About Global Events

Consider Scenario B in our System Reliability Analysis Example, which contains two Actions that require a system shutdown: Redesign Impellers and Replace Seals. The Redesign Impellers Action has a duration of one week, and the Replace Seals Action has a duration of one day. Performed independently of one another, they would result in a system shutdown lasting a total of eight days.

Now, assume that you group the two Actions together using a Global Event with a Max Delay value of 3 months and a Max Advance value of 4 weeks. This Global Event specifies that the two Actions will be rescheduled and performed together during the same system shutdown, as long as the Actions fall into the time period from 3 months before the Global Event and 4 weeks after the Global Event. Managing the Actions in this way would result in a shutdown lasting the longest of the two durations, or seven days. This approach is preferable, as it would save one day of costs associated with the system shutdown.

System Reliability Analyses support the use of two types of Global Events:

• Action-driven Global Events: A collection of Actions that may occur based on the occurrence of a driving Action. When the driving Action occurs, any Actions that fall into the time range specified by the Max Advance and Max Delay values are triggered to be rescheduled and performed with the driving Action. Action-driven Global Events can occur only one time in a simulation. If you select a recurring Action as the driving Action, the Global Event will occur the first time that the driving Action occurs. If you select more than one Action as the driving Action, then the first driving Action that occurs will trigger the other Actions in the Global Event.

  For example, in Scenario B of our System Reliability Analysis Example, you might create an Action-driven Global Event, which is assigned both the Redesign Impellers and Replace Seal Actions, with the Redesign Impellers Action designated as the driving Action. In this case, when the Redesign Impellers Action occurs according to the properties specified in the System Action record that represents it, the Global Event will trigger any Replace Seals Action that falls within the time period specified by the Max Delay and Max Advance values to be rescheduled and completed with the occurrence of the Redesign Impellers Action.

• Date-driven Global Events: A date-driven Global Event is a collection of Actions that may occur on a certain date. When the simulation reaches the date of the Global Event, any assigned Actions that fall into the time range specified by the Max Advance and Max Advance Duration values are triggered to be performed on the date of the Global Event. A date-driven Global Event can occur one or more times throughout the simulation period.

  For example, in Scenario B of our System Reliability Analysis Example, you might create a date-driven Global Event and specify that it should occur on a date halfway through the simulation. To this Global Event you would assign the Redesign Impellers and Replace Seals Actions. In this case, the Global Event would trigger both of the Actions that fall into the time period specified by the Max Advance Duration and Max Delay Duration values, almost three and a half years into the simulation, regardless of what properties existed in the System Action records that represent the Redesign Impellers and Replace Seal Actions.

Note: While Global Events limit downtime and the history of a Global Event can be seen in the Event Logs generated from a System Reliability Analysis which contains a Global Event, the effects of Global Events are not presented explicitly anywhere in the simulation results. The effects of the Global Events are expressed as less downtime for the system, which means lower lost production costs.