I would use caution. I have looked into this in the past and possibly there have been recent developments that would change what I learned. My main concern is the cycle life rating of the switch. For what ever reason, many E-Stop switches had a rating of only a few thousand cycles while your normal on/off controls often have more than 100,000 cycle ratings. I have recommended to clients that on this alone, they should not be using an E-Stop for routine on/off control.
That said, I have seen recent offerings of long life E-switches with greater han 1 million cycle ratings. So I would say it pays to read the ratings of the particular switch you are using and specicfically to learn if the life cycle rating is controlled by the product certifications, or not. -Doug Douglas E Powell Laporte, Colorado USA doug...@gmail.com LinkedIn <https://www.linkedin.com/in/coloradocomplianceguy/> (UTC -06:00) Mountain Time (US-MDT) On Tue, May 31, 2022 at 6:28 PM IBM Ken <ibm...@gmail.com> wrote: > 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) <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>
