NOR Gates

A NOR gate has a true output event when all input events are false. In other words, if none of the input events occur, then the output event will occur. This is logically equivalent to using an OR gate followed by a NOT gate.

 

          

NOR gates are available only in analytical fault trees. There is no equivalent configuration in reliability block diagrams. The inputs to a NOT gate must be fixed probabilities, or evaluate to fixed probabilities; this is checked at analysis, and any input that evaluates to a time-varying model will result in an error, indicated with a flag applied to the gate. Subdiagrams cannot be inputs to NOR gates.

To configure a NOR gate, only the common block properties are available. No further configuration of the gate is necessary.