Greetings Peter,
In most general terms,the Conflict Rules are to prevent conditions to be set on a plant floor that are unsafe or impossible to maintain for certain objects. You set the Conflict Rules for particular Operational Conditions in an Operational Group. Also,you maintain them both ways, i.e. Condition 1 to Condition 2, but also Condition 2 to Condition 1. Conflicts can be Green, Yellow (warning message) or a Red conflict. A Red conflict cannot be passed without special authorisation. The conflicts are checked when switching WCD items.
For example,if two conditions are used, like OPEN and CLOSE: if you have a technical object such as a BYPASS VALVE, then if on two WCDs you will have,at the same time,the same valve,with the tagging condition specified as OPEN, then both works can be processed safely at the same time,since they need similar conditions. So this would be configured as a Green conflict rule - for the OPEN/OPEN pair of conditions. But if for one WCD you have the required tagging condition as OPEN and for the other you have CLOSED, then making the tagging for one prevents preparing the safe workplace for the other. Therefore the pairings OPEN/CLOSED & CLOSED/OPEN would be a Red conflict.
Then with some pairings it may either be impossible to determine the safety without additional knowledge (decision of Operations is required) or the change in conditions is possible,but should be noted (e.g. if a breaker is disconnected and then removed completely; DISCONNECT & REMOVE could be a Yellow conflict (but you can still set the opposite to Red to maintain higher safety)
Generally,a conflict rule either allows, warns of, or prohibits setting a technical object to an Operational Condition based on the Operational Condition of the same technical object on another Item or Document active.
Note that what are Green conflicts at the time of the tagging, may become Red at untagging phase as one WCD may be already untagged,but the other still in progress (this necessitates that the untagging conditions are adjusted)
See more info:
Conflict Rules - Work Clearance Management (PM-WCM) - SAP Library