and dozens of insulator strings are laid out near an impromptu helli-pad. PG&E trucks have converged on the area for the last few days and skilled workmen have been perched near the top of the towers where an aerial dance occurs as the old insulators are removed and new insulator strings ferried to the top of the towers are secured in place by these brave guys who are seemingly vertigo free.

A ground crew supports the operation by securing new insulators to the line coming off the choppers and observing the guys at the top of the transmission towers through a spotting scope on a nearby picnic table. As might be expected, safety is a major consideration. According to the foreman on the scene, the high voltage power has been shut down on the half of the transmission tower where the insulators are being changed out. Weather is also an issue. On Sunday when the photos in this story were taken, the winds had really kicked up and the decision was being made whether or not to try to continue operations in a less windy location.

Here are some photos of the operations on Sunday:

Their work is cut out for them!
Insulators in the foreground will be installed on high tension towers soon.

If everyone in Los Banos would just take 1 or 2 hours a month to do something to help their neighborhood or their community we could truly make Los Banos the gem of the valley.

The above is only my personal opinion and I strongly encourage readers to seek out more information from expert sources. Copyright 2009