Dependency Page
The Dependency page in the block’s Calculation Properties window specifies dependency group information. Dependency information is independently defined for each block. For more information, see Using Dependency Groups. The following table describes the properties on the Dependency page.
|
Property
|
Description
|
|---|---|
|
Dependency group
|
The dependency group to which the block is assigned. Each block can be assigned to only one group from all the groups that are inserted for the diagram. If you have not inserted any groups for the diagram, the only choice available is None, which indicates that no group is assigned.
|
 |
When clicked, the RBD Dependency Groups window opens, displaying all groups inserted for the diagram. You can expand the identifier assigned to the group to view all blocks assigned to the group. Additionally, you can insert new groups, delete existing groups, and highlight blocks in a group. For more information, see RBD Dependency Groups window.
|
|
Dependency trigger
The properties under this heading define the event that spurs the performance of the specified action. If the component represented by this block is failed, or if it is already undergoing maintenance, the dependency information for this block is ignored.
|
|
|
Trigger type
|
The event that causes the maintenance specified for Trigger action to be performed. Choices are:
• None. When selected (default), no event causes the maintenance to be performed.
• Block Failure. When selected, a failure of another block in the same diagram causes the maintenance to be performed. Trigger source becomes available so that you can select any block in the diagram except repeat occurrences of the current block.
• Member of Group Failure. When selected, the failure of any block in a dependency group causes the maintenance to be performed. Trigger source becomes available so that you can select any group in the diagram.
• Local Diagram Failure. When selected, a failure of the diagram in which the block is located causes the maintenance to be performed.
• System Failure. When selected, system failure causes the maintenance to be performed.
|
|
Trigger source
|
Specifies the block or group for the failure event. This property is available only when Block Failure or Member of Group Failure is selected for Trigger type.
• When a block failure is the trigger event, choices include the blocks in the diagram. You can select any block except repeated occurrences of the current block.
• When a failure of any block in a dependency group is the trigger event, choices include all groups created for the diagram, including the one to which the block is assigned.
|
|
Trigger action
|
Specifies whether to perform corrective maintenance or a maintenance task. When a maintenance task is performed, for Maintenance to perform, you select the specific task. Choices for the action triggered are:
• Fail. When selected, corrective maintenance is immediately started.
• Perform Maintenance. When selected (default), the task selected for Maintenance to perform is immediately started.
• Perform Maintenance if Almost Due. When selected, the task selected for Maintenance to perform is started only if it is due within the time interval specified for Time span until due.
|
|
Maintenance to perform
|
Specifies the task to perform. This property is available only when Perform Maintenance or Perform Maintenance if Almost Due is selected for Trigger action. Choices include all tasks inserted on the block’s Maintenance page. It does not include a choice for performing corrective maintenance.
|
|
Time span until due
|
The amount of time before its next scheduled due date that a task can be started. The default is 0 so that the task is not started before it is due. This property is available only if Perform Maintenance if Almost Due is selected for Trigger action. The task specified for Maintenance to perform is started only if it is scheduled to occur within the time span you specify here. The units for the value that you enter are selected to the right. Choices are Hours (default) or Percent of Interval. To use a percentage of the task’s scheduled interval, you enter a percentage value (0 to 100).
For example, assume that the task selected for Maintenance to perform is scheduled to be performed on a block, Boiler A, every 1000 hours, and it has been 900 hours since this task was last performed. Also assume that Boiler A is dependent on Boiler B failing. If Boiler B fails and the value entered for Time span until due for Boiler A is 100 hours (or 10% of the task interval), this task is started on Boiler A. If the time span is less than 100 hours (or 10% of the task interval), this task is not started on Boiler A until the 1000 hours is reached.
|