While EN 954 has been a popular functional safety standard in the United States and Europe, its time is quickly passing. The rise of standards EN ISO 13849 and IEC 61508 and its derivatives have seen to that. Yet many manufacturers appear not to have made this realization. Many machine builders are familiar with the straightforward, step-by-step, "cookbook recipe" approach offered by EN 954. However, with the increasing use of innovative technology and more complex machinery controls the approach in EN954 is no longer viable. With the introduction of EN ISO 13849, machine builders can now take a more probabilistic and analytical approach which more fully addresses the safe implementation of these new state-of-the-art safety solutions.
EN 954 classifies functional safety based on "categories." Safety ratings are stated in terms of categories B, 1, 2, 3, 4. With the implementation of the new standards, particularly ISO 13849 in the new European Machinery Directive, buyers will be looking for new kinds of safety ratings. This change is upon us: in Europe, after December 31, 2011, all machinery-related products must be evaluated to EN ISO 13849 instead of EN 954. Categories must give way to Performance Levels in this case, or to Safety Integrity Levels if EN/IEC 62061 is used.
So this problem looms: you’ve been operating with a component rated to category 3 from EN 954. That component needs to be replaced; but, manufacturers no longer sell components rated to categories. What PL-rated or SIL-rated component do you purchase to replace it?
“We can help the customer by identifying and integrating functional safety components that are PL-rated or SIL-rated,” says Thomas Maier, principal engineer, functional safety, at UL. “We can also help manufacturers in doing PL or SIL verification or validation for the safety-related control systems in their products.”
Still thinking in terms of “safety categories”? It’s time to think again. Contact Kevin Connelly today to find out why: