I caught up with Emerson’s Dan Jacobsmeyer this past October at the Emerson Exchange. Dan is a Flexconnect product specialist and a member of the migration best practices exchange group in the project management office. Dan started to mention some lessons learned on process automation system migration projects and my ears quickly perked up. This sounded like great stuff for a blog post.
Most people modernizing their control systems spend a lot of time in the system configuration with the I/O, control strategies, and graphic displays engineering everything properly in preparation for the cutover to the new system.
Dan’s experience is that the source of a lot of the troubleshooting issues and time spent is often associated with the field instrumentation. A critical step in the migration process before the cutover begins is to verify that all instruments in the control system database are working prior to the cutover. Another key step is to find all the loops that are currently operating in manual mode and have a thorough understanding from the operators as to why this is so.
Dan cited some examples seen by the migration specialists that these checks have caught–known bad transmitters, missing process variable (PV) signals from multi-variable transmitters, short circuits caused by water-filled transmitter housings, missing agitator belts, disconnected field wiring, etc.
Each alone can be fixed without too much time and trouble, but when done as part of a complete system switchover, it can take much more time. This is because the source of the error can be anywhere along the path from the system to the instrument. It takes time to troubleshoot each point along this path.
After doing these checks and beginning the cutover, what do you do when instruments do not commission on startup? Dan suggests you disconnect the instrument from the termination panel and test the transmitter or final element. Test the field wiring for opens, grounds, or shorts. Simulate or source the loop to systems like the DeltaV system. Output current and test the loop. Finally, reconnect the transmitter or final element and test it again.
Dan also recommends you have spare instruments available, the specifications to all of the instruments, location drawings of the instruments, and an available instrument technician to field test the instruments where required.
Having the documentation and pre-cutover checks done can save quite a bit of time during the heat of the battle when the unexpected surprises occur, as the firm believers of Murphy’s Law can attest they will.
Thanks for sharing these lessons and letting me pass them along, Dan!
