OPALCO Fares Well in Electrical Storms
OPALCO’s system stood up to the test in the recent back-to-back electrical storms over San Juan County. System Engineer Joel Mietzner said “it is unusual to get electrical storms in our area and particularly two such storms back to back.” However, OPALCO’s system is built out with voltage arrestors to handle lightning strikes like we saw with these storms – some of which carried as much as 90,000 volts as measured when it hit our equipment.
The outage events began on Friday at about 6:00 p.m. when lightning struck a home in the Cape San Juan area, grounding itself through the wiring in the home and blowing out an OPALCO transformer. This caused a fault in that circuit, cutting power to approximately 200 meters in the area. Power was restored by 7:30 p.m.
At 7:26 p.m., the Orcas submarine cable terminal opened up in response to a fault. The system is designed to open up (and shut down power) as soon as a fault in the line is detected. The fault was cleared and power restored automatically in eleven seconds. At 7:42 p.m. something, such a limb, blew into the transmission lines on Shaw Island and the terminal on Lopez opened up, cleared the fault and restored power automatically within the same eleven-second timeframe. These smart “auto reclosure” devices save our crews hours of time; in the past when a fault opened up a switch, they would have to drive the lines to try and visually locate the cause of the outage – sometimes requiring crews to travel to the outer islands during foul weather to try and locate a fault.
The big outage occurred Friday night at 8:46 p.m. when a fault was detected on the mainland at Puget Sound Energy’s Burrow’s Bay substation, where all of the power transmitted to the islands is routed. All of San Juan County was without power. PSE crews worked through the night and power was re-routed to the islands at 2:50 a.m. The fault was likely caused by a lightning strike.
On Saturday morning, an underground fault in the Cape San Juan area cut power again to about 75 meters. This was likely a result of the Friday evening lightning strike event. Power was restored to most meters by noon.