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Independent system operator (ISO)
(US) Entity, regulated by the Federal Energy Regulatory Commission (FERC), that is responsible for ensuring the efficient use and reliable operation of the transmission grid and, in some cases, generation facilities. Individual ISOs cover either a single state (for example, the California ISO) or a region (for example, the Midwest ISO). ISO responsibilities vary by jurisdiction, but can include co-ordinating scheduling for transmission transactions; overseeing the instantaneous balancing of generation and load; managing and redispatching generation in system emergencies; managing operating reserves; ensuring new transmission facilities are built when and where needed; and co-ordinating transmission payments. In some cases, ISOs are also responsible for managing power exchange activities.