Complementary Protective Measures

Can Emergency Stop be used as an “on/off” control?

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Emergency Stop Button
This entry is part 16 of 16 in the series Emer­gency Stop

Every couple of months I get an email ask­ing me if there is any reas­on why e‑stop func­tions can­’t be used as the primary power con­trol (on/off but­ton) for machinery. Fol­low­ing a recent exchange, I thought I would share the reas­ons for why this is such a bad idea. The short answer The short answer is an unequi­voc­al NO. Don’t […]

Complementary Protective Measures

Introduction to Functional Safety Seminars

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Man training a group of people, pointing to Functional Safety topics on the whiteboard

If you are inter­ested in func­tion­al safety, and I know many read­ers are based on the stat­ist­ics I see for my oth­er func­tion­al safety-related posts, I think you will be inter­ested in this. I am col­lab­or­at­ing with the IEEE Product Safety Engin­eer­ing Soci­ety’s Vir­tu­al Chapter to provide a series of three 35 minute sem­inars dis­cuss­ing the fun­da­ment­als of func­tion­al safety. The […]

Complementary Protective Measures

Emergency Stop Pull-Cords

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This entry is part 15 of 16 in the series Emer­gency Stop

This art­icle was updated 2019-04-26, adding spe­cif­ic details related to IEC 60947 – 5‑5. When it comes to emer­gency stop devices there is no doubt that the red mush­­room-head push but­ton is the most com­mon – they seem to be every­where. The second most com­mon emer­gency stop device is the pull-cord, and like the light-cur­­tain in safe­guard­ing […]

Canada

Safe Drive Control including Safe Torque Off (STO)

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Graph illustrating STO Function
This entry is part 12 of 16 in the series Emer­gency Stop

Ed. Note: This art­icle was revised 25-Jul-17 to include inform­a­tion on safe stand­still. Safe Drive Con­trol includ­ing STO Motor drives are every­where. From DC vari­able speed drives and index­ing drives, through AC Vari­able Fre­quency drives, servo drives and step­per motor drives, the cap­ab­il­it­ies and the flex­ib­il­ity of these elec­tron­ic sys­tems has giv­en machine design­ers unpre­ced­en­ted […]

Canada

ISO 13849 – 1 Analysis — Part 7: Safety-Related Software

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General architecture model of software
This entry is part 7 of 9 in the series How to do a 13849 – 1 ana­lys­is

Safety-Related Soft­ware Up to this point, I have been dis­cuss­ing the basic pro­cesses used for the design of safety-related parts of con­trol sys­tems. The under­ly­ing assump­tion is that these tech­niques apply to the design of hard­ware used for safety pur­poses. The remain­ing ques­tion focuses on the design and devel­op­ment of safety-related soft­ware that runs on that […]

Canada

ISO 13849 – 1 Analysis — Part 2: Safety Requirement Specification

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This entry is part 2 of 9 in the series How to do a 13849 – 1 ana­lys­is

Devel­op­ing the Safety Require­ment Spe­cific­a­tion The Safety Require­ment Spe­cific­a­tion sounds pretty heavy, but actu­ally, it is just a big name for a way to organ­ise the inform­a­tion you need to have to ana­lyse and design the safety sys­tems for your machinery. Note that I am assum­ing that you are doing this in the “right” order, mean­ing that you […]

Canada

ISO 13849 – 1 Analysis — Part 1: Start with Risk Assessment

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This entry is part 1 of 9 in the series How to do a 13849 – 1 ana­lys­is

I often get ques­tions from cli­ents about how to get star­ted on Func­tion­al Safety using ISO 13849. This art­icle is the first in a series that will walk you through the basics of using ISO 13849. Keep in mind that you will need to hold a copy of the 3rd edi­tion of ISO 13849 – 1 [1] and the 2nd edi­tion of […]

Canada

Understanding the Hierarchy of Controls

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The Hierarchy of Controls illustrated as an inverted triangle with each level of the hierarchy written one above the other, starting with Inherently Sfe design, then Engineering Controls, then Information for Use, then Administrative Controls and finally descending to PPE at the bottom. An arrow with the text "Effectiveness" on it runs parallel to the triangle and points downward from Inherently safe design to PPE.
This entry is part 4 of 5 in the series Hier­archy of Con­trols

(Eds. note: This art­icle was ori­gin­ally writ­ten in 2011 and was updated in Nov. 2018.) The “Hier­archy of Con­trols” is one approach to risk reduc­tion that has become entrenched in the Occu­pa­tion­al Health and Safety (OHS) sec­tor. There are oth­er approaches to risk reduc­tion which are equally effect­ive but are less rigidly struc­tured. If you […]

Canada

Emergency Stop Categories

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Emergency Stop on machine console
This entry is part 4 of 16 in the series Emer­gency Stop

I’ve noticed a lot of people look­ing for inform­a­tion on Emer­gency Stop cat­egor­ies recently; this art­icle is aimed at those read­ers who want to under­stand this top­ic in more depth. First, a cla­ri­fic­a­tion: Emer­gency stop cat­egor­ies DO NOT EXIST, but stop cat­egor­ies do. A stop cat­egory is a descrip­tion of a con­trol func­tion – what the con­trol does – and […]