Safety Integrity Level Explained How To Determine The

Here, we explain what is IEC 61508 and provide safety integrity level (SIL) basics including what is SIL and how to determine the SIL level.

Read along or jump ahead to the section that interests you the most: What Is IEC 61508 IEC 61508 Overview What Are Safety Inte grity Level (SIL) Basics Guide to IEC 61508 Software Compliance What Is IEC 61508 IEC 61508 is an international functional safety standard and it provides a framework for safety lifecycle activities.

Titled Functional Safety of ElectricalElectronicProgrammable Electronic Safety-related Systems (EEPE, or EEPES), 61508 is the umbrella functional safety standard and the source for industry-specific standards.

Safety Integrity Level Explained Software Development Teams

Here, we give an overview of the safety standard and Safety Integrity Level (SIL) basics plus compliance tips for software development teams.

IEC 61508 Overview Functional safety is important in every industry.

IEC 61508 Scope The standard covers safety-related systems that incorporate electrical electronic programmable electronic devices.

The standard specifically covers hazards that occur when safety functions fail.

And the main goal of the safety standard is to reduce the risk of failure to a tolerable level.

What are the 8 Parts of IEC 61508 The eight parts of the standard: Part 0: Functional safety as it relates to the standard.

Part 2: Requirements for EEPE safety-related systems.

Part 3: Software requirements.

Part 5: Examples of methods for the determination of safety integrity levels.

The rest spell out the guidelines and provide examples for development.

What Are IEC 61508 Certification for Tools The certification for development tools is optional.

Although, it does provide peace of mind, and it makes tool qualification easier.

Ideally, all tools used in safety-critical product development would be certified against the safety standard.

You should look for tools, like Helix QAC, that have been certified by an independent organization such as SGS-TV Saar, for use in the development of safety-critical systems.

Related Functional Safety Standards There are several industry-specific adaptations of the safety standard: ISO 26262 for automotive electricelectronic systems.

EN 50128 for railway applications.

Related Resource: Guide to Functional Safety What Are Safety Integrity Level (SIL) Basics The safety standard focuses on functional safety.

And, assigning a Safety Integrity Level (SIL) is an important component of functional safety.

What Is SIL SIL is a relative level of risk reduction provided by a safety function.

They determine the performance required to maintain and achieve safety and the probability of failure.

And the greater the risk of failure, the stricter the safety requirements.

Safety Integrity Level Probability of Failure on Demand Risk Reduction Factor SIL 4 10 5 to 4 100,000 to 10,000 SIL 3 10 4 to 3 10,000 to 1,000 SIL 2 10 3 to 2 1,000 to 100 SIL 1 10 2 to 1 100 to 10 Note that SILs for the safety standard are quite different from ASILs for ISO 26262 and safety levels from other standards.

A hazard analysis identifies all possible hazards created by a product, process, or application.