MRL-News 32/06/11 1. It has been some time since we issued a new edition of the MRL News for you.

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1 EC MACHINERY DIRECTIVE MRL-News 32/06/11 1 New information on the subject of:»safety of Machinery and Machine Control Systems«Issue 32/06/11 Dear dear customer, customer, It has been some time since we issued a new edition of the MRL News for you. In the meantime round 1 of this year s tec.nicum on tour! lecture events has taken place; in addition our new technical book Best of MRL-News and other Schmersal/ Elan publications appeared at the start of the year (see Page 4 et seq.). Today we are continuing this with a regular new edition of the MRL News. As well as the abovementioned technical book (and another book by Dr. Alfred Neudörfer; see Page 38), we present a new interpretation document from the Federal Ministry of Labour and Social Affairs (BMAS) on the subject of Assemblies of Machinery and further attempt to provide an explanation of it (see Page 6 et seq.). If you do not do so already, you will also get to know about a few new Type A and B standards (see Page 22 et seq.). In conjunction with this, we invite you to be a guest during round 2 of our tec.nicum on tour! lecture events in autumn this year. The key subjects here will especially be the changes in standards regarding the safety-related requirements placed on functional machinery safety that are in the pipeline (see Page 29 et seq.). Invitation Register now for round 2/2011! (PTO)

2 2 MRL-News 32/06/11 Nevertheless even on this occasion (in this edition of the MRL News) it is not possible to avoid providing more information on EN ISO (see Page 32 et seq.). Last but not least, we let you know about special products and product innovations Page 39. We hope you find this interesting reading. With kind regards, Friedrich Adams K.A. SCHMERSAL Holding GmbH & Co. KG, Wuppertal Head of Schmersal tec.nicum Wettenberg/Wuppertal, 30 June 2011 Published by: Elan Schaltelemente GmbH & Co. KG Im Ostpark Wettenberg/Germany Telephone +49 (0) Fax +49 (0) Internet: info-elan@schmersal.com Editor responsible: Friedrich Adams, c/o K.A. SCHMERSAL Holding GmbH & Co. KG, Möddinghofe 30, Wuppertal/Germany; fadams@schmersal.com Production: flick-werk Werbe-Grafik Heinz Flick, Gladenbach/Germany

3 MRL-News 32/06/11 3 Table of Contents Best of MRL News and other Schmersal/Elan publications... 4 New interpretation document... 6 Will we now have a break from more changes to laws or standards? Try to make the best of it! Replacement of EN 954-1:1996 New requirements relating to the safety-related parts of control systems...32 Book discussion: 4th edition of Neudörfer: Designing safety-related products methods and collection of systematic solutions for the EC Machinery Directive published!...38 New from the Schmersal Group: Thinking safety technology Developed for food production Range of control panels is expanded Function modules instead of programming Spring-return joysticks with robust design...48 linked

4 4 MRL-News 32/06/11 Best of MRL-News and other Schmersal-/Elan publications For many years we have been giving you continuous and up-to-date information on what is new in the area of safe machinery and safe machine control systems in our own journal, the MRL-News and other publications, whether this information is of a legal, normative or any other practical nature. Just recently a great deal has taken place in the area of machine safety that both you and we have to contend with, such as the new EC Machinery Directive or the replacement of EN 954-1:1996 and its successor EN ISO :2008 (2006), as well as other revisions to standards and contemporary matters. For this reason we have compiled the most important changes and the current issues in this Best of book. It is divided into the following chapters: 1. Current legal foundations of machinery safety in Europe and elsewhere; 2. New requirements and the configuration of safety-related parts of control systems (replacement of EN and EN ISO :2008/2006, the standard that succeeded it); 3. Other current or new duties and issues concerning machine safety; 4. Technological developments in safety components.

5 MRL-News 32/06/11 5 In the book you will find updated articles from MRL-News and other Schmersal/Elan publications that have been written by well-known external experts and by our own staff. Once again this is intended to give you an overview, an update and, hopefully, many useful suggestions concerning safe machinery that you will find useful in your work. We would be happy to send you this book free of charge. Please use the reply form on Page 50/51.

6 6 MRL-News 32/06/11 For our readers outside Germany: the following refers to interpretations as represented in Germany. They are partly based on official interpretation papers which are also at the disposal of the EU Commission and have been acknowledged by it. However, there may well be other views in other EEA states because the issues discussed in the following also pertain to national law and also permit other interpretations. Further please note: not all of the documents taken following into reference are available in English language! New interpretation document In the case of machinery or parts of machinery designed to interact with each other, the machinery must be designed and constructed in such a way that the stop controls, including the emergency stop control devices, can stop not only the machinery itself but also all related equipment, if its continued operation may be dangerous. If these conditions apply, as formulated in Paragraph of Annex I of the EC Machinery Directive (MD), this concerns a socalled assembly of machinery which requires an additional conformity assessment to be conducted insofar as the assembly concerned has not been supplied as MD-compliant or CE-compliant from a single source from the start. The term assembly of machinery was created by the new MD 2006/42/EC that came into effect starting from and, according to expert opinion, more appropriately replaces the earlier term of interlinked installation (or machinery, as we also frequently called it). But how can these conditions be made more concrete? What are the assessment criteria that produce an assembly of machinery? When is this involved, and when not? This issue is specifically dealt with by a new interpretation document from the Federal Ministry for Labour and Social Affairs (BMAS) and the Länder that has now been published under reference number IIIb (see above) and which supersedes an earlier document on this subject from In view of the new MD and practi-

7 MRL-News 32/06/11 7 cal experience, it has been updated in a working group comprising the BMAS, Federal Institute for Occupational Safety and Health (BAuA), the Ministry of the Environment, Nature Protection and Transport in the Land of Baden-Württemberg in coordination with the market surveillance authorities of the Länder, the German statutory accident insurance (DGUV), individual accident insurance bodies and the German Engineering Federation (VDMA); on 5th May 2011 it was published in the Joint Ministerial Gazette (please google BMAS, Interpretationspapier ʻGesamtheit von Maschinen to download the interpretation document on machinery assemblies. NEW: only two decision-making stages Unlike the earlier interpretation document, in future only two (decision-making) stages are required to find out whether the machinery constitutes an assembly of machinery, with additional conformity assessment where applicable, or whether the conformity assessment of the respective units of machinery is sufficient (possibly with additional consideration of interface see section Additional consideration of interfaces ). According to the flowchart seen in Figure 1, it must first be determined whether there is a so-called production-related connection and, if the answer to this is YES, whether in addition there is a so-called safety-related connection [1]. The production-related connection i.e. stage 1 is characterised by the fact that the machinery or partly completed machinery is arranged as an assembly (whereby it is in particular constructed coherently), interacts and is operated to form a unit directed towards a common objective (e.g. the manufacture of a product). Such a connection exists if the machines or partly completed machinery are linked to each other mechanically or by the control system and where there is a common or overriding control system that is required for the production procedure or where there are common control devices. The common or overriding control system is therefore significant and makes the targeted production-related interaction of a group of machines or partly completed machinery as an assembly possible in the first place. If there is no such production-related connection, then this is not an assembly of machinery within the meaning of the MD, and no EC declaration of conformity takes place for the machine installation as an assembly of machinery, but rather only for the units of machinery. Stage 2 concerns the question of whether safety measures are required for the assembly to prevent hazards caused by machinery or partly completed machinery. This is referred to as a safety-related connection that is characterised, for example, by the fact that the safety of the assembly is guaranteed by a safety control system or by safety components that do not belong to this control system, such as fixed guards.

8 8 MRL-News 32/06/11 Assembly of machinery? 1st stage Production-related connection present? No A special consideration on exclusively e-stop-links you will find on page 12. Yes EC declaration of conformity and CE marking of units of machinery 2nd stage Safety-related connection No Yes Assembly of machinery within the meaning of the MD EC declaration of conformity and CE marking of the assembly of machinery Fig. 1: Decision-making steps assembly of machinery according to the Machinery Directive 2006/42/EC and Machinery Ordinance The risks arising at the interfaces of machinery or partly completed machinery from their interaction must similarly be taken into consideration in the risk assessment for the assembly. The new Guide to the application of the Machinery Directive 2006/42/EC [2] from the European Commission supports this and in 38 points out in particular that the safety of an assembly of machinery depends not only on the safe design and construction of the constituent units, but especially on the suitability of these units when used with each other. Above all the interfaces between them must be examined here. An EC declaration of conformity must be issued for the assembly of machinery (installation) and affixed to the machinery.

9 MRL-News 32/06/11 9 Additional consideration of interfaces Where there is a production connection according to stage 1, but where there is no safety-related connection according to stage 2, the linked machinery may continue to be considered as units of machinery. However the interfaces between the units of machinery must additionally be taken into consideration here. If, according to the result of the risk assessment, the risks arising from the interfaces are also deemed to be low and can be eliminated or reduced to an acceptable level of risk using simple technical, automatic protective measures, e.g. through fixed guards or through incorporation in the safety concept of the units of machinery, the machinery may continue to be considered as units of machinery. End of largely verbatim quote E Risk 4. Certain occurrence 3. Very probable 2. Probable 1. Unlikely 1. Minor injury 2. Reportable accident 3. Permanent personal injury 4. Death S Compulsory technical protective measures required Organisational/simple technical measures ALARP (as low as reasonably possible) No special measures required, possibly instruction, safety-related signs or similar. Risk weighting would also be conceivable to arrive at a suitable assessment in this regard, in which case one could use the following diagram as a guide: Without wishing to offend those involved with the updated interpretation document, one can describe it as upward compatible to the previous document. Whilst it contains an adaptation to the new terms and regulations in MD 2006/42/EC, it itself creates some new terms; however in terms of content and/or formally, it does not make any substantial

10 10 MRL-News 32/06/11 changes, although it does clarify some aspects for consideration and officially specifies some areas which over the years were interpreted between the lines of the earlier interpretation document. Attempt at a practical summary Without any claim to completeness, this framework means that the installation of partly completed machinery will in general always result in a conformity assessment in accordance with MD 2006/42/EC (see 39 of the Guide to application of MD 2006/42/EC [2]); An industrial robot (partly completed machinery) loads and unloads a processing machine (complete machinery) inside a protective fence. the installation of interchangeable equipment (or similar, e.g. the installation of a continuous conveyor) does not generally form an assembly of machinery, but may require the additional consideration of interfaces referred to above and where there is interaction between what are self-contained ( complete ) units of machinery that can or could also be operated separately, the answer depends on the result of a risk assessment. See Page 13 et seq. for the inclusion of existing machinery. The best commonly used method for conducting the risk assessment is based on the question of whether adjacent (production-related linked) machinery can continue to operate without danger for the operator(s) if the machinery is stopped (units of machinery no assembly of machinery) or cannot ( assembly of machinery). One possible example that can be mentioned here is the opening of a guard door of a common fence. In a paper published by BG-Chemie, the former employers liability insurance association for the chemicals industry (which is now the BG RCI), this is also referred to as exporting the risk from one machine to another. The question here is therefore whether when an individual machine or part of machinery is stopped, an operator who is working (or could work) in what is now a non-critical

11 MRL-News 32/06/11 11 danger area can also do this work safely (i.e. without a reaction), bearing in mind the adjacent machinery. The abovementioned Guide to application of MD 2006/42/EC [2] ( 203) expresses this as follows: if continued operation of other elements may give rise to a hazardous situation ( concerns an assembly of machinery). On the other hand (see 38): A group of machines that are connected to each other but where each machine functions independently of the others is not considered as an assembly of machinery in the above sense. The words in the above sense (referring to an assembly of machinery) define that, for a group of units of machinery to be considered as an assembly of machinery, all of the following criteria must be fulfilled: the constituent units are assembled together in order to carry out a common function, for example, the production of a given product; the constituent units are functionally linked in such a way that the operation of each unit directly affects the operation of other units or of the installation as a whole, so that a risk assessment is necessary for the whole installation; the constituent units have a common control system. Documentation of the entire deliberation process is always recommended regardless of which conclusion is arrived at. Declaration of conformity The manufacturer of an assembly of machinery, also the incorporator/assembler [3], must go through the required conformity procedure in accordance with MD Article 5 and affix additional labelling for example on a special sign (including the CE marking). Article 5: Placing on the market and putting into service Before placing machinery on the market and/or putting it into service, the manufacturer or his authorised representative shall: (a) ensure that it satisfies the relevant essential health and safety requirements set out in Annex I; (b) ensure that the technical file referred to in Annex VII, part A is available; (c) provide, in particular, the necessary information, such as instructions; (d) carry out the appropriate procedures for assessing conformity in accordance with Article 12; (e) draw up the EC declaration of conformity in accordance with Annex II, part 1, Section A and ensure that it accompanies the machinery; (f) affix the CE marking in accordance with Article 16.

12 12 MRL-News 32/06/11 Emergency stop links If the decision-making plan set out above is followed, emergency stop control devices do not need to be linked to each other if there is no safety-related connection between the machines. This does not, however, rule out conflicts with occupational health and safety if it is possible for an emergency stop command to be initiated spontaneously ( without involving a great deal of conscious effort ) also by someone who is not familiar with the machinery concerned. This means that whilst such a device may well create the impression of also switching off other machinery or parts of machinery, for example due to spatial layout, it does not necessarily have to be able to do so on the basis of the above considerations. If, as a result of such conflicts, emergency stop control devices are linked to each (other voluntarily so to speak), this commendable undertaking does not mean that an assembly of machinery is suddenly created in the sense of the MD. The interpretation document states this clearly in express terms: If constituent units are exclusively linked by a common emergency stop control device, an assembly of machinery is not created by virtue of this connection alone. Large industrial installations In connection with large industrial installations (iron and steel works, power stations, installations in the chemicals industry), the new document also makes reference to the familiar interpretation that other issues are involved here, i.e. that at best partial MD competences exist. Nevertheless please note! The new interpretation document primarily addresses questions concerning functional machinery safety. However MD 2006/42/EC also now is responsible for electrical hazards (in place of the Low Voltage Directive that was responsible in the past). Light must therefore be shed on risks of this kind during decision-making stages 1 and 2 (see above) and measures taken into consideration where necessary. Furthermore the entire or partial application of other EC directives may also be necessary for aspects that (1) are not dealt with in the Machinery Directive in a comparable or as detailed manner or (2) are not dealt with at all. Examples of (1) are the Pressure

13 MRL-News 32/06/11 13 Equipment Directive and/or the ATEX Directive; examples of (2) are the EMC and/or the Outdoor Directive. It should be pointed out in addition to this that the new interpretation document does not specifically look into the integration of machinery that has already been placed on the market or put into service according to an earlier MD into a new assembly of machinery (the same applies to the incorporation of so-called used machinery constructed before the MD). An attempt to look into this can be found in the section below dealing with existing machinery. Incorporation of existing machinery in an assembly of machinery In practice it is very frequently the case that not only new machinery (= machinery that was placed on the market or put into service for the first time) is incorporated in an assembly of machinery whose safety-related character the EC Machinery Directive (now MD 2006/42/EC) is essentially responsible for. Particularly machinery that has already been put into service and to which the directive on the use of work equipment 2009/104/EC [4] applies must be incorporated where applicable or should remain linked. In order to have a distinction to new machinery following these machines will be called existing machines. In cases such as these the difficult question arises as to how (and according to which rules) the safety-related connection (i.e. the link between the various constituent parts of an installation) should be executed. In this respect the abovementioned Guide to application of MD 2006/42/EC [2] essentially confines itself to the consideration of how new machinery should be integrated into existing assemblies of machinery in an MD-compliant manner. The following (general guidance) is set out on this question below the heading for 39 Assemblies comprising new and existing machinery : 1. If the replacement or the addition of a constituent unit in an existing assembly of machinery does not significantly affect the operation or the safety of the rest of the assembly, the new unit can be considered as machinery subject to the Machinery Directive and, in that case, no action is required according to the Machinery Directive for the parts of the assembly that are not affected by the modification. The employer remains responsible for the safety of the whole assembly according to the national provisions implementing Directive 2009/104/ EC.

14 14 MRL-News 32/06/11 If the new unit is complete machinery that could also operate independently, that bears the CE marking and is accompanied by an EC Declaration of Conformity, the incorporation of the new unit into the existing assembly is to be considered as the installation of the machinery and does not give rise to a new conformity assessment, CE marking or EC Declaration of Conformity. If the new unit is constituted by partly completed machinery accompanied by a Declaration of Incorporation and assembly instructions, the person incorporating the partly completed machinery into the assembly is to be considered as the manufacturer of the new unit. He must therefore assess any risks arising from the interface between the partly completed machinery, other equipment and the assembly of machinery, fulfil any relevant EHSRs that have not been applied by the manufacturer of the partly completed machinery, apply the assembly instructions, draw up an EC Declaration of conformity and affix the CE marking to the new unit as assembled. 2. If the replacement or the addition of new constituent units in an existing assembly of machinery has a substantial impact on the operation or the safety of the assembly as a whole or involves substantial modifications of the assembly, it may be considered that the modification amounts to the constitution of a new assembly of machinery to which the Machinery Directive must be applied. In that case, the whole assembly, including all its constituent units, must comply with the provisions of the Machinery Directive. This may also be required if a new assembly of machinery is constituted from new and secondhand units. In our view [5] this leads to three ambiguous situations: Situation 1 a new assembly of machinery develops within the meaning of Number 2 above: to find out whether this is the case a second ministerial interpretation document containing the established interpretation today may be useful to explain the delineation between modifications and essential modifications [6]. In the most extreme case (with maximum assumable modification/quoted from Alois Hüning, BGHM), according to MD 2006/42/EC the new entity must be reassessed from A to Z and, presumably, subjected to substantial upgrading. Situation 2 below the level of the 1st situation : a potentially necessary safetyrelated link between the constituent units of machinery emerges when considering

15 MRL-News 32/06/11 15 interfaces. Both new machinery and existing machinery are chiefly considered using a black box approach, however the (control system-related) link between the interfaces is established according to the state of the art and the modification relates exclusively to this (to the control system-related link). Everything else remains the same! The essential prerequisite for this, however, is that the existing machinery complies with the valid requirements, i.e. a) that machinery constructed in 1995 et seq. at the latest conforms to the requirements of the EC Machinery Directive that were valid at the respective time they were placed on the market or put into service (and that CE is not only written on the machinery but is also inside it); b) that (even) older machinery (so-called used machinery) complies with minimum safety requirements according to the German Ordinance on Industrial Health and Safety (BetrSichV) Annex I and the accident prevention regulations of the employers liability insurance associations (BG) as of and has been upgraded where necessary [7]. In this respect also see extract from FM-Info No. 1 of the former Mechanical Engineering and Metal BG, Machinery Safety department (now BGHM). Quote: In this largely safe state (even if not all requirements of the relevant internal market directives are satisfied), used machinery can be taken into consideration during the risk assessment that must be conducted for the installation. In this respect refer also to extract from FM-Info No. 1 in the postscript to this article. Situation 3 this concerns the incorporation of partly completed machinery for which either the procedure applied in Situation 1 ( upgrading the machinery resulting from the installation of the partly completed machinery to meet the valid MD level) or Situation 2 (simplified interfaces/black box consideration in exceptional cases) would come into question, depending on the risk assessment. If in doubt it is certainly advisable to consult the relevant employers liability insurance association or market surveillance authority. Declaration of conformity In this sense our understanding would be as follows [5]: 1) An existing assembly of machinery that consists of existing machinery and into which new machinery is integrated (as a replacement and also as an addition) re-

16 16 MRL-News 32/06/11 tains its existing declaration of conformity and the resultant CE marking as long as this does not entail a substantial modification as set out under Situation 1 or Number 2 of the Guide to the application of the Machinery Directive 2006/42/EC [2] (see above). The aforementioned interpretation document [6] and the way it is currently interpreted could serve as the criterion here. In this sense the requirements of the BetrSichV would apply here, as would the two exemption clauses set out in the opening paragraph of Annex I of the BetrSichV in individual cases, despite the fact that a finely dosed application is strongly recommended: With respect to work equipment that has already been put into service, the employer does not need to take the measures pursuant to the basic requirements for new work equipment in order to satisfy the minimum requirements set out below, if a) the employer takes a different, equally effective measure; or b) compliance with the basic requirements would lead to disproportionate hardship in a given case and departure from them is compatible with the protection of staff. 2) Pursuant to MD 2006/42/EC, a newly designed assembly of machinery consisting of existing machinery and new machinery, as well as an assembly exclusively consisting of existing machinery where applicable, does require a new declaration of conformity and a resultant CE marking. In principle, therefore, the existing machinery must be upgraded to MD 2006/42/EC. It might, however, be acceptable to leave the existing machinery as it is if it has been inspected, using an analysis of difference for example, to ascertain that there are no significant safety-relevant differences between the state of the safety-related understanding valid up to that time for the existing machinery, also including its future use, and the current state of safety-related understanding (MD 2006/42/EC). In this case it would be possible to apply Recital (14) at the start of the MD 2006/42/ EC and Number 3 of the General Principles of MD Annex I (simplified: under some circumstances it is not possible to achieve the state of the art). Interim solutions are conceivable, but here too it is advisable if in doubt to get in touch with the responsible employers liability insurance association or market surveillance authority. One could also treat the installation of so-called parts of machinery or machinery that is not ready for use in the same way. Under earlier versions of the MD, these were placed on the market or put into service accompanied by a manufacturer s declaration.

17 MRL-News 32/06/11 17 Extract ( 161) from the Guide to MD 2006/42/EC [2] General Principle 3 (see above) first recalls that the essential health and safety requirements (referred to below as EHSRs), when they are applicable to a given model of machinery (in conjunction with this representation: assembly of machinery), are legally binding. In this respect, it is important (however) to distinguish the EHSRs of Annex I from the specifications of harmonised standards, the application of which is voluntary ; however it is clear from Recital 14 that the notion of the state of the art includes both a technical and an economic aspect. In order to correspond to the state of the art, the technical solutions adopted to fulfil the EHSRs must employ the most effective technical means that are available at the time for a cost which is reasonable taking account of the total cost of the category of machinery concerned and the risk reduction required. Irrespective of this, the control-related connection must be executed in accordance with today s state of the art. Therefore it is possible that an assembly of machinery in accordance with MD 2006/42/EC has CE marking, but that it contains machinery with an earlier CE marking or even used machinery. In this respect also see extract from FM-Info No. 1 of the former Mechanical Engineering and Metal BG, Machinery Safety department (now BGHM) on the incorporation of ʻused machinery (extract in the postscript to this article). 3. Pursuant to MD 2006/42/EC, a declaration of conformity must be conducted for a (complete) unit of machinery that is created through the installation of partly completed machinery unless there are good reasons for an exemption (see above). One of the above statements (depending on applicable) could then be applied to the safety-related interaction with the other machinery parts. Of course it is important to document these deliberations carefully; after all this process is nothing other than a risk assessment. Application of EN ISO :2006 (2008) As the question we are dealing with basically concerns the configuration of safety-related parts of control systems (SRP/CS [8]), where there is a requirement to realise the

18 18 MRL-News 32/06/11 state of the art, these deliberations are then also based on the way of thinking about this subject in today s standard EN ISO :2006 (2008). In particular this means that an SRP/CS comprises subsystems that are found in an assembly of machinery (as a chain), partly in the existing machinery, partly in the new machinery. In their entirety they then make up the safety function (a safety-related connection between the machine parts). The following is divided into [I] for the input level, for example control devices with human protection function (two-hand switches, enabling switches), a protective device (light barrier, light grid, safety mat etc.), signals for position monitoring of an access door in a common fence etc. [L] for the logic level, i.e. the signal processing (also the common control system of an assembly of machinery) etc. and [O] for the actuator level, i.e. contactors, drive control system, fluidics etc. that ultimately account for the hazardous movements. In accordance with EN ISO , the required Performance Level (PL r ) basically always refers to the entire safety function, i.e. from the sensor level [I] to the logic level [L] and through to the actuator level [O]. Accordingly the aim is to configure the common safety function, which may consist of various parts of an existing and a new machine, consistently, i.e. according to the respective PL r. Where MD 2006/42/EC does not apply as a benchmark for an assembly of machinery in its entirety (see Situation 1, which EN ISO would then also apply to from start to finish), but rather Situation 2 (interface or black box consideration), and if for good reasons one does not wish to throw the baby out with the bathwater, then a consideration based on dividing a safety function into so-called subsystems as described in Annex H of EN ISO , would come into question: Case 1: Assumption: [O] level in the existing machinery [I] and [L] level in the NEW parts (new machinery, safety components etc.)

19 MRL-News 32/06/11 19 EN ISO is realised at the [I] and [L] level according to a PL r as would be commensurate with the risk assessment for the active (critical) [O] level in the existing machinery. The actual [O] level in the existing machinery would then be left out, however. Instead of this the risk assessment for it would be conducted in such a way that the solution previously realised for the [O] level is adequate as long it fulfils the CE and MD requirements (see above) at the time of placing on the market/putting into service or the minimum safety requirements in accordance with BetrSichV Annex I and the accident prevention regulations of the employers liability insurance associations as of and has been upgraded where necessary. Case 2: Assumption: [O] level in the new machinery [I] and [L] level in the existing components (machinery and machinery parts with earlier CE marking, used machinery etc.) By contrast, if the existing parts are situated in the [I] and/or [L] level, while the [O] level is realised in the new machinery with familiar PL r, a safety-related upgrade of the [I] and/or [L] level is advisable (because comparatively reasonable) because, in line with the philosophy of EN ISO , the safety integrity is always determined by the weakest links in the chain. For example it would make no sense from a safety point of view to move a safe drive to the stop position using an unsafe control system. However application of EN ISO is preferable. Since, however, it is generally not possible to ascertain a PL for used SRP/CS parts in line with the principle set out in EN ISO , it should be sufficient to apply the consideration to the necessary architecture (to the necessary control category). This simplification is also permitted according to the remark in Section of EN ISO : In some cases, arising from a specific solution or determined by a type C standard, the safety-related capacity of the SRP/CS can only be stipulated using a category without additional PL r. In such special cases the safety is in particular provided by the architecture, and the requirements relating to the MTTF, the DC and the CCF are not applicable. Reference is also made to a publication on the subject of Used machinery: Re-use and Re-invest from the former Metal BG Nord Süd Mainz (now BGHM): If it is not possible to procure data, e.g. on the components for a used industrial robot, it is recommended that the machine control system is ʻinterpreted according to the remark in DIN EN ISO , Section (see above).

20 20 MRL-News 32/06/11 Closing remarks We cannot expect to have dealt with all ambiguous situations arising for an assembly of machinery in the above presentation and deliberations, particularly where both new and existing machinery are involved. We would also have liked to have been able to use more precise formulation in some areas. However our presentation can be viewed as a pointer, indicating how to come closest to achieving the objective of safe machinery bearing in mind the tensions between protecting vested rights, the state of the art and practical feasibility. Postscript Extract from FM-Info No. 1 from the former Mechanical Engineering and Metal BG, Machinery Safety department (now BGHM) on the subject of used machinery It follows from this that in the case of concatenations, integrated used machinery without CE marking must itself only satisfy the basic requirements of the MD and other internal market directives to the extent that this is technically possible and economically reasonable. The safety concept for the installation must be stipulated in such a way that the assembly of machinery complies with all requirements of the MD where possible. Here an attempt must be made to integrate used machinery in a manner that complies with the Directive. This applies in particular to interfaces, operating modes, protective measures for manual interventions and incorporation in a higher-ranking system controller. An example of how to do this is to safeguard an area using partial or complete fencing around the installation. Newly assembled installations into which used machinery has been integrated according to the principles referred to can be labelled in their entirety with CE. Where necessary, it should be possible to see the requirements in relevant directives that used machinery are unable to realise on a supplementary sheet to the EC declaration of conformity that belongs to the installation.

21 MRL-News 32/06/11 21 Concatenation of machinery to production installations Integration of used machinery New and used machinery is frequently concatenated to form one installation. In principle an assembly of machinery of this kind also falls within the scope of the EC Machinery Directive (MD) because after its completion it will be put into service for the first time in this form. Used machinery without CE marking often does not itself satisfy all requirements of relevant internal market directives. Since it was in service before these directives came into effect, no requirements can be demanded of it which at the time of Footnotes [1] The explanations for stages 1 and 2 including the statements set out under additional consideration of interfaces largely correspond to verbatim quotes. [2] German quotes from the Guide are based on what is as yet an unofficial German translation. [3] Specific extract from Article 2 Letter i) for incorporators: ʻManufacturer means any natural or legal person who designs and/or manufactures machinery (therefore also an assembly of machinery) covered by this Directive and is responsible for the conformity of the machinery for his own use. In the absence of a manufacturer, any natural or legal person who puts... machinery (i.e. also again an assembly of machinery)... into service is considered to be a manufacturer. [4] In Germany this is transposed into national law through the Employment Protection Act (ArbSchG) and the Ordinance on Industrial Health and Safety (BetrSichV). [5] Our understanding to the best of our knowledge and in good faith, but without assuming any liability! There are other views on the subject from market surveillance authorities, employers liability insurance associations and others in the field. [6] BMA interpretation document dated on the subject of substantial modifications ; ref. IIIc [7] To avoid confusion: this requirement generally applies irrespective of whether or not these machines will be integrated in an assembly of machinery. [8] SRP/CS = Safety-Related Part(s) of Control System(s)

22 22 MRL-News 32/06/11 Will we now have a break from more changes to laws or standards? Let us assume you have converted your machinery to the revised Machinery Directive 2006/42/EC (which came into force on ) in good time, and have done the same (although a little time remains for this) with respect to converting safety-related parts of control systems to EN ISO :2006 (2008), or where applicable to EN IEC :2005 (2008), one might think that at the moment you would be able to enjoy a bit of a break in terms of new statutory and normative framework conditions. The exception to this would be if there were revised or new C standards for your machinery. But there have also been a number of changes at the A and B standard level, albeit chiefly, but not solely, of an editorial nature: Type A standards Design guidelines and risk assessment for machinery and installations B1 standards: General higher-ranking safety aspects Type B standards B2 standards: Specifications etc. for protective devices Type C standards Specific safety requirements placed on individual types of machinery Structure of the European standards governing Safety of Machinery, i.e. the requirements of the EC Machinery Directive are substantiated using EN standards that are divided into three hierarchically constructed type classes: Type A standards basic standards; Type B standards group standards (divided into Type B1 standards safety aspects and Type B2 standards protective devices etc.); Type C standards technical and product standards.

23 MRL-News 32/06/11 23 New basic standard EN ISO :2010 The first is the new standard (DIN) EN ISO :2010: Safety of machinery General principles for design Risk assessment and risk reduction. This standard, which already has the status of a harmonised standard [1], combines the content of previous standards EN ISO :2004 [2] and EN ISO :2004 [3] including the revisions made to both standards which were published in 2009 and also standard EN :2007 [4]. The presumption of conformity of the replaced standards ends on [1] See C 110/29 in the Official Journal of the European Union dated which updates the list of harmonised standards that are currently to be found under the umbrella of the MD 2006/42/EC. [2] Safety of Machinery Basic concepts, general principles for design Part 1: Basic terminology, methodology [3] Safety of machinery Basic concepts, general principles for design Part 2: Technical principles [4] Safety of machinery Risk assessment

24 24 MRL-News 32/06/11 At the level of the so-called A standards, therefore, we will only have to deal with a single document in future, something which will definitely promote better understanding of the basic requirements placed on the safety of machinery while in addition preventing the use of the redundancies that were previously present. Irrespective of this there will still be the Technical Report ISO/TR (Risk assessment Practical guidance and examples of methods) (which is still only available in English). If the aim is to understand Annex I of the EC Machinery Directive with its legally prescribed essential health and safety requirements relating to machinery, the new combined document could prove all the more useful, in particular for newcomers, if this requirements catalogue were expressed using engineering wording. What is important is that the new standard only represents an editorial revision and has not added or changed any of the requirements. In terms of content, therefore, everything remains the same. Furthermore, technical and other documents that are based on the old editions of the standard do not need to be changed merely because of the publication of this new edition. If you wish to know where items can be found in the new (DIN) EN ISO :2010 standard in future, the competent standards committee has produced a comparison, the Table of correspondence between ISO :2003, ISO :2003, ISO :2007 and the new ISO :2010. This can be easily found by searching for the above title on Google.

25 MRL-News 32/06/11 25 New B1 standard (DIN) EN ISO :2010 This concerns the successor to standard EN 999:1998+A1:2008, and goes by the unaltered title of Arrangement of protective devices with respect to the approach speeds of parts of the human body. The purpose is therefore to ensure that the safety distance between the protective device and hazardous area is dimensioned so that a hazardous movement is stopped before a part of the body of the operator is able to reach the hazardous area. The standard succeeding it already has presumption of conformity (as from ) while, conversely, EN 999 has lost it. Refer also to Page 33 [1]. It is also worth noting that EN ISO :2010 is now an international standard, while EN 999:1998 was only relevant in Europe. (DIN) EN ISO :2010 largely equates to an editorial revision, but there are also some new aspects. In particular we must emphasise the fact that the standard now explicitly also applies to guards (guard doors, protective covers, fences etc.) with interlocks. A solenoid interlock must be provided where the required safety distance cannot be achieved. The method used here is to calculate the approach of persons based on a walking speed of 1.6 m/s and an approach speed of upper arms of 1.6 m/s. A further novelty is that the requirements relating to the size of safety mats have been specified in detail in the standard itself (and no longer in Annex B as was previously the case). However this may also be regarded as an editorial change. Factors influencing safety distance The formula for calculating the safety distance remains in place, i.e. S = K T + C. S = Safety distance K = The approach speed of the person (or parts of the person s body) to the hazardous area T = The response time (stopping time) of the hazardous machinery state C = An additional safety factor which depends on the detection ability of the protective device The new standard deals with the parameter T in greater detail, in other words the response time of the entire system. This is composed of the response time of the protective device and the reaction time of the control system (which in general should be a substantially smaller element in T ) and the response time of the drives and mechanical elements (which are usually the substantially larger element in T. Consequently this latter section accounts for large safety distances which are often difficult to achieve

26 26 MRL-News 32/06/11 in practice and which sometimes result in considerable effort and expense as well as in unacceptable compromises. In this connection, and on the basis of the motto of giving credit where credit is due, it is worth quoting from a technical paper written by our colleague Otto Görnemann, Manager Safety & Regulations at SICK AG, Waldkirch: In particular the reaction time of the control system and the response time of drives and mechanical elements should be reduced through use of the following measures: Reduction in the kinetic energy of the machine elements. The masses of the moving machinery parts and tools should be kept as low as possible. With rotating elements, the masses should be close to the centre of rotation to keep the inertia torque low. In many cases it is possible to optimise kinematics and motion sequences. Speeds, pressures and other factors should be reduced to the necessary level. Use of additional brakes. Additional brakes can be decisive in reducing response time. As a rule the extra expenditure here low compared to other measures. Geeignete Schutzbeschaltung von Schützen und Ventilen. Due to the design, fast elements (contactors, valves) should be used in the control circuits affected. To reduce the number of models, overdimensioned elements are frequently deployed which cause a higher response time because of inertia. Use of suitable safety-related control systems and bus systems. Electronic control systems and bus systems are increasingly deployed in safety-related parts of control systems. This can lead to undesirably high reaction times due to high bus loads, certain procedures (polling) and high program cycle times. The use of suitable procedures such as interrupt or alarm processing, structured programming, the separation of safety-related and non safety-related signals and bus systems or direct connection (wiring) of protective devices can help here. Suitable safety wiring of contactors and valves. Freewheeling diodes often provide effective spark suppression, but have a strong dropout delay (up to 14 times, depending on the design of the coil). Good spark suppression without strong dropout delay is achieved using RC elements or varistors. Optimised interlocking of electromechanical elements. In many cases electromechanical switching elements (switchgear) are cascaded with each other to create the required interlocks. Undesirable delays can be prevented using suitable switching elements and switching technology.

27 MRL-News 32/06/11 27 Selection of suitable protective device. Due to the type of detection of the respective protective device, people or parts of the body may enter the direction of the hazardous area unnoticed before the protective device triggers. This is the reason for the detection-related supplementary letter C. The greatest safety distances arise when using horizontal protection of an area, and the smallest when using light grids with high resolution (light curtains). When using light curtains with vertical arrangement, differences of up to 1.2 m can arise compared to horizontal systems." However the C parameter is also explained in greater detail in the new standard. Among other things this concerns the reference to EN ISO (loc. cit) and the resultant compatibility issues. Brief information containing a summary of the new standard can be ordered from the publisher Beuth-Verlag ( de) for Sorry: German language information only! New standard EN ISO :2008 Whilst this standard came into force somewhat longer ago, it may still be perceived as new. Below we quote the introductory article to the standard which can be found at www. beuth.de: Standard DIN EN ISO stipulates values for safety distances to prevent hazardous areas of machinery in commercial and public areas being reached. The safety distances are suitable for protective structures. It also contains information on distances which prevent free access by lower limbs. It refers to people aged 14 and older (the 5th percentile for people over 14 equates approximately to 1,400 mm). For upper limbs it also provides information for children aged over three years (the 5th percentile for people over three years old equates approximately to 900 mm) if it is necessary to take reaching through openings into consideration. The safety distances are intended to protect such persons who try to reach hazardous zones under the specified conditions. The values for safety distances contained refer to the situations of reaching upwards, reaching over protective structures, reaching round and reaching through regular openings. Information on the prerequisites for ap-

28 28 MRL-News 32/06/11 plication of values and on risk assessment, on the influence of additional protective structures on safety distances and their use where openings with an irregular shape exist can also be found in DIN EN Values that deviate from this standard can be dealt with in specific standards. For example, special test procedures for safety distances that apply to using a test finger in electrotechnical applications are described in electrotechnical standards. For occasions where interim values need to be taken into consideration due to practical situations, the use of the values in the tables relating to reaching over protective structures is explained in an annex on the basis of three examples. The standard is the result of combining standards DIN EN 294 on Safety distances to prevent hazard zones being reached by upper limbs and DIN EN 811 on Safety distances to prevent hazard zones being reached by lower limbs, in which the examples for applying the values in the tables relating to reaching over protective structures were transferred from the normative part to an informative annex, taking interim values into consideration. A good overview for how to deal with the new standard can be found in a leaflet from the Printing and Paper Processing employers liability insurance association (BG Druck- und Papierverarbeitung now BG ETEM). You can search for BG ETEM, Faltblatt, Nr. 68 on Google. Sorry: German language version available only! Outlook The state of relative quiet assumed above, if this exists at all, may change considerably in the near future, however, if a number of other more or less far-reaching revisions to standards lie ahead for mechanical engineering in the near future.

29 MRL-News 32/06/11 29 Invitation Register now for round 2/2011! This autumn we want to give you information on this area in the second round of our tec.nicum on tour! lecture events which goes under the heading Current changes in safety-related requirements relating to functional machine safety. In addition to specific issues still arising from MD 2006/42/EC and EN ISO :2006 (2008), we would like in particular to concentrate on the following revisions to standards: EN ISO Interlocking devices with and without guard locking EN ISO Validation of safety-related parts of control systems EN ISO Emergency stop as well as the abovementioned new standard releases. Sorry: German language presentations only! You can register today. As always participation in the lecture events is free of charge and you will be our guest for the duration of the events. Each starts at 8.30 a.m. (for coffee) or 9 a.m. and ends at approx. 4 p.m. (including time for coffee breaks and light lunch). The speakers will be Frank Schmidt, K.A. Schmersal GmbH, Wuppertal Friedrich Adams, K.A. Schmersal Holding GmbH & Co. KG, Wuppertal

30 30 MRL-News 32/06/11 Dates for round 2 of our tec.nicum on tour! lecture event: : Hamburg : Bielefeld : Wuppertal : Dresden : Erfurt : Hennigsdorf : Eschborn : Böblingen : Landsberg/Lech : Bad Dürkheim : Ulm-Seligweiler : Fürth : A-4020 Linz : A-6900 Bregenz : CH-4622 Egerkingen : Wuppertal : Bad Zwischenahn (Nähe Oldenburg) Registration form on next page!

31 MRL-News 32/06/11 31 Anmeldeformular SCHMERSAL-/ELAN-Vortragsveranstaltungen Bitte diese Seite fotokopieren und per Post an: Elan Schaltelemente GmbH & Co. KG z. Hd. Frau Gottwalz Im Ostpark 2 D Wettenberg per Fax an: + 49 (0) Elan Schaltelemente GmbH & Co. KG z. Hd. Frau Gottwalz Ort und Termin Name Telefon Firma Abteilung Straße Ort Weitere Teilnehmer Abteilung/ Weitere Teilnehmer Abteilung/ Sie erhalten umgehend Ihre Teilnahmebestätigung mit dem Veranstaltungshotel. Bei Rückfragen steht Ihnen Frau Anja Gottwalz gern zur Verfügung: Telefon: + 49 (0) Telefax: + 49 (0) agottwalz@schmersal.com

32 32 MRL-News 32/06/11 Try to make the best of it!* Replacement of EN 954-1:1996 New requirements relating to safety-related parts of control systems Even if objections are still being raised about the successor standards EN ISO :2006 (2008) and EN IEC :2005 (2008) and it is further assumed that a large section of industry affected has still not reacted, there is no reason to expect any repeated prolonging of the current status; in other words that the presumption of conformity for EN 954-1:1996 will be extended again beyond This means that the result of a CEN, CENELUC and EU symposium on 9 September 2010 in Brussels, whose precise purpose was said to be to examine this very matter, has changed nothing. At the time this result was worded as follows: In the final conclusion the improvement of user-friendliness of the standards was again highlighted as an important objective of the event. In summary it can be noted that the event has successfully offered a platform for a lively discussion between representatives from standardisation bodies and potential standards users. The constructive exchange of positions to a complex item being of general importance for the whole machinery sector could be seen as a facilitator to overcome remaining problems regarding the comprehension and application of the standards in question. * Please note: not all of the documents following taken into reference are available in English language!

33 MRL-News 32/06/11 33 It is now up to the relevant standardisation bodies, to consider the messages/suggestions elaborated at the symposium as soon as possible in the context of a next revision of the standards for functional safety. The emphasis in the summary would appear to be on next revision. However the question is whether this would then lead to combining the above two standards EN ISO and EN IEC in an improved form, whatever that might mean. Whilst in the meantime such a standardisation initiative exists, this project (Safety functions of control systems) does not find universal favour. For example on the German side there has been a decision to vote against the acceptance of this standardisation project. Instead reference is made to a 4-step plan to first check both standards in terms of essential improvements and only then (after 5 years at the earliest) to aspire to combining them. For example reservations on the part of the German Machine Tool Builders Association VDW) are already known. These would appear to be no longer directed at difficulties in calculating the PL of existing typical safety functions. 12 sample calculations with 35 extremely complex safety functions that are typical for machine tools have been defined and quantified by VDW and the DGUV Institute for Labour Protection (IFA) during a 2-year research project. The results and a final report will be presented to member companies at a VDW information day in August Rather it now concerns the calculation of the PL r(equired). If we understand it correctly, what is meant here is being able to incorporate or also incorporate the aspect of proven operation in a PL r or PL consideration. Starting point for estimating risk reduction S 1 S 2 F 1 F 2 F 1 F 2 P 1 P 2 P 1 P 2 P 1 P 2 P 1 P 2 Low risk High risk Required Performance Level PL r a b c d e S Severity of the injury S1 Slight (usually reversible injury) S2 Serious (usually irreversible injury including death) F Frequency and/or duration of the exposure to the hazard F1 Rare to less frequent and/or the period of exposure to the hazard is short F2 Frequent to continuous and/or the time period of exposure to the hazard is long P Possibilities to prevent the hazard or limit the damage P1 Possible under certain circumstances P2 Hardly possible Risk graph according to Annex A of standard EN ISO : specification of parameters and consideration of proven operation required!

34 34 MRL-News 32/06/11 This direction is one that is also pursued in a comment by the VDMA Robotics + Automation professional association entitled Problems with DIN EN ISO , in which it proposes a uniform definition for the consideration parameters S, F and P in the risk graph in Annex A of the standard. It also addresses problems affecting overlapping hazards, pneumatics and control category 2. PS: overlapping hazards means that at a certain place (in a certain area), e.g. in a robot installation, hazards emanating from various machines (e.g. robots) impact on an operator. In other words: overlapping hazards are characterised by the simultaneous impact of more than one individual hazard on one or several of the persons to be protected, their body parts or limbs, who can be located in or reach hazardous zones. But irrespective of how things proceed, the new standard/the new approach for designing safety-related parts of control systems must be adhered to from 1 January 2012 at the latest. Therefore in summarising we come to the heading above: Try to make the best of it! We chose this in preference to Never give up hope, which we managed to resist. However we will take the opportunity to point out new publications from the Institute for Labour Protection in St. Augustin; our seminars on the subject of EN ISO ; and consultancy services from the new Schmersal Safety Consultants. One of the new IFA publications is a paper on the subject of overlapping hazards as well as the three so-called SISTEMA cookery books that are now available for when you wish to use software to make PL calculations. They can be downloaded from or found by searching for the respective title on Google.

35 MRL-News 32/06/11 35 Our safety consultants will also be happy to help if individual support is required to implement EN ISO You can find information on this at Safety Consulting. Last, but not least, the following seminars have been planned by Schmersal tec.nicum on the subject (Sorry: German language presentations only!): Safe solutions for your industry K1/11: EN ISO :2008 workshop: CONTROL CATEGORY becomes PERFORMANCE LEVEL replacement of EN 954-1:1996 and the successor standard EN ISO :2008 (2006) Our workshop familiarises you with which new aspects are important when estimating the required Performance Level PL the future benchmark for the safety integrity of the parts of your control systems which assume personal protection or safety functions (SRP/CS). In 6 steps we explain how you can calculate a Performance Level in future. This basic seminar is a good introduction for familiarising yourself with the new materials. Participation is also worthwhile and strongly recommended if you are considering implementing the new requirements using the SISTEMA software (see tec.nicum Seminar K2/11 which takes place on the following day).

36 36 MRL-News 32/06/11 Contents: Legal and normative requirements What a PL stands for Arriving at the Performance Level in 6 steps Calculation parameters Calculation methods and examples Help and tools each with detailed explanations and background information Dates: (tec.nicum Wuppertal) (DME Maulbronn) (tec.nicum Wuppertal) (tec.nicum Wuppertal) K2/11: Software-supported PL calculations: ½-day seminar on using the SISTEMA software tool and typical FAQs in conjunction with this Without wishing to claim that our information covers every last detail and informs you of every finesse available, we would like to familiarise participants with the SISTEMA [1] software tool using practical examples and calculation examples. Please bring your laptop if you want to get some hands on experience. In order for us to be able to help you, please note that the software-supported calculation of a Performance Level requires basic knowledge of EN ISO :2008 (2006). For this we recommend the tec.nicum K1/11 seminar which takes place the day be fore. [1] The SISTEMA (Sicherheit von Steuerungen an Maschinen) software assistant for the safety of machine control systems provides help when assessing the safety of control systems as specified by DIN EN ISO The Windows tool replicates the structure of the safetyrelation parts of a control system (SRP/CS, Safety-Related Parts of [a] Control System[s]) on the basis of the so-called designated architectures and calculates reliability values at various levels of detail including the Performance Level (PL) achieved. Risk parameters for determining the required Performance Level (PL r ), the category, the measures to prevent common cause failures (CCF) in multichannel systems, the mean time to failure (MTTF d ) and the average diagnostic coverage (DC avg ) of building elements or blocks can be determined step by step. The impact of every parameter change on the entire system is displayed immediately and can be printed out as a report.

37 MRL-News 32/06/11 37 Dates: (K2.6/11), 9.00 a.m. to 1.00 p.m. (DME Maulbronn) (K2.4/11), 8.30 a.m. to p.m. (tec.nicum Wuppertal) (K2.7/11), 8.30 a.m. to p.m. (tec.nicum Wuppertal) Further information Schmersal tec.nicum

38 38 MRL-News 32/06/11 Book discussion 4th edition of Neudörfer: Designing safetyrelated products methods and collection of systematic solutions for the EC Machinery Directive published! This standard work on safety technology, which after all is now in its 4th edition, is in particular characterised by the fact that it presents the subject of machine safety in its entirety, and especially because as stated in the title it also includes the aspect of DESIGNING in great detail. Unlike other technical books, not excepting our own, the reader is given a through insight into what inherently safe design really means, about the role played by ergonomics and what must be taken into consideration for safety-related signs. Scientifically well-founded and structured educationally, the volume offers an overview of standardised as well as new and tried and tested design ideas. It indicates methods that can be used to solve safety-related problems in mechanical engineering. A collection of solutions offers numerous practical examples for design safety features and protective devices together with a summary of ergonomic aspects. The 4th edition considers a number of current European standards in addition to the Machinery Directive 2006/42/EU. You can order the book, which it must be admitted is not cheap, in bookshops and also from: konstruieren-sicherheitsgerechter-produkte.html, where using Google Preview you can take a look inside at the Table of Contents and a few sample pages. Preview Sorry: German language version only!

39 MRL-News 32/06/11 39 New from the Schmersal Group Thinking safety technology In addition to the ability for individual coding of the counterpart, the new Schmersal RSS 36 safety sensors also retain all of the functional and safety-related properties and features familiar from the current CSS family. One example of this is security integrity which corresponds to PL e or SIL 3 and which is also guaranteed without restriction and without additional measures when used in series connections. The devices are deployed to lock mobile protective devices that operate where there are particularly stressful conditions which can consequently generate a greater incentive for manipulation on the part of machine operators. Another special feature of the devices, and which was similarly the force behind the CSS technology, is the use of self-monitoring circuitry for fault tolerance in the case of certain faults. Fig. 2: Previous CSS family members : various types of safety sensors with and without guard locking (of which one is with magnetic operating principle without latch ) Fig. 1: Thanks of the use of RFIDtechnology the new electronic sensors of series RSS 36 provide additional functionalities, which i.e. increase their performance against defeating.

40 40 MRL-News 32/06/11 Fault tolerance is a permitted safety-related property that can considerably increase the availability of a machine or installation but which, here and now, as the state of the art is still very unusual in mechanical engineering. By contrast it is typical and frequently seen in high availability systems. Whilst customary safety components in mechanical engineering switch off directly in the event of a fault, leading to an operational stoppage and possibly interrupt production procedures and processes at the worst possible moment, fault tolerance means that this does not occur as long as a specific fault remains noncritical in terms of safety (and can therefore be conditionally tolerated). This is usually the case with interlocking devices as long as a protective device is in protective position (i.e. is closed) when the machine is running, so that from the point of view of the operator, the machine is not in a dangerous state for him. If a fault occurs, the machine control system initially receives a warning signal instead of a shutdown signal, for example so that a workflow or process that might otherwise be randomly interrupted, notwithstanding any subsequent damage, can be concluded in a deliberate manner. The fault tolerance ends after an operational stoppage (i.e. no restarting is possible), if the safety function is requested, i.e. the guard door is opened; irrespective of this it ends after 30 minutes at the latest, however, if nothing is done in spite of the warning. In safety philosophy, these 30 minutes represent a measure regarding the so-called probability of the occurrence of a second fault. In other words: after 30 minutes (fault tolerance) the machinery is always switched off and its restarting is inhibited. Type tests by the IFA, the Institute for Labour Protection (previously BGIA), and TÜV Rheinland approve of this particular function; in the case of RSS and CSS sensors it refers to the following faults: Faults in output test of channel 1 or voltage on the output; Ditto, but referring to channel 2; Cross-short between the two outputs or faults in both outputs; Temperature fault in the sensor. Other features and properties The first special feature is that the type of these sensors supplied, which operate on the basis of RFID technology, reacts exclusively to an individual counterpart that has been previously taught ; alternatively a second version is offered that can also be adapted to a new individual coding using a special procedure. In this way the potential for ma-

41 MRL-News 32/06/11 41 nipulating protective devices in everyday operation is almost excluded thanks to RFID technology. The new range is furthermore characterised by its universal assembly possibilities. A magnetic catch can also be supplied as an option, and enables the use of the sensor as end stop in smaller guard doors. A large switching distance gives the user greater freedom when mounting the sensor and counterpart. The devices have also been tested by ECOLAB for use in the food and drinks industry; their protection class corresponds to IP 69K. RSS 36 safety sensors in keywords Interlocking device without guard locking Contactless coded electronic system 12 mm switching distance The long side permits a maximum height offset (x) of sensor and actuator of around ± 8 mm (e.g. assembly tolerance or due to the guard door subsiding). The maximum traverse offset (y) is ± 18 mm. Plastic housing P-switching short-circuit resistant safety outputs Integral detection of cross-shorts, wire breakage and external voltage PL e, SIL 3, also in series connections Y X M Please use the Reply form on Pages 50/51 if you are interested in further information on the new electronic safety sensors in the RSS 36 range.

42 42 MRL-News 32/06/11 New from the Schmersal Group Developed for food production Hygiene-compliant safety magnetic switches Mechanical engineering for the food industry is one area for which the Schmersal Group has developed specific ranges and solutions in terms of machine safety. Recently we presented a magnetic safety switch that was likewise developed with a view to the special demands of food production. Two characteristic properties of the BNS 40S can be recognised at first glance: the slim design with smooth surface blends in well with the typical design environment of food machinery. The housing is made from stainless steel, so that resistance to corrosion and cleaning fluids may be assumed. The developers at Schmersal have designed the seal of the sensor and actuator to provide a high protection class: IP 69K means that the safety magnetic switch is resistant to high pressure cleaning. The high switching distance also permits concealed mounting behind non-magnetic covers. The design has furthermore placed paid particular attention to avoiding areas where dirt can accumulate. With these qualities the BNS 40S complies in all respects with the demands of Hygienic Design and can also be used in wet areas. Its wiring is suitable for the food industry, while the actual sensor complies with the requirements of UL and ECOLAB.

43 MRL-News 32/06/11 43 Two versions of actuator for a horizontal or vertical direction of approach permit flexible mounting of the new safety magnetic switches. An easy to clean door stop with integrated magnetic latch, similarly in stainless steel and with the same design, is also offered as accessory kit. The BNS 40S extends the BNS range that has traditionally frequently been deployed in machinery and installations used in food production. Installation dimensions and switching distances are compatible with those in the tried and tested BNS 33S, so that users can deploy the modern safety sensor technology without changing the design environment. Please use the Reply form on Pages 50/51 if you are interested in further information on the new electronic safety sensors in the BNS 40S range.

44 44 MRL-News 32/06/11 New from the Schmersal Group Range of control panels is expanded Standard in high design quality instead of Do it yourself Safety and ergonomics on guard doors Standardisation with the highest quality: very briefly summarised, this is the advantage offered by control panels in the BDF range. Mechanical engineers do not need to worry about the design, integration and production of operating elements on the guard door. Instead they select the desired solution from a number of housing sizes and a broad range of operating elements, and this is then supplied ready to install. The range starts with the BDF 200, which provides room for four operating elements such as emergency stop control device, LED indicator lights, selector switch etc. The BDF 100 is new to the range, and has just one operating element which can be used for a standardised emergency stop function.

45 MRL-News 32/06/11 45 Both control panels can be operated quickly on commercial aluminium profile systems. As all operating elements are equipped with the same contacts, the user is able to define where to place them on the control panel according to individual requirements. It is also possible to freely select the plastic-covered label which is attached to the labelling area. As separate unit that is not connected to a door handle or the safety switchgear, the control panels can be installed in an ergonomically favourable position. The mechanical engineer can also mount two panels on top of or next to each other. Mounting directly on the guard door ensures ergonomic operation and a fast reaction speed in the event of a hazard. The operator controlling or monitoring the process can trigger the emergency stop function in the shortest possible time, for example if there is a build-up of material, if any other irregularity occurs or if personnel are at risk. Another novelty in the BDF range is a version of the BDF 200 with integrated AS-i safety interfaces and A/B slave. This makes it easier to integrate the control panels in AS interface systems. Please use the Reply form on Pages 50/51 if you are interested in further information on the new extensions to the control panel range.

46 46 MRL-News 32/06/11 New from the Schmersal Group Function modules instead of programming New compact safety control system permits a high degree of flexibility despite its simple configuration In the newly developed PROTECT-SELECT range, the Schmersal Group presents a compact safety control system that can be configured without programming knowledge and without assignment of specific manufacturer parameters. In spite of this the user has extensive opportunities to adapt the control system to his requirements. This is because a wide number of preconfigured, practical programs are available to him from which he can simply select the one that applies to his application which is where the term Select comes from.

47 MRL-News 32/06/11 47 The program is directly selected on the device in a short dialog by means of a toggle switch and a display, using which extensive diagnostics information can also quickly be accessed. 18 safe digital and two safe analogue inputs can be interconnected in different ways respectively via the total of twelve typical safety programs available and assigned to the six safe outputs. As such the approach can best be compared to a wiring diagram. Settings for specific applications, such as determining the sensor signals on the corresponding input (isolated or non-isolated) or a required drop-out delay time on a certain output can be assigned using a dialogue function on the display. One of the special features of PROTECT-SELECT is the ability to safely evaluate two analogue input signals. Upper and lower limits can be stipulated for this analogue value; deviations from defined ranges will then be processed accordingly in the safety program. Both the 18 digital inputs and the six safe outputs in pairs satisfy the requirements for PL e in accordance with EN ISO The two analogue inputs are each suitable for applications up to PL d. Customised variations of the control system are furthermore available; these are marketed under the designation PROTECT-OEM and are adapted to individual requirements in cooperation with the customer. They enable the user to realise the desired extra functions precisely without having to undertake the work of parameter assignment himself. In practice a PROTECT-SELECT system can replace five to six conventional safety relay modules. With this range, the Schmersal Group provides a new way of accomplishing all control-related machinery safety functions in small and medium-sized applications. Please use the Reply form on Pages 50/51 if you are interested in further information on the new function modules in the PROTECT-SELECT range.

48 48 MRL-News 32/06/11 New from the Schmersal Group Spring-return joysticks with robust design For tidy man-machine interfaces and intuitive operation Forwards, backwards, right and left: with a spring-return joystick from the Schmersal Group the operator can move the machine tool in four directions. Or, if the mechanical engineer has selected the maintained joystick switch variation, using a single switching device he actuates four different functions that then engage. This enables the designer of the machine to combine four functions in one operating element and thereby achieve the conditions necessary for a compact control panel. At the same time he simplifies the man-machine interface and enables intuitive, faultfree operation. This adds both to machine safety and to productivity. Another benefit of the spring-return and maintained joystick comes from the freedom offered by these operating elements at the control-related level: electrical interlocks exclude the combined actuation of functions that are not compatible with each other. What is common to both versions is the robust design which also has a long service life under unfavourable ambient conditions. The spring-return and maintained joystick satisfy the requirements of