On Fri, 11 Jan 2008 16:28:14 -0800, you wrote: >On Sat, 2008-01-12 at 00:01 +0000, Steve Blackmore wrote: > >> I use KBIC speed control on my mill, I simply reverse the DC output >> using a 20A DP/DT relay. > >You don't switch it while the motor is running, do you? The KBIC manual >says that you will damage the controller by doing that. I have had >another look at the schematic and I am thinking that if you disconnect >the armature, you will get a voltage spike high enough to cause SCR1 to >conduct in reverse. If SCR2 is on, which is likely, you will have a >direct short between the mains, L1 and L2.
No - there's a delay set on CW/CCW. >I think if inhibit is invoked long enough ( 20ms ?) to insure that both >SCR's are off, switching the armature will be okay. I just won't know >for sure until I try it. Which will have to wait until I get the parts >to fix the controller due to my last experiment. It needs to be long enough to ensure there is no output from the KBIC or back emf generated by the motor under any condition - I use 1 second. On a mill that should be plenty, on a lathe, however, where there may be lots of inertia due to a heavy chuck, it may need to be longer. >I am playing with ideas on how EMC could be used to enhance what people >already have. These KBIC controllers seem to be quit popular. EMC should already run one fine, if you use an external isolator board. Steve Blackmore -- ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
