AS IEC 62682 :2017 pdf download – Management of alarm systems for the process industries.
The philosophy starts with the basic definitions and extends them to operational definitions. The criteria for alarm prioritization and the definition of alarm classes, performance metrics, performance limits and reporting requirements are based on the objectives and principles for alarm systems. The schemes for presentation of alarm indications in the HMI. including use of priorities, are also set in the alarm philosophy, which should be consistent with the overall HMI design. The philosophy specifies the processes used for each of the alarm management lifecycle stages, such as the threshold for the management of change process and the specific requirements for change. The philosophy is maintained to ensure consistent alarm management throughout the lifecycle of the alarm system.
The development of the ASRS is included in the philosophy stage of the lifecycle. The specification can be plant specific, providing details on restrictions or options, and can be the basis for selecting new or modifying existing control systems. The specification typically goes into more detail than the alarm philosophy and may provide specific guidance for system design.
5.2.2.3 Identification (B)
The identification stage is a collection point for potential alarms proposed by any one of several methods for determining if an alarm might be necessary. These methods are defined outside of this standard so the identification stage is represented as a predefined process in the lifecycle. The methods can be formal such as process hazards analysis, safety requirements specifications, recommendations from an incident investigation, good manufacturing practice, environmental permits, P&ID development or operating procedure reviews, Process modifications and operating tests can also generate the need for alarms or modifications. Some alarm changes will be identified from the routine monitoring of alarm system performance. At this stage the need for a new alarm or modifications to an existing alarm has been identified and it is ready to be rationalized.
5.2.2.4 Rationalization (C)
The rationalization stage reconciles the identified need for an alarm or alarm system change with the principles in the alarm philosophy. The steps can be completed in one process or sequentially. The output of rationalization is documentation of the alarm, including any advanced alarm techniques, which can be used to complete the design.
Rationalization is the process of applying the requirements for an alarm and generating the supporting documentation such as the basis for the alarm setpoint, the consequence, and corrective action that can be taken by the operator.
Rationalization includes the prioritization of an alarm based on the method defined in the alarm philosophy. Often priority is based on the consequences of the alarm and the allowable response time.
Rationalization also includes the activity of classification during which an alarm is assigned to one or more classes to designate requirements (e.g., design, testing. training, or reporting requirements). The type of consequences of a rationalized alarm, or other criteria, can be used to separate the alarms into classes as defined in the alarm philosophy.
The rationalization results are documented, typically in the master alarm database (i.e., an approved document or file), which is maintained for the life of the alarm system.
5.2.2.5 Detailed design (D)
In the design stage, the alarm attributes are specified and designed based on the requirements determined by rationalization. There are three areas of design: basic alarm design, HMI design, and design of advanced alarming techniques.
5.2.2.6 Implementation (E) In the implementation stage, the activities necessary to install an alarm or alarm system and bring it to operational status are completed. Implementation of a new alarm or a new alarm system includes the physical and logical installation and functional verification of the system. Since operators are an essential part of the alarm system, operator training is an important activity during implementation. Testing of new alarms is often an implementation requirement. The documentation for training, testing, and commissioning may vary with classification as defined in the alarm philosophy. 5.2.2.7 Operation (F) In the operation stage, the alarm or alarm system is in service and it performs its intended function. Refresher training on both the alarm philosophy and the purpose of each alarm is included in this stage. 5.2.2.8 Maintenance (G) In the maintenance stage, the alarm or alarm system is not operational but is being tested or repaired. Periodic maintenance (e.g., testing of instruments) is necessary to ensure the alarm system functions as designed.