It is not necessary to use the reliability elements solely to determine the reliability or availability The probability that a component or system is performing its required function at any given time. of a particular system. In many cases, a model will need to model systems or components that could fail and either directly or indirectly lead to the consequence you are interested in.
Typically, these types of models will use the status output of a Function component (e.g., if a pump is operating then a certain amount of water is removed), the ActionOK/ActionFailed outputs of an Action element (e.g., to determine whether a control action was successful), or the StopOperating output to determine when a critical component goes offline.
The model file Overtop.gsm, found in the Reliability Examples folder in your GoldSim directory (accessed by selecting File | Open Example... from the main menu), is a simple risk analysis/assessment.
In this model, a water reservoir has a stochastic inflow and consumption rate. It also has two spillways: a passive spillway that begins to drain the reservoir when the water level reaches 16 feet, and an emergency spillway that is opened when the water level reaches 17.5 feet, and is closed when it returns to 16 feet. The flow rates out of the spillways are dependent on the amount of water in the reservoir.
The opening of the emergency spillway is modeled with an Action element called Open_Emergency_Spillway that is triggered when the water level reaches 17.5 feet. It requires that either the Power_Grid function element or the Backup_Generator function element is operating. The Open_Emergency_Spillway, Power_Grid and Backup_Generator elements all have exponential failure modes that are automatically repaired.
The reservoir overtops with potentially catastrophic consequences when the water level reaches 20ft.
The model is run for 5 years, and the probability of the reservoir spilling its banks at least once during that period can be viewed by double clicking on the "Overtop Result" Result element:
It shows that there is a 25% probability that the dam's reservoir would overtop during a given five year period.
The model could be used to evaluate the impact on the probability of overflow of larger spillways, changing the level at which the passive spillway begins to bypass the dam, and changing the levels at which the emergency spillway activates and deactivates.
- Example: Creating User-Defined Base Variables
- Example: Handling Actions Internally
- Example: Modeling Changing Operational Environments Using Failure Mode Acceleration
- Example: Modeling Component Maintenance and Replacement
- Example: Modeling Dependencies on Other Reliability Components
- Example: Modeling Dynamic Failure Mode Behavior Such as Burn-In
- Example: Modeling Non-Fatal Failure Modes
- Example: Modeling Resource Requirements for Reliability Elements
- Example: Modeling the Switchover to a Backup Component
- Example: Understanding the Differences Between Failure Mode Base Variables
- Example: Using Custom Reliability Outputs to Report Throughput Calculations
- Example: Using Reliability Elements for a Dam Risk Assessment
- Example: Using Reliability Elements to Model Failing Pumps
- Example: Using the Reliability Element's Primary Output
- Example: Working with Internal and External Requirements