System Reliability

In System Reliability Analysis, the site is assigned based on the user's selection in the Site control, and all data added or imported to the System Reliability Analysis must match the analysis's site assignment.

In System Reliability Analysis, Rules, users will see only data that is assigned to their site(s) or that is global data.

The following diagram shows how the families used in System Reliability Analysis are related to one another.

In the above image:

• Black arrows and boxes represent entity families, relationship families, and associated relationship definitions that are configured in the baseline database and do not require customization for the baseline functionality to work.
• Red arrows and boxes represent entity families, relationship families, and associated relationship definitions that may require customization.
• The System Action box represents one of four System Action subfamilies in which records can exist: System Condition Monitor, System Inspection, System Preventive Maintenance, or System Special Action. The specific family that is used will depend upon the type of Action that is created for a given Asset or Switch element.
• The Distribution box represents one of four Distribution subfamilies in which records can exist: Normal, Weibull, Exponential, Lognormal, Triangular, Gumbel, or Generalized Extreme Value record. The specific family that is used will depend upon the distribution type selected for the associated Risk.

Throughout this documentation, we use the term System Reliability Analysis to mean the combination of the root System Analysis record and all records that are linked to it.

The Total Cost graph displays the average total cost for each Scenario. The total cost represents the sum of costs in the following categories:

• Lost Production Cost
• Action Cost
• Planned Correction Cost
• Unplanned Correction Cost

Details

The following image displays an example of the Total Cost graph.

The categories in the Total Cost graph are calculated for each Scenario as described here:

• Action Cost: The average Action cost across all the iterations. Action cost includes any materials or personnel needed to complete any Actions that exist in the Scenario and any Resources used to complete the Actions. The following fields are used to calculate Action costs:
  • System Action record: Action Cost.
  • System Resource record: Fixed Cost, Variable Cost, and Variable Cost Units.
  • System Resource Usage record: Duration, Duration Units, and Quantity.
• Lost Production Cost: The average lost production cost across all iterations. Lost production cost includes the cost of lost production for any element when it is stopped or unable to run, according to the value in the Lost Product Cost field of the record that represents that element.
• Planned Correction Cost: The average planned correction cost across all the iterations. Planned correction cost includes the cost to repair an element that is identified as having a potential failure by an inspection or condition monitoring Action and any Resources used. The following fields are used to calculate planned correction costs:
  • System Subsystem record: Variable Cost, and Variable Cost Units.
  • System Asset record: Variable Cost and Variable Cost Units.
  • System Switch record: Variable Cost and Variable Cost Units.
  • System Risk record: Planned Correction Cost, Planned Correction Duration, and Planned Correction Duration Units.
  • System Resource record: Fixed Cost, Variable Cost, and Variable Cost Units.
  • System Resource Usage record: Duration, Duration Units, and Quantity.
• Unplanned Correction Cost: The average unplanned correction cost across all the iterations. Unplanned correction cost includes the cost to repair any failed element and any Resources used to do so. The following fields are used to calculate unplanned correction costs:
  • System Asset record: Fixed Cost, Variable Cost, and Variable Cost Units.
  • System Switch record: Fixed Cost, Variable Cost, and Variable Cost Units.
  • System Risk record: Fixed Unplanned Correction Cost, Variable Unplanned Correction Cost, and Variable Unplanned Correction Cost Units.
  • System Resource record: Fixed Cost, Variable Cost, and Variable Cost Units.
  • System Resource Usage record: Duration, Duration Units, and Quantity.

The Total Cost Trend graph displays the average total cost for each Scenario for each analysis time interval in the simulation period.

The following image displays an example of the Total Cost Trend graph.

The Annual Action Cost graph displays the average cost of actions per year for each Scenario.

The following image displays an example of the Annual Action Cost graph.

You can also compare the cost of different types of actions on this graph.

The Action Cost Trend graph displays the average total cost for actions in each Scenario for the analysis time interval in the simulation period.

The following image displays an example of the Action Cost Trend graph.

The Resource Occurrence graph displays statistics about the total use of each Resource when the value in the Count Occurrence field of the associated System Resource record is set to True. The Resource occurrence count is calculated from the average total usage across all iterations.

The following image displays an example of the Resource Occurrence plot:

The Resource Time graph displays the total amount of time that each Resource is used per Scenario. The total amount of time is calculated as the average total amount of time that the Resource is used for all the iterations.

The following image displays an example of the Resource Time graph:

The Resource Cost graph displays the total cost of all Resources used in the Scenario. The total cost is calculated for each Scenario as the average total Resource costs for all the iterations.

The following image displays an example of the Resource Cost graph:

The Elements section contains a grid that displays specific results for the elements that exist in a System Reliability Analysis.

The grid contain the following columns of information:

• Element: Contains a hierarchy that lists the components in the System Reliability Analysis.
• Failures: Contains a value that indicates the average number of times the selected item failed during the analysis period for all iterations of the Scenario to which it belongs.
• Downtime (Days ): Contains a value that indicates the average number of days that the selected item was out of service due to failures or shutdowns for all iterations of the Scenario to which it belongs.
• Cost (Currency): Contains a value that indicates the average total cost of the selected item for all iterations of the Scenario to which it belongs. This includes the cost of any items that belong to the item, lost production costs, fixed costs, variable costs, Action costs, planned or unplanned correction costs, and Resource costs.

• Reliability: Contains a value that indicates the percentage of iterations that the selected item never failed across the total number of iterations in the Scenario to which it belongs.

  Note: Reliability is calculated from actual data collected from the iterations and does not represent an average value.
• Availability: Contains a value that indicates the average percentage of the time that the selected item was available and running for the Scenario to which it belongs.
• Next Failure (Days): Contains a value that indicates the average amount of time, in days, from the analysis Start Date until the next failure occurs for the selected item.
• Action Cost (currency): Contains a value that specifies the average Action cost across all the iterations. Action cost includes any materials or personnel needed to complete any Actions that exist in the Scenario and any Resources used to complete the Actions.
• Lost Production Cost (currency): Contains a value that indicates the average lost production cost across all iterations. Lost production cost includes the cost of lost production for any element when it is stopped or unable to run, according to the value in the Lost Product Cost field of the record that represents that element.
• Planned Correction Cost (currency): Contains a value that indicates the average planned correction cost across all the iterations. Planned correction cost includes the cost to repair an element that is identified as having a potential failure by an inspection or condition monitoring Action and any Resources used.
• Unplanned Correction Cost (currency): Contains a value that indicates the average unplanned correction cost across all the iterations. Unplanned correction cost includes the cost to repair any failed element and any Resources used to do so.

By selecting a cell in the grid, you can view detailed information in the following graphs:

• Histogram plot
• Trend plot
• Impact plot

The Actions section contains a grid that displays specific results for the Actions that exist in a System Reliability Analysis.

The grid contain the following columns of information:

• Action : Contains a hierarchy that lists the Actions that exist in a System Reliability Analysis. The Actions appear below the element in the Diagram to which they belong.
• Occurrences : Contains a value that indicates the average number of occurrences of the Action from all iterations of the Scenario to which it belongs.
• Cost (currency): Contains a value that indicates the average cost of the Action, including any Resources used by the Action, for the Scenario to which it belongs.
• Detected Failures: Contains a value that indicates the average number of potential failures detected in advance by the Action. This result is calculated only for Inspection Actions and Condition Monitoring Actions, which are the only Actions that can detect potential failures.

By selecting a cell in the grid, you can view detailed information in the following graphs:

• Histogram plot
• Trend plot

The Resources section contains a grid that displays specific results for the Resources that exist in a System Reliability Analysis.

The grid contain the following columns of information:

• Resource : Displays a hierarchy that lists the Resources that exist in the System Reliability Analysis. The Resources appear below the Scenario in the hierarchy to which they belong.

• Occurrences: Contains a value that indicates the average number of times the Resource is used during the simulation period.

  Note: For System Resource records in which the Count Occurrences field is set to False, the value in this column will be 0 (zero).
• Time (Days): Contains a value that indicates the average amount of time, in days, accumulated by the Resource.
• Cost (currency): Contains a value that indicates the average cost accrued by the selected Resource.
• Action Resource Cost: Contains a value that indicates the total cost of Resource needed for Actions.
• Planned Correction Resource Cost (currency): Contains a value that indicates the total cost of all planned Resources needed for Actions.
• Unplanned Correction Cost (currency): Contains a value that indicates the total cost of all unplanned Resources needed for Actions.

By selecting a cell in the grid, you can view detailed information in the following graphs:

• Histogram plot
• Trend plot

The Histogram Plot provides a visual representation of the frequency distribution of the result that you selected in the grid in the Elements section.

Details

The Histogram Plot shows the distribution of the actual values from all iterations that were used to calculate the average value. The distribution of the actual values spreads across a series of data ranges, which are called bins and are represented by columns on the Histogram Plot. When an actual value from an iteration falls into a bin, it is included in the associated column. The higher the column is, the more values have fallen into the bin.

Additional values are represented by the following lines in the Histogram Plot:

• Optimistic Value: Leftmost gray vertical line in the Histogram Plot. This line represents the lower level of the confidence interval.
• Average Value: Red line in the Histogram Plot. This line represents the mean value, which is the mean value of the values from the iterations of the Scenario.

• Realistic Value: Blue line in the Histogram Plot. This line represents the median value, which is the median value of the values from the iterations of the Scenario.

  Note: If the median value falls in between two values, then the larger value will be used as the Realistic value.
• Pessimistic Value: Rightmost gray vertical line in the Histogram Plot. This line represents the upper level of the confidence interval.

The Trend Plot provides the average value for each analysis time interval, as defined by the value in the Time Analysis Type field in the root System Analysis record, of the result that you selected in the grid.

If the Time Analysis Type field is set to:

• Yearly, the Cost Trend Plot will display the Cost Trend for each year in the simulation period.
• Monthly, the Cost Trend Plot will display the Cost Trend for each month in the simulation period.

The Impact Plot provides visual representation of the average values that are combined to make up the average value of the result that you selected in the grid.

The Impact Plot displays how the average failure value is calculated as a total of the individual Risk failure averages.

The average total is the average of all the totals across all iterations of a simulation, which is calculated by the APM system for each simulation. Average totals are calculated for various types of numeric values in a simulation, such as cost in the Total Cost Trend plot or time in the Resource Time plot.

Some results of a System Reliability Analysis are presented according to the simulation period that you have selected. The simulation period is defined by the values in the System Analysis record:

• The values in the two Period boxes. The Period boxes represent the Period and Period Units fields in the System Analysis record and determine the length of the simulation.
• The value in the Time Analysis Type box. The Time Analysis Type box represents the Time Analysis Type field in the System Analysis record, and the value determines whether results are calculated for each year or each month of the simulation. If the Time Analysis Type is set to:
  • Yearly, the graphs display values for each year included in the simulation period, which is defined by the values in the Period, Period Units, and Analysis Start Date fields in the System Analysis record.
  • Monthly, the graphs display values for each month included in the simulation period, which is determined by the values in the Period, Period Units, and Analysis Start Date fields in the System Analysis record.

The Show Total check box is a feature that is available on the following System Reliability Analysis results plots:

• Total Cost plot
• Annual Action Cost plot
• Resource Cost plot

In these graphs, each column represents a separate Scenario. The Show Total check box determines how the columns are displayed, as described in the following list:

• When the Show Total check box is cleared, the plots display one column that is divided into sections representing the individual cost types or resources within that Scenario. In addition, the legend displays labels for the individual categories that are represented in each column.
• When the Show Total check box is selected, the plots display one column that is not divided into sections but instead displays the total cost associated with all categories in that Scenario. In addition, the legend displays the label Total.

The following image shows the Total Cost plot for our System Reliability Analysis Example when the Show Total check box is selected.

The following image, on the other hand, shows the Total Cost plot for our System Reliability Analysis Example when the Show Total check box is cleared.