Machinery Safety 101

Interlock Architectures – Pt. 1: What do those categories really mean?

Basic Stop/Start Circuit
This entry is part 1 of 8 in the series Cir­cuit Archi­tec­tures Explored

In 1995 CEN pub­lished an import­ant stand­ard for machine build­ers – EN 954 – 1, Safety of Machinery – Safety Related Parts of Con­trol Sys­tems – Part 1: Gen­er­al Prin­ciples for Design. This stand­ard set the stage for defin­ing con­trol reli­ab­il­ity in machinery safe­guard­ing sys­tems, intro­du­cing the Reli­ab­il­ity cat­egor­ies that have become ubi­quit­ous. So what do these cat­egor­ies mean, and how are they applied under the latest machinery stand­ard, ISO 13849 – 1?

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Interlock Architectures – Pt. 2: Category 1

This entry is part 2 of 8 in the series Cir­cuit Archi­tec­tures Explored

This art­icle expands on the first in the series “Inter­lock Archi­tec­tures – Pt. 1: What do those cat­egor­ies really mean?”. Learn about the basic cir­cuit archi­tec­tures that under­lie all safety inter­lock sys­tems under ISO 13849 – 1, and CSA Z432 and ANSI RIA R15.06.

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Interlock Architectures – Pt. 3: Category 2

ISO 13849-1 Figure 10
This entry is part 3 of 8 in the series Cir­cuit Archi­tec­tures Explored

This art­icle explores the require­ments for safety related con­trol sys­tems meet­ing ISO 13849 – 1 Cat­egory 2 require­ments. “Gotcha!” points in the defin­i­tion are high­lighted to help design­ers avoid this com­mon pitfalls.

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Interlock Architectures – Pt. 4: Category 3 – Control Reliable

Category 3 Architecture Logic Block Diagram
This entry is part 4 of 8 in the series Cir­cuit Archi­tec­tures Explored

This post was updated on 2020-03-28. Cat­egory 3 sys­tem archi­tec­ture is the first cat­egory that could be con­sidered to have sim­il­ar­ity to “Con­trol Reli­able” cir­cuits or sys­tems as was defined in… 

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Interlock Architectures – Pt. 5: Category 4 – Control Reliable

This entry is part 5 of 8 in the series Cir­cuit Archi­tec­tures Explored

Ed. note: I’ve made a few updates to this art­icle since it was first pub­lished in 2011, with the most recent on 2020-05-11. – DN – The most reli­able of the five… 

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