IEEE PSES Functional Safety Seminar – Part 3

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

Doug Nix will be giv­ing the third ses­sion in the three-part Intro­duc­tion to Func­tion­al Safety sem­in­ar series at the IEEE Product Safety Engin­eer­ing Soci­ety Vir­tu­al Chapter meet­ing.’ In this third of three ses­sions, Doug will be intro­du­cing key func­tion­al safety con­cepts MTTFD, DCavg, and CCF, and will be dis­cuss­ing Safety-related Soft­ware Devel­op­ment and Veri­fic­a­tion and […]

Control Functions

Q & A: Category 2 and Testing Intervals

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Logical block diagram for ISO 13849-1 Category 2 architecture.
This entry is part 1 of 2 in the series Q&A

Dur­ing the Free Safety Talks that we did with Schmersal Canada and Frank­lin Empire, we had a “hot ques­tion” come up regard­ing Cat­egory 2 archi­tec­ture and the test­ing inter­val require­ment. In the short video below, Doug answers that ques­tion. If you have more ques­tions or felt some­thing was­n’t clear in the video, leave us a com­ment and […]

Events

Five reasons you should attend our Free Safety Talks

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Banner for the Free Safety Talks

Reas­on #1 – Free Safety Talks You can­’t argue with Free Stuff! Last week we partnered with Schmersal Canada and Frank­lin Empire to put on three days of Free Safety Talks. We had full houses in all three loc­a­tions, Wind­sor, Lon­don and Cam­bridge, with nearly 60 people par­ti­cip­at­ing. We had two great presenters who helped […]

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 […]

Control Functions

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

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

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. Book List Here are some books that I think you may find help­ful on this jour­ney: [0]     […]

Canada

ISO 13849 – 1 Analysis — Part 8: Fault Exclusion

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

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 one. This a def­in­itely non-trivi­al […]

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 6: CCF — Common Cause Failures

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

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 the same time from a single […]

Canada

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

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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

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 MTTFD, I brought up the […]

Canada

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

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

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 let­ters. Using MTTFD is […]