Functional Safety
When the functionality of an element within a system can compromise its safety, primary safety is no longer enough, its functional safety must be guaranteed.
The rapid technological development has led to an exponential increase in the use of automated systems within the production processes, which are responsible for ensuring the safety and reliability of machinery and systems.
NORMATIVE REQUIREMENTS
The topics covered by the family of standards IEC 61508 – Functional safety of electrical/electronic/programmable electronic safety systems and by those related to them (ISO 13849s, ISO 16232s, IEC 62061, IEC 61800-5-2, IEC 61496s, EN 50495 , etc.), constitute the state of the art and the regulatory reference for the design and management of safety systems in plants, with particular attention to electrical, electronic and programmable electronic systems; they are widely used in various industrial sectors such as chemical, petrochemical, refining, nuclear, transport, electro-medical, industrial automation and automotive.
The 2006/42/EC Machinery Directive requires that the safety-related parts of the control system be designed and constructed in such a way as to ensure that any faults in the machine control logic do not cause dangerous events. The aim is therefore to determine the Performance Level (PL) achieved, based on the parameters of the chain of command and in particular the Diagnostic Coverage (DC) and the Mean Time To Dangerous Failure (MTTFD) or B10D for electromechanical/mechanical components.
The purpose of these standards is to determine the Performance Level (PL) or the Safety Integrity Level (SIL) achieved, based on the system architecture and the reliability of the components.
HOW ECO NEXT WORKS
The verification – by ECO Next – of the safety-related parts of the control system is a voluntary modular service structured in phases that was created to accompany machine manufacturers in defining the safety functions and deriving from the risk analysis of the machine, to then move on to the definition of the functional diagrams (Functional Block Diagram, FBD and Reliability Block Diagram, RBD), up to the evaluation of the functional safety parameters required and the relative level of reliability (SIL/PL required), finally verifying the correct design through the evaluation of the reliability parameters analyzed (SIL/PL verification), including the drafting of the related manual sections (Manuals for Safety Loops).
PROCESS INDUSTRY – SAFETY INTEGRITY LEVEL (SIL)
Activities for the design, definition and verification phases of the “Safety Integrity Level”:
- Analysis of the machine for the identification of the safety functions
- Evaluation and analysis of the SIL required based on risk identification
- Design of safety functions
- Functional and Reliability Block Diagrams (FBD, RBD)
- Support for machine software design
- Verification of the Safety Integrity Level of the safety functions according to IEC 61508, IEC 61511
- Validation and Tests in Use of safety functions
- Tool Used: EXIDA EX-SILENTIA SOFTWARE IEC 61508, IEC 61511
PERFORMANCE LEVELS (PL)
Activities for the design, definition and verification phases of the “Performance Level”:
- Analysis of the machine for the identification of the safety functions
- Evaluation and analysis of the Performance Level required based on the identification of the risks
- Design of safety functions
- Functional and Reliability Block Diagrams (FBD, RBD)
- Support for machine software design
- Verification of the Performance Level of the safety functions according to ISO 13849
- Validation and Tests in Use of safety functions
- Tool used: IFA SYSTEM SOFTWARE ISO 13849
REFERENCE STANDARDS BY SECTOR
Functional Safety in Industrial Automation
- ISO 13849-1: Safety-related parts of control systems – Part 1: General principles for design
- ISO 13849-2: Safety-related parts of control systems – Part 2: Validation
- IEC 62061: Functional safety of safety-related electrical, electronic and programmable electronic control systems
- IEC 61496s: Electrosensitive protective equipment
- IEC 61800-5-2: Adjustable speed electrical power drive systems – Part 5-2: Safety requirements – Functional
- ISO 15998: Earth-moving machinery – Machine-control systems (MCS) using electronic components -Performance criteria and tests for functional safety
- ISO 22201s: Lifts (elevators) – Programmable electronic systems in safety-related applications
- ISO 25119s: Tractors and machinery for agriculture and forestry – Safety-related parts of control systems
Functional Safety in the Process Industry
- IEC61508s: Functional safety of electrical/electronic/programmable electronic safety-related systems
- IEC61511s: Functional safety – Safety instrumented systems for the process industry sector
- IEC 60079-29-3: Explosive atmospheres – Part 29-3: Gas detectors – Guidance on functional safety of fixed gas detection systems
Functional safety in explosion risk
- EN 15233: methodology for evaluating the functional safety of autonomous protection systems
- ISO 80079-37: Explosive atmospheres – Part 37: Non-electrical equipment for explosive atmospheres
- EN 50495: Safety devices required for the safe functioning of equipment with respect to explosion risks
- EN 50402: electrical equipment for the detection and measurement of combustible or toxic gases or vapours, or of oxygen
Functional Safety in the Aerospace sector
- US RTCA DO-178B: North American Avionics Software
- US RTCA DO-254: North American Avionics Hardware
- EUROCAE ED-12B: European Airborne Flight Safety Systems
Functional safety in the automotive sector
- ISO 26262s: Road vehicles – Functional safety
Functional Safety in the Rail sector
- EN 50126 (IEC 62278): RAMS (Railway applications – Specification and demonstration of reliability, availability, maintainability and safety)
- EN 50128 (IEC 62279): Telecommunications, signaling and processing – software for control and protection systems
- EN 50129 (IEC 62425): electronic safety systems for signalling
Functional safety in the medical sector
- IEC 60601-1: Medical electrical equipment – Part 1: General requirements for basic safety and essential performance
Functional safety of automatic electrical control devices
- IEC 60730s: Automatic electrical controls for household and similar use