Greetings to All!! I have an industrial machine with blades that has to be changed out by the User/Operator. The blade is behind a door with a positive mechanical action switch that when opened puts the motor's VFD into a Safe Stop Function Mode (this is a certified Safety Function). In addition, power is removed from the Start Button circuit so the motor cannot unexpectedly start.
When the E-Stop button is pressed, it does the same as the Door Switch above, but in addition, it also opens the Motor Enable Relay which removes the 3-phase power from the VFD. Now the motor really really cannot unexpectedly start. I think this circuit arrangement is typical. We noticed that many of our Customers instruct their Employees (Operators) to PRESS the E-STOP Button before changing out the Blade taking advantage of the extra layers of protection. So here is my question. Is it OK to instruct the Operator in OUR MANUALS to Press the E-Stop when changing the blades? We have always been told that the E-Stop function should ONLY be used for Emergency and not for routine tasks. Is there any additional liability on our company if we give these instructions? In doing so, are we admitting that our product is unsafe or not as safe and may unexpectedly start unless you press the E-Stop? What is your opinion of this topic? Thanks to all. The Other Brian - ---------------------------------------------------------------- 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>
