Homeland Security and Emergency Services

Terms to Know

  • Brownout: A drop in voltage in an electrical power supply. The term comes from the dimming experienced by lighting when the voltage sags. Brownouts can cause poor performance of equipment or even incorrect operation.
  • light bulbs

  • Blackout: The total loss of power to an area and is the most severe form of power outage that can occur. Blackouts which result from or result in power stations tripping are particularly difficult to recover from quickly. Outages may last from a few minutes to a few weeks depending on the nature of the blackout and the configuration of the electrical network.

  • Rolling Blackout: Temporary power shortage that happens when power companies turn power off in certain areas to curb usage, usually during peak seasons and hours of energy consumption, e.g., summer, 4-7 p.m. Power companies try to warn affected areas of planned rolling blackouts, but they cannot always do so. Power is usually out for only about an hour.

  • Solar Storms (also called "space weather"): Emissions that erupt from the sun as magnetic energy build to a peak at the sun's surface, sending radiation, solar winds, or magnetic, high energy particles through space into Earth's atmosphere - resulting electromagnetic fields may cause extreme power surges in wires, power line disruptions, and even widespread blackouts.

  • Permanent Fault: A massive loss of power typically caused by a fault on a power line. Power is automatically restored once the fault is cleared.

  • Surge Protector: An electrical device designed to protect electronic equipment (e.g., computers) against the harmful effects of power surges and spikes, and sudden outages.