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A rolling blackout, also referred to as rotational load shedding or feeder rotation, is an intentionally engineered electrical power shutdown where electricity delivery is stopped for non-overlapping periods of time over different parts of the distribution region. Rolling blackouts are a last-resort measure used by an electric utility company to avoid a total blackout of the power system. They are a type of demand response for a situation where the demand for electricity exceeds the power supply capability of the network. Rolling blackouts may be localised to a specific part of the electricity network or may be more widespread and affect entire countries and continents. Rolling blackouts generally result from two causes: insufficient generation capacity or inadequate transmission infrastructure to deliver sufficient power to the area where it is needed. Rolling blackouts are a common or even a normal daily event in many developing countries where electricity generation capacity is underfunded or infrastructure is poorly managed. Rolling blackouts in developed countries are rare because demand is accurately forecasted, adequate infrastructure investment is scheduled and networks are well managed; such events are considered an unacceptable failure of planning and can cause significant political damage to responsible governments. In well managed under-capacity systems, blackouts are scheduled in advance and advertised to allow people to work around them, but in most cases they happen without warning, typically whenever the transmission frequency falls below the 'safe' limit. Rolling blackouts are also used as a response strategy to cope with reduced output beyond reserve capacity from power stations taken offline unexpectedly such as through an extreme weather event. ==Canada== In January 2014, the Canadian province of Newfoundland & Labrador renewed rolling blackouts to compensate for the cascading failure of the Holyrood generating station after a fire at the Sunnyside substation on Jan 4 following a blizzard. The rolling blackouts started before the storm on the 4th, rather were caused by extreme cold weather and a high demand for power at the time.〔(【引用サイトリンク】title=Newfoundland outages worsen amid sudden 'generation problems' )〕 On 9 July 2012, the Alberta Electric System Operator ordered power companies in the province of Alberta to institute rolling blackouts during a heat wave as six generating plants failed during peak demand in the heat of the afternoon. Because the shortage increased the amount consumers paid to generators, Members of the Alberta Legislative Assembly voiced concerns that price manipulation might have been involved In both cases the blackouts were rolled fairly rapidly, so that no area had to spend more than one hour without power.〔〔 ==Egypt== Summer blackouts have been common in Egypt since 2010 but became more severe and widespread after the 2011 revolution. In April 2014, the Minister of Electricity and Renewable Energy said that the problem would take a few years to resolve.〔(【引用サイトリンク】title=Preventing summer blackouts in Egypt is ‘impossible’: Minister )〕 The government is blaming the unrest the country is experiencing for the blackouts. However, blame between different ministries reveals their poor organization. Some also point to the fact that the infrastructure is old and lacks maintenance.〔(【引用サイトリンク】title=Egypt to see blackouts for three years at least: Experts )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「rolling blackout」の詳細全文を読む スポンサード リンク
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