Right.. the safety regs say that you can do what you need to bring the machine to safe stop, but in the end the power has to be dumped to the drives or they need to go into a STO condition - Safe Torque Off mode.
The big thing is that the safety controls are suppose to override the normal controls, so you can't (or are not suppose to) rely on the general machine controls to stop the machine safely. This is why safety rated controllers (PLCs) are becoming so popular. It is difficult, to near impossible to do this with conventional safety relays. The entire safety discussion becomes complex with you are trying to stop moving machinery that has multiple intelligent devices. Then again a lot of it depends on the insurance company and what they require. Trying to stay on top of the latest government safety requirements can be a full time job. I have a large CNC lathe that has contactors wired in between the servo drives and the motors and on an Estop, the contactors drop out and the 3 phase servo motor windings are shorted together to stop the motors. I have never had to Estop that lathe during a move - so far! Dave On 2/12/2013 10:08 AM, Todd Zuercher wrote: > I am not always a fan of just killing the power to every thing on an e-stop. > On our high speed routers if you just kill power to the spindle, they can > coast for hours. It takes quite a while to stop from 18K rpm with out any DC > braking. So I have the e-stop triggering the external fault circuit on the > spindle inverters instead of just cutting power to them. > > ----- Original Message ----- > Hey guys, > I have been hurriedly trying to find the cash for my new components > for this retrofit. Some of you may recall that I am essential gutting this > control and starting over with all new parts and a PC running linuxcnc. > Well as of this week I am finally in a position to order the brand new > motors and drivers for the machine. I am going with all Teco units and I > am ordering them tomorrow. > > I kinda wanted some specific input on getting started with the new > electronics here. My machine will run entirely on single phase input power. > I have already got the heavy gauge wiring run to the large on off contactor > in the top of the cabinet. My plan is to use the existing 24volt power > supply and a couple of the large three phase relay setups that are still in > the cabinet along with the estop button to build the basic input power > structure. I want to end up with an estop circuit that will kill power to > everything in the machine except the computer in case of an emergency. I'd > like to hear all of your thoughts on this matter and any advice on the best > method of wiring this up. The24 volt power supply in the machine can run > on either single or three phase input so that should not be a problem. I > will have lots of further questions about this build as I go along and will > be chronicling the build on my Cincinnati thread on the cnczone. Any ideas > guys? Peace > > Pete > ------------------------------------------------------------------------------ > Free Next-Gen Firewall Hardware Offer > Buy your Sophos next-gen firewall before the end March 2013 > and get the hardware for free! Learn more. > http://p.sf.net/sfu/sophos-d2d-feb > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
