A 9.44-mile transmission line reconductoring project in Sac County will not only advance Corn Belt Power Cooperative’s strategic plan to strengthen and update its transmission system, but will also include fiber optic cable, technically known as optical ground wire (OPGW), to facilitate a loop for a more reliable communications system.
This fall, Corn Belt Power crews will reconductor a north-south section of line that starts near MidAmerican Energy Company’s Buena Vista County Switching Station between Alta and Storm Lake and runs south to MidAmerican’s Sac County Switching Station three miles north of Schaller.
The reconductoring project will add heavier conductor and space poles more closely together to strengthen the line, originally built in 1950. Corn Belt Power’s strategic plan includes reconductoring approximately 50 miles of line per year. The cooperative selected this section of line for its 2018 work plan because of the line’s age and potential impact on system reliability due to location.
This reconductoring project adds a new twist for Corn Belt Power crews – they will install OPGW for the first time in place of a static wire.
Part of the southwest microwave loop project, the OPGW will facilitate communications between MidAmerican Energy’s Sac County and Buena Vista County switching stations and continuing to Corn Belt Power’s Storm Lake Switching Station. The new southwest microwave loop will run between these Corn Belt Power microwave sites: Pocahontas to Sherwood to Drager to Carrollton to Toyne to Wheatland to Odebolt. It will then run to MidAmerican Energy’s Sac and Buena Vista switching stations.
Corn Belt Power experienced challenges obtaining a clear microwave path to its Storm Lake Switching Station from MidAmerican’s Sac County Switching Station. The option to add fiber to Corn Belt Power’s transmission line to carry communications and complete the loop into the Storm Lake Switching Station solved those challenges.
Additionally, fiber provides a wider bandwidth to carry more data than radio communications can. Having fiber to carry data will also help the cooperative deal with the threat that the Federal Communications Commission may sell off more radio frequencies, making them unavailable for Corn Belt Power use.
Also, using OPGW as part of the microwave loop will help save money by eliminating the need for a new, taller microwave tower at the Storm Lake Switching Station.
The Sac County reconductoring project offers the first opportunity for Corn Belt Power crews to install OPGW. They have trained by watching Hi Line Construction add OPGW as it builds Corn Belt Power’s Prestage to Willemssen transmission line in Wright County.
Jeremy Stattelman, transmission superintendent, says, “(Line Foreman)Travis Hefty has been doing a lot of research. We’ve been watching Hi Line and, just like other projects, we will learn by doing. It is the same thing as when we put up oval conductor at Glidden for the first time.”
Stringing fiber requires use of a bull wheel to keep the tension on the OPGW constant as it unwinds. Corn Belt Power has rented both the bull wheel and large dollies that are needed for the OPGW installation.
Corn Belt Power’s communications personnel are also involved in the fiber project. The crew has purchased new testing and splicing equipment and will be responsible for completing the indoor splicing step of the installation process.
The reconductoring project will cost approximately $100,000 a mile, or a total of $1 million. Installing OPGW in place of static wire accounts for approximately $20,000 of the cost for each mile completed.
The project is scheduled to be done by December of this year, depending on when farmers’ crops are out of the field and work can proceed. Future Corn Belt Power reconductoring projects will likely continue to install OPGW in place of a static wire.