Helicopter helps repair north metro transmission line

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Helicopter helps repair north metro transmission line

August 26, 2016

Minneapolis—August 25, 2016—A helicopter is being used to repair 8-miles of high voltage transmission lines damaged by severe storms July 5 near Rogers. The helicopter is helping workers be more efficient and protect the environment while rebuilding and repairing lines in an area surrounded by wetlands and farmland. Work on the line is expected to last up to three months and the 345-kilovolt (kV) line is expected to be returned to service in November.

“In recent years, we’ve used helicopters to help build and repair our transmission lines,” said Teresa Mogensen, senior vice president, transmission, Xcel Energy. “Helicopters can speed up construction times by reducing the need to move and set up large equipment on the ground, and that also helps reduce impacts in sensitive or hard to reach areas.”

Threading the needle

To repair the line damaged in July, crews are performing an interesting technique called ‘threading the needle’ to install a ‘lead line’ in which the transmission wire is attached and installed on the transmission towers. The approach is unique in the industry and generally only used with H-frame structures, such as the ones being repaired this month. The center wire in an H-frame structure is surrounded by the wooden poles. The helicopter pilot inserts a lead line rope through the equipment using a remote control device and flying technique, guiding it through the phase to the other side of the structure.

Flights to continue through the fall

To repair the damaged 345-kV lines, helicopters are installing wire and conductor on the transmission line, as well as installing other components on this and adjacent lines. While crews are working the next three months in the north metro area, they’ll use the opportunity to install bird diverters that help birds identify transmission lines and avoid collisions.

While the damage to two 345-kV lines in July was significant, customer outages after the storm were caused by damage to local distribution systems, not the damaged transmission lines. Hundreds of miles of redundant transmission lines in the Upper Midwest deliver electricity to customers and provide service in the event of damage, as experienced here. While nearly 250,000 customers experienced electric outages after the storm, all power was restored over the course of several days.

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