Commission receives 2013 report on the reliability of the city utility
WILLMAR — An annual report shows Willmar Municipal Utilities continues to provide reliable electric service to the city’s more than 9,200 customers.
Wesley Hompe, utility general manager, said the average service availability index, which is a ratio of the number of available customer service hours to total customer hours demanded, is 99.988 percent for 2013.
Hompe said 2013’s result is under Willmar’s normal reliability index of 99.99 percent.
“That’s our goal is that nobody is ever out,’’ he said. “But we know there are squirrels. There are dig-ins. There are many, many other factors affecting our system where we’ve got a lot of exposure out there in various ways. But our goal is to have zero outages and I think our customers expect that.’’
Since 1992, the utility has logged distribution system outages; reported on the system’s reliability; and kept track of four different reliability performance indexes.
A 2000 state law sets an outage goal of one hour or less. According to an index that measures the system average interruption duration, Willmar exceeded the 60-minute goal by 3 minutes and 24 seconds.
In another index that measures the duration of the customer average interruptions, Willmar was under the 60-minute goal by 8 minutes and 55 seconds.
Hompe said Xcel Energy in 2013 had outages of well over two hours per customer per year, due mainly to the company’s reliance on overhead power lines. Willmar’s distribution system is mainly underground, he said.
The annual reliability performance report, the report on miles of distribution and transmission lines, service quality performance report, and safety report were given to the Municipal Utilities Commission on Monday.
Commission President Steve Salzer said Hompe has many times talked about reliability.
“This truly is customer service and satisfaction,’’ he said, adding that he read Xcel Energy has many outages. “So we are very good I think compared to some of the others.’’
Salzer said those utilities probably have more overhead power lines. But he said, “Reliability is a very important thing as we look to the utility.’’
Hompe said the commission 35 years ago began placing overhead power lines underground. He said underground service greatly affects reliability because tree limbs don’t fall on overhead wires. Today, Willmar has 84.79 percent underground and 15.21 percent overhead.
“We’re lucky that we’re able to have a commission that was forward-thinking enough to say let’s put all this as much as possible underground. Those parts that we have overhead, we’re able to maintain very well. We keep the trees trimmed and we’re able to keep an eye on our main feeders. If anything does happen, we’re able to fix them relatively quickly,’’ he said.
Hompe said the underground system is “looped’’ and can back-feed an area with an outage.
The report said 2013 outages totaled 9,916.47 hours, down from 15,467.89 in 2012. Outages in the transmission system, which brings in power from outside sources, totaled 7,523.72 hours in 2013, down from 11,429 hours in 2012.
Remaining outages were linked to natural, electrical-mechanical, animal and human causes.
The utility had three major service interruptions during 2013. A major service interruption is defined as an interruption of service at the feeder level and above which affects 500 or more customers for one or more hours.
The first occurred on Sept. 21 when a terminator on a 69-kilovolt line faulted. The second occurred on Nov. 7 when a switch failed to operate correctly during maintenance on the power plant transformer and the third on the same day when three feeder lines lost power in efforts to isolate the transformer.
During 2013, the utility undertook five projects to help resolve outage problems. The report said much of the 2013 construction season was spent on replacing failed lines and on preventive installation of underground facilities.