AADvance Safety Manual - Tuv-fs.com

AADvance Safety ManualCross Reference CheckingWhile the aim shall be to minimise the coupling and dependencies between individualprograms, there will inevitably be occasions where, for example, a variable is usedwithin two or more programs. It is important to ensure that any application programchanges that affect these interactions do not jeopardise the functional safety.On-line ModificationIt is highly recommended that on-line changes are not performed unless absolutelynecessary as it could reduce the safety integrity of the system while doing the changes.Where changes have to be carried out on-line alternative safety measure should beimplemented for the duration of the change procedure.Certain modifications can be performed without directly affecting the system's safetyfunction, for example the installation of additional modules. Although thesemodifications will not affect the system's operation until the system configuration andapplication program have been modified, caution shall be exercised to ensure that themodifications do not affect other safety related functions.Changes that affect the system's ability to respond safely, or thatmay cause other plant disruption shall not be performed on-line unlessalternate protection measures can be implemented for the duration of suchmodifications.Physical InstallationThe AADvance controller equipment (base units and modules) is designed for usewhen it is installed upright, that is with the base units in a vertical plane and theventilation slots on the modules at the top and bottom. This orientation is essential toensure non-forced air cooling is effective and the controller meets the specified MTBFof the modules. This rule applies to all installations regardless of ambient temperatureand any additional forced air cooling that may be applied.5-32 Document number 553630 Issue 7: February 2010