June 12, 2017

BSSE Transmission Line project using helicopters to assist in stringing conductor


Today the Big Stone South-Ellendale (BSSE) 345-kV Transmission Line project began using helicopters to assist in stringing conductor (transmission line) nine miles west of Big Stone City. The helicopters will work their way west toward Aberdeen, South Dakota, then northwest toward Ellendale, North Dakota. The project team expects to complete stringing in October 2018.

How stringing works

“Using helicopters to assist in stringing conductor is more efficient and economical and safer than other options and minimizes ground impacts,” said Cris Oehler, Vice President, Public Relations, for Otter Tail Power Company. Here’s how it works:

  • Because conductor is too heavy for a helicopter to lift, the helicopter first carries a rope from the ground to the top of the structure.
  • Hovering between 30 and 80 feet from the structure, the helicopter sets the rope into the traveler, which looks like a pulley. The traveler has a trap door to allow the rope in but to prevent it from falling out, securing it in place.
  • The helicopter continues on to the next structure, pulling the rope as it goes.
  • After the helicopter installs the rope, crews connect the rope to the conductor. Crews then use a machine on the ground to pull the rope and set the conductor.

Safety is top priority

“We want to ensure the safety of our team and the community,” said Oehler. “So, before any work begins for that day—on the ground or in the sky—we carefully take into account the weather, visibility, and other conditions that could interfere with working conditions. It’s simple. If conditions aren’t safe, we don’t work.”

The project team encourages community members, especially motorists, who notice the helicopters at work to focus on safety and stay at least 500 feet away. To ensure public safety, the project limits access to areas under the helicopter’s path. “Please don’t attempt to watch while driving or from the side of the road,” said Oehler. “If you’re interested in seeing this work up close, you’ll soon be able to view photos and videos at BSSETransmissionLine.com.”

About the project

When complete, the line will connect the new Big Stone South Substation near Big Stone City,
South Dakota, to the new Ellendale Substation near Ellendale, North Dakota. Project owners, Otter Tail Power Company and Montana-Dakota Utilities Co., expect to complete construction late in 2018. To view construction progress, visit BSSETransmissionLine.com/maps.