Page 93 - Safety Risk Management for Medical Devices

72 Safety Risk Management for Medical Devices

Figure 12.2 Fault Tree Analysis symbols.

Definitions of FTA symbols
Basic Event A basic initiating event, e.g., component faults, requiring no further
development
Undeveloped An event that is not further developed due to lack of information, or
Event when the consequences are not important
Normal Event An event that is normally expected to occur, e.g., the device gets
used
Top/Intermediate An event that is further analyzed
Event
OR Gate Output occurs when one or more of the inputs occur
AND Gate Output occurs when all of the inputs occur
XOR Gate Output occurs when only one of the inputs occurs
Transfer A symbol that shows part of the tree is transferred to another
location. Used to manage the size of the tree on a page, and to
avoid duplications