Why Rotating Outages?	Back to Previous Page  Download Adobe Reader

In times of electrical shortage, it is far preferable to deal with controlled rotating power outages than to allow uncontrolled or cascading power outages that could damage key components of the grid. If demand exceeds supply, and the California ISO does not act to protect the state’s grid, the first effect would be drop in system frequency throughout the West. Low-frequency conditions can damage electrical appliances in homes and businesses, as well as the transformers, switching gear and other key components of the grid. If those components are damaged or destroyed, it could take hours or even days to restore power. Despite the inconvenience and difficulty posed by rotating outages, it is far preferable to control a shortage of electricity by reducing demand on the system, than to allow the shortage to damage the generation equipment and result in uncontrolled power outages throughout California and the West. Matching the supply and demand of electricity is a constant balancing act. The weather, level of imported power and conservation efforts can cause fluctuations in the forecasts for blackouts. For these reason, the public should be prepared for warnings that are not followed by blackouts. In many cases, increased conservation from the warnings alone could help prevent the blackouts from occurring. Conversely, quick substantial fluctuations can necessitate outages without warning. How the ISO Calls for Rotating Outages Operators in the ISO Control Room continuously monitor the supply and demand of electricity in California. If reserve levels begin to drop, the ISO communicates with local utilities and electrical generators, asking them to produce more power if possible. Simultaneously, the ISO issues news releases and public calls for conservation. Often, consumers respond by using less electricity, helping to avoid rotating outages. In a Stage Two Emergency, when reserves dip below five percent, the ISO can also call on voluntary load reduction, or rotating outages may become necessary, which occurs in a Stage Three Emergency. ISO operators determine how many megawatts of load reduction are needed, and that figure is divided among the state’s utility distribution companies on a pro-rata basis, and communicated to the utilities. It is up to the utilities to actually determine how and where they can reduce their load by the assigned number of megawatts. The local utilities therefore will have the best information about specifically where the outages are occurring in a given area. Blackout Warning Notification Program The ISO has in place a 48- and 24-hour warning system that alerts utilities, key governmental agencies and the public via email and pages when there is a potential for rotating blackouts. The notices are an extension of the ISO’s electrical emergency notifications issued through its Alerts, Warnings and Emergencies System.