ABSTRACT

Products that serve a critical function should contain a backup power supply to ensure continuous operation in the event of a power outage. At well-equipped hospitals, a loss of electrical power from the external grid triggers a backup power generator that restores power quickly and might provide power for several days. Backup power supplies that serve a critical safety function should indicate that they are functioning properly. Some ski lifts have both backup electrical power and backup motors to deal with temporary outages. In other cases, power can be provided by large, portable backup units. In an aircraft that loses main engine power, backups might come in several forms, including batteries, an auxiliary power unit, and a Ram air turbine, which is basically a high-tech version of a windmill. Backup power sources can be necessary in situations such as during bird strikes or when the engine fails due to ingesting volcanic ash.