Background to BS EN IEC 62061
BS EN IEC 62061:2021 ‘Safety of equipment — Functional protection of safety-related manage systems’ is the 2d version of a key equipment security standard. It cancels and replaces the first version and the two amendments, BS EN IEC 62061:2005+A2:2015, which have been withdrawn. ‘BS’ shows this is a British Standard posted by way of BSI; ‘EN’ shows ratification with the aid of a European requirements agency (CEN, CENELEC, or ETSI). ‘IEC’ suggests it is a worldwide preferred posted through the IEC (International Electrotechnical Commission). The fashionable has been closely revised. This article consequently provides an overview of what has been modified in BS EN IEC 62061:2021.
First of all, the new version is nonetheless a Type-B1 equipment protection standard. It specifies necessities and makes suggestions for the design, integration, and validation of safety-related management structures (SCS) for machines. It offers a methodology and requires customers to:
assign the required protection integrity for every protection characteristic to be applied with the aid of the SCS (known as Safety Integrity Levels, or SILs);
enable the layout of the SCS excellent to the assigned protection (control) function(s); and
integrate safety-related subsystems designed in accordance with different relevant practical safety-related standards.
Anyone acquainted with the preceding version will be aware that ‘SCS’ has changed ‘SRECS’ (safety-associated electrical manipulation system). This is due to the fact the general is no longer confined to electrical, digital, and programmable digital systems.
Note that IEC 62061 is the laptop quarter particularly trendy inside the framework of core purposeful security widespread IEC 61508.
Why revise BS EN IEC 62061?
There are two worldwide purposeful protection requirements relevant to machinery, IEC 62061 and ISO 13849. For quite a few years a Joint Working Group of ISO/TC 199 and IEC/TC forty-four had been working to align the two. The closing intention was once to merge them into a single practical security fashionable IEC/ISO 17305. However, even though the two requirements have many similarities, there are additionally great differences. Consequently, an entire merger is not going to show up any time quickly – and perhaps now not at all. Nevertheless, one of the consequences of this task was once an acknowledgment that some matters in ISO 13849 have been better. This is what lies at the back of some of the modifications brought in the 2021 version of BS EN IEC 62061.
The security of manipulating structures has been a trouble for a lengthy time. But industrial structures these days are some distance extra linked than they have been in 2005. It has consequently turned out to be quintessential to consist of protection inside the standard. A safety breach may want to have an effect on safety, whether or not the breach is due to human error or a malicious act.
Other adjustments in IEC 62061 deliver it up to date, introduce upgrades and dispose of areas that had been open to interpretation. The committee that developed the general believes the new version is clearer, greater undemanding, and higher overall.
Is BS EN IEC 62061:2021 a distinctive or harmonized standard?
At the time of writing (March 2022) the 2021 version used to be no longer distinct for UKCA marking to The grant of equipment security policies (SMSR) for putting on the market in Great Britain (GB). Nor used to be it harmonized for CE marking to the European Machinery Directive. (See right here to analyze the variations between UKCA marking and CE marking). However, EN IEC 62061:2021 is in the listing of revised EU Machinery Directive harmonized requirements posted in April 2022. Given that the preceding version of EN IEC 62061 was once certain for the SMSR, it is a secure wager that the 2021 version will be.
When compiling a Declaration of Conformity (DoC) for equipment or protection components, you have to list the designated/harmonized requirements that had been complied with so as to advantage of the presumption of conformity. As there is a transitional length till eleven October 2023, you can presently work on both versions for CE marking. But be positive to quote the proper one on the DoC.
Similarly, if you are the use of BS EN IEC 62061 for CE marking a partly done machine, then you can work on both versions and refer to the one you have used when drawing up the Declaration of Incorporation (DoI).
If you are UKCA marking to the SMSR, you may want to work to BS EN IEC 62061:2021 and quote it on the DoC/DoI. This version of the popular is an extra consultant of the country of the art.
Remember there is no criminal requirement to comply with standards. However, complying with designated/harmonised standards is the best way to fulfil the crucial fitness and security requirements (EHSRs) of the legislation/regulations. There is a prison duty to meet the EHSRs.
What are the foremost modifications in the 2021 version of BS EN IEC 62061?
BS EN IEC 62061:2021 is a predominant transformation of the standard, no longer purely an assortment of minor updates and additions. This article cannot, therefore, exist a clause-by-clause evaluation of the changes.
First of all, the title has changed. It is now ‘Safety of equipment — Functional security of safety-related manage systems. Previously it used to be ‘Safety of machinery. Functional protection of safety-related electrical, digital and programmable digital management systems. These tips at one of the most necessary changes. The popular now covers all applied sciences used for safety-related management systems, now not simply electrical, digital and programmable digital systems. For example, hydraulic and pneumatic safety-related manipulate structures can now comply with BS EN IEC 62061.
The 2021 version accommodates a wide variety of massive technological changes. The ‘Tracked Changes’ model of the trendy suggests all the deletions and additions. However, there are so many modifications that it can be tough to see what is going on. Fortunately, the Foreword consists of a precis of what has been modified in BS EN IEC 62061:2021.
As stated already, the revised preferred now consists of non-electrical/electronic/programmable digital safety-related management systems. In addition, there are revisions to the shape and updates to the contents to replicate the security feature sketch process. There are new references to security, necessities for testing, and for impartial verification and validation of software.
Other modifications encompass up-to-date definitions and normative references, improved necessities concerning software-based parameterization, upgrades and clarifications on architectures and reliability calculations, a shift from ‘SILCL’ (SIL Claim Limit) to ‘maximum SIL’ for subsystems, and some reorganization of clauses and subclauses to create a greater logical flow.
New annexes
Although the annexes are on the whole informative, and no longer normative, they comprise a wealth of beneficial information, education, and examples. The annexes in BS EN IEC 62061:2021 are ways extra widespread than in the preceding edition.
New informative annexes exhibit examples of security features and MTTFD (mean time to hazardous failure) values, diagnostic coverage, security features, and structure calculation methods. Other new annexes cowl the following: recommendations for software; simplified processes for evaluating the PFH price of a subsystem; the practical security format and format activities; and education on the stage of independence wanted for opinions and testing/verification/validation activities. After the annexes, the 2021 version has advantages from a new Bibliography.
Miscellaneous specific changes
Aside from the huge modifications referred to above, right here are some miscellaneous unique points.
Definition 3.2.27, excessive demand mode – this is now described as a ‘mode of operation in which the frequency of needs of a protected characteristic is increased than one per year. Previously, ‘high demand or non-stop mode’ shared a definition.
Definition 3.2.28, non-stop mode – this is now described as ‘mode of operation the place the protection characteristic retains the equipment in a secure nation as a phase of regular operation’. Continuous and excessive demand modes are now described one by one due to the fact this is applicable for the qualification of diagnostic measures, however, it is now not applicable for goal failure measures and SIL assignment.
Definition 3.2.29, common frequency of a hazardous failure per hour – this has been renumbered from 3.2.28, and the terminology in the past used to be ‘probability of hazardous failure per hour. Despite the title change, the acronym PFHD is retained.
Clause 4, Design system of an SCS and administration of practical security – this clause was once in the past titled ‘Management of purposeful safety’. It has been completely revised. There is a greater emphasis on the technique to be accompanied and they want to work from an ISO 12100 danger assessment.
Subclause 7.3.3.4, Functional checking out to discover fault accumulation and undetected faults – this new subclause refers to redundant structures in which an accumulation of faults over time may lead to the loss of the security function. The trend now states that when a purposeful take look is crucial to realize a feasible accumulation of faults or an undetected fault, it shall be made at least each and every month for SIL three and at least every 12 months for SIL 2.
Subclause 7.3.4.2, Relationship of applicable parameters – this new subclause gives a technique for calculating MTTFD for elements through the use of B10D values. This is beneficial due to the fact reliability information for fluid power, mechanical and electromechanical elements is regularly supplied as B10D values.
Clause 8, Software – this new clause introduces special stages of software. Then, one after the other for Level 1 and Level 2, there are subclauses covering, for example, the software program security lifecycle, software program design, module design, coding, testing, documentation, and configuration, and change management. Additional hints for the Level 1 software programs are furnished in the (informative) Annex F. Examples of Level 1 software programs are a protection PLC with constrained variability language (LVL) or a programmable security relay. An instance of a Level two software program is a protection PLC with full variability language (FVL). Level three utility software program – such as a protection PLC with LVL or FVL – complies with IEC 61508-3 and is now not blanketed by using IEC 62061:2021. Some of the fabric in Clause eight and Annex F used to be blanketed in the preceding version of the well-known (subclauses 6.10, 6.11, and Annex C). However, typically the fabric referring to the software program has been redrafted.
Clause 9, Validation – this is now not a new clause but, whereas it prolonged to about one web page in the preceding version of IEC 62061 (then numbered Clause 8), it now runs to about ten pages due to the giant reworking. Subclause 9.1 (Validation principles) consists of a new requirement that ‘Validation shall be carried out by way of humans who are impartial from the diagram of the SCS’. But a word says the use of an ‘independent person does no longer always suggest a third-party check is required. Further training is furnished in Annex J (informative), Independence for critiques and testing/verification/validation activities.
Annex A, Determination of required security integrity – this annex indicates a modified way to decide the required SIL. In addition, Table A.6, the Matrix project for identifying the required SIL for a security function, now additionally suggests required Performance Levels (PLr) alongside every required SIL. A new be aware states: ‘SIL two at Class three and four in the preceding posted version is now decreased to SIL 1 due to the fact of the low rating for the training of Frequency, Probability and Avoiding Harm.’
Conclusion
Despite all the tough work that has long gone into enhancing BS EN IEC 62061, many laptop builders and gadget integrators will conclude that the different purposeful security standard, BS EN ISO 13849, nevertheless meets their desires and they will now not favor using BS EN 62061:2021. However, some will have used the preceding version of BS EN IEC 62061 for electrical, digital, and programmable digital safety-related management structures and will be delighted that they can now follow the equal preferred to hydraulic and pneumatic systems.
If you have been the use of BS EN IEC 62061:2005, then migrating to the 2021 version needs to now not be too onerous. A device designed and constructed to the preceding version is possible to comply – or almost comply – with the 2021 edition. The tactics and documentation may additionally want updating however the closing manage gadget may additionally nicely be fine.
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