Additional Resources > Windchill Risk and Reliability Practitioner’s Guide > Fault Tree Analysis > Events and Gates > NOR Gate
NOR Gate
The NOR gate functions like a combination of an OR gate and a NOT gate. The NOR gate is used to indicate that the output occurs when all the input events are absent. The output of a NOR gate can be the top event or an intermediate event. The input events can be basic events, intermediate events or a combination of both. The presence of a NOR gate may give rise to non-coherent trees, where the lack of one or more events causes the top event to occur.
Logic Summary
If there is at least one true input event, the output is false. Table 5-7 shows the input and output events for a NOR gate.
Table 5-7. Truth Table for NOR Gate
Input A
Input B
Output
T
T
F
T
F
F
F
T
F
F
F
T