The Water and Power Authority on Sunday restored power to parts of St. Thomas that experienced a two-hour outage, the utility announced Sunday night.
WAPA’s largest generating unit tripped at 5:40 p.m. Sunday, leaving the Randolph Harley Power Plant with less than adequate generation capacity to meet the demands of the island district. As a result, a portion of Feeder 6A and all of Feeders 7A and 9C were taken off line for approximately two hours.
Unit 23’s failure on Sunday evening initially caused eight feeders to fall off line. At the time two other generating units, Units 14 and 25, were on line. Plant personnel brought a third unit, Unit 15, on line and achieved full restoration just before 7 p.m. By 7:23 pm, however, the island’s demand for power exceeded the 52-megawatt combined capacity of the three generating units which led to Feeders 7A and 9C being taken off line as well as a portion of Feeder 6A, according to WAPA’s news release.
Service was restored to all customers just before 9 p.m. Sunday after a successful restart of Unit 23, which provided an additional 25 megawatts of generating capacity to the grid. Plant personnel determined that Unit 23’s trip was caused by a failure with one of the unit’s battery chargers.
As of about 10 p.m. Sunday generating units 14, 15, 23 and 25 were on line and plant personnel expected that as the night went on and the power demand decreases, Unit 14 will be taken off line and placed in standby mode.
Unit 18 is not available as plant personnel are conducting maintenance on one of the generating unit’s transformers.
