Fault Tree Analysis Constraints

In order to permit analysis, all fault tree diagrams created in BlockSim must conform to the following constraints:

• A diagram must contain a top gate and at least one event.
• All blocks in the diagram must be connected.
• An event can have only one output event, and no input events or gates.
• Additional gates are not allowed below a load sharing gate or standby gate.
• The inputs to negative gates (i.e., NOT, NAND and NOR gates) 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.