Design News, April 2013

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Automation & Control The Convergence of Safety & Control Systems Integrated safety is becoming predominant in automation strategies. By Michael ParadiSo, oMroN STi F or the better part of the last decade, a vigorous and healthy debate has ensued over separate versus integrated safety and control systems. While the debate continues in some quarters, the de facto outcome is clear: Integrated safety is becoming predominant in automation strategies as these systems continue to converge. Technology has been the principal driver of this convergence as new products demand more advanced safety functionality, and others provide the means to deliver it. system, they had to be hard wired into it — there was no other way. Typically this was done to meet a specific and narrowly defined safety objective. Separate No More As technology advanced, safety systems became increasingly configurable and programmable, allowing system maintenance without equipment shutdown or undue work stoppage. This increased throughput and improved operational efficiency. While this evolution was moving safety from simple elec- Historically, safety and control systems were separate. Safety products were distinct units used to protect machine operators from hazardous motion, and principally safeguarded components were designed to allow a process to function safely. If any safety signals needed to get into the control This approach had numerous drawbacks, including: • Material and labor costs associated with wiring; • Diminished production due to line shutdowns necessary for system maintenance; • Lack of programmable control. The harmonization of international safety standards, including iec 61508 and iSo 13849 in the european Union, makes it easier to select an appropriate safety integrity level (Sil). S4 aUT OM aT I O N & c ON T R O L / a s U p p Le M e N T T O d e s I g N Ne ws A p ril 2013 [www.designnews .com]

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