Electrical service to customers in the St. Thomas-St. John district
was restored late Sunday afternoon, after a district-wide electrical
service interruption which occurred at 9:35 a.m.
“Initially, we are focused on confirming whether a suspected transformer
fault at the point where generators connect to the transmission and
distribution system is the cause of today’s service interruption,” said
Clinton T. Hedrington, Jr. WAPA’s Chief Operating Officer, Electric
System. At the time of the interruption, the three new Wartsila units
were dispatched providing a combined 21 megawatts of electricity to the
grid, and Units 15 and 27 were also dispatched. The apparent fault
triggered protection schemes which shutdown the Wartsila units, and
resulted in a cascading effect on the other two units, he added. The
islands of St. Thomas, St. John, Hassel Island, and Water Island were
affected by the service interruption.
Plant personnel worked to restore Units 15 and 27 to service. “There is
an extensive restart procedure that must be followed when the unit’s
trip off-line with full load as they did today,” Hedrington explained.
“At times, this involves hours-long procedures to properly restart the
units and reconnect them to the electric grid.”
At 1:45 p.m., and with Unit 15 back on-line, plant personnel began
restoration of service first to Feeder 5A, and then to a number of
feeders including 8A, 9B, 7B 10B, 8B, and 7A. Later, with two additional
generating units, Units 25 and 27, on-line, all remaining feeders were
fully restored at 5:10 p.m. “Our team of engineers will continue to
evaluate the apparent fault which resulted in today’s service
interruption,” Hedrington said.
Additionally, a line department crews was dispatched late Sunday
afternoon to investigate the cause of an apparent isolated interruption
on Feeder 9E which serves a portion of St. John. All customers on the
feeder were restored at 6:35 p.m.