Duff/Coleman grid expansion project moves forward
345 kV project will span 30 miles when complete
EnergyLines April 2020
Republic Transmission (through a Hoosier Energy and LS Power partnership) together with Big Rivers Electric Corporation, have completed about five miles of the single circuit 345 kilovolt Duff/Coleman line. Spanning 30 miles, this transmission line will cross sections of Dubois County, Indiana; Spencer County, Indiana; and Hancock County, Kentucky.
Recently, conductor was pulled through structures spanning over I-64. Pulling conductor is a process that begins with a rope, or straw line. The straw line is fed through massive pullies attached to each H-frame structure. The straw line helps guide the conductor into position. To help keep the conductor level as it travels through the pullies, a device called a gator is used.
For this project, conductor is pulled through 6-7 miles at a time using reels of wire that have 2 miles of conductor spooled. As one spool of conductor ends, it needs to be attached to the next spool to meet the desired length for the pull. Dynamite is used to fuse the wire together.
“We do this at the pulling station. The connection made is 200 percent stronger than a compression connection and 200 percent better for amperage,” said Jon Osborn of Republic Transmission.
The project is estimated to provide over $1 billion in benefits, which far exceeds the cost for the project. Republic Transmission is leveraging its technical capabilities in the construction and operation of the project, benefitting from Hoosier Energy’s existing local operations, maintenance experience and capabilities.