Creative repair prevents costly replacement

If you crane your neck up to see the very top of a CapX2020 transmission line, you’ll see a wire above all the rest. This is the optical ground wire, and it is serves two purposes: grounding and communications.

a crane repairs a transmission line

Completed in 2016, CapX2020 was the largest electricity transmission expansion in Minnesota since the 1970s.

Great River Energy maintains the Brookings County-Hampton CapX2020 line, and during a recent ground patrol a line technician noticed that the optical ground wire was fraying, likely due to lightning strikes.

Closer inspection showed that the signal in the fiber was strong, but eight of the 16 strands were severed. Eleven strands are needed to maintain the strength of the wire. Fewer strands increased the risk of damage to the fiber, which would lead to a $300,000 replacement.

Great River Energy crews immediately installed repair rods to hold the strands in place and prevent further deterioration.

The transmission construction and maintenance department then got to work to find a permanent fix. According to Transmission Construction and Maintenance Supervisor Kevin Hodgson, Great River Energy contacted a specialized vendor that that builds equipment to restore the electrical and mechanical strength of damaged transmission lines.

“They had done it twice before: once in Canada and another time in Australia,” Hodgson said.

The equipment is now in use in Minnesota. After a few weeks to manufacture the equipment, Great River Energy crews installed it using a 180-foot crane. The low-cost fix prevented a costly overhaul and maintained the integrity of the line.