Norwich — Working at a century-old public utility with some systems that go back into the 19th century can feel like being in a museum one moment and a space-age computerized control room the next, with all eras in between included in the mix.

Norwich Public Utilities crews face those challenges daily, General Manager Chris LaRose said, as they try to ensure today’s customers receive service with as few interruptions as possible.

To that end, Eric McDermott, NPU electric division integrity manager, presented the Board of Public Utilities Commissioners with a summary of projects either recently completed or underway to upgrade electric systems that date back to the 1920s, '50s and '60s to increase power capacity and improve reliability of service.

NPU has a 20-year electricity upgrade plan that calls for spending $2 million per year on system upgrades with a long-term goal of ensuring that major components are no more than 30 to 50 years old. The plan helps reduce surprises and costly emergencies that could cause a spike in electric rates, LaRose said, as well as maintain NPU’s high service reliability record.

NPU has replaced a 50-year-old substation on Dudley Street and a 30-year-old substation on Providence Street in Taftville with smaller but more powerful units that will save substantially on annual operations and maintenance costs, McDermott said.

NPU also recently finished replacing the last 1,200 individual electric meters throughout the city with so-called smart meters. The new units use a radio system to report electric usage directly to NPU and send alarms if power is cut off. In an emergency, NPU can even shut off the power remotely from its main control room at the utility’s headquarters in Greeneville, LaRose said.

“It’s part of the technology in improving response time,” McDermott said. “When a meter loses power, it sends an alarm to the control room and plots where the outage is contained to.”

The control room can track outage problems and give line crews much more exact information on where problems have occurred along the wires or at the substations, LaRose said. “We are getting people out to the outage problems quicker than before,” he said.

Electric system upgrade projects now underway include replacing a 40-year-old substation in Bean Hill near the entrance to the Norwich business park and upgrading 60-year-old electric and mechanical systems in a North Main Street substation, again cutting down on maintenance and operations costs, McDermott said.

Part of the system upgrade is replacing old 4.8-kilovolt power distribution circuits to 13.8-kilovolt circuits, including the upgrade of power systems crossing the Shetucket River to the East Side and Laurel Hill. In short, LaRose said, power travels much more efficiently at higher voltage.

Sometimes, electricity service reliability comes down to something as mundane as the need to trim trees and brush back from power systems, McDermott said. A system reliability chart showed NPU slipped slightly in some categories in 2019 compared to 2018. The system average interruption duration went up from 71.78 minutes to 94.71 minutes, but customer average interruption duration dropped from 117.4 minutes to 91 minutes.

McDermott said NPU has hired an additional tree trimming crew for one month to address high-risk areas and has revised bid documents to call for a 40% increase in efficiency in trimming. More pole replacements are planned, and older equipment will be replaced. 

When it comes to hydropower technology, NPU officials have learned that the best technology can be over 100 years old. NPU budgets $100,000 annual maintenance on the Greeneville Dam and $50,000 for the canal offshoot from the Shetucket River that runs through the hydropower unit.

The Greeneville Dam was constructed in 1882, and significant repairs were made in 1886 and after the 1938 Hurricane, NPU spokesman Chris Riley said. When the dam needs repairs, NPU sticks with the proven 19th century technology of rocks encased in wooden boxes.

“We looked at modernizing, and that is still the best technology,” Riley said.

But in September, a 1923 hydropower generation shaft and impeller — the device with blades that spins as water rushes through — at the Second Street hydropower unit broke. The blades had become lopsided and sheared off, McDermott said. The half-megawatt generating plant was shut down, and the equipment stripped to the foundation.

No replacement parts are available, so NPU has enlisted a Midwest firm to replicate the antique impeller using a cast model of the original. The $500,000 repair is funded in the capital budget. When operating, the hydropower plant saves NPU $750,000 per year by lowering the purchased power requirements.

The Second Street hydropower system produces enough electricity to power several hundred homes, Riley said. It also is certified by the Low-Impact Hydropower Institute as a green renewable energy facility, which gives NPU environmental credits it can sell to fossil fuel companies to meet environmental regulations, LaRose said, so NPU wants to keep it going through the 21st century.

c.bessette@theday.com