Inspecting High Voltage Power Lines From The Air

Posted at 6:00 PM, May 21, 2014
and last updated 2014-05-21 18:00:56-04

GRAND RAPIDS, Mich. (May 21, 2014) -- While as much as 345,000 volts hum through power lines that march across the Michigan countryside, a helicopter whizzes by at tower level.

There's a reason to do such an apparently reckless thing.

There are more than 8,800 miles of high voltage lines owned by ITC Transmissions, and the company inspects every mile twice a year. To do that, pilots, engineers, and forestry experts spend a lot of time in helicopters.

"They're looking for anything that could potentially cause a problem," says ITC Chief Operating Officer Jon Jipping. "any of these insulators that might be cracked, frayed wires." Field inspectors are also on the lookout for any potential structural problems with the towers themselves.

Vegetation on the ground is no less a concern. "We've had issues with some of the dead trees that could potentially fall onto the lines," says Jipping. Cutting trees can be locally controversial, "so I-T-C has worked very closely with landowners to try to strike that balance where we may remove a tree that's close to the power lines, but then we'll plant something somewhere else," says Jipping.

The inspections are done as the helicopter flies at an altitude that is about even with the tops of the tallest towers. On a recent ride, the pilot followed a line with shorter towers that runs parallel with US-131 in Gaines Township. It seemed as if we were skimming along the treetops.

There are some no-fly zones for the helicopter, such as airports and congested urban areas. Inspections on those areas are done on foot. In addition, about 10 percent of the towers in ITC's system get personally inspected by experts who climb the towers.

05-21-14 High voltage power line aerialThe helicopters and pilots are contracted through Bijan Aviation in Ann Arbor, one of only a few companies in Michgan that make the sensitive flights required.

Michigan's initiative to generate 10 percent of the state's electricity through renewable energy has created the need for the first new high voltage lines in the state in many years. Called the Wind Zone Project, new towers are going up in Michigan's Thumb area, where a network of wind turbines is being assembled. The line will go active in 2015.

The highest voltage lines carry 345,000 volts of power. Compare that to your typical household outlet with 220 volts.

ITC, based in Novi, is a relatively young company. A few years ago, it bought the high voltage lines owned by Consumers Energy and Detroit Edison, as those utilities worked to concentrate their time on generating electricity and distributing it to customers. ITC is like a freeway: electric companies put their energy on ITC lines to get it to their customers.