Safebook 3 - Safety related control systems for machinery

13 February 2011

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Safebook 3 - Safety related control systems for machineryRockwell Automation is offering the Safebook 3 - Safety related control systems for machinery, covering principles, standards and implementation (this version was fist published in February 2009). [Review by Jon Severn, Editor,]

Safebook 3 is written for machine builders, system integrators and specifiers operating in the European and North American markets, as it discusses not only EU Directives (such as the Machinery Directive and the Use of Work Equipment Directive) but also US and Canadian Regulations.

A separate section covers standards, including International (ISO and IEC), European Harmonised (EN), US (OSHA, ANSI and NFPA), Canadian (CSA) and Australian standards (which are mostly aligned with International and European standards).

A useful chapter within Safebook 3 is that devoted to Safety strategy. This explains how risk assessment and risk reduction interrelate, and presents a risk assessment methodology. At the end of this section there is a list of standards for risk assessments on machinery (eg ISO 14121, ANSI B11.TR3 and AS 4024.1301-2006).

Protective measures and complementary equipment are covered in the next chapter, with references to applicable standards where relevant - such as in relation to the size of openings in machine guards. This is an extensive section within Safebook 3 in order to address all the different types of safety measures and complementary equipment available. However, there is no list of applicable standards as there is for the risk assessment section.

Safety distances and the calculation thereof are covered in Chapter 5. Care must be taken when reading this chapter because of the differences between the International/European standards and those encountered in the USA/Canada. Note also that Safebook 3 only refers to ISO 13855 and EN 999, not the more recent EN ISO 13857.

Safety-related control systems

A major section of the book, Chapter 7, considers the structure of safety-related control systems. This discusses categories (as in EN 954-1 and ISO 13849-1) in some detail, illustrated with block diagrams and circuit diagrams.

The next chapter introduces functional safety of control systems, though there is a cautionary note to the effect that the standards are relatively new and changes are likely, so the information in Safebook 3 cannot be assumed to be up to date.

Following on, the next two chapters address system design in accordance with IEC/EN 62061 and ISO 13849-1, respectively. These both include a fair degree of detail, culminating in a double-page table listing MTTFd (mean time to dangerous failure) for each channel and the corresponding average probability of a dangerous failure per hour (PFHD) and Performance Level (PL).

Overall the Safebook 3 contains plenty of information and helpful illustrations. Clearly it has been written from an international perspective, which can hinder clarity for readers who are only interested in one market (the USA or Europe, for example), and, in common with other books published on the subject of standards and directives, it feels as if it is not quite up to date (for example, the chapter on Regulations still refers to Machinery Directive 98/37/EC, which was superseded by 2006/42/EC on 29 December 2009). However, it is a useful work and definitely worth requesting from Rockwell Automation.

For copies of the free Safebook 3 - Safety related control systems for machinery, go to the Rockwell Automation Safety Solutions Portal.

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