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ETA diagram building |
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ETA diagram building |
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ETA diagram building
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ETA diagram building |
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ETA diagram building |
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When a new diagram is opened, Initial event and outcome event are created, so the tree building can be started immediately by adding regular events among the initial and outcome columns.
To add an event, select another event and
| • | right-click on it and choose “Append event” from the pop-up menu to add a new event to the end of the diagram (before Outcome) |
- or -
| • | right-click on it and choose “Insert event” from the pop-up menu to insert a new event before the selected event |
You will get an ETA element data screen:
The following data may be entered:
Field |
Field description |
|---|---|
Code |
Element code. Should be unique inside the diagram. |
Name |
Element name |
Description |
Element description |
Event logic |
Success/Failure – choose if the event’s outcome is described in Success or Failure True/False – choose if the event is a failure which may occur or may not Custom – choose if event’s logic is not binary, for example “North wind”, “South wind”, “West wind” etc. |
Probabilities in different branches |
The same probabilities – choose if event probability in different sequences is the same Different probabilities – choose if event probability differs and depends on previous events (for example if event #2 probability is different if event #1 is true and if event #1 is false) |
Probability source |
Set up probability calculation method: User-defined Calculated Calculated using Product Tree/FMECA data Using FTA Basic Event – pick "Linked to FTA Basic Event" button and click on arrow in FTA Basic Event. In the opened FTA Events Library select FTA Basic Event. Using FTA top event/gate – pick "Linked to FTA Gate/Top Event" button, click on arrow in FTA tree and select required tree. Click on arrow in FTA Gate/Top event and select the gate or event from tree selected before. |
Background color |
Background color of the element |
Foreground color |
Foreground color of the element |
Font |
Font of the element |
Load from Library |
Press the button to update event’s data from the library (library should contain event with the same Code) |
Load to library |
Press the button to save event’s data in the Library |
Automatically update from Library |
Check the checkbox if you wish to update event’s data from the event’s library automatically when library record with the same Event Code is changed. |
To edit event, double-click on it, or right – click on it and choose “Edit” from the pop-up menu. Data screen described above will be displayed.
If you choose to use calculated probability, you have to press “Calculate” button and enter calculation parameters:
Field |
Field description |
|---|---|
FR |
Failure rate (failures per million or billion of hours, depends on project settings) |
Probability q |
Probability q |
Frequency f |
Frequency F |
MTTR |
MTTR (Mean Time To Repair), hours |
Test interval |
Test interval - time between periodical tests, hours |
Time to first test |
Time to first test, hours |
Mission time |
Mission time, hours |
Q(t) |
Unavailability Q(t) - probability of failure at a given time point |
Q mean |
Probability or long-term steady-state average unavailability, Q |
Tree ID |
For events, ID of linked element in Product Tree |
FM number |
For events, number of FMECA Failure Mode of linked element in Product Tree |
New event will be created with its gates for each sequence:
Any number of events may be added to the diagram. Then you may define all outcomes (Code, Name, and Description) and calculate the probabilities of consequences.