American Transmission Co., Madison, Wisconsin, U.S., will conduct a week-long helicopter inspection of an energized 345-kV electric transmission line that runs through Columbia, Dodge, Green Lake and Fond du Lac, Wisconsin, counties beginning March 31.

To assess the condition of the line and related equipment at critical points, an engineer will be suspended from each wire to x-ray them at the point of connection with the poles. This work will take four helicopter passes and about 45 minutes at each individual pole.

ATC regularly conducts aerial surveys of the transmission system. But work on an energized line is unusual.

“We are simply out of breathing room in many key spots on the electric grid,” said Mark Williamson, ATC vice president of major projects. “This line is part of the backbone of the network. We are hard-pressed to take such a critical line out of service at most times of the year to do basic maintenance and still keep the lights on. This live inspection illustrates why we need major new projects in southern Wisconsin.”

Williamson highlighted ATC plans for new 345-kV lines to improve reliability in southern Wisconsin: • A new transmission line to tie Madison and Milwaukee together electrically needed by 2009.
• A new transmission line from Christiana to West Middleton needed by 2011.
• A new transmission line from West Middleton to northern Dane County needed by 2013.
• A new transmission line connecting Wisconsin to either Iowa or Illinois.
• ATC placed a new 345-kV line from Beloit to northern Illinois in service Friday.

All projects are needed to prevent low voltages (which can cause dimming of lights or harm to sensitive equipment), to help keep the lights on during summer peak or stressful periods, and to keep pace with the rising demand for electricity.

This inspection is a result of years of intensive study and the development of new technology that allows x-rays to be taken from the air. The inspection will allow ATC to better monitor the condition of the line and install more effective protection equipment. Needed repairs will be made during the last two weeks in April. ATC hopes to make repairs from the air although weather and complexity may require work from the ground. This work is part of an ongoing maintenance program for this transmission line to help prevent equipment failures.