ABB DCS programming at Lomanis fuel terminal

Background

The ABB System 800xA distributed control system is the monitoring and control centre for the terminal process. After an unplanned shutdown caused by a PLN power failure and lightning, alarms and signals on the DCS did not fully return to normal.

Scope of work

• DCS and HMI troubleshooting. Process overview, signal status at the operator station, active alarms and events, and the link between field signal, I/O module, controller and HMI. Valid alarms were separated from false ones.

• Flowmeter and totalizer. The CB1 flowmeter hunted with no flow. The CY1 flowmeter gave no reading on the HMI, and its totalizer signal was too weak for the DCS I/O module. Signal tracing and injection showed the I/O modules were not damaged. The fault on CY1 sat in the flowmeter and totalizer controller, not in the DCS I/O.

• I/O signal verification. Field-to-DCS input checks, functional tests of the I/O modules, signal simulation and HMI response, to decide whether a fault came from the DCS or from the field and controller.

• False alarms. Alarms were traced one by one through the 800xA alarm and event log: log review, operator confirmation, genuine versus false classification, alarm logic checks, clean-up and retesting. Persistent false alarms can reduce operator attention to genuine process alarms.

• Alarm logic correction. The alarms were linked to abnormal conditions after the power failure, probably simultaneous high and low signals in the alarm logic. The alarm configuration was cleaned and corrected. The alarms that remained reflect actual field conditions.

• Process and HMI consistency. Possible mismatches were found: some DCS pages not updating, product tanks on the HMI that may differ from the real ones, pipe routes to verify, and P&ID and PFD documents that were hard to find and need re-documentation.

• Additional finding. The battery charger panel was not working, and follow-up was recommended.