ISA TR18 2 4-2012 Enhanced and Advanced Alarm Methods.pdf

1、 TECHNICAL REPORT ISA-TR18.2.4-2012 Enhanced and Advanced Alarm Methods Approved 6 September 2012 Copyright 2012 ISA. All rights reserved. ISA-TR18.2.4-2012, Enhanced and Advanced Alarm Methods ISBN: 978-1-937560-19-5 Copyright 2012 by the International Society of Automation. All rights reserved. Pr

2、inted in the United States of America. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording, or otherwise), without the prior written permission of the publisher. ISA 67 Alexander Driv

3、e P.O. Box 12277 Research Triangle Park, North Carolina 27709 E-mail: standardsisa.org ISA-TR18.2.4-2012 Copyright 2012 ISA. All rights reserved. 3 Preface This preface, as well as all footnotes, is included for information purposes only and is not part of ISA-TR18.2.4-2012. This technical report ha

4、s been prepared as part of the service of ISA, the International Society of Automation, toward a goal of helping in the understanding and use of ANSI/ISA-18.2-2009, Management of Alarm Systems for the Process Industries. To be of real value, this document should not be static but should be subject t

5、o periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to the Secretary, Standards and Practices Board; ISA, 67 Alexander Drive; P.O. Box 12277; Research Triangle Park, NC 27709; Telephone (919) 549-8411; Fax (919) 549-8288; E-mail: stand

6、ardsisa.org. The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards, recommended practices, and technical reports. The De

7、partment is further aware of the benefits of USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce SI-acceptable metric units in a

8、ll new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI): The Modern Metric System, published by the American Society for Testing systematically compare alarms to the alarm philosophy; and d

9、etermine the alarm setpoint, consequence, operator action, priority, and class. Activities include, but are not limited to, identification, justification, prioritization, classification, and documentation. (As of the publication of this technical report, the draft, dTR2, had not been published.) ISA

10、-dTR18.2.3, Basic Alarm Design dTR3, provides guidance on basic alarm design, focuses on the scope of Clause 10 of ISA-18.2, and may include other clauses as needed (e.g., Clause 14 on operations and Clause 15 on maintenance). Basic alarm design covers the selection of alarm attributes (e.g., types,

11、 deadbands, and delay times) and may be specific to each control system. (As of the publication of this technical report, the draft, dTR3, had not been published.) ISA-TR18.2.4-2012, Enhanced and Advanced Alarm Methods TR4, provides guidance on enhanced and advanced alarm methods and focuses on the

12、scope of Clause 12 of ISA-18.2. Enhanced alarm design covers guidance on additional logic, programming, or modeling used to modify alarm behavior. These methods may include: dynamic alarming, state-based alarming, adaptive alarms, logic-based alarming, and predictive alarming, as well as most of the

13、 designed suppression methods. ISA-TR18.2.5-2012, Alarm System Monitoring, Assessment, and Auditing TR5, provides guidance on monitoring, assessment and audit of alarms and focuses on the scope of Clauses 16 and 18 in ISA-18.2. Monitoring, assessment, and audit cover the continuous monitoring, perio

14、dic performance assessment, and recurring audit of the alarm system. ISA-TR18.2.6-2012, Alarm Systems for Batch and Discrete Processes TR6, provides guidance on the application of ISA-18.2 alarm lifecycle activities to batch and discrete processes, expanding on multiple clauses of ISA-18.2. The guid

15、ance as presented in this document is general in nature and should be applied to each system as appropriate by personnel knowledgeable in the manufacturing process and control systems to which it is being applied. This guidance will evolve with experience and technology advancements. ISA-TR18.2.4-20

16、12 Copyright 2012 ISA. All rights reserved. 10 Introduction Alarm management lifecycle ISA-18.2 gives requirements that address alarm systems for facilities in the process industries to improve safety, quality, and productivity. The general principles and processes in ISA-18.2 are intended for use i

17、n the lifecycle management of an alarm system based on programmable electronic controller- and computer-based human machine interface (HMI) technology. These requirements are presented in the standard, using the alarm management lifecycle shown in ISA-18.2. Note 1: The box used for stage B represent

18、s a process defined outside of ISA-18.2. Note 2: The independent stage J represents a process that connects to all other lifecycle stages. Note 3: The rounded shapes of stages A, H, and J represent entry points to the lifecycle. Note 4: The dotted lines represent the loops in the lifecycle. Figure 1

19、 Alarm management lifecycle (ISA-18.2) Monitoring to help decide whether or not they should consider enhanced and advanced alarming techniques; and if so, which specific techniques should be incorporated into their alarm philosophy and work processes c) to help those involved in the design, procurem

20、ent, implementation, maintenance, and operation of enhanced and advanced alarming methods, for both existing systems and new systems d) to provide guidance and examples to help ensure successful deployment of the solutions Report organization Clause 12 of ISA-18.2 divides enhanced and advanced alarm

21、ing into four categories based on type of solution: information linking, logic-based alarming, model-based alarming, and additional alarming considerations. This technical report is organized by type of alarming problem, rather than by solution technique. The intent is to cover all the techniques bu

22、t to cover them in the context of the site problems that they address. Some techniques can be used to address multiple problems, and in the more complex problems and solutions, multiple techniques may be used, as shown in some of the examples of this report. The technical report is organized as foll

23、ows: Clause 1 discusses the scope of this technical report, including important exclusions. Clause 2 gives normative references. ISA-TR18.2.4-2012 Copyright 2012 ISA. All rights reserved. 12 Clause 3 provides definitions of terms and acronyms used in this technical report, most of which are defined

24、in ISA-18.2 and used here. Clause 4 discusses the primary differences between enhanced/advanced alarming methods and basic alarming methods, including discussion of situations that may lead to the need for enhanced and advanced methods. Clauses 5 through 10 provide guidance and examples for using en

25、hanced or advanced alarm ing methods to solve alarm system problems that remain after application of the basic alarming techniques. The problems, with their solutions, are presented roughly in their order of complexity. Clause 5 discusses situations in which the information embedded in the alarm its

26、elf may not be enough to guide the operator to appropriate action. Often the appropriate guidance has already been identified during the rationalization stage. This clause discusses information linking techniques, such as those for presenting this and other guidance to operators at the appropriat e

27、times. Clause 6 discusses situations in which changing plant operating conditions may lead to the need for advanced methods, such as designed suppression or changing alarm attributes, in order for the alarm system to properly track the changing states of the process. This can occur for planned opera

28、ting states, such as start-up, shutdown, and different feedstocks; or it can occur due to unplanned events, such as a compressor trip. Clause 7 builds upon this discussion. In some cases, the dynamic alarmin g methods of Clause 6 still do not provide adequate operator guidance, and enhancements may

29、be needed to provide appropriate guidance for all anticipated process situations. Clause 7 discusses utilization of dynamic cause analysis to provide more tailored operator guidance in such situations. Clause 8 discusses situations in which the basic alarm system alone does not deliver the alarm to

30、the person (i.e., role) on the operating team who (based on the operating philosophy) should react to the alarm. In some situations, the responder is not in the control room or is in the control room but at a different console due to process dynamics, scheduling, or other competing plant floor activ

31、ities. This clause discusses these issues and related solutions. Clause 9 discusses appropriate use of alerts. As identified in ISA-18.2, alerts share some of the same characteristics but do not meet all of the criteria of alarms. Though they are not alarms, the use of alerts relative to alarms is i

32、mportant and is discussed in this clause. Clause 10 briefly discusses the use of enhanced/advanced alarming methods for batch and discrete processes. These methods are more broadly covered in TR6. Clause 11 discusses how the alarm system integrity is maintained through appropriate application of sit

33、e work processes, including those discussed in ISA-18.2. If appropriate care is not taken in the application of the enhanced and advanced methods presented here, loss of alarm integrity and other problems can result. Clauses 12 and 13 provide a list of references and a bibliography. ISA-TR18.2.4-201

34、2 Copyright 2012 ISA. All rights reserved. 13 1 Scope 1.1 Exclusions The following is a list of items not discussed in this technical report. In general they are left out of this report, not because they are unimportant, but because they are already covered by another ISA-18 technical report or othe

35、rwise assumed to be part of basic alarm management. 1.1.1 Alarm rationalization and basic alarm design This technical report assumes that alarm rationalization and basic alarm design, as discussed in ISA-18.2, are being performed. Rationalization, also discussed in dTR2, is performed at an appropria

36、te level, basic to advanced, as determined by the alarm philosophy (see dTR1) of the site. Basic alarm design is discussed in dTR3. Together these activities include such techniques as properly chosen alarm setpoints, deadband selection, use of on and off delays, and proper range specification. 1.1.

37、2 Process variable calculations Most process variable calculations (analog and logical) are performed in the control system and considered as part of the basic alarm design process. PV calculations can be complex yet have basic alarming functionality. This includes such techniques as: a) common alar

38、ms, e.g., a common high-temperature alarm coming from multiple temperature transmitters on a tank, or a common toxic-gas alarm coming from multiple gas detectors b) numeric calculations within the control system used with basic alarming, such as rate calculations (producing rate-of-change alarms), s

39、tatistical calculations (producing statistical alarms, such as alarming on standard deviations, etc.) and other complex calculations c) simple to complex models used to estimate process values online, often referred to as virtual sensors d) high-speed counters and accumulators, often needed in discr

40、ete manufacturing applications, which accumulate and aggregate within the control system before applying basic alarming e) logic calculations within the control system to create an alarm only when it is a valid alarm , e.g., a calculation including a logical AND of low pressure and the associated pu

41、mp running, to create a logical PV that is alarmed NOTE If the alarm is created by the control system, and logic is added to conditionally suppress it, this falls under the definition of advanced alarming and is discussed in Clause 6. 1.1.3 Operating displays for basic alarming strategies Often it i

42、s important for operating display design and alarm design to go hand in hand. This may be for basic or enhanced/advanced alarm strategies. This technical report deals with some human interface design issues but only as related to the enhanced/advanced alarming strategies presented. 1.1.4 Audible ind

43、ication strategies The use of different audible alarm indications (sounds) to distinguish operating consoles for multiple console control rooms is considered to be a human interface strategy, rather than an enhanced alarm strategy. For the purposes of this technical report, the use of specialized au

44、dible sounds is not covered here. 1.1.5 Alarm shelving As discussed in 11.7 of ISA-18.2, alarm shelving is an important recommended function and can be used in a number of ways. It is also discussed in dTR1. Its use is not considered advanced or enhanced alarming. ISA-TR18.2.4-2012 Copyright 2012 IS

45、A. All rights reserved. 14 1.1.6 Maintenance strategies As discussed in Clause 15 of ISA-18.2, maintenance is an important topic to address in alarm management at any site, and it can be addressed to varying degrees of sophistication, including communication support between members of the operating

46、team. Such strategies, though important, are not considered to be enhanced/advanced alarming for the purposes of this technical report. 1.1.7 Model-based predictive alarming/alerting ISA-18.2, Clause 12, briefly discusses model-based predictive alarming. It is not included in this technical report a

47、t this time. Very often, application of these techniques does not result in explicit operator notifications; and if there are notifications, they are often alerts and not alarms due to either the lack of immediate urgency or the inability of the system to treat them as alarms. As this technology dev

48、elops and comes more into common use, such techniques may be included in a future version of this technical report. 1.1.8 Basic alarms on advanced control Advanced control, such as model-based predictive control, usually needs some basic alarming to go with it. Though the overall control strategies

49、are advanced, the alarming may not be. Basic alarming on an advanced control system is not in the scope of this technical report. 1.1.9 Advanced alarm analysis techniques There are many advanced alarm analysis techniques in use today, including relative time-based analysis and post-mortem, alarm-pattern recognition. Such techniques are discussed in TR5. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the refe