The Alarm Problem
A poorly functioning alarm system is often noted as a contributing factor to the seriousness of upsets, incidents, and major accidents.
Significant alarm system improvement is needed in most industries utilizing computer-based SCADA or distributed control systems ; it is a massively common and serious problem. Most companies have become aware of the need to thoroughly investigate and understand their alarm system performance.
Alarm management is a fast-growing, high profile topic in the process industries. It is the subject of constant articles in the trade journals and at various technical society meetings and symposia .
Having decided to investigate this area, how do you proceed? Your time and resources are always limited. The subject is complex. Alarm system improvement involves an interlinked combination of technology and work processes.
People Who Can Help
You should seek help from the best experts in the field. You want information, advice, products, and services from:
• People who are acknowledged experts in the alarm management field, with in-depth understanding of the historical and current problem, the science and literature, the studies and standards, and the range of solutions
• People with in-depth knowledge of process control, distributed control systems, human-machine interfaces, process networks, and critical condition management
• People with experience in every stage of a successful alarm system improvement project, along with many examples of successful projects
• People who understand work processes based on successful experience in different industry segments. You want to know what your industry is doing, what are the best and most efficient practices , and frankly, what the worst practices are.
The ANSI/ISA-18.2-2009 Alarm Management Standard
In 2003, ISA began developing a standard on alarm management. Dozens of contributors (including the authors) from many industry segments spent thousands of person-hours participating in the development. After six years of work, the new standard “ANSI/ISA-18.2-2009 Management of Alarm Systems for the Process Industries” is now available at www.isa.org.
The issuance of ISA-18.2 is a significant and important event for the process industries. It sets forth the work processes for designing, implementing, operating, and maintaining a modern alarm system, presented in a life cycle format. This standard will definitely have a regulatory impact, but more on that later.
This second edition contains a lengthy chapter on understanding and implementing this standard. Readers of this book should not expect to learn much that is basically new or different from reading ISA-18.2. Standards intentionally limit and concern themselves with what to do rather than how to go about doing it in an effective and efficient manner. By design, standards contain the minimum acceptable and not the optimum. This book exists to provide detailed guidance and impart detailed knowledge far exceeding the content of a standard.
There is no conflict between this seven step approach and the
ISA-18.2 life cycle approach —there is only some different nomenclature and arrangement of the topics. The seven step approach is well proven for efficiency and effectiveness.
Seven Steps to a Highly Effective Alarm System
Always needed steps:
Step 1: Develop, Adopt, and Maintain an Alarm Philosophy
Step 2: Collect Data and Benchmark Your Systems
Step 3: Perform Bad Actor Alarm Resolution
Here is a brief outline of a best practices approach in a typical alarm management project. These straightforward steps can be easily implemented in any work process framework, such as Six Sigma . The first three steps are universally needed for the improvement of an alarm system. They are often done simultaneously at the start of a project.
These first three steps are placed first in the process because they collectively provide the most improvement for the least expenditure of effort. They provide the best possible start and the fundamental underpinnings for the remainder of steps necessary for effective alarm management.
Steps to implement to improve alarm system performance:
Step 4: Perform Alarm Documentation and Rationalization (D&R)
Step 5: Implement Alarm Audit and Enforcement Technology
Step 6: Implement Real-time Alarm Management
Step 7: Control and Maintain Your Improved System
Step 1: Develop, Adopt, and Maintain an Alarm Philosophy
An Alarm Philosophy is a comprehensive guideline for the development, implementation, and modification of alarms. The philosophy says “Here’s how to do alarms right!” It provides an optimum basis for alarm selection, priority setting, configuration, response, handling methods, system monitoring, and many other topics. You will learn exactly how to develop an Alarm Philosophy, complete with examples. An Alarm Philosophy will be an immediately useful document covering the entire range of alarm topics. It will reflect a full understanding of the alarm problem and the proper practices to follow.
Step 2: Collect Data and Benchmark Your Systems
Analysis is fundamental to improvement. You must analyze your alarm system to improve it. You should look for alarm analysis software with full graphical and tabular output, easy access to the full control system event journal entries, automatic report generation, web-based report viewing, and so forth. You want a comprehensive and complete set of alarm analyses to enable you to pinpoint your exact problems and apply the most efficient solutions.
Since operator changes (e.g., controller setpoints, modes, and outputs) are recorded by most DCSs in a similar fashion to alarm events, you will want software that includes the analysis of such events. The results can be amazingly useful, and can point out areas where control schemes are not working as designed or where operating procedures or operator training need improvement. While this book is focused on alarm management, we include a section on the benefit of these operator change analyses.
There can be no improvement without an understanding of your starting point. A comprehensive Baseline Report sets your benchmark and will enable you to target your resources to get the most improvement possible for the minimum cost and effort. The start of an improvement effort requires an examination of your actual data.
Step 3: Perform Bad Actor Alarm Resolution
Based on the analysis of hundreds of systems, there are always several varieties of nuisance or Bad Actor alarms. It contains an efficient and effective process for analyzing these and provides exact recommendations for configuration changes to improve their performance. The average improvement is over a 50% reduction in overall alarm events for a relatively minimal effort. While on some systems this result may not meet an overall improvement goal, it is a great first step, providing much-needed immediate relief. It also establishes the credibility of the alarm management effort with an immediate early success.
These first three steps are universally needed for the improvement of an alarm system. The following steps generally involve more time, resources, and expense. Some of them may or may not be needed depending on the performance characteristics of your system.
Step 4: Perform Alarm Documentation and Rationalization (D&R)
Many existing systems need a total rework—a review of the configuration and purpose of every alarm. We call this Alarm Documentation and Rationalization (D&R) , also commonly called Alarm Objective Analysis , among other terms. You will want to use a software-assisted methodology to make D&R fast and efficient. Besides just having software, there is an art to performing a D&R in an efficient manner. The knowledge herein is based upon participation in the rationalization of hundreds of thousands of points. This experience provides detailed knowledge of the common problems and the best solutions, which are provided here in this book. One result of a D&R effort is the creation of a Master Alarm Database, which contains the post-rationalized alarm configuration with changed setpoints, priorities, and so forth. A Master Alarm Database has several uses.
Step 5: Implement Alarm Audit and Enforcement Technology
Once your alarm system is improved, it is essential to ensure the configuration does not change over time unless the changes are specifically authorized. DCS and SCADA systems are notoriously easy to change, which is why software mechanisms that frequently audit (and enforce) the current configuration versus the Master Alarm Database are needed. Paper-based Management of Change solutions for DCS configuration (alarm or otherwise) have a wide and consistent history of failure.
Step 6: Implement Real Time Alarm Management
Based on the performance you need your alarm system to achieve and the nature of your process, you may want to implement more advanced alarm handling solutions , such as the following:
• Alarm Shelving : A safe, secure way to temporarily disable a nuisance alarm until the underlying problem can be corrected. Most control systems have inadequate mechanisms to properly control temporary alarm suppression . Computerized lists of shelved alarms, with time limits, reminders, and auto-re-enabling are necessary. It must be impossible to temporarily suppress an alarm and then forget about it—a very common and dangerous occurrence throughout industry.
• State-based Alarming and Alarm Flood Suppression : Algorithms detect when the plant changes operating state (such as startup , shutdown , different products, rates, feedstocks, etc.) and dynamically alter the alarm settings to conform to the proper settings for each state. State-based settings for inadvertent shutdown of a piece of equipment have proven to be effective in managing most alarm flood situations.
• Operator Alert Systems : Once the alarm system has been properly reserved for things meeting the requirements of what should actually be an alarm , there may remain a need for an operator-configurable notification tool explicitly separate from the alarm system. Such operator alert systems are a best practice and are described later in this book.
Step 7: Control and Maintain Your Improved System
Processes and sensors change over time, and alarm behavior will change with them. Alarms working correctly now may become nuisances or malfunction in the future. Effective management of change methodologies, and an ongoing program of system analysis and correction of problems as they occur, is needed for an effective alarm system.
Summary
If you know or suspect you have an alarm problem, read this post and begin doing the things it recommends.
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