Machinery Safety 101
27 April, 2015

Testing Emergency Stop Systems

by Doug Nix
in Canada, CE Mark, Control Functions, Control Reliability, Emergency Stop, EU European Union, Functional Safety, Interlocks, International, ISO 13849, Uncategorized /
5 Comments
This entry is part 11 of 16 in the series Emer­gency Stop

Updated 2020-10-31. DN I’ve had a num­ber of ques­tions from read­ers regard­ing test­ing of emer­gency stop sys­tems, and par­tic­u­larly with the fre­quency of test­ing. I addressed the types of tests that might… 

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3 July, 2017

Safe Drive Control including Safe Torque Off (STO)

by Doug Nix
in Canada, CE Mark, Complementary Protective Measures, Control Functions, Control Reliability, Emergency Stop, EU European Union, Functional Safety, Guards and Guarding, Interlocks, Interlocks, ISO 13849, Ontario /
5 Comments
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,… 

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10 July, 2017

Emergency Stop Failures

by Doug Nix
in Emergency Stop
This entry is part 13 of 16 in the series Emer­gency Stop

I am always look­ing for inter­est­ing examples of machinery safety prob­lems to share on MS101. Recently I was scrolling Reddit/r/OSHA and found these three real-world examples. Broken Emer­gency Stop But­tons The… 

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28 August, 2018

Emergency Stop Pull-Cords

by Doug Nix
in Complementary Protective Measures, Emergency Stop /
2 Comments
This entry is part 15 of 16 in the series Emer­gency Stop

This art­icle was updated 2020-06-13, adding links to the Rock­well Auto­ma­tion and Schmersal pull-cord data, and on 2019-04-26, adding spe­cif­ic details related to IEC 60947 – 5‑5 [7]. When it comes to… 

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20 April, 2019

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

by Doug Nix
in Complementary Protective Measures, Control Functions, Emergency Stop, Functional Safety /
4 Comments
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… 

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25 April, 2019

More E‑Stop Questions

by Doug Nix
in Canada, Control Functions, Emergency Stop, EU European Union, Standards, USA /
10 Comments
This entry is part 17 of 16 in the series Emer­gency Stop

Here are some more ques­tions I’ve been asked regard­ing emer­gency stop require­ments. These ones came to me through the IEEE PSES EMC-PSTC Product Com­pli­ance For­um mail­ing list. Primary Sources There… 

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