All-day power outages on St. Thomas, St. John and Water Island were the result of an oil leak that caused the Randolph E. Harley Power Plant’s 42-megawatt workhorse generator to trip offline, according to the V.I. Water and Power Authority.

"The big unit [no. 23] tripped offline between 7 and 7:30 [a.m.], and in a domino effect the load shifted from unit to unit and the system couldn’t carry it that time of day, with energy use ramping up as schools, government offices and businesses opened up, so safety systems shut down the entire plant to protect itself," said WAPA spokeswoman Cassandra Dunn, in a phone conversation Wednesday evening.

"We knew before Carnival we had a problem with an oil leak, but we thought we would be able to get through Carnival without serious problems and in the meantime bring unit no. 18 online back online after being overhauled," Dunn said. "As luck would have it, we did not finish before no. 23 tripped out this morning."

Now they are working to bring both units online, she said.

WAPA is ready to fix the oil leak, but they do not know if there may be any additional problems with the unit, she said. Meanwhile, the St. Thomas grid is being powered by four smaller generators.

Dunn said that as crews worked to restore each feeder line, WAPA “tried to restore power to schools first."

By noon, service had been fully restored to several feeders and to portions of most feeders serving the St. Thomas/St. John district, according to a statement from WAPA.

By 2 p.m., technicians were able to bring steam turbine unit no. 11 online and restore several more feeders. Four hours later, no. 23 was back in service, and all feeders had been fully restored, according to WAPA.

No. 23, the unit that tripped and triggered the blackout, is the newest and largest St. Thomas generator. It was down for a major overhaul from mid-October through late December last year, and its absence played a role in a series of St. Thomas outages last fall.

Last November, WAPA’s governing board authorized spending a total of $3.1 million for the Wood Group, gas turbine specialists, to inspect and repair the unit, replacing rotors, stators and other parts.