Before the era of distributed control systems (DCS), the alarm was hard-wired to a fixed alarm panel installed on the wall of the control room. The panel consists of a discrete input and a red indicator light (connected by a wire) at the window.
Alarm creation has long been done manually, because the installer must drill holes in the panel and lay copper wires to activate the signaling device. This method requires careful consideration of which events to issue an alarm and specific reasons.
The introduction of DCS has changed the traditional way of alarming. Today, alarms are integrated into distributed control system application software, so new alarms can be created with relatively simple software changes.
This can lead to an increase in alarms that are meaningless or irrelevant to the operator. Concentrating on a large number of false alarms will cause operators to ignore new alarms and also cause them to miss critical alarms.
Since adding new alarms becomes easy, implementing effective alarm management procedures is more important than ever.
It takes months to design and deploy new equipment, and the equipment will run for more than 20 years. This means that during the design and implementation phase of the project, operators are likely to need to adapt to decisions made by others for a long time.
Most of the additions, enhancements and migration operations of the distributed control system are implemented as specific projects.
However, alarm management is never-ending and requires your unremitting efforts. Therefore, a key to building a successful alarm management program is to realize that it is not just a project, but a long-term process. The ISA-18.2 standard points out that alarm management not only involves hardware or software, but also relates to the working process or alarm management cycle.
To ensure the successful implementation of the alarm management project in PlantPAx DCS, Rockwell Automation and the certified Encompass partner exida condensed the alarm management cycle into seven steps:
1. Benchmark the performance of the alarm system. Quantify the average number of alarms/operators and identify false alarms and "bad factors".
2. Develop an alarm concept. What constitutes the need for alarms? How to prioritize alarms?
3. Rationalize the alarm. The purpose is to create the best possible alarm combination to ensure the safety of the equipment and keep it within the normal operating range. At the same time, the basis for the necessity of each alarm must be recorded.
4. Advanced alarm design. Add logic to suppress the alarm when the device is not in use or after the device is tripped to prevent the alarm from flooding.
5. Implement rationalization results. Load the alarm configuration changes into the PlantPAx system and create alarm response steps to present to the operator on the HMI side.
6. Performance monitoring and evaluation. Regularly review the performance of the alarm system to promote continuous improvement.
7. Audit. Compare the PlantPAx alarm settings with the rationalized alarm settings to confirm that the relevant procedures and steps have been followed.
To achieve proper alarm management requires unremitting efforts. In the PlantPAx system, we have no reason to adapt to a poorly performing alarm system. The system software configuration is simple, and the Rockwell Automation Process Object Library integrates the alarm configuration and general suppression technology, which can reduce engineering time and deployment workload.
It only takes a few simple steps to successfully implement and maintain alarm management in the distributed control system.
