March 15, 2013 by Kristina Urquhart
All of us are aware of the amount of data available from modern control systems, their field devices and the algorithms used to infer additional information from that data. The challenge is managing and understanding that data by converting it first into information that we as humans can understand, and then into knowledge upon which we can take appropriate actions.
We have learned a lot about how to display data since the introduction of the DCS and computer displays in the 1970s, when the display was a colour version of the Piping & Instrumentation Diagram (P&ID) with key process values shown numerically and electronic versions of strip charts to allow operators to observe process trends. We then “progressed” to Windows-based HMIs with even more distractions of spinning pump impellers, fluidized beds and all the wizardry of computer gaming at that time. Fortunately, research has shown simplicity and low-key use of colour is better, with this information being codified in the work of two ISA standards committees: ISA18—Instrument Signals and Alarms and ISA101—Human Machine Interfaces.
From its purpose and scope on the ISA web site, the ISA18 committee “develops standards, technical reports and guidelines for alarm systems including annunciators, process automation systems and the general development, design, installation and management of alarm systems in the process industries. They do so by establishing terminology and practices for alarm systems, including the definition, design, installation, operation, maintenance and modification and work processes recommended to effectively maintain an alarm system over time.”
In addition to updating the 2004 revision of the ISA18.1 standard on ‘Annunciator Sequences and Specifications,’ it is focused on the development of a series of technical reports on ‘Management of Alarm Systems for the Process Industries’ as part of the ISA18.02 standard set.
Each of the six working groups are developing reports as follows:
• WG1—Alarm Philosophy: Provides guidance for successful management of the alarm system. The resulting work will cover the definitions, principles and activities by providing overall guidance on methods for alarm identification, rationalization, classification, prioritization, monitoring, management of change and audit.
• WG2—Alarm Identification and Rationalization: Addresses the processes to determine the possible need for an alarm or a change to an alarm, systematically compare alarms to the alarm philosophy and determine the alarm setpoint, consequence, operator action, priority and class. To accomplish this work, the resulting outputs will address the identification, justification, prioritization, classification and associated required documentation for the creation and maintenance of individual alarms and associated support systems.
• WG3—Basic Alarm Design: Covers the selection of alarm attributes such as types of alarms, deadbands and delay times. Because each control system has different capabilities with respect to alarms, the resulting implementation of this work may be specific to each control system.
• WG4—Enhanced and Advanced Alarm Methods: Will provide guidance on additional logic, programming, or modeling used to modify alarm behaviour. The resulting tools to support advanced alarm methods will likely include dynamic alarming, state-based alarming, adaptive alarms, logic-based alarming, predictive alarming, as well as a number of approaches to logically implement designed suppression of redundant and condition-based alarms.
• WG5—Alarm Monitoring, Assessment and Audit: Focuses on monitoring, assessment and audit for the continuous monitoring, periodic performance assessment and recurring audit of the alarm system to keep system and operator performance from deteriorating over time. Fortunately, many modern alarm systems contain the tools to assist in this activity already.
• WG6—Alarm Design for Batch and Discrete Processes: Providing guidance on the application of alarm design of batch and discrete processes.
Similar to ISA18, the ISA101 committee’s purpose and scope are to establish standards, recommended practices and/or technical reports pertaining to human-machine interfaces in all manufacturing industry applications.
The areas covered within ISA101’s work will include: menu hierarchies, screen navigation conventions, graphics and colour conventions, dynamic elements, alarming conventions, security methods and electronic signature attributes, interfaces with background programming and historical databases, popup conventions, help screens and methods used to work with alarms, program object interfaces and configuration interfaces to databases, servers and networks.
As you can see from the above there is significant activity underway to ensure that we will be able to properly manage the plethora of data available in today’s control systems. The one thing that modern HMI and operator interfaces, both in the control room and on smaller devices, are doing is helping us to make informed decisions faster, less stressfully and with less chance for error.
This article originally appeared in the March/April 2013 issue of Manufacturing AUTOMATION.