A transformer at the MBTA’s South Boston power plant — the largest source of power for the transit system — failed early Tuesday morning and triggered a circuit breaker that caused systemwide outages, said interim T general manager Jeff Gonneville.
The reason for the failure, which prompted a stop-in-place for all trains, is still under investigation, he said.
“All trains are told to standby at their locations so we can determine what is functioning and what isn’t,” Gonneville said. “That’s what our customers experienced this morning. Trains were held and began moving into stations.”
The South Boston power plant has two main outside sources of energy from Eversource, but one of those has been down while the T and the utility company work on it, Gonneville said. The MBTA does not yet know if the outage would have been more limited if the two feeds were up and running, he said.
The failure caused the T to lose power to its signals and switches in the downtown area, and some stations throughout the system lost power entirely — including to lighting, elevators, and escalators, Gonneville said.
Power was restored about 10 minutes later, but it took around 25 minutes for the signal and switch systems that control train travel on the tracks and in the tunnels to be re-energized, he said.
According to updates from the MBTA’s Twitter account, it took longer to restart service at the Orange Line’s Forest Hills station and the Green Line’s Copley and Arlington stations. Operations at Copley and Arlington stations fully resumed around 10:47 a.m., the MBTA said.
At a morning event in Weston, the state’s transportation secretary, Gina Fiandaca, said “It does take a little bit of time for the system to catch up after a power outage like that. They are working hard to get all of the information out to our riders.”
When the MBTA tweeted that it was addressing the power issue, passengers who were stuck on trains or waiting on platforms were quick to voice their frustration.
“[One hundred-plus] people just standing around at Malden with no updates on when any trains will arrive,” a passenger wrote. “Have you considered people need to go to work?”
One person said they were stuck on a train at the JFK/UMass Station with the doors wide open as snow came down.
“Can you close the doors,” the person tweeted to the T. “It’s soooo cold!!!”
Other riders reported their trains had been at a standstill for 15 to 20 minutes and that they had received little information about how long the delays might last.
“Need more transparency than this,” a rider tweeted.
According to recorded transmissions of MBTA operations from Broadcastify, escalators came to a sudden halt in a number of stations, and a woman was stuck in a stalled elevator at Copley Station.
Brian Alkins, a spokesman for the Boston Fire Department, said firefighters removed the woman from the elevator shortly before 8 a.m.
Earlier in the day, Tatiana Niebuhr, 23, hopped on the Green Line at the Riverway stop for her commute to the Financial District. She was hoping to get to her office by 8 a.m., but when her train stopped at the Symphony stop, she knew that would be impossible.
“I’m texting my colleagues right now,” Niebuhr said.
Carly Rounds, 28, said she was heading to State Street when her Orange Line train stopped for about 15 minutes.
“It definitely adds a lot of stress and anxiety to the morning,” Rounds said. “Normally I’m there by 8 a.m., so I had to message everyone that I would be late, like, ‘Hey, standing by on the Orange Line.”
Rounds said her commute had already taken at least 50 minutes.
“I know the MBTA is under a lot of pressure, but maybe just like, try to prioritize those fixes for people’s morning commutes,” she said.
Emily Sweeney and Samantha Gross of the Globe staff contributed to this report. This a developing story and will be updated.
John R. Ellement can be reached at john.ellement@globe.com. Follow him @JREbosglobe. Katie Mogg can be reached at katie.mogg@globe.com. Follow her on twitter @j0urnalistkatie Steve Annear can be reached at steve.annear@globe.com. Follow him @steveannear. Taylor Dolven can be reached at taylor.dolven@globe.com. Follow her @taydolven.