Function level vs function loss

When a simulation is started, the simulation core will generate a sequence of events that represent the failure occurrences or planned maintenance activities. E.g. an event can be the start of a maintenance action. Each start event will also create an end event (i.e. the end of the maintenance action, based on the maintenance duration parameters). Each event will cause a system to potentially adjust its function level. Function levels indicate the availability of (the function of) a system. The parameters Function Loss and Maintenance Effect are used to adjust the function level at each event.  Setting the function loss to 100(%) means the functional level is set to 0%, meaning the system is completely ‘down’. A function loss of 0(%) implies a function level of 100(%), meaning the system is completely ‘up’. Using a function loss number between 0 and 100, implies that the system will be partially ‘up’, according to the formula: function level = (100-function loss). The function loss is used to calculate the actual downtime, by first calculating the downtime (based on the downtime decision tree described below) and multiplying this by the function level.

Example: If the simulation core calculates a downtime of 4 hours, and a function level of 75%, then the actual recorded downtime will be 75% x 4 = 3 hours.