Chelan PUD technicians and engineers conducting an extensive investigation into the cause of the Friday the 13th substation outage have identified the likely cause. After testing all other critical components within the substation, wiremen and technicians identified worn wiring connections in the monitoring device that detects an internal fault in the system. The monitor was installed in 1989.
“Although it was bitterly cold that morning, the increased load (energy use) wasn’t the cause,” says Chad Rissman, director of the District’s Asset Management program. “The substations capacity was sufficient to handle the demand.” During the inspection and testing, technicians found all other components to be in good condition.
Power went out to about 2,000 customers that morning. Although power was returned to most customers before noon, about 300 customers remained without power until 6 p.m. The District worked to shift the energy load to other substations, but the final group of customers couldn’t be restored until the mobile substation unit was moved into place and brought into service. The mobile sub continues to operate at the site.
It’s anticipated that the Miller Substation will be returned to full service within the next few days. However, the mobile unit will remain onsite as a precautionary back-up until the temperatures warm a bit more and remain above freezing.