A power outage (also known as power cut, power failure, power loss, or blackout) is the loss of the electricity supply to an area.
The reasons for a power failure can for instance be a defect in a power station, damage to a power line or other part of the distribution system, a short circuit, or the overloading of electricity mains. While the developed countries enjoy a highly uninterrupted supply of electric power all the time, many developing countries have acute power shortage as compared to the demand.
Some developing countries and newly-industrialized countries have several hours of daily power-cuts in almost all cities and villages because the increase in demand for electricity exceeds the increase in electric power generation. Wealthier people in these countries may use a power-inverter (rechargeable batteries) or a diesel/petrol-run electric generator at their homes during the power-cut. The use of standby generators is common in industrial and IT hubs.
A power outage may take one of three forms:
Power failures are particularly critical for hospitals, since many life-critical medical devices and tasks require power. For this reason hospitals, just like many enterprises (notably colocation facilities and other datacenters), have emergency power generators which are typically powered by diesel fuel and configured to start automatically, as soon as a power failure occurs. In most third world countries, power cuts go unnoticed by most citizens of upscale means, as maintaining an uninterruptible power supply is often considered an essential facility of a home.
Power outage may also be the cause of sanitary sewer overflow, a condition of discharging raw sewage into the environment. Other life-critical systems such as telecommunications are also required to have emergency power. Telephone exchange rooms usually have arrays of lead-acid batteries for backup and also a socket for connecting a diesel generator during extended periods of outage.
Under certain conditions, a network component shutting down can cause current fluctuations in neighboring segments of the network, though this is unlikely, leading to a cascading failure of a larger section of the network. This may range from a building, to a block, to an entire city, to the entire electrical grid.
Modern power systems are designed to be resistant to this sort of cascading failure, but it may be unavoidable (see below). Moreover, since there is no short-term economic benefit to preventing rare large-scale failures, some observers have expressed concern that there is a tendency to erode the resilience of the network over time, which is only corrected after a major failure occurs. It has been claimed that reducing the likelihood of small outages only increases the likelihood of larger ones. In that case, the short-term economic benefit of keeping the individual customer happy increases the likelihood of large-scale blackouts.
Title XIII of the Energy Independence and Security Act of 2007, signed by President Bush on December 19, 2007, makes it the policy of the United States to upgrade the United State's existing electricity grids with advanced communications and embedded sensors to create a "Smart Grid" that can avoid power outages (in addition to lowering grid-related CO2 and reducing energy consumption). The Electric Power Research Institute (EPRI) has estimated that each year power outages and disruptions cost Americans more than $100 Billion.
Cascading failure becomes much more common close to this critical point. The power law relationship is seen in both historical data and model systems. The practice of operating these systems much closer to their maximum capacity leads to magnified effects of random, unavoidable disturbances due to aging, weather, human interaction etc. While near the critical point, these failures have a greater effect on the surrounding components due to individual components carrying a larger load. This results in the larger load from the failing component having to be redistributed in larger quantities across the system, making it more likely for additional components not directly affected by the disturbance to fail, igniting costly and dangerous cascading failures. These initial disturbances causing blackouts are all the more unexpected and unavoidable due to actions of the power suppliers to prevent obvious disturbances (cutting back trees, separating lines in windy areas, replacing aging components etc). The complexity of most power grids often makes the initial cause of a blackout extremely hard to identify.
In addition to the finding of each mitigation strategy having a cost-benefit relationship with regards to frequency of small and large blackouts, the total number of blackout events was not significantly reduced by any of the above mentioned mitigation measures.
|U.S.A., State, City/Area||ELECTRIC OUTAGE MAP LINK|
|CA, San Diego||http://outages.sdge.com/publicOutageWeb/servlet/OutageMap|
|GA, Forsyth, Fulton, Dawson, Lumpkin, Cherokee, Hall, & Gwinnett Counties||http://sawneearcsrv.sawnee.com/outagemap/|
|IN, south central||http://sciremc.maps.sienatech.com/|
|MD, Montgomery & Prince George's County||http://potomacelectricpowerco.net/home/emergency/maps/zip/default.aspx|
|MI, SE, Detroit||http://my.dteenergy.com/map/zipCodeOutageMap.pdf|
|MN, Wright & Hennepin Counties||http://wh-oms.whe.org/|
|MO, Kansas City||http://www.kcpl.com/kcmaps/frameset_menus.htm|
|NH, Belknap, Coos, Carroll, Cheshire, Grafton, Hillsborough, Merrimack, Rockingham, Strafford, Sullivan County||http://www.nhec.com/oms.php|
|NJ, Atlantic City||http://www.atlanticcityelectric.com/home/emergency/maps/outage/|
|NY, Long Island||http://www.lipower.org/stormcenter/outages/outagemap.html|
|TX, Texarkana, Longview||http://www.swepco.com/news/outages/default.asp|
|WA, Puget Sound||http://www.pse.com/safetyReliability/pseservicealert/Pages/LatestUpdates.aspx#|
|COUNTRY||Province, City/Area||ELECTRIC OUTAGE MAP LINK|
|AUSTRALIA||Central, Northern and Southern Queensland||http://www.ergon.com.au/network_info/unplanned_outages.asp|