Confusion over the implementation of European Union directives is nothing new, but two U-turns within a month must make something of a record even by European Commission standards. Back in the summer, machine builders and control system suppliers were in some cases looking forward to and in others resigned to the imminent implementation of new safety standards in the European Machinery Directive which were due to come into effect on December 29 next. In essence, the new standards update the previous standard, EN 954-1, which dates back to the era of electromechanical safety devices, and harmonizes standards across the EU, thereby removing barriers to trade and ensuring that a machine bought in one EU country complies with regulations in any other.
Two Standards
There are actually two new standards involved, both European implementations of international standards, in one case from ISO and the other from IEC. EN ISO 13849 essentially extends the concepts of EN 954-1, most significantly by adopting a probabilistic method for the determination of safety integrity. Safety integrity is measured according to "performance levels" which are specified in terms of the average probability of a dangerous failure per hour. Readers familiar with IEC 61508 and 61511 will recognize the approach which relies on being able to identify the reliability of the individual safety components within a system, and it is the non-availability of such reliability data for some components which is said to be one of the problems with meeting the December 29 deadline, despite the fact that the standard was adopted by ISO nearly three years ago, incidentally with only three countries – the US, the UK and Japan – opposing it.
Rather less contentiously, the second standard deals with the specific issue of the use of safety PLCs in electrical, electronic and programmable electronic safety systems and applies the, to the process industries, increasingly familiar concept of Safety Integrity Levels or SILs.
It's worth noting that a further degree of complexity is introduced by the fact that the Directive doesn't just apply to individual components or machines in isolation but also to entire production lines created by interlinking existing machines.
Change of Mind
Typically such new standards are welcomed by equipment suppliers, despite denials to the contrary, as an opportunity to persuade, or is that scare, customers into investing in new or upgraded equipment, and this has been no exception, not least because of the current economic downturn. Machine builders and control system vendors have invested in new compliant offerings and produced supporting literature, written endless articles in trade magazines, organized seminars and, as the deadline has loomed, issued dire warnings of what will happen if users fail to comply by the due date, after which, they stress, there would be no period of grace. All of which looked pretty silly when, at the beginning of September and less than four months before the Directive was due to come into force, the Commission announced that it had changed its mind and decided to delay implementation until 2012. In the meantime the previously discredited EN 954-1 would remain in force for the intervening three years, despite the fact that it predates the introduction of safety PLCs and is of doubtful applicability to today's complex safety equipment.
Typical of the comments from vendors who had made the effort to comply was that from Schneider Electric's industry standards manager Peter Still, who described the old standard as "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, "he added, "but it can achieve greater levels of safety throughout the machine's life."
As You Were
Clearly companies like Schneider have friends in some pretty high places however because, if one volte face were not enough to thoroughly confuse machine builders and their unfortunate customers, just a week after its announcement of the delay in implementation of the Directive and resuscitation of the catatonic EN 954-1, the Commission withdrew the decision and reinstated the original deadline. Even then, however, under the pressure on the one hand from those machine builders who weren't ready to implement the change, and on the other from safety experts who queried whether EN 954-1 could provide an acceptable level of safety, the Commission said that it will not make a final decision until early December, just weeks before its original deadline for compliance.
Intriguingly Schneider's Peter Still says that the issue is not about vendors profiting by bringing new products to market, although he may have difficulty persuading some observers of the truth of that assertion when he says that " ... manufacturers have not been developing new technologies purely to comply with the new standards; in fact the same equipment can often still be used ... From a manufacturer's point of view, the main differences will be the data that is supplied with the products and the way that they are integrated into a control system."
Whether the Commission will stick by its December 29 deadline when it finally makes up its collective mind seems impossible to predict, leaving the wise virgins of the machine building industry little choice but to beat the deadline and comply while offering their foolish sisters more than glimmer of hope that not bothering was the right policy. What all this has to do with protecting workers is hard to discern; what it has to do with power politics is rather more obvious. So which way did the Irish vote in the end?
