Thanks for the response guys. You are helping ease my pain.
We are experiencing issues with our existing Limitorque actuators similar to the Rotork problem mentioned above. So it looks like there is no silver bullet. Limitorque has told us to modify our wiring and also upgrade 14 of our actuators to their latest generation to mitigate our problem. My confidence level is 60%…..
Mitch – regarding sequencing logic…… unfortunately that is the direction we have headed. We have built a gory spreadsheet defining each sequential step with the required valve positions. We tried using a simple permissive table (not step dependent) and it was too complicated with way too many “if” statements that were cycle time dependent. It seemed much simpler to just walk straight through the steps. I’m going to have our team review the spreadsheet and identify the valves that we don’t care to tie into the logic for the next move – that way if we do have a valve with a communication issue, it doesn’t hose the logic for every step. It would only hose the steps where it’s position is critical. I wonder if Foster Wheeler has a standard design/logic we could purchase? Seems like everyone could benefit if there was a standard design.
Regards,
Craig
