Answer Description
Brownouts, or temporary power drops in voltage, are as dangerous to systems as blackouts. Any interruption of voltage to a computer can cause damage or loss of data.
Wikipedia
A brownout is an intentional or unintentional drop in voltage in an electrical power supply system Intentional brownouts are used for load reduction in an emergency The reduction lasts for minutes or hours, as opposed to short-term voltage sag (or dip) The term brownout comes from the dimming experienced by incandescent lighting when the voltage sags A voltage reduction may be an effect of disruption of an electrical grid, or may occasionally be imposed in an effort to reduce load and prevent a power outage, known as a blackoutIn some countries, the term brownout refers not to a drop in voltage but to an intentional or unintentional power outage (or blackout)
Brownout_(electricity) - Wikipedia, the free encyclopedia