Wide-area power outage hits Southwest US
Large areas of Southern California and Arizona experienced a power outage from around 4 p.m Thursday 8th September continuing into Friday for many.
The outage appears to have been caused by human error which was then exacerbated by a system failure.
Many businesses were forced to close early or to activate business continuity plans. Two nuclear reactors in the region were shut down due to lack of power supply.
APS, a regional power provider, issued the following press notice in relation to the incident:
Cause of Widespread Outage under Investigation
At approximately 3:30 pm today, the North Gila – Hassayampa 500 kV transmission line near Yuma, Ariz., tripped off line resulting in a major power outage across southwest Arizona and into Southern California. Among APS customers, approximately 56,000 lost service throughout Yuma, Somerton, San Luis and Gadsden. APS is in the process of restoring service to customers in these communities.
The outage appears to be related to a procedure an APS employee was carrying out in the North Gila substation, which is located northeast of Yuma. Operating and protection protocols typically would have isolated the resulting outage to the Yuma area. The reason that did not occur in this case will be the focal point of the investigation into the event, which already is under way.
“We are working hard to restore our customers as quickly and safely as possible,” said APS President and Chief Operating Officer Don Robinson. “We take great pride in our hard-earned reputation for safe and reliable service, and we will work hard to identify the cause.”
APS is Arizona’s largest and longest serving electric utility and serves more than 1.1 million customers in 11 of the state’s 15 counties. With headquarters in Phoenix, APS is the principal subsidiary of Pinnacle West Capital Corp.
The latest sitrep from SDGE, another affected operator reads as follows:
Our transmission line from Arizona is now operational, and electric service has been restored in many areas. While it may take more than 24 hours to restore power to all our communities, our crews are working as quickly and safely as possible.
If power is out in your area:
If power has been restored in your area:
Thank you for your patience. Please continue to be safe.
•Date: 9th September 2011 • Region: US •Type: Article • Topic: BC general