IEC 61508-6:2010

Overview

IEC 61508-6:2010 is a critical international standard published by the International Electrotechnical Commission (IEC) that addresses the functional safety of electrical, electronic, and programmable electronic (E/E/PE) safety-related systems. As Part 6 of the IEC 61508 series, this standard provides comprehensive guidelines on the practical application of IEC 61508-2 and IEC 61508-3, which focus on hardware and software requirements respectively. The second edition of IEC 61508-6 represents a technical revision with enhanced explanations and updates, aiming to support engineers and safety professionals in implementing effective safety systems.

Key Topics

IEC 61508-6:2010 covers several vital aspects of functional safety related to E/E/PE systems:

• Application Guidelines for IEC 61508-2 and IEC 61508-3
  Annex A offers an overview of the essential requirements and functional steps in applying the hardware (Part 2) and software (Part 3) standards.

• Hardware Failure Probability Calculations
  Annex B details example techniques for evaluating the probabilities of hardware failure. It provides methods for calculating failure rates, taking into account diverse system configurations like 1oo1, 1oo2, and 2oo3 architectures, essential for reliability and safety assessments.

• Diagnostic Coverage and Safe Failure Fraction
  Annex C presents worked examples illustrating how to calculate diagnostic coverage and safe failure fractions, crucial metrics to measure how effectively failures are detected and managed.

• Common Cause Failures Methodology
  Annex D explains methods to quantify the impact of hardware-related common cause failures (CCF), which are key to understanding correlated failures in redundant systems.

• Software Safety Integrity Applications
  Annex E showcases practical examples applying software safety integrity level tables from IEC 61508-3, illustrating how to meet SIL 2 and SIL 3 requirements.

• Updated Technical Revisions
  Incorporates significant adjustments and clarifications from the previous 1998 edition to enhance usability and align with the evolving functional safety ecosystem.

Applications

IEC 61508-6:2010 is applicable in diverse industries where functional safety and reliability of electronic safety-related systems are paramount, including:

• Industrial Automation and Control Systems
  Ensuring machinery and process control systems operate safely under programmable electronic controls.

• Smart Grid Technologies
  Supporting reliable and safe operation of smart electrical grids by managing safety integrity levels and failure probabilities of protection devices.

• Automotive and Transportation Systems
  Enhancing safety features implemented via embedded electronic systems controlling brakes, steering, and collision avoidance.

• Railway Signaling and Control
  Assuring fail-safe design and operation of electronic signaling systems.

• Process Industries (Chemical, Oil & Gas, Pharmaceuticals)
  Safeguarding against hazardous failures in critical control and safety instrumented systems (SIS).

Professionals use the guidelines to:

• Conduct detailed safety integrity assessments
• Calculate hardware and software failure probabilities
• Model diagnostic capabilities and manage common cause failures
• Design and validate functional safety to achieve required SIL levels

Related Standards

IEC 61508-6 integrates closely with and extends the following standards in the IEC 61508 series and beyond:

• IEC 61508-1: Framework, definitions, and general requirements for functional safety
• IEC 61508-2: Hardware requirements for safety-related systems
• IEC 61508-3: Software requirements for safety-related systems
• IEC 61508-4 to IEC 61508-7: Additional parts covering supporting processes and sector-specific applications
• Industry-specific functional safety standards such as IEC 62061 (machinery safety), IEC 61511 (process industry) and IEC 61850 (power utility communications including Smart Grid)

Utilizing IEC 61508-6 enables organizations to effectively interpret and apply hardware and software safety requirements, ensuring compliance and promoting reliable system design in accordance with the global functional safety best practices.

This guideline-rich standard is essential for engineers and safety managers aiming to optimize safety-related system design, verification, and validation, supporting safer operation of programmable electronic systems in critical industrial applications worldwide.