Why fault tree analysis

One of the important factors in qualitative analysis of fault tree is to identify minimal cut set. For instance complex and large fault tress have to use superior tools algorithms for extraction to get the minimal cut sets. Minimal cut set: A cut set with minimal number of events that can still cause the TOP undesirable event.

In other words the TOP undesirable event occurs if one or more minimal cut set occurs. A fire broke out at unit 1 of XYZ cable manufacturing company despite safety system in-place. General Manager was very concern about the accident and requests safety in-charge to evaluate the system. However as part of initial analysis of the existing system, safety team using FTA to identify the different causes for accident. Top undesirable event occurs if one or more of the minimal cut set occurs, hence the main target is to identify minimal cut sets.

Moreover if all the minimal cuts are independent to each other, then we could compute the probability of top undesirable event by:. The water pump will fail because of value failure and value closed or fault indicator or light fail or control command fail or operator unable to open valve. I originally created SixSigmaStudyGuide.

Go here to learn how to pass your Six Sigma exam the 1st time through! View all posts. Thank you very much Sir for your explanation of FTA.

God Bless you! Be as specific as possible in the definition. This is called the top event. Record these events at the next level, under the event they would cause. Evaluate whether it is a basic failure or can be further analyzed for immediate causes.

Circle the event if it is a basic failure and enscribe it within a rectangle if it can be analyzed for its own causes. ASK how the events you have identified are related to the event they cause.

Show relationships via gate symbols. Lower-level events are called input events and the event they cause is denoted as the output event. Pay closest attention to failures that are the most likely to happen. Undeveloped event usually denotes something that needs no further breakdown or investigation or an event for which no further analysis is possible because of a lack of information.

A conditioning event is a restriction on a logic gate in the diagram. These gate symbols describe the Boolean relationship between outcomes. Browse SmartDraw's entire collection of fault tree examples and templates. Learn More. Benefits of Fault Trees A fault tree creates a visual record of a system that shows the logical relationships between events and causes lead that lead to failure.

Gate symbols can be the following: OR gate - An event occurs as long as at least one of the input events takes place AND gate - An event occurs only if all input conditions are met Exclusive OR gate - An event occurs only if one of the input conditions is met, not if all conditions are met Priority AND gate - This is probably the most restrictive scenario when an event occurs only after a specific sequence of conditions Inhibit gate - An event will only occur if all input events take place as well as whatever is described in a conditional event How to Make a Fault Tree: Steps to Fault Tree Analysis Define the undesired event: the primary fault or failure being analyzed Deduce the event's immediate causes Keep stepping back through events until the most basic causes are identified Construct a fault tree diagram Evaluate your fault tree analysis Sign up for SmartDraw Free.

Start Now. Fault Tree Example - Vehicle Collision.