Reliability HotWire: eMagazine for the Reliability Professional
Reliability HotWire

Issue 60, February 2006

Tool Tips

* How is a maintenance tasks assigned interval determined in RCM++?
The assigned interval for a maintenance task is how often that task will be performed. This is entered on the Task page of the Task Properties window, as shown next.

Here, the assigned interval for this On Condition task is 600 hours, based on Item Age. This means that the user has selected to perform the inspection at 600-hour intervals, based on the age of the item since the last corrective maintenance. That is, if the item fails and is repaired at 400 hours, the inspection will be performed at 1000 hours, 1600 hours, 2200 hours and so on. If the assigned interval were based instead on System Age, the inspection would be performed at 600-hour intervals based on the age of the system regardless of any corrective repair performed (i.e. at 600 hours, 1200 hours, 1800 hours, etc. even if the system fails and is repaired at 520 hours). If, at any inspection, the item is found to be failed or about to fail, the preventive maintenance action will be performed.

The assigned interval can be assigned manually by the user, and may be the same as the proposed interval or it may be different due to incorporation into a maintenance package or for a variety of other reasons. In the case of tasks of type Repair/Replacement, if the assigned interval is based on Item Age, the Calculate Optimum Interval button becomes available. This automatically calculates the optimum interval for performing the maintenance task, based on corrective maintenance cost, preventive maintenance cost and cause probability.

* Does RENO provide any way to make building equations easier?
RENOs equation-enabled windows (used by Equation Variables, Functions and Standard Blocks) provide a number of intelligent features to help you enter equations more quickly and accurately. These include:

Auto-Complete/Intelli-Sense: When you press Ctrl+Space while building an equation, RENO provides a list of recognized Definitions and reserved keywords.

Color-Coding: As you type, RENO automatically color-codes recognized Definitions, reserved keywords and operands to make it easy for you to spot typing errors, undefined variables, unmatched parentheses, etc.
Variable Preview: RENO provides a summary of the properties of each defined variable that you use in your equations and allows you to view/edit the full definition with the click of a button.

Note that if you prefer to have drag-and-drop functionality available for building your equation, you can click the Function Wizard icon to open the Function Wizard, which allows you to drag Definitions, reserved keywords and predefined functions into the Composite Function area at the bottom of the window to build your equation, as shown next.

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