a period of time when there is no electricity supply 停电，断电
Examples from the Corpus
power failure• This will prevent the loss of much of your work in the event of a power failure or other mishap.• It's only a power failure.• The average freezer will keep food frozen for two days in the time of a blackout or a power failure.• Half way between Victoria and Gatwick there was a power failure, the lights went out and the train ground to a halt.• The last locally-caused power failure of greater magnitude was the Loma Prieta earthquake in October, 1989.• Finally, an emergency lighting kit should always be ready in an accessible place, in case of a sudden power failure.