Machinery Safety 101

Safe Drive Control including Safe Torque Off (STO)

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…

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How to do a 13849 – 1 analysis: Complete Reference List

This entry is part 8 of 9 in the series How to do a 13849 – 1 ana­lys­is

Post updated 2019-07-24. Ed. As prom­ised in pre­vi­ous posts, here is the com­plete ref­er­ence list for the series “How to do a 13849 – 1 ana­lys­is”! If you have any addi­tion­al resources you think read­ers would find help­ful, please add them in the com­ments. Copy­right secured by Digi­prove © 2017 – 2018Acknow­ledge­ments: As cited.Some Rights ReservedOri­gin­al con­tent here is pub­lished under these license terms: X License Type:Non-com­mer­cial, Attri­bu­tion,…

ISO 13849 – 1 Analysis — Part 8: Fault Exclusion

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

Post updated 2019-07-24. Ed. Fault Con­sid­er­a­tion & Fault Exclu­sion ISO 13849 – 1, Chapter 7 [1, 7] dis­cusses the need for fault con­sid­er­a­tion and fault exclu­sion. Fault con­sid­er­a­tion is the pro­cess of examin­ing the com­pon­ents and sub-sys­tems used in the safety-related part of the con­trol sys­tem (SRP/CS) and mak­ing a list of all the faults that could occur in each…

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

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

Post updated 2019-07-24. Ed. 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…

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An update on CE Marking Electrical Cable

CE Mark­ing Wire and Cable In an earli­er post, I wrote about the require­ments for CE Mark­ing wire and cable and dis­cussed the <HAR> mark. In 2016, the Con­struc­tion Products Reg­u­la­tion 305/2011 (CPR) came into effect, repla­cing the Con­struc­tion Products Dir­ect­ive 89/106/EEC. The CPR included pro­vi­sions cov­er­ing any kind of mater­i­als that could be used in…

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ISO 13849 – 1 Analysis — Part 6: CCF — Common Cause Failures

This entry is part 6 of 9 in the series How to do a 13849 – 1 ana­lys­is

Post updated 2019-07-24. Ed. What is a “Com­mon Cause Fail­ure”? There are two sim­il­ar-sound­ing terms that people often get con­fused: Com­mon Cause Fail­ure (CCF) and Com­mon Mode Fail­ure. While these two types of fail­ures sound sim­il­ar, they are dif­fer­ent. A Com­mon Cause Fail­ure is a fail­ure in a sys­tem where two or more por­tions of the sys­tem fail at…

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ISO 13849 – 1 Analysis — Part 5: Diagnostic Coverage (DC)

A graph showing the theoretical "bathtub curve" for product failure rate over the lifetime of the product.
This entry is part 5 of 9 in the series How to do a 13849 – 1 ana­lys­is

Post updated 2019-07-24. Ed. What is Dia­gnost­ic Cov­er­age? Under­stand­ing Dia­gnost­ic Cov­er­age (DC) as it is used in ISO 13849 – 1 [1] is crit­ic­al to ana­lys­ing the design of any safety func­tion assessed using this stand­ard. In case you missed a pre­vi­ous part of the series, you can read it here. In the last instal­ment of this series dis­cuss­ing…

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Problems with our websites

Apo­lo­gies Just a quick note to all our read­ers to explain the out­ages we’ve been hav­ing. First, I want to apo­lo­gise for the down­time and sporad­ic out­ages you’ve prob­ably exper­i­enced. We tried and failed to avoid those issues, but we think everything is sor­ted out now. Mov­ing house is nev­er easy We out­grew the cap­ab­il­it­ies of our…

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A Note about Our Travel Policy

We believe travel gives us a broad per­spect­ive both per­son­ally and pro­fes­sion­ally. Our focus is glob­al. Our eth­ic­al pos­i­tion is clear; we believe in the health and safety of ALL people. We believe in the power of sci­entif­ic data, and in the power of con­nect­ing with oth­ers glob­ally, so we might learn from one anoth­er. Com­pli­ance…

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ISO 13849 – 1 Analysis — Part 4: MTTFD – Mean Time to Dangerous Failure

This entry is part 4 of 9 in the series How to do a 13849 – 1 ana­lys­is

Post updated 2019-07-24. Ed. Func­tion­al safety is all about the like­li­hood of a safety sys­tem fail­ing to oper­ate when you need it. Under­stand­ing Mean Time to Dan­ger­ous Fail­ure, or MTTFD, is crit­ic­al. If you have been read­ing about this top­ic at all, you may notice that I am abbre­vi­at­ing Mean Time to Dan­ger­ous Fail­ure with all cap­it­al…

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