Rockwell Automation AADvance Controller Safety Manual - Manual (Page 26)

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2-2 Document: 553630
ICSTT-RM446K-EN-P Issue: 10 _C
Safety Manual (AADvance Controller)
The Safety Life-cycle
The safety life-cycle is defined by the IEC 61508 standard. It is designed to
structure a system's development into defined stages and activities as
follows:
 Scope definition
 Hazard and risk analysis
 Functional and safety requirements specification
 System engineering
 Application programming
 System production
 System integration
 System installation and commissioning
 Safety system validation
 Operation and maintenance plan
 System modification
 Decommissioning
The definition of each life-cycle stage shall include its inputs, outputs and
verification activities. It is not necessary to have separate stages within the
lifecycle addressing each of these elements independently; but it is
important that all of these stages are covered within the lifecycle. Specific
items that need to be considered for each of these life-cycle elements are
described in the following sub-paragraphs.
Scope Definition
The scope definition is the first step in the system life-cycle. You have to
identify the boundaries of the safety-related system and provide a clear
definition of its interfaces with the process and with all third party
equipment. This stage should also establish the derived requirements
resulting from the intended installation environment, such as
environmental conditions and power sources.
In most cases, the client will provide this information. The system
integrator must review this information and gain a thorough
understanding of the intended application, the bounds of the system to be
provided, and its intended operating conditions.
Hazard and Risk Analysis
The hazard and risk analysis has three objectives:
 The first objective is to determine the hazards and hazardous events
of the controlled system for all reasonably foreseeable circumstances,
including fault conditions and misuse.