08 September 2009
The upcoming change to the new machine safety standards received widespread publicity, and in fact in Control Engineering Europe’s June 2009 edition published the article, ‘The first steps to safety In the new European Regime’ with the subheading ‘Acquiring some practical application knowledge is the best way to master the new machine safety regulations.’Many machine builders and control system suppliers have invested time and money in preparing to follow the new standards. Controller manufacturers were heavily involved in producing equipment to be used to help machine builders comply with the new directive, and they published materials and organised seminars to publicise the event. Many of them issued stern warnings to the industry to hurry up and comply—time is running out.And Brammer UK Managing Director Ian Ritchie explained that the Directive does not just relate to individual machines and safety components—it also covers processes and control systems, meaning every aspect of a production line created by interlinking a series of existing machines must comply with the Directive.Surprise reversalIn a surprise reversal, the European Commission has decided to delay the implementation of the safety standards until 2012.The new European safety law certainly has its good intentions. The two prime objectives were to remove trade barriers such as those caused when an importer says: ‘That machine doesn’t meet my country’s safety standards so I can’t buy it,’ and to ensure that all European states meet the same high levels of safety protection.The directive includes two standards, EN ISO 13849 and EN IEC 62061.EN ISO 13849 was designed to extend the concepts of the previous safety standard, EN 954-1. Its most significant change is the emphasis on a probabilistic method for determining safety integrity and the control of systematic faults and errors, and introduces a concept called ‘performance levels’ as a measure of safety integrity, which are specified in terms of the average probability of a dangerous failure per hour. It lays heavy emphasis on the reliability of individual safety components, and for many of these components, reliability data are not yet available. EN ISO 13849 was adopted in Nov. 2006 with the U.S., U.K., and Japan the only three countries voting against it.A second standard, EN IEC 62061, is specifically tailored to machine builders using programmable safety (safety PLCs) to implement their safety requirements, applying them to electrical, electronic and programmable electronic safety systems. The resulting safety hardware and software is referenced as a Safety Integrity Level (SIL 1 - 3). Apparently, some organisations had difficulty preparing for the change, and so the EC has decided the previous safety standard EN 954-1 will stay in effect for three more years. Control manufacturers hasten to point out that EN 954-1 was written before 1996, well before programmable safety controllers were available, so it is rapidly becoming outdated. There are some questions as to the applicability of this ‘old’ standard in the era of complex safety equipment.For example, Peter Still, industry standards manager at Schneider Electric, comments: ‘BS EN 954-1 is well understood and is seen as simple to use, but is not really rigorous enough to ensure sufficient safety integrity in many modern and complex machines. Complying with the new standards may be more time consuming, but it can achieve greater levels of safety throughout the machine’s life.’Mr. Still likely speaks for a majority of the control companies involved in producing safety equipment when he says ‘At Schneider Electric we are fully supportive of the new directive and have therefore invested in a product range that helps meet the new standards and have made our functional safety data visible to help with compliance. Despite the deadline extension, it’s really important that machine builders start complying with the two new standards as soon as possible, to ensure they are working to the highest level of safety.’ Undoubtedly Schneider Electric and the other industrial control companies benefitted from the pressure to conform to the new standard. As a result they will have to be patient and realise slower returns on their investments. But for most machine builders, the news comes as a great relief and a welcome gift from the government authorities. Schneider Electric has published a Safe Machines Handbook which can be downloaded at the company’s website.
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