NOVI – What can a utility do when an existing transmission line does not meet clearance criteria? One option would be to build a new transmission line, but this would be expensive and could take many years just to get the required permits. Instead, ITC Holdings Corp. — faced with such an issue — opted to raise 25 steel lattice towers by 10 ft or 20 ft each to enable the line to operate at its design rating, saving both time and money.
eThe methodology and cost considerations involved in raising existing lattice towers make an interesting story that includes the project’s critical path items and potential improvements.
As the largest independent electric transmission utility in the U.S., ITC invests in the electric transmission grid to improve reliability and expand access to energy markets. This enables new generating resources to interconnect to its transmission systems and lowers the overall cost of delivered energy. ITC owns and operates high-voltage transmission facilities in Michigan, Iowa, Minnesota, Illinois, Missouri, Kansas and Oklahoma. ITC’s operations in Michigan include most of the Lower Peninsula, largely served by its Michigan Electric Transmission Co. (METC) operating subsidiary.
Prior to ITC’s acquisition of METC in 2006, clearance issues had forced a derating of the 345-kV Argenta-Palisades transmission line as a result of excessive line sag. In 2009, ITC’s transmission engineers investigated the option of restoring this critical 40-mile (64-km) double-circuit line to its design rating to meet increasing demand. The utility confirmed the need for the uprating and identified three alternative approaches to accomplish its goal without having to build a new transmission line. After conducting a thorough evaluation, the utility was able to make an informed decision on the best approach.
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