NOT Gates

The NOT gate functions as an inverter; the output event is the inverse of the input event. Thus, in cases where you are dealing with true/false values, a false input event will lead to a true output event, and vice versa (i.e., the output occurs when the input event does not occur, and vice versa).

In cases dealing with probabilities and/or reliability calculations, the output is equal to 1-input.

NOT 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 NOT gates.

To configure a NOT gate, only the common block properties are available. No further configuration of the gate is necessary.