Ice & Wind Cause Outages on Friday, March 6
On Friday, March 6th at 6:37pm, the Cape Hatteras Electric Cooperative had a power outage affecting all of Hatteras and Ocracoke Islands. The outage was caused by galloping lines in Buxton. We have received many questions from the membership about Friday’s outage that we would like to take the time to answer.
What are “galloping lines”?
Galloping lines are a phenomenon mostly seen in the upper Midwest where flat terrain and harsh winters leave power lines susceptible to ice formation. Ice causes normally round power lines to take on the airfoil shape of an airplane wing. This causes the wire to lift in the wind leading to a violent up and down whipping motion. This causes the lines to bump into each other and adds additional stress to the insulators holding the wires in place.
Why did it take so long for crews to discover the problem?
When the lights went out, CHEC’s relay system notified crews that the breaker at Oregon Inlet had opened, and that the problem was in the vicinity of that breaker. Crews immediately headed toward Pea Island to locate the problem.
Crew leaders soon came to find that there was no problem in the area of Pea Island, and that the relay system had delivered incorrect information on where the fault was. The crews now had to systemically work their way down the island to locate the issue.
This is a new relay system that the Cooperative installed in November 2014. CHEC management is diligently working to correct the issues with the new system’s programming to avoid such extended outages in the future. Normally, it would have not taken crews so long to find the issue. The new system had an equipment malfunction and delivered false information.
Why did some village have power restored before others?
At 10:05, crews had cleared the system south through Avon and transmission power was restored to Rodanthe, Waves, Salvo and Avon. The issue had been isolated to the area of Buxton. It was around this time that the galloping lines were discovered on the 115kV transmission line that runs behind the Fessenden Center in North Buxton.
At this point, CHEC managers knew that it would not be a quick fix and may take several hours to repair. The villages of Buxton, Frisco, Hatteras and Ocracoke had been in the dark for nearly 4 hours and outside temperatures were in the 30’s.
The decision was made to turn on the diesel generator plant in Buxton to provide temporary power to some members. Because of the size of the load, the plant was only able to pick up Hatteras Village. Shortly after, the transformer in the Hatteras substation tripped offline due to the load being too large. CHEC issues a conservation notice to Hatteras Village in an attempt to get them back on.
Tideland Electric Membership Corporation, which serves Ocracoke Island, also made the decision to run the generator on Ocracoke, rotating the power throughout the village.
Why didn’t CHEC start the generator sooner?
The generator cannot be started until the entire system has been cleared and the reason for the outage discovered. Putting electricity back onto the grid before the problem is isolated is a safety hazard.
CHEC used all of its manpower to find the problem on Friday night. It also takes a certain amount of manpower to serve the circuits when the generator is running. In addition, the load on the generator was too great to carry more than one village.
How did CHEC linemen correct the galloping lines?
CHEC linemen had a daunting task on Friday night. After spending hours in freezing rain and wind, their next challenge was accessing the poles, as they are located in thick marsh. Because the bucket trucks could not drive to the poles, CHEC linemen had to manually climb the icy poles to stop the lines from galloping. This was an especially difficult task to complete in the icy winter weather.
At 12:23am on Saturday morning, crews had successfully made their repairs and were able to start picking up the rest of the circuits on transmission power, starting with Buxton. Hatteras and Frisco circuits followed and the island was back on transmission power by 1:01am with the exception of scattered outages. Crews quickly regrouped and returned to the field to finish restoring these scattered outage, mostly caused by high load as a result of the extended outage and cold weather.
CHEC is proud to report that the repairs were made without any injury or accident.
We are grateful for our linemen, who put their lives on the lines to restore power to Hatteras and Ocracoke Islands, using all of their training and knowledge to complete this laborious task. We are also thankful for our loyal and supportive membership and the patience that they gave us on Friday night.
No matter the condition we must face, Cape Hatteras Electric Cooperative will always do everything we can to provide you and your family with reliable and safe electric service. When outages occur, we will work diligently to restore power to you as expediently and safely as possible.
During an outage, we ask our members and visitors to report any unusual sights or sounds on the electric system. If you see anything unusual, please call us at 866-511-9862 immediately, no matter how small you may think it is.Remember that if you see a downed line, don’t touch it! You should always assume that a downed wire is live.
CHEC Employees Hit Safety Milestone
As of December 31, 2014, CHEC employees reached a significant milestone by working over nine years and more than 500,000 hours without a lost time accident. This has been accomplished while working in the aftermath of several minor and at least one major hurricane.
Ken Park, Loss Control Specialist with Federated Insurance, works with cooperatives all over the country and has commented that achieving more than 500,000 hours without a lost time accident is very rare in the industry. It is especially rare for a cooperative of CHEC’s small size.Safety is CHEC’s number one priority for employees, members and visitors. Whatever the task, the first aspect of performing that job is determining how it can be done safely. These practices extend from the most dangerous tasks of restoring power after a storm to simple everyday jobs. CHEC is committed to continuing to work in a culture of safety that permeates everything the cooperative does.