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 […]

Control Functions

Trapped Key Interlocking

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This is a trapped key interlock on the door of an electrical switchgear cabinet. To open the door the key must be inserted and turned to withdraw a bolt that holds the door closed. With the bolt withdrawn, the key is held in the lock. The upstream switching device is held open by another interlock using the same key; since the key can only be in one of the two locks, it prevents accidentally closing the upstream switch while the cabinet is open for maintenance. The interlock is attached to the door with one-way screws to discourage casual removal of the lock, which would defeat the system.
This entry is part 3 of 7 in the series Guards and Guard­ing

Many machine design­ers think of inter­locks as exclus­ively elec­tric­al devices; a switch is attached to a mov­able mech­an­ic­al guard, and the switch is con­nec­ted to the con­trol sys­tem. Trapped Key Inter­lock­ing is a way to inter­lock guards that is equally effect­ive, and often more appro­pri­ate in severe envir­on­ment­al con­di­tions. Copy­right secured by Digi­prove © 2018Acknow­ledge­ments: As cited.Some Rights ReservedOri­gin­al con­tent here is pub­lished under […]

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 3: Architectural Category Selection

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This entry is part 3 of 9 in the series How to do a 13849 – 1 ana­lys­is

At this point, you have com­pleted the risk assess­ment, assigned required Per­form­ance Levels to each safety func­tion, and developed the Safety Require­ment Spe­cific­a­tion for each safety func­tion. Next, you need to con­sider three aspects of the sys­tem design: Archi­tec­tur­al Cat­egory, Chan­nel Mean Time to Dan­ger­ous Fail­ure (MTTFD), and Dia­gnost­ic Cov­er­age (DCavg). In this part of the […]

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

Testing Emergency Stop Systems

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This entry is part 11 of 16 in the series Emer­gency Stop

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 be needed in anoth­er art­icle cov­er­ing Check­ing Emer­gency Stop Sys­tems. This art­icle will focus on the fre­quency of test­ing rather than the types of tests. The Prob­lem Emer­gency […]