maintenance. Where as for the electric grid, management is divided amongst several specialised teams. Fault management Fault management involves monitoring the behaviour of the power system so as to identify and correct issues that affect the system's reliability. Fault management can be specific and reactive: for example, dispatching a team to restring conductor that has been brought down during a storm. Or, alternatively, can focus on systemic improvements: such as the installation of reclosers on sections of the system that are subject to frequent temporary disruptions (as might be caused by vegetation, lightning or wildlife). Maintenance and augmentation In addition to fault management, power systems may require maintenance or augmentation. As often it is neither economical nor practical for large parts of the system to be offline during this work, power systems are built with many switches. These switches allow the part of the system being worked on to be isolated while the rest of the system remains live. At high voltages, there are two switches of note: isolators and circuit breakers. Circuit breakers are load-breaking switches where as operating isolators under load would lead to unacceptable and dangerous arcing. In a typical planned outage, several circuit breakers are tripped to allow the isolators to be switched before the circuit breakers are again closed to reroute power around the isolated area. This allows work to be completed on the isolated area. Frequency and voltage management Beyond fault management and maintenance one of the main difficulties in power systems is that the active power consumed plus losses must equal the active power produced. If load is reduced while generation inputs remain constant the synchronous generators will spin faster and the system frequency will rise. The opposite occurs if load is increased. As such the system frequency must be actively managed primarily through switching on and off dispatchable loads and generation. Making sure the frequency is constant is usually the task of a system operator. Even with frequency maintained, the system operator can be kept occupied ensuring: Notes See also Power system simulation References External links IEEE Power Engineering Society Power Engineering International Magazine Articles Power Engineering Magazine Articles American Society of Power Engineers, Inc. National Institute for the Uniform Licensing of Power Engineer Inc. Power engineering Electric power