Great River Energy repairs two transmission towers
On temporary routeElk River, MN (May 29, 2001) - Recently, Great River Energy has experienced two fires on transmission towers along its temporary 230 kV line route near Devils Lake. The utility has since made changes to each tower to prevent further mishaps. Both towers are located on Highway 19 near the Devils Lake Airport and both have a unique design called an in-line dead end which contributed to the fires.
The fires were caused when a build-up of moisture on the arm of the transmission tower caused a condition called “tracking.” Because water is a conductor of electricity, leakage current will travel through the moist, wooden crossarm. In this case, the current heated the bolt holding the crossarm to the pole and caused a fire. In addition, because these particular structures need to be lower near the airport for aircraft clearance, their particular design may have contributed to excessive leakage current during moist conditions, increasing the opportunity for a fire. No one was injured because of the fires, and no customers experienced a loss of electricity service.
“These are the only two power structures along this temporary route with this particular design,” said Will Kaul, Great River Energy’s vice president of transmission. “The changes we are making should mitigate any chance of another fire.”
Great River Energy transmission workers removed the idler insulator string, from the transmission structures and they grounded the hardware to a driven ground rod.
Great River Energy will build a permanent 230 kV line from the Ramsey Substation in Devils Lake to the McHenry Substation near Minot. It is currently seeking permits and easements for the new facility. Construction is targeted to be completed by March, 2002. Once the permanent line is constructed, the temporary line will be removed.
