The purpose of the Fault Tree Analysis view is to support viewing and editing of so-called Fault Trees, used in Fault Tree Analysis (FTA). The view can be configured to suit specific meta models and needs. This article introduces the SystemWeaver FTA meta model and covers how to configure the Fault Tree Analysis view as well as how to incorporate fault trees in reports for printing. 


Prerequisites

  • Fault Tree Analysis meta model
  • SWExtension.FaultTreeGraph.dll extension is included in your SystemWeaver client installation
  • Assignment of the SW Architect role in the database

FTA Meta Model

Below is the basic SystemWeaver meta model used in the Fault Tree Analysis solution.

Item Types

Icon
SID
Name
Definition

2CEU
Fault Tree Analysis
The Fault Tree Analysis container item, i.e., the top-level item in the structure.

2CET
Fault Event
A failure or error in a system component or element. They can be root or intermediate.

2CEV
External Event
An event that is normal and guaranteed or expected to occur. They are not considered to be faults, but still contribute to the generation of faults.

2CLD
Logic AND
An AND gate that interconnects contributory events and conditions in the fault tree. The output occurs only if all inputs occur (inputs are independent).

2CLO
Logic OR
An OR gate that interconnects contributory events and conditions in the fault tree. The output occurs if any input occurs.

Importing the Meta Model

To import the SystemWeaver Fault Tree Analysis solution's meta model, you will need to have a SystemWeaver .xml file containing the FTA meta model (including item types, part types and attribute types) ready for import. 


Example

Contact Systemite at support@systemite.se for more information. How to complete the import is described in How to Import a Meta Model


FTA View Configuration

Configuration of the Fault Tree Analysis view is done in Configure the explorer in the File menu.



Click Edit configuration to open the Edit XML dialog. 


The configuration shown below will be used by default. However, you can configure it to suit specific meta models and needs.


<Configs>
  <FaultTreeGraphConfig>
    <ContainerItem sid="2CEU"/>
    <LeafItem sid="2CET"/>  
    <ExternalEventItem sid="2CEV"/>
    <AndItem sid="2CLD"/>
    <OrItem sid="2CLO"/>
    <RootNodePart sid="2IFW"/>
    <LogicInputPart sid="2IFI"/>
    <TimeScaleAttribute sid="FRTS"/>
    <ProbabilityAttribute sid="FTAR"/>
    <TransferLabelAttribute sid="TRAN" />
  </FaultTreeGraphConfig>
</Configs>


The ContainerItem sid attribute defines the item type of the top item ("Container item") in a Fault Tree Analysis model.

The RootNodePart sid attribute defines the part type of the root fault under the Container Item.

The LeafItem sid attribute defines the item type of a fault event.

The optional ExternalEventItem element specifies the item type used for the External Event items*.

The AndItem sid attribute defines the item type of an And gate in the Fault Tree Analysis model.

The OrItem sid attribute defines the item type of an Or gate in the Fault Tree Analysis model.

The LogicInputPart sid attribute the part type used for a sub tree item in the fault tree. Note that since this is a common part for the And and Or gates these need to be sub types of a common (abstract) gate type.

The IntermediateNodeDefinitionAttribute sid attribute defines an attribute type that can be used for the definition of the "intermediate event" symbol in the fault tree, used only for events: the intermediate event of logic gates is defined as the name of the gate. The attribute is a part attribute on the LogicInputPart where the DefType is an event.

The TimeScaleAttribute sid attribute defines the alternative time scales assumed for the ProbabilityAttribute value.

Note: This value is used by the Grid sub view, and that view only accepts a single common value used for all events within a single fault tree.


The ProbabilityAttribute sid attribute defines a numerical (integer, float) attribute type that represents the probability of an event (expressed at the time scale of the TimeScaleAttribute attribute).

The optional TransferLabelAttribute attribute specifies an item attribute to be used as a label for transfer in and transfer out symbols in a report where the FaultTreeGraph tag is used.

* External events represents events that are not considered as being faults, but still contributes to the propagation of faults.


Including Fault Tree Graphs in Reports

Reports can be configured to include fault trees using the extension-specific tag "SWExtension.FaultTreeGraph".


<Extension name="SWExtension.FaultTreeGraph" maxTreeHeight=""/>


The optional attribute maxTreeHeight controls the depth of the produced tree. Any truncated tree branches will be indicated by so-called transfer in symbols.


Example XML

<Report>
  <Extension name="SWExtension.FaultTreeGraph" maxTreeHeight="2" transferOut="false"/>
  <!-- do nothing special since this level is covered in tree graph-->
  <ForEach select="/2IFW/2IFI/2IFI[SID!='2CET']">
    <ApplyTemplate name="SubTree"/>
  </ForEach> 

  <Template name="SubTree">
    <Extension name="SWExtension.FaultTreeGraph" maxTreeHeight="2" transferOut="true"/>
      <!-- do nothing special since this level is covered in tree graph-->
      <ForEach select="/2IFI/2IFI[SID!='2CET']">
        <ApplyTemplate name="SubTree"/>
      </ForEach>
  </Template>
</Report>


Example Result

The fault tree graph of the selected fault tree item is produced:


What's Next?

Learn more about how to interact with the view in the Explorer client.