A tornado obliterated six transmission towers and ripped apart three 500-kV lines last March in Cartersville, Georgia. By using a new conductor cleaning tool developed by the Electrical Power Research Institute (EPRI; Palo Alto, California), Southern Company (Atlanta, Georgia) line crews were able to restore the first line in eight days and get the rest of the system up in three weeks. The new cleaning process enabled the line crews to complete more than 80 conductor cleanings in two weeks and save more than 32 hours.

On this kind of restoration project, linemen normally would wire brush the conductors, install the sleeve and put the conductor back in the air. However, this method is not preferred by the conductor manufacturers, because it can lead to termination failures.

Over the past few years, vendors have advised linemen to unstrand the wires of the conductor, wire brush each strand and then restrand them after each strand is clean. Some of the conductors, however, have up to 54 strands. The 500-kV lines in Cartersville had three subconductors per conductor. To clean each conductor strand prior to installing the sleeve could take up to 30 minutes per subconductor.

Also, when linemen try to clean each of the strands in an aluminum conductor manually, it is challenging, if not impossible, for them to put them back correctly after the cleaning. And if the strands are not laid in place correctly, the linemen will struggle to get the sleeve on the conductor.

For that reason, Southern Company searched for a way to clean the conductors without taking every strand apart. When EPRI invited the utility to participate in a research project on conductor cleaning, the utility decided to jump on board to try to solve an on-going problem with conductor failures.

Research Process

Southern Company first became interested in this research project through its involvement in EPRI. The company participates in working groups, which are always looking at ways to better maintain the transmission system. The working groups' primary function is to come up with research projects that eliminate the issues.

When the issue of conductor failures came up, Southern Company knew it was a big deal and would be a good project to fund. The line personnel serve as advisors for EPRI and have online and face-to-face meetings at the different research facilities. As such, they were very involved in the implementation and development of the conductor cleaning tool.

Southern Company became one of seven utilities to participate in the research project. In addition to Southern Company, American Transmission Co., Tennessee Valley Authority, Public Service Electric & Gas Co., Oncor Electric Delivery, CenterPoint Energy and East Kentucky Power Cooperative helped to develop the conductor cleaner.

By participating in the project, Southern Company hoped to end up with an effective, time-efficient and less costly strategy to make a termination. If the tool did not perform well in the test, Southern Company was prepared to go back to its old method of wire brushing. The tool, however, did meet Southern Company's goals and expectations.