Heh heh, I see a religious argument ensuing. Either you believe that powering the machine down is the only guarantee of safety, or you believe that your electronics are unquestionably reliable and you are a statistician. If the vfd has power and rather than power it down you command it to brake, and it (or say the control computer) is malfunctioning, perhaps it will speed up, or reverse or some other bad thing. On the other hand, the probability that the emergency at hand is related to bad computer or vfd is small and therefore it might be a safer (quicker) stop to command it so. I am not sure either argument wins. Ideally you want to de-power everything and (separately) mechanically brake motors, no?
I know there are papers written on this subject and I believe controlled estop is considered to be better in some cases. In my case I had originally planned to do it controlled, but couldn’t figure out a circuit that would still allow me to use a charge pump to trip the contactors in case the computer goes south. Hence I needed to delay the initialization of the modbus component…. -Tom > On May 14, 2015, at 11:34 PM, Dave Caroline <dave.thearchiv...@gmail.com> > wrote: > > To bring a vfd to stationary fastest the vfd has to have control to > use the deceleration curve/braking resistors if fitted and used. > Therefore keeping the vfd powered is safer in the initial stop, only > then should it be powered down. > > Dave Caroline > > On 14/05/2015, John Kasunich <jmkasun...@fastmail.fm> wrote: >> >> >> On Thu, May 14, 2015, at 03:25 PM, Sebastian Kuzminsky wrote: >>> >>> It seems fairly common for people to build machines where the spindle >>> VFD power goes on and off along with the servo amp power (F1 in Axis), >>> which (as you point out) means something like this feature is required. >>> >>> I think this is the wrong way to handle VFD power, i prefer to have the >>> VFD turn on when you turn on the control computer, and stay on until you >>> power the control computer down. >>> >>> But it's easy to support both preferences, using code like you describe, >>> so it's fine. >>> >> >> IMO estop should ensure (in a fail-safe way) that the spindle won't turn. >> Unless you are going to put a contactor on the VFD output (usually >> discouraged by VFD makers), killing the VFD power is the only way. >> >> As you say, it is good to support both. >> >> >> -- >> John Kasunich >> jmkasun...@fastmail.fm >> >> ------------------------------------------------------------------------------ >> One dashboard for servers and applications across Physical-Virtual-Cloud >> Widest out-of-the-box monitoring support with 50+ applications >> Performance metrics, stats and reports that give you Actionable Insights >> Deep dive visibility with transaction tracing using APM Insight. >> http://ad.doubleclick.net/ddm/clk/290420510;117567292;y >> _______________________________________________ >> Emc-developers mailing list >> Emc-developers@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-developers >> > > ------------------------------------------------------------------------------ > One dashboard for servers and applications across Physical-Virtual-Cloud > Widest out-of-the-box monitoring support with 50+ applications > Performance metrics, stats and reports that give you Actionable Insights > Deep dive visibility with transaction tracing using APM Insight. > http://ad.doubleclick.net/ddm/clk/290420510;117567292;y > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
