Definitions for "fail-safe"
(IEEE) A system or component that automatically places itself in a safe operational mode in the event of a failure.
guaranteed not to fail; "a fail-safe recipe for cheese souffle"
eliminating danger by compensating automatically for a failure or malfunction; "a fail-safe device in a nuclear weapon to deactivate it automatically in the event of accident"
An action taken to avoid a disaster.
An electrical system so designed that a failure of any component in the system will prevent unsafe operation of the system.
Railway equipment in Britain is designed so that if it fails then safety is maintained. If a signal fails then it is designed to show a red aspect. Circuits are installed to ensure that an aspect is 'proved lit', if not then the previous signal will display the aspect instead. Train brakes are operated by air or vacuum. The system effectively causes air pressure (or vacuum) to hold the brakes off. If air pressure is lost then the brakes come on. It is possible that a signal will fail unsafe. This rare event is called a wrong-side failure. The Clapham disaster in 1988 was a wrong-side failure caused by redundant wiring coming into contact with signalling circuits after work on enhancing the signalling system.
FLOOR-OPERATED CRANE
When multiple lamps are used & if one lamp fails, the projector will still continue to function. If a second fails, the projector automatically switches to standby mode.
A characteristic of a particular type of actuator, which upon loss of power supply will act in a predetermined way, i.e. cause the valve plug to fully close, fully open or remain in fixed position.