Harley Power Plant

Generators at the V.I. Water and Power Authority’s Harley Power Plant on St. Thomas went offline Thursday because of an equipment malfunction.

ST. THOMAS — An hourlong power outage swept St. Thomas and St. John on Thursday after a fuel service interruption at the V.I. Water and Power Authority’s St. Thomas power plant, officials said.

The outage began at 3:09 p.m. and lasted until 4:11 p.m., when officials began restoring power, according to WAPA spokesman Jean Greaux Jr. All power had been restored by about 4:45 p.m., Greaux said.

The interruption began when a fuel vaporizer that converts liquid petroleum into gas suffered a malfunction. As a result, the vaporizer shut down, which interrupted the fuel supply to four generators, Greaux said.

Unable to handle the demand, the fifth and sixth generators rented from APR Energy, which are oil-fired, shut down immediately, Greaux said.

“The alarm occurred and the system protected itself,” he said.

Three of the six generators online at the time were the new small-capacity generators manufactured by Finnish-headquartered Wärtsilä. The fourth natural gas generator was the WAPA-owned Unit 15.

The Wärtsilä generators haven’t officially been commissioned yet, but provide mainline power generation at the Harley Power Plant from time to time, Greaux said.

“They were dispatched providing regular capacity,” he said.

While the Wärtsilä units periodically step in to provide electricity, testing for the equipment continues, Greaux said. The units have not been formally given numbers yet, Greaux said.

While power outages of varying lengths are common in the territory, Thursday’s outage differed in its cause, Greaux said.

“In this case, it had nothing to do with the generating,” he said.

Thursday’s outage was at least the second outage to affect the Wärtsilä generators, which officials have said are intended to improve reliability and efficiency in local power generation.

The outage comes amid testimony by WAPA seeking to justify an electric rate increase for consumers. WAPA officials have cited declining electric sales, and the loss of major electrical customers, as a reason they’re seeking increased rates.

The outage occurred at roughly the same time authorities reported a power pole fire in Coral Bay, St. John, though Greaux said the fire and the outage were unrelated.

— Contact Brian O’Connor at 340-714-9130 or email boconnor@dailynews.vi.