Reliability	Back to Previous Page  Download Adobe Reader

The California ISO Control Center is the high-tech electricity traffic controller for 75 percent of the state, directing some 200 billion kilowatt-hours of electricity annually to utilities that serve an estimated 30 million Californians. Because reliability is a 24-hour job, 365 days a year, operators must assess the status of the transmission system at all times. There are 15 operators on shift around the clock at the ISO monitoring critical information displays that are updated every four seconds. As one of four Security Coordinators for the Western Electricity Coordinating Council (WECC), the California ISO also monitors transmission security for a portion of 11 western states, British Columbia and northern Mexico. Rotating Outages In times of electrical shortage it is 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 ISO did not act to protect the California grid, the first effect would be a drop in voltage. Low-voltage 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 were 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. How Does the ISO Call 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 reserve levels dip below five percent, the ISO can also call on voluntary commercial and industrial customers to reduce their loads. If that is still not enough, involuntary load reduction, or rotating outages may become necessary. 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 where specifically the outages are occurring in a given area. Blackout Warning Notification Program The ISO has in place a 48- and 24-hour electronic warning system that alerts utilities, key governmental agencies and the public via e-mail and e-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. 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 this 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.