Fault Tree Analysis Diagram (FTA)

FTA (Fault Tree Analysis) diagram is used to analyze and understand possible risks, especially in high-hazard industries. It is a top-down diagram that organized the events and lower-level events using Boolean logic operators.

What is Fault Tree Analysis?

A fault tree analysis is realized using a top-down diagram to analyze an unwanted state or failure o a system. Events are break down to lower-level events that are combined using Boolean logic operators (AND, OR, and their variations). The goal of the analysis is to identify and minimize the risks and failures of systems.

Fault Tree Analysis Usage

FTA is used in reliability engineering and safety engineering to identify ways the systems can fail and bring the best solutions for minimizing risk.

It is used in the following industries to mitigate and reduce the hazard:

  • aerospace industry
  • chemical and process industry
  • nuclear power industry
  • petrochemical industry
  • pharmaceutical industry
  • software engineering

Fault Tree Analysis Symbols

A fault tree analysis diagram offers the tools for these elements:

  • And Gate
  • Priority And Gate
  • Or Gate
  • Exclusive Or Gate
  • Inhibit Gate
  • Basic Event
  • Conditioning Event
  • External Event
  • Intermediate Event
  • Undeveloped Event
  • Transfer In
  • Transfer Out
  • Connector
FTA Symbols Overview
FTA Symbols Overview

How to Draw a Fault Tree Analysis Diagram?

You can create a new FTA diagram in multiple ways:

  • Click on a Plus button in the tab switch bar, navigate to Other group and click on the Fault Tree Analysis Diagram item
  • Press CTRL+SHIFT+D, choose Fault Tree Analysis from the Other group, enter the name and click on the OK button.
  • Switch to Project tab in the ribbon and click on the Fault Tree Analysis item in the Content gallery.
  • Open Project sidebar, right-click on a project (or a folder) node, and in the Add Diagram submenu, choose Fault Tree Analysis from the Other submenu.

How to Draw FTA Elements?

How to Draw an And Gate?

  • Click on the And Gate button in the Flow Tree Analysis group in the toolbox.
  • Specify the bounds of the new AND gate by dragging on the diagram canvas.
  • If you want to add an AND gate with the default size, just click on a diagram canvas and the AND gate symbol will be inserted to the specified position. You can also drag the And Gate button from the toolbox and drop it to the desired position on the diagram.
  • If you want to insert multiple AND gates in a row, double click (or click twice) on the And Gate button in the toolbox and draw so many AND gates elements as you want in the diagram editor. If you do not want to add any more elements, press the ESC key or click to the Selection tool button.

How to Draw an Or Gate?

  • Click on the Or Gate button in the Flow Tree Analysis group in the toolbox.
  • Specify the bounds of the new OR gate by dragging on the diagram canvas.
  • If you want to add an OR gate with the default size, just click on a diagram canvas and the OR gate symbol will be inserted to the specified position. You can also drag the Or Gate button from the toolbox and drop it to the desired position on the diagram.
  • If you want to insert multiple OR gates in a row, double click (or click twice) on the Or Gate button in the toolbox and draw so many OR gates elements as you want in the diagram editor. If you do not want to add any more elements, press the ESC key or click to the Selection tool button.

How to Draw a Basic Event?

  • Click on the Basic Event button in the Flow Tree Analysis group in the toolbox.
  • Specify the bounds of the new basic event by dragging on the diagram canvas.
  • If you want to add a basic event with the default size, just click on a diagram canvas and the basic event symbol will be inserted to the specified position. You can also drag the Basic Event button from the toolbox and drop it to the desired position on the diagram.
  • If you want to insert multiple basic events in a row, double click (or click twice) on the Basic Event button in the toolbox and draw so many basic events elements as you want in the diagram editor. If you do not want to add any more elements, press the ESC key or click to the Selection tool button.

How to Draw a Connector?

  • Click on the Connector button in the Flow Tree Analysis group in the toolbox.
  • Drag from an element (e.g. Gate) to another element (e.g. Event). The connector shows the direction of data transfer between the two entities.
  • Another way you can insert a connector between two entities is to click on the Connector button in the toolbox and drag it in between the desired entities (e.g. Event and Gate). The diagram editor shows you which two elements will be connected when you release the button.
  • If you want to insert multiple connectors in a row, double click (or click twice) on the Connector button in the toolbox and draw the desired number of connectors in the diagram editor.

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