Nixa Utilities will again have a vital piece of equipment in place to fully restore the city’s electric system after the unexpected failure of a substation transformer in June of 2017.
A new 30MVA transformer will be delivered to the electric substation behind Espy Elementary on S. Gregg Road around 9 a.m. on Tuesday, March 13.
It will take a couple of weeks to connect and test the new transformer, but it will be online before the summer heat brings the peak electric demand.
“The new transformer will mean that the city’s electric grid will be more robust than ever, helping us provide the exceptionally reliable power which our customers have come to expect from us,” says Brian Denney, Electric Superintendent for Nixa Utilities.
All told, the cost of the new transformer and installation costs adds up to about $620,000.
The City’s insurance policy on the failed transformer plus the sale of the failed transformer parts will return over $415,000.
The balance of the cost for the new transformer comes from the electric department reserve fund.
The reserve fund is kept for just such occasions, so the city can afford to purchase expensive electrical equipment as needed in the case of unforeseen circumstances.
On June 4th, 2017, the 25MVA transformer at Nixa’s Espy substation (the city’s largest of its four substations) failed at the same time that the downtown substation was offline for a transformer upgrade which had been delayed by a supplier.
This meant the city, which normally spreads electric demand across four substations, was suddenly operating with only two substations during the summer peak season. Nixa Utilities was forced to rush to bring the downtown substation online which had been waiting for connection and testing of its new 25MVA transformer which was replacing an older 12MVA unit.
The utility then also created longer distribution loops around the city in order to serve all its customers from those three substations.
The longer loops meant that when lightning, trees, or squirrels caused a regular outage, it took longer for linemen to trace the source of the outage before they could repair it.
The old 12MVA transformer from the downtown substation was then temporarily placed at the Espy substation in order to take some load off the other three substations.
However, despite technically having four substations online, all of them were serving modified distribution loops to serve all the city’s customers, but not with the optimal layout for redundancy to ensure reliability and short repair times.
This meant that small routine outages caused by squirrels or trees could take hours longer to address while affecting more customers.
These short-term adjustments were determined to be the best possible temporary solution while the city waited for a new 30MVA transformer to be built and delivered.
Once the new Espy substation transformer is online, Nixa electric crews will be able to restore the city’s distribution loops to the designed layouts for optimal redundancy and reliability.