Search results
Results from the WOW.Com Content Network
In engineering, a fault is a defect or problem in a system that causes it to fail or act abnormally. The ISO document 10303-226 defines fault as an abnormal condition or defect at the component, equipment, or sub-system level which may lead to a failure. The United States Glossary of Telecommunication Terms defines fault for telecommunications as:
An example of this would be the thermostat in a home heating system – the operation of the heating equipment is controlled by the difference (the error) between the thermostat setting and the sensed air temperature.
An open-circuit fault occurs if a circuit is interrupted by a failure of a current-carrying wire (phase or neutral) or a blown fuse or circuit breaker. In three-phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a "ground fault" or "earth fault", current flows into the earth.
The false positive rate (FPR) is the proportion of all negatives that still yield positive test outcomes, i.e., the conditional probability of a positive test result given an event that was not present.
There is a difference between fault tolerance and systems that rarely have problems. For instance, the Western Electric crossbar systems had failure rates of two hours per forty years, and therefore were highly fault resistant. But when a fault did occur they still stopped operating completely, and therefore were not fault tolerant.
graph with an example of steps in a failure mode and effects analysis. Failure mode and effects analysis (FMEA; often written with "failure modes" in plural) is the process of reviewing as many components, assemblies, and subsystems as possible to identify potential failure modes in a system and their causes and effects.
However, many problems only occur as a result of multiple failures or errors. This is particularly true of fault tolerant systems, or those with built-in redundancy. Features that add redundancy, fault detection and failover to a system may also be subject to failure, and enough different component failures in any system will "take it down."
Segmentation faults can also occur independently of page faults: illegal access to a valid page is a segmentation fault, but not an invalid page fault, and segmentation faults can occur in the middle of a page (hence no page fault), for example in a buffer overflow that stays within a page but illegally overwrites memory.