Using Transfer Gates
Fault trees can become quite large and complex, containing many gates and events. In these cases, for ease of analysis, it might be helpful to break the single fault tree up into smaller fault trees that are all linked together. Additionally, you might want to repeat the same logic in two different places.
In both of these cases, a type of gate called a transfer gate is very useful. Transfer gates are not associated with any logic operation themselves, but they enable you to break up fault trees for visual reasons or to handle repeated logic.
1. In the FTA Diagram, select the Mech Fault OR gate.
2. Right-click the gate and select Break into Transfer.
A new fault tree is inserted. The Mech Fault OR gate is the top gate, and all of its lower inputs are intact. The triangular symbol shown with this top gate indicates that it is part of another fault tree.
3. To return to the original fault tree, right-click the top gate of the new fault tree and select > . In the original fault tree, a Mech Fault Transfer gate has replaced the Mech Fault OR gate.
You can bring the newly created Mech Fault fault tree back into its original location in the main fault tree.
4. Right-click the new Mech Fault Transfer gate and select > to go back to the Mech Fault tree.
5. In this fault tree, right-click the Mech Fault OR gate and select Collapse Transfer to return the fault tree to the original diagram.
You can also insert new Transfer gates directly into your fault trees just like any other gate.