AND Gates

AND gates allow you to represent a scenario in which the output event occurs if all input events occur. In system reliability, this implies that both components must fail (input) in order for the system to fail (output). In a reliability block diagram, this is equivalent to a simple parallel configuration.

The next two figures show both the fault tree diagram and reliability block diagram representation of a system with two components, A and B, in which the system fails if both A and B fail. In a fault tree, this is modeled using the AND gate.

In an RBD, it is a parallel configuration.

To configure an AND gate, only the common block properties are available. No further configuration of the gate is necessary.