BY ANN THELEN
Did you know squirrels, lightning and trees have something in common? They all have the potential to knock out your electricity.
Iowa’s electric cooperatives work hard to keep your lights on 24/7, but unplanned circumstances can occasionally create power outages.
The top three troublemakers to electric reliability are trees falling on power lines and other interferences from vegetation, lightning strikes and animals encountering electric equipment.
Power line structures provide perching, roosting and nesting areas for birds and raptors (larger birds of prey, including owls, eagles and falcons). When birds come into power equipment – lines, conductors or transformers – it can result in bird fatalities, power outages and pole fires. Birds are number one in causing more power system outages than any other animal.
According to U.S. News and World Report, Iowa has the most reliable electrical grid of any state in the U.S. with Iowa’s electric cooperatives boasting a 5-year reliability average of 99.97 percent.
Iowa’s electric cooperatives work hard to maintain this exceptional reliability standard and reduce the amount of time members are without power from an outage. Among the techniques being used to foil critter catastrophes are snake barriers around substations, buzzard shields on transmission towers and mesh coverings on wood poles to prevent damage from woodpeckers. Some co-ops have also found that burying lines underground is a viable strategy.
Although it’s not required by state law or through the Iowa Utilities Board, most electric cooperatives have an avian protection plan – both for outage reductions and environmental responsibility.
Lyon Rural Electric Cooperative (REC) serves members over nearly 900 miles of line in Lyon County, which is the most northwesterly county in the state. Being situated along the Big Sioux River brings beauty and some challenges for overhead lines.
The river valley region can make power restoration more difficult and extended when storms wreak havoc on power line infrastructure. Some areas have steep ditches and roads that may quickly become impassable during snow and ice storms. This is one reason Lyon REC has been undergoing a multiyear project to bury all its power lines.
“Because we don’t serve an urban area, it makes sense for Lyon REC to bury our electric equipment underground,” says Ross Loomans, general manager, Lyon REC.
“In this part of Iowa, we’ve had a lot of issues with rats, mice, snakes, possums and skunks interfering with equipment.”
At the direction of its board of directors, the co-op has a goal of being 100 percent underground with electric equipment. With 775 miles of lines complete, they are well on their way to reaching the goal.
“We’re sealing the equipment to the point where rodents can’t get in, which is good for the critters and our members,” Loomans adds. “We’ve also added lightning arresters throughout our system to mitigate outage impacts and damage from lightning strikes.”
The proof is in Lyon REC’s improved reliability statistics.
One measure is called the System Average Interruption Duration Index (SAIDI) and is the average outage duration for each member served. Lyon REC has cut its SAIDI nearly in half, going from 57.5 to 33.62 minutes. Nationwide and according to Institute of Electrical and Electronics Engineers (IEEE) standard, the median value for North American utilities is approximately 90 minutes.
An April 2013 ice storm resulted in millions of dollars’ worth of infrastructure damage for Lyon Rural Electric Cooperative, Osceola Electric Cooperative and Iowa Lakes Electric Cooperative. The damage was so extensive that a Presidential Disaster Declaration was issued. Federal Emergency Management Association (FEMA), provided an eligibility amount of roughly $28,500 per mile of line to replace storm-damaged equipment.
“There’s a perception that going underground is more expensive, and in some cases, it is,” Loomans says. “However, our actual costs have been nearly 9 percent less than the allocated amount from FEMA.”
When power infrastructure is underground, it takes different equipment, such as backhoes, vacuum excavators and fault-finding equipment. A fault interrupts the quality of power supply and is caused by fires, ice storms, animal electrocutions or equipment.
“It’s a different mindset,” he adds. “Instead of training line workers to climb poles, we train them to find underground faults.”
Taking system cover
T.I.P. Rural Electric Cooperative in Brooklyn serves members over nearly 1,800 miles of line in the Iowa counties of Benton, Iowa, Keokuk, Johnson, Jefferson, Mahaska, Poweshiek, Tama, Wapello and Washington.
“Our most effective strategy is covering up critical pieces of equipment,” says Dean Huls, assistant general manager/operations manager. “With the covers, if a bird or raptor lands on the equipment they aren’t injured by electric voltage, and there isn’t a resulting outage.”
The cover-ups are made of plastic mesh and are placed on equipment, such as regulators. The regulator generates a fixed-output voltage that remains constant for any changes in electricity load conditions. It acts as a buffer for protecting components from damages.
The cover-ups also prevent bird nests. It’s a priority to prevent bird nests, because birds attract other animals, such as raccoons. With raccoons’ climbing ability, they can cause equipment damage by chewing small wires or creating pole fires by encountering equipment.
“We’re on a 10-year inspection cycle with all our underground residential distribution risers (devices that connect an overhead line to an underground line),” Huls explains. “When we’re doing an inspection and see there isn’t a cover-up in place, a service order is put in to have it installed.”
Without covering or sealing up the equipment, Huls says it’s not uncommon to see several birds at the base of a transformer. Those situations increase bird mortality and contribute to power outages.
“Every year, our animal-reported outages have gone down,” Huls says. “It’s good for reliability and it saves our members money. We have less equipment to repair and use less staff time in removing nests and other hazards.”
Ann Thelen is the editor of Living with Energy in Iowa.