Control Functions

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

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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?

EMC

Inside Apple’s EMC Lab

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Mac­world was invited inside Apple’s EMC test lab for a tour – the first time journ­al­ists have been per­mit­ted into this area. This art­icle looks at what Apple does to make sure their products meet EMC design require­ments. Test­ing indus­tri­al equip­ment is often sim­pler that this, and you don’t need to buy your own labs to do it. Are your machine designs com­pli­ant? Would you know if they

Asides

Interlocked gate testing

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Did you know that inter­locked gates require stop­ping per­form­ance test­ing?

Machinery needs to be able to stop in the time it takes a per­son to open the guard and reach the haz­ard. If the dis­tance from the guard open­ing to the haz­ard is short enough that a per­son can reach the danger point before the haz­ard can be con­trolled, the guard is use­less. The res­ult­ing situ­ation may be worse