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TVA crisscrosses region during aerial inspection of transmission lines

August 14th, 2013 9:01 pm by Gary B. Gray

TVA crisscrosses region during aerial inspection of transmission lines

TVA makes aerial inspections by helicopter and ground inspections of its transmission lines and surrounding areas twice a year to insure that the system remains safe and reliable. View of TVA Boone Dam located near TN State Highway 75. (Lee Talbert/Johnso

Doing about 60 knots more than 150 feet above the ground as a Tennessee Valley Authority helicopter pilot and line inspector scour high-voltage transmission lines brings a visual perspective to the term “power grid.”

TVA towers connect and guide lines carrying 500,000 volts — the first utility ever to do so. The structures are much more visible from this vantage point, as a Johnson City Press reporter and photographer found out Wednesday while piggybacking on a check of a small portion of the system’s 16,000 miles of “circuit” line — enough to span the nation more than six times. 

It’s an extensive network that originates from electricity spawned at hydroelectric dams and coal-fired and nuclear plants. It then surges through a massive web of aluminum and copper power lines, collects at substations where the voltage is reduced and gets passed along by utility companies, such as the Johnson City Power Board. Then it’s on to your home, where flicking a switch powers up the washers and dryers, television sets and vacuum cleaners.

“We have about 103,000 transmission line structures and 500 substations and switch yards,” Tracy Flippo, TVA transmission operations and maintenance energy delivery vice president, said Friday while briefing media members before boarding a Bell 407 helicopter for a closer peek. “We have a line patrol that visually inspects the system twice a year, and that’s what we’re showing you today. It’s preventative maintenance, and it’s a 24/7 job.”

Flippo said TVA also does a ground patrol. And whether from the ground or the air, linesmen hunt for broken or sagging lines, broken transmitters, structural damage and foliage that may be interfering with the lines.

“The line patrol flies specifically at lower speeds, and that gives them a chance to look at insulators and wire damage,” he said. 

So what about a sagging line?

“We’ll make an immediate decision on whether we need to take it,” he said. “If it were a threat to service, we would land the helicopter and contact our people. We sometimes use a helicopter to ‘pull’ lines. We also use helicopters in emergency situations.”

Linesmen are constantly logging information into a laptop computer while onboard the helicopter, which allows TVA to exchange information instantly. The onboard electronics allow TVA to detect and report the exact location of problems it may encounter.

The flight offered a view of just how extensive the system really is. It also provided a chance to look down on Boone Lake Hydroelectric Dam and to see up close how the massive towers are constructed to serve their purpose.

TVA provides more than 9 million people with power. And one very serious and highly publicized incident in 2003 shows why the lines and other equipment is checked so thoroughly. That year, a single tree came in contact with an electric transmission line in Ohio. Within two hours, 50 million people in Canada and the northeastern U.S. were without power.

Eleven people died and the outage caused $6 billion of damage to the North American economy.

TVA owns and operates one of the largest transmission systems in North America, covering 80,000 square miles and spanning portions of seven states. It serves 155 local power companies and 57 large industrial and federal customers across the region.

Within that entire domain, the average power outage duration in the last three years is 13 minutes, according to TVA.

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