Doug, These type of interlock switches are new to me. They are used in industrial applications where they protect the user from a very hazardous condition.
These switches usually have what is called a Positive Mechanical Action or Certified Direct Opening mechanism which forces a Normally Closed contact OPEN when in the SAFE State. In these cases, when the key is removed from the switch there is an internal mechanism which forces a NC contact OPEN (removing the hazard). If the contact is stuck closed, then the key cannot be removed from the switch. There are usually other contacts within the switch that can be used to monitor the switch to verify its proper function. If the switch is certified to EN60947-5-1 for the direct opening mechanism, the switch will have a symbol that looks like an arrow pointing to the right inside a circle. That is about all I know about these. The Other Brian From: Doug Nix [mailto:d...@ieee.org] Sent: Tuesday, February 05, 2019 11:36 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] A question about FDA language and interlocking devices Colleagues, I had a question come my way yesterday that I need a little help with. Here’s the question: I have a customer that produces X-ray equipment. The FDA requires that the door that gives access to the X-ray source must have an interlock with a ‘knife-edge and finger stock’ type connection. Also the FDA mentions that interlocks should be of conventional design. What is understood by “conventional design”? My reading on this requirement is that any conventional electromechanical interlocking device like this: [Image result for keyed interlock switch images] will meet the basic requirements as described by the FDA as “knife-edge and fingerstock” connection, but I am concerned that this may not be at all what is meant. As always, any guidance you can offer will be welcomed and appreciated! Best, Doug Nix d...@ieee.org<mailto:d...@ieee.org> +1 (519) 729-5704 - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org<mailto:emc-p...@ieee.org>> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)<http://www.ieee-pses.org/list.html> List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org<mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org<mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org<mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com<mailto:dhe...@gmail.com>> ________________________________ 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. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
