House Event
A house event is a special type of event that you typically employ for one of the following uses:
• To represent an event that is normally expected to occur
• To disable or enable parts of a fault tree to make them functional or non-functional
• To represent trigger events, switching events, and external events
A house event can be turned on or off to specify the conditions present under a specific scenario. When a house event is turned on (TRUE), that event is presumed to have occurred, and the probability of that event is set to 1. When a house event is turned off (FALSE), it is presumed not to have occurred, and the probability is set to 0.
House events are commonly used to make branches of a tree functional or non-functional. To more effectively analyze large trees having multiple levels, you can “turn off” portions of the tree to evaluate varying scenarios.
House events can also be used to model “trigger” events. When a trigger event occurs, the associated logic path is considered. When the trigger event does not occur, the associated logic path is ignored.
Example
A compressor tank will fail when electrical power is not available. Because the presence of electrical power is assumed, the event, PowerOn, is inserted as a house event. The house event is turned on to indicate that the event has occurred.
