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What Is IEC 61508?

Safety-critical industries, like automotive, avionics, and manufacturing, for example, rely on a myriad of systems and equipment that are all incredibly complex. Although it is generally agreed that being completely risk-free is impossible, manufacturers of safety-critical products are always looking to reduce risks and create fail-safes so that the odds of something going wrong are kept as low as humanly possible. This is why industry experts developed standards like the IEC 61508 to reduce the risks involved in developing safety-critical products. Read on to learn more about this standard, its background and content, and how to best meet its requirements to ensure safe end products and a swift go-to-market process!

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Background of IEC 61508

Every time elevator doors don’t close on you while you’re coming in or out, or a smoke detector goes off, or an electronic device shuts down to avoid overheating, you are benefiting from the systems which ensure functional safety. 

Functional safety as a concept emerged in the 1980s as a result of major global accidents and the increasing use of programmable electric systems (PES). Manufacturers and industry experts in the International Electrotechnical Committee Advisory Committee of Safety (IEC ACOS) established a team to address concerns regarding functional safety and come up with a standardized way to ensure lower levels of risk. 

As a result, the IEC 61508 was developed, which unlike its more prescriptive predecessors, is a performance-based standard with an emphasis on safety lifecycles, measurable risk reduction, and practical guidelines that can be put into use.

So what exactly is IEC 61508?

IEC 61508’s full name is the Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems (E/E/PE, or E/E/PES)). It is a basic functional safety standard which, interestingly, applies to all industries (there are other, industry-specific standards that are based on it). IEC 61508 is internationally recognized and provides practical guidelines to manufacturers in general as well as developers of safety-critical products. Basically, it defines the functional safety requirements for electrical, electronic, and programmable electronic safety-related systems.

Functional Safety refers to the safety system which aims to reduce risks as much as possible. It is achieved when every safety function works properly and the risks involved are reduced to the appropriate level. IEC 61508 defines functional safety as: “part of the overall safety relating to the EUC (Equipment Under Control) and the EUC control system which depends on the correct functioning of the E/E/PE safety-related systems, other technology safety-related systems and external risk reduction facilities.”

What is the purpose of IEC 61508?

The purpose of IEC 61508 is to help manufacturers across a variety of industries ensure that any safety-related system will actually work, and as a result, reduce risk as much as possible. That is what IEC 61508’s safety lifecycles serve: mitigating risks by either reducing the likelihood that they will happen, or the severity of the consequences if you can’t avoid the risk coming to pass.

IEC 61508 is based on two fundamental principles:

  • The use of safety lifecycles that provide best practices regarding discovering risks and eliminating design errors.
  • A probabilistic failure approach, meaning that the assumption is devices will fail, so there always needs to be a fail-safe in place.

Contents of IEC 61508

IEC 61508 details a lifecycle with 16 phases in 7 parts:

  1. Parts 1–3 contain standard requirements
  2. Part 4 contains definitions
  3. Parts 5–7 contain guidelines and relevant development examples 

Here is an overview of the 7 parts detailing the requirements, guidelines, and examples to achieving compliance with IEC 61508:

  • IECTR 61508-0, Functional safety and IEC 61508
  • IEC 61508-1, General requirements
  • IEC 61508-2, Requirements for E/E/PE safety-related systems
  • IEC 61508-3, Software requirements
  • IEC 61508-4, Definitions and abbreviations
  • IEC 61508-5, Examples and methods for the determination of safety integrity levels
  • IEC 61508-6, Guidelines on the application of IEC 61508-2 and IEC 61508-3
  • IEC 61508-7, Overview of techniques and measures

Advantages of complying with IEC 61508

We know, another day in product development, yet another standard to comply with – however, it really does pay off. There are many advantages to ensuring functional safety with IEC 61508 so we put a list of a few examples together to show you that it’s worth the effort:

  • Human safety: whether it’s a civilian, employee, or equipment operator, the most important thing is to make sure they are safe using the product.
  • Environmental protection: many of these safeguards also make sure that nothing happens to our environment as a result of the products we develop.
  • Regulatory compliance: if any accidents do occur, auditors will check to make sure how compliant you are, and if you are found lacking there can be severe consequences, both financially and to your brand reputation.
  • Competitive edge: for many projects, being compliant with certain standards is a prerequisite for contractors who want to win bids, so if you can demonstrate compliance you’re already a step ahead of competitors.
  • Cost-cutting: being compliant with IEC 61508 and achieving a high level of functional safety also means going to market faster, spending less money on correcting errors, and lower insurance policy costs to boot.

In addition to all this, a range of different industry-specific standards is actually derived from IEC 61508, making it a universal standard.

IEC 61508 and risk

Hazardous risk management is central to IEC 61508 as a standard. Each safety function comes with concepts of probabilistic risk which determine how likely those threats are. Then the risk is reduced to what is considered a tolerable level by applying the appropriate best practices or safety functions.

IEC 61508 states the following principles about risks:

  • Zero risk is not possible; it’s only the probability that can be lowered
  • Non-tolerable risks must be reduced as much as possible 
  • The highest level of functional safety is achieved when it is maintained throughout the safety lifecycle.

What are Safety Integrity Levels (SILs)?

Safety Integrity Levels, or SILs as they are commonly referred to, are a way to measure the performance of safety systems. There are four different SIL levels: SIL 1, SIL 2, SIL 3, SIL 4. Basically, the higher the SIL level, the higher the safety level which is being ensured and the lower the probability is that a system will fail. Different industries and different products have varying requirements where SIL levels are concerned. Also, as the SIL level gets higher, the production and maintenance cost, as well as the system complexity, tends to increase in tandem.

IEC 61508 compliance

When it comes to complying with complex standards and developing even more complex systems safely, following carefully constructed workflows and meticulous documentation can make all the difference. That’s where using the right tools can help.

Intland Software’s codebeamer is a highly adaptable and configurable enterprise Application Lifecycle Management platform that takes the guesswork out of your IEC 61508 compliance journey. A smart, integrated, and cross-functional platform, codebeamer coordinates and manages all activities and artifacts associated with developing software and helps you streamline your development processes and cut costs in no time.

Interested in learning more? Check out our guide to find out exactly how codebeamer can support your IEC 61508 compliance efforts:

Managing Functional Safety & IEC 61508 Compliance with codebeamer

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