1、 RECOMMENDED PRACTICE ISARP77.60.052001(R2012) Fossil Fuel Power Plant Human-Machine Interface Task Analysis Approved 27 March 2012 ISA-RP77.60.05-2001 (R2012) Fossil Fuel Power Plant Human-Machine Interface Task Analysis ISBN: 978-1-937560-35-5 Copyright 2012 by ISA. All rights reserved. Not for re
2、sale. Printed 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 Alexa
3、nder Drive P. O. Box 12277 Research Triangle Park, North Carolina 27709 USAISA-RP77.60.05-2001 (R2012) Copyright 2012 ISA. All rights reserved. 3 Preface This preface, as well as all footnotes and annexes, is included for information purposes and is not part of ISA-RP77.60.05-2001 (R2012). The stand
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6、n prepared as part of the service of ISA toward a goal of uniformity in the field of instrumentation. To be of real value, this document should not be static but should be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms and asks that they be addressed to
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10、I): The Modern Metric System, published by the American Society for Testing b) what the optimal configuration is for the new consoles and work areas; c) wh ether any instrumentation should remain hardwired, and if so, where this equipment should be located relative to the digital displays and contro
11、ls; d) what the best strategy is for organizing displays and quickly accessing digital and soft control stations; and e) when the periods of greatest operator workload should be, and what staffing level is needed to operate the new systems. 4.2 Overview of analysis and needed resources The type of d
12、ata collected during the task analysis process can vary greatly, depending on the specific application. In general, a greater level of detail is required for addressing design-related issues than for training applications. As a minimum, the process may result in a temporarily ordered sequence of sta
13、tements of operator ISA-RP77.60.05-2001 (R2012) Copyright 2012 ISA. All rights reserved. 11 actions and decisions to be made during a defined operating condition or scenario. It should include an assessment of the criticality of the tasks, the potential time constraints in performing the activities,
14、 as well as recommended equipment (information and controls) and supporting job aids for each activity. Other useful data fields include the potential for making an error while performing the task and a description of communication requirements. The task analysis format may be tabular or graphic. Pl
15、ant engineers and designers, human factors engineers, and subject matter experts familiar with facility operations generally work as a team in conducting the analysis. 4.3 Application of task analysis during the design process The task analysis process is central to human factors engineering analysi
16、s, design, and validation. It is applicable to several phases of the design and development of a new system or controls area. It is an iterative process that is best initiated during concept development and continues through preliminary and detailed design. Figure 1 provides a graphic representation
17、 of the role of task analysis in the system development or upgrade process. Task analysis also provides the primary input to plant operating procedures, operator training, and staffing. Figure 1 Task analysis in the system development cycle ISA-RP77.60.05-2001 (R2012) Copyright 2012 ISA. All rights
18、reserved. 12 5 Specification of design requirements prior to task analysis As noted in Figure 1, several decisions should be made and documented by management and the design team prior to conceptual design and before conducting a task analysis. This is particularly important for the design of new sy
19、stems. These decisions are considered in the following subclauses. 5.1 Identifying system/subsystem requirements and goals Systems analysis techniques offer a means for designers to identify what the underlying system processes and requirements are. A top-down approach should be used to determine th
20、ose design characteristics needed for an effective operator equipment interface. A first step is to identify the overall goals and requirements of the system. Typical goals for power plant design include considerations for the safe, economic, reliable, and responsive generation of power. These broad
21、 goals are further translated into plant-specific functional requirements at the system and subsystem level. For example, the reliability of a new distributed control system (DCS) may be unacceptable, given overall plant operational goals and, therefore, require redundant backup systems, use of supp
22、lementary hardwired instrumentation, or new design approaches. The functions that must be performed by the new system in achieving its objectives should now be analyzed. When redesigning control centers associated with Plant Life Extension Programs, overall plant system objectives and functions have
23、 generally been established. During the initial phases of the development of a new control room design concept, decisions must still be made concerning how tasks are apportioned between humans and automated components in accomplishing the goals of the new system. This analysis process is known as fu
24、nction allocation. It relies on an understanding of the inherent capabilities of the operators and the automated components as well as factoring plant lessons-learned data into allocation decisions. Most often the functional allocation decision is made with relatively little analysis by the designer
25、. It is, however, a decision that establishes the framework within which task analysis is performed. Contemporary approaches to functional allocation (Price, 1985; EPRI CS-3745) rely heavily on subjective weighing criteria (i.e., system performance, safety, technical feasibility, cost maintainabilit
26、y, scheduling, and training issues) and recognize that the majority of functions are shared between humans and machines. Empirical study may also be needed to identify all variables and their impact on design performance. 6 Conduct of task analysis during conceptual design As indicated in Figure 1,
27、task analysis should be applied to numerous design decisions early in the system development or upgrade cycle. Because a complete task analysis can be a time-consuming process, it is critical that the analysis focus on those control room activities that are either highly critical for successful plan
28、t operations or are performed most frequently. An approach to sampling operator activities for design applications is considered in 6.1. Subclause 6.2 discusses the mechanics of task analysis. 6.1 Identifying operator tasks and developing scenarios Those functions that have been allocated to operato
29、rs (or maintainers) can be further broken down in to tasks so that task performance requirements can be identified, and a preliminary definition of information and control requirements can be made. This becomes the first step in the task analysis process. For application to the redesign of a control
30、 room, inputs from experienced operators should be solicited and existing plant documentation utilized in defining tasks for further analysis. ISA-RP77.60.05-2001 (R2012) Copyright 2012 ISA. All rights reserved. 13 Using a questionnaire format, plant operators can be asked to list the most common pl
31、ant upset conditions (e.g., condenser leaks, drum-level excursions) and then to rank these according to frequency of occurrence. It is also beneficial to determine which plant upsets require an immediate operator response to avoid a possible hazardous condition or plant trip. From this list, five or
32、 six scenarios are selected for conducting task analysis. Plant start-up and shut-down functions should also receive high priority for further analysis. These functions are often stressful and demanding in terms of manpower and include a significant number of plant systems. If plant procedures exist
33、 for addressing start-up and shut-down, then these may serve as a template for defining and ordering these tasks. Finally, operators should be asked to identify those parameters that are most important to monitor during load changes and full-power operations. This analysis is especially critical for
34、 defining the display requirements of new electronic screen display-based DCS workstations. Task data for normal operations will provide clues indicating what parameters will most likely provide operators with a “situational awareness“ of the status of the plant. 6.2 Analysis of tasks to identify de
35、sign requirements Once scenarios have been selected to represent critical operator functions, subject matter experts familiar with plant operations should be asked to provide ordered task listings for further analysis. The process involves a table-top review of the tasks to establish information and
36、 control requirements and other relevant characteristics of task performance. Table 1 lists types of task data that can be analyzed during this process to support human machine interface design. Depending on the application, additional task analyses are also suggested. The designer is encouraged to
37、see DOD-HDBK-763 and Kirwan and Answorth (1992) for further information on the supplementary methods. Table 1 Task analysis data field for human factors engineering design applications Behavioral Requirements (Knowledge, Action, and Decision) Task Significance (Importance, Frequency, Time Criticalit
38、y) Error Potential and Consequences Instrumentation and Information Requirements Including I/O Number Job Aids/Communications Requirements Related System and Function Figure 2 provides an example of a fairly simple task worksheet, useful in the analysis of a unit start-up scenario. The particular ta
39、sk analyzed in this case involves starting the main unit turning gear motor. Recorded on the worksheet are the necessary cues to initiate the activity (if applicable), the associated plant system, and which controls and information feedback are required. Also indicated is a rating (using a 3 point s
40、cale in which 1 is least critical and 3 is most critical) of task importance and time criticality in performing the task. Task analysis data as described should be used during conceptual design to suggest which control stations need to be frequently and rapidly accessed, what feedback is required wh
41、en a particular action is taken, and how much and what type of communication is necessary during various plant operating modes. For a DCS control room upgrade, task analysis data at this level may suggest what special function keys (quick-select) ISA-RP77.60.05-2001 (R2012) Copyright 2012 ISA. All r
42、ights reserved. 14 are required for rapid control access. If a multi-unit control room is being upgraded, then equipment common to all units will also be identified and analyzed in an operational context. TASK Page _ of _ No. Task Cue Systems Controls Information I* TC* 5 Start the main unit turning
43、 gear motor _ Main turbine Main turbine Turning gear control Main turbine turning gear motor amps. 3 2 Turning gear status lights (slow-fast-auto engaged) or RPMs 3 2 *I = rating; TC = time criticality NOTE Adapted from presentation by Schroeder and Stultz: “Incorporating Human Factors Principles in
44、 Distributed Controls Upgrades,“ 31st Power Instrumentation Symposium, May 23-25, 1988. Figure 2 Example task analysis worksheet 7 Application of task analysis during preliminary design During the preliminary design of a workstation (especially one involving the application of a DCS), decisions must
45、 be made concerning how all displays and control stations should be organized for rapid access and ease of operator learning. In the case of electronic screen displays, it is most common to conceive of displays organized in a top-down hierarchical fashion, expressing major plant systems, subsystems,
46、 and components. Other organizational schemes relying on plant mode (e.g. start-up display, plant overview during normal operations, specific display for upset conditions) or plant function can also be envisioned. In any case, task analysis data will assist the designer in identifying the associatio
47、ns among required workstation controls and displays and in prioritizing instrumentation for ease of access. 7.1 Identifying electronic screen and other display requirements Task analysis is recognized as being important to computer-generated display development (EPRI NP-3701). During preliminary sys
48、tem design, information requirements for displays can be established. At this time, however, the specific format and characteristics of the displays are not yet identified. Listed below is the type of data typically collected for each proposed display in documenting initial display requirements. a)
49、Display number b) Title c) Display type d) Applications e) Contents ISA-RP77.60.05-2001 (R2012) Copyright 2012 ISA. All rights reserved. 15 f) Special features g) Access modes/links A complete set of display outline sheets provides information on the numbers, types, and inter- relationships among proposed displays for the new system. It serves as the foundation for subsequent screen prototyping. 7.2 Evaluating design options using task analysis data A number of system design opt
