I agree completely with Ted's comments - UL 1998 is a good standard and certainly applies in the US. For Canadian markets, the IEC standard still applies since Canada is an IEC country and CSA has no formal adoption, nor a National Standard on this subject to draw on. -- Doug Nix, A.Sc.T. IEEE PSES Kitchener-Waterloo Section, Ontario, Canada
[email protected] mobile (519) 729-5704 fax (519) 653-1318 Find me LinkedIn at http://www.linkedin.com/in/dougnix On Jul 20, 2007, at 10:01, [email protected] wrote: > Let me add a bit to Doug Nix's comments. > > For the United States, the applicable standard is UL 1998. > http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=1998.html > I strongly recommend implementing interlocks in hardware. The UL > group > that handles software and firmware testing is backlogged and works > slowly. > There will also be limits on what you can do to update electronics and > firmware. The amount of testing required is very extensive because > there > are may types of single faults that could occur that may result in a > hazards. > > Search for "Therac 25" at Google or some other search engine and > you will > see one of the worst-case results of a reliance on silicon for > interlocks. > > Ted Eckert > American Power Conversion/MGE > http://www.apc.com/ > > The items contained in this e-mail reflect the personal opinions of > the > writer and are only provided for the assistance of the reader. The > writer > is not speaking in an official capacity for APC-MGE or Schneider > Electric. > The speaker does not represent APC-MGE's or Schneider Electric's > official > position on any matter. > > > > "Kunde, Brian" > <brian_kunde@leco > > tc.com> To > Sent by: <[email protected]> > emc- > [email protected] cc > > > Subject > 07/20/2007 08:29 Interlock Circuits Firmware/ > Silicon > AM Controlled > > > > > > > > > > > I have limited experience working with industrial machines with moving > parts so I would appreciate any help you can provide. > > To protect an operator from moving parts, my understanding is that I > have to use an approved interlock device (in this case a switch) > and it > has to directly control the device that makes the motion (pneumatic > solenoid). > > But on a future project, we would like to have the interlock switch > talk > to an FPGA (silicon) and have firmware and software controls the > motion > device after many sensor checks are made. These "checks" are quite > complex where many things have to be just right in the right sequence > for the motion to occur. Engineering is saying that the sequence is > too > complex to limit with a simple interlock switch system. > > Is it possible to use silicon chips, firmware, and software in such a > circuit? Can such an approach be used and if so what is involved in > qualifying it? > > Thanks, > The Other Brian > > LECO Corporation Notice: This communication may contain confidential > information intended for the named recipient(s) only. If you > received this > by mistake, please destroy it and notify us of the error. Thank you. > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
