JAN-FEB 2019

Issue link:

Contents of this Issue


Page 33 of 55

34 INTECH JANUARY/FEBRUARY 2019 WWW.ISA.ORG AUTOMATION IT an assembly line, or tens of thousands of tablets or capsules on a pharmaceutical finishing line). So alarms are often gen- erated based on a statistical algorithm (e.g., statistical deviation within a lot) rather than a continuous analog signal (e.g., a temperature measurement ex- ceeding its deadband). Furthermore, the generation of a "process measure- ment value" (PV ) for use in a discrete process alarm algorithm can, itself, be challenging, as sensors for such infor- mation can include sophisticated vision systems, robotics, and RFID chips, with part of the challenge being to export the appropriate information from such sophisticated microprocessor-based sensor systems to a plant's central alarm system. The need for any such specialized alarm algorithms should be identified in a plant's alarm philos- ophy, with details determined during alarm identification and rationaliza- tion life-cycle activities. TR7: Alarm management when utilizing packaged systems Integrating packaged systems into cen- tralized plant automation systems is often one of the most challenging tasks faced by automation professionals. From a process design point of view, packaged systems (PS) play an impor- tant role, as they are specialized pieces of process equipment with customized control systems that are specific to their function. However, packaged systems— due to their custom nature—are often the source of many headaches when it comes to integrating them into a plant's basic process control system and into a plantwide alarm system. It is not un- common for a packaged system to use a completely different control technology platform than the rest of the plant, often causing a multitude of system integra- tion challenges. Common examples of plant equip- ment in the process industries that use packaged systems include: chillers, compressors, turbines, furnaces, batch reactors, packaging equipment, UV dis- infection systems, and sump pump con- trollers, just to name a few. Though each is different in its function, they share a common feature of typically using indi- vidual control systems that are different from the centralized system (e.g., distrib- uted control system) in the plant where they are installed. TR7 begins by defining what packaged systems are and the various pros and cons of packaged systems from a sys- tem integration perspective. The TR also establishes a set of standard terminol- ogy that can be used to clearly define the various forms of packaged system con- trol systems. For example, the location, role, and placement of packaged system control panels, which typically include alarm information, can be implemented in many ways, and the pros and cons of various commonly used configurations are discussed. Commonly used techniques to inter- face PSs into plantwide alarm systems are covered, including best practices, and, again, the pros and cons of various approaches. Frequently encountered challenges with interfacing PSs are also covered, with the goal of helping the reader avoid many of the common issues when it comes to integrating packaged systems within a plant's larg - er overall control system. There are a wide variety of methods that can be used to interface a PS with a plant's alarm system (and a plant's over- all control system). There are also several ways to apply the ISA-18.2 alarm man- agement life cycle to packaged systems. TR7 provides a framework of how to ef fectively cover packaged system alarms within a facility's alarm philosophy. The TR then discusses the unique details of packaged systems one by one, and how this in turn relates back to the alarm phi- losophy, complete with examples. The text of TR7 includes a discussion of how using packaged systems impacts each of the work processes of the ISA-18.2 alarm management life cycle. The design- oriented alarm management work pro- cesses of identification, rationalization, detailed design, and implementation are covered first. The TR has a step-by-step method of how to develop packaged sys- tems alarms, which includes leveraging the knowledge and expertise of the pack- aged system vendor, as well as the needs of the end user. Specific emphasis is put on resolving alarm management issues during the design process, rather than waiting until fabrication or commission- ing of packaged systems. The TR then covers some of the more operations-oriented aspects of alarm management, namely operation, main- tenance, and alarm system performance monitoring and assessment. A strong em- phasis is put on how changes to the alarm system with respect to packaged systems and packaged system interfacing must be made carefully as part of a management of change process. Making changes with packaged systems can sometimes be difficult because of warranty and com- mercial considerations, so the TR gives advice for project leaders about talking to vendors and end users about the ben- efits of applying alarm management to packaged systems. Lastly, the TR7 tech- nical report provides guidance on how to au dit alarm management processes when packaged systems are involved. Helpful guidance Every process facility is different, so there is no "one size fits all" approach to doing alarm system design. For plants that make use of complex processes, batch processes, Figure 3. Example of how a packaged system can be integrated into a plantwide control system

Articles in this issue

Links on this page

Archives of this issue

view archives of InTech - JAN-FEB 2019