7.1 Single‐Phase System
The system contains components with (different) individual failure probabilities. Some components can fail also as a result of different common causes (CCs). These CCs can be associated with failures of other system components or with some external shocks. The system structure function is given in the form of a fault tree (FT) model [4], which defines the entire system state for any combination of the component states.
The PCCF gate (Figure 7.1) is used to model the PCCF behavior [5]. This gate is designed based on the FDEP gate [2] . The input of the PCCF gate is a trigger event representing the occurrence of a certain CC. The gate also has one or more dependent events representing failures of system components affected by the CC; these dependent components form a probabilistic common‐cause group (PCCG). When the trigger event occurs, the dependent events are forced to occur with certain (maybe different) probabilities, represented by switch symbols...