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…
Read MoreIntroduction to Functional Safety Seminars
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…
Read MoreTrapped Key Interlocking
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…
Q & A: Category 2 and Testing Intervals
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…
Read MoreFive reasons you should attend our 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…
Read MoreQ & A: Can Safety PLCs be used for Lockout?
The question of lockout and the use of safety PLCs as a means to meet the lockout requirements comes up more and more frequently these days. Can Safety PLCs be used for lockout? Safety professionals don’t always agree on this controversial topic! During the Free Safety Talks that we did with Schmersal Canada and Franklin Empire, this…
Read MoreSafe Drive Control including Safe Torque Off (STO)
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…
Read MoreHow to do a 13849 – 1 analysis: Complete Reference List
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
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
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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