Actuated valves get open at field without any command from DCS
We are using the ABB 800xA system for our Resin preparation plant.on 26th May suddenly bottom valve along with inlet valve of six down stream vessels got open while batch was processing in the reactor.As per the control logic all the inlet valve of down stream vessel & bottom valve of reactor are in interlock.
There is no event of auto open command.Suddenly all the valves got object error and after few secons they got open FB in field where Out0=1.
After the incedent we have checked the continuity and hotloop testing and resuilt was normal
There was no trace of signal cable brunt or loose connection for voltage intereference.
No power cable laid near to the control cable .
We are using rotex acutator wich was connected to DO810 via Stahl make barrier.
Request all to share your experience or opinion which will help us for the Root cause alysis