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Threats & Emergencies
Blackouts
Blackouts Home • Preparing for Blackouts • Responding to Blackouts
Blackouts and the Power Grid
When the power grid breaks down due to an overwhelming power demand, a blackout can occur. The power grid is a network of power plants that collectively produce enough power to meet demand. If one plant suddenly quits producing power (lightning strike, downed power line or mechanical failure), the other plants on the network increase their output to make up the difference. If the power plants are already working near their maximum output, they will automatically shut down rather than exceed their maximum threshold. As plants shut down, they place the burden on remaining plants, which in turn also shut down. This system failure can cause blackouts that can last a few hours or days.
The loss of power and damage associated with fluctuations in the power grid do not always coincide with inclement weather. Power spikes and surges can happen when least expected, quickly and without anyone noticing.
Blackouts can knock out traffic lights, stop subway systems and shut down airports. Telephone systems crash and any electronic banking ceases.
Other Types of Power Outages
Sags and brownouts involve a dip in the grid’s voltage for short periods of time. Sags, caused by heavy equipment being turned on, large electrical motors being started and the switching of power mains, are sudden and last only a few seconds. Brownouts are a bigger dip in voltage and last a few minutes or a few days. Utility companies use brownouts intentionally during times of peak demand in order to prevent any one plant on the grid from approaching its maximum power supply and shutting down, which might lead to a blackout. Both power sags and brownouts can have detrimental effects on computer hardware and software and electrical equipment, including a home's appliances.
A power surge occurs when the grid voltage suddenly goes from the normal supply to 110 percent above normal supply. When large electrical equipment is shut off, the grid momentarily supplies too much power. Surges last only a few moments, but can have the same damaging effects as power sags on electrical equipment that isn’t protected by a surge suppressor. A power spike is an even larger increase in power in a shorter time span.
Line noise is disruption of the voltage traveling through power lines caused by lightning, transmitters, electrical equipment that produce Radio Frequency Interference or Electromagnetic Interference. Line noise can cause a multitude of problems, from keyboard lock-ups to data crashes.
Threats & Emergencies