>From a practical standpoint, some designs use an EPO/EMO in series with a motor or other high current device potentially creating a hazard (laser, linear actuator, etc). I can see why you would not want to use an EPO in this manner (breaking significant current on a regular basis could cause damage to the switch terminals). However, if your EPO goes to a logic-level or low power control input to a relay, perhaps that is OK. The standard I work with does not prohibit you from doing this. You would need to show that the relay is designed appropriately to function as an on/off switch. You might also want to consider the effect of 'training' users to use the EPO switch during service- that might lead to some learned behavior that is not appropriate for other pieces of equipment.
-Ken A On Tue, May 31, 2022 at 9:20 AM Brian Kunde <bkundew...@gmail.com> wrote: > 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) <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> > Mike Cantwell <mcantw...@ieee.org> > > For policy questions, send mail to: > Jim Bacher <j.bac...@ieee.org> > David Heald <dhe...@gmail.com> > - ---------------------------------------------------------------- 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>
