Designers, OEMs and end users can get confused when confronted with a multitude of safety protocols and legislation that sometimes seem to have different requirements or even appear to contradict each other.
Rockwell Automation is therefore organising Functional Safety Seminars to clarify the current standards. The seminars are designed to provide practical advice on changes in relevant EU Directives and legislation, application guidance, demonstrations of evaluation tools that simplify the use of ISO 13849-1 and an opportunity to see and experience (via workshops) associated safety systems and products.
According to Rockwell Automation, the concept of functional safety will change the behaviour of users and designers of automation systems, with the publication of ISO 13849 leading to a growing interest in performance levels (PLs) and Safety Integrity Levels (SILs).
The standards that define PLs and SILs both cover safety-related electrical control systems (SRECS), producing the same or similar results – albeit via different methods – and in some cases giving users an option to choose the one most suitable for their situation. The outputs of both standards offer comparable levels of safety performance or integrity but each standard offers different routes appropriate to their intended use.
Part 2 of the standards
Derek Jones of Rockwell Automation states: "It is important for people to read both parts of EN 954 and ISO 13849 as they provide extremely good design standards for safety systems. The main issue is that part one is well known, but part two is less well studied and, as it provides guidelines for validation and technological considerations, this is an oversight on the part of the many people who only read part one; the bigger picture is not always appreciated. One primary issue with these standards is that interpretation differs from designer to designer, mainly because of what they do not say as opposed to what they do say.
"It is a very big step to move from categories to SILs but, at the present time, the standards do not compete. The recent EN/ISO 13849-1:2006 standard offers a transition path from categories to SILs via its own classification – PL (performance level) – and sits nicely in the middle between the two. It does have some compromises to simplify usability, but offers robust and inclusive requirements. With regard to simple systems, the requirements are very similar but as systems get more complex the gap widens."
The Functional Safety Seminars will also show attendees how to use SISTEMA (Safety Integrity Software Tool for the Evaluation of Machine Applications), a tool for the easy application of the control standard EN ISO 13849-1. The SISTEMA software utility provides designers of safety-related machine controls with comprehensive support in the evaluation of safety in the context of ISO 13849-1. The tool enables users to model the structure of the safety-related control components based upon the designated architectures, thereby permitting automated calculation of the reliability values with various levels of detail, including that of the attained Performance Level (PL).
A series of seminars will take place throughout the UK in May and June 2009. The morning seminars will be followed by a Connected Components Exhibition and optional focussed workshops. Register now at www.rockwellautomation.co.uk/safetyseminars.