Setting new standards in safety
With recent and upcoming changes in safety standards, the machinery directive has evolved into one that more readily embraces contemporary technology. Many see this as a challenge; but, as we discuss here, the opportunities these changes will enable are wide reaching and in all instances a positive step forward for machine builders and end user alike.
Derek Jones, Business Development Manager at Rockwell Automation elaborates: "It was realised some time ago that the standards that deal with the safety of machinery had not kept pace with developments in the automation of machinery. In order to help towards both the safety and productivity of contemporary machinery, safety-related control systems themselves often need to use complex and programmable technologies. Machinery safety related control system standards, such as EN 954- 1 (ISO 13849-1: 1999), have served us well for many years, but are now too simplistic to cope with the technology."
In its place two new standards have been introduced, which take into account advances in technology, removing the deployment shackles put in place by the incumbent standards. The two new-generation standards for machine-safety-related control systems, IEC/EN 62061 and EN ISO 13849-1:2008, can both be used to show conformity with the European Machinery Directive.
They both have different system classifications: IEC/EN 62061 uses Safety Integrity Level (SIL) and EN ISO 13849-1 uses Performance Level (PL). SIL and PL can be said to be variations on the same theme and the decision on which standard to use is governed by what is best for your application.
If you are familiar with the use of the EN 954-1 Categories and use relatively straightforward conventional safety functions, then EN ISO 13849-1 (PL) is probably appropriate. If you are specifically required to use SIL, or if your application uses complex multi-conditional safety functionality, then EN/IEC 62061 may be the most suitable. It is important to note that EN ISO 13849-1 covers all technologies, whereas EN/IEC 62061 only covers electrical-based systems.
"In general terms," Jones explains, "62061 can be more complex to use and is more suited to complex applications, whereas 13489-1 has geater simplification but at the expense of some design constraints. After the withdrawal of EN 954-1 I expect the early deployment of the two new standards to be roughly 10 and 90% respectively."
So what does this mean for industry? EN 954-1 was a simple standard to use but a lot of the features in the new standards were simply not part of EN 954-1 and this lack of features was one of the primary drivers for the introduction of the new contemporary standards. Jones continues: "In the last 10 years the trend has been threefold: smaller, more complex and programmable. We have moved a long way forward from strong and simple, which is still good, don't get me wrong, but modern machines are adaptable and programmable and machinery safety has to adapt with them."
The industrial manufacturing environment is constantly evolving; driven by the need to achieve a competitive edge. One of the most decisive factors for success is the automation of machinery and processes to facilitate powerful, flexible and reliable operation. This requires the intensive use of complex, programmable technologies linked through communication networks to fast, accurate and powerful actuators.
So, what should you do? Jones explains: "The ideal first step is to read both standards in order to understand their requirements and implications. Perhaps the most daunting aspect is the fact that both require some calculations based on reliability data that the safety component manufacturers should supply. However, this has been considered and help is at hand thanks to the IFA in Germany, which provides a comprehensive calculation tool for EN ISO 13849-1 called SISTEMA."
Available for free, a link to the SISTEMA tool is available through the Rockwell Automation website where you can also register and download (for free) the Rockwell Automation product ‘data library’ for use in the SISTEMA tool. Using this product data, users can simply click information into the schema and the software will output information towards safety accreditation according to EN ISO 13849-1.
The complexity issue is one envisaged by many OEMs alongside the cost of change, but according to Jones: "The perception of cost and complexity tends to be greater than reality." Instead of these exaggerated issues, users should instead look at the benefits the new standards bring. In the first instance technology can now be used that meaningfully could not be used before. Jones elaborates: "With many seeing safety as a bit of a black art, the uptake of modern technology may well have been discouraged. However, these new standards positively embrace new technology and will allow machine builders to integrate their safety and control networks into one infrastructure; greatly simplifying their machines and given them a significant competitive edge." Other positive aspects of the ability to adopt newer technology are reliability, flexibility, productivity and controllability – especially when one considers the replacement of a mechanical cam with a motion solution for example.
Jones concludes: "The most important aspect of functional safety is the recognition that machines are used to make things. If a machine is not working, it is dangerous; people tend to climb in and do things they wouldn't normally do. If functional safety is integrated with the automation controller then the machine can be bought to a safe state and the operators are protected. Functional safety equals functional control plus safety... and in my book that equates, very simply, to good engineering design."
With years of experience and involvement around standards, regional legislation and the practical implementation of safety and automation solutions, Rockwell Automation can offer you the support you need, such as risk assessments services, design assistance and much more. Many years as a leading automation supplier allow Rockwell Automation’s customers to reap the advantage of partnering with a supplier that not only knows safety but is also an expert in automation control.
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