On 03/13/2016 08:03 AM, Gene Heskett wrote: > On Sunday 13 March 2016 07:40:25 John Thornton wrote: > >> On my GS-2 with the braking resistor I go from 1800 fwd to 1800 rev in >> 1 second. I have both acceleration and deceleration set to 1/2 second. >> >> JT > That would be considerably more usefull than the controllers default of > 30 seconds. Do you recall the specs of the resistor you used? > > Take the line current rating of the motor, multiply by 1.7 (to make it "single phase current" then multiply by 1.5-2 for a peak current rating. Now, compute 340 / (number calculated above) and that is your resistor value. These are rough calculations, but when the drive's controller detects a high bus voltage it will turn on the braking transistor until the voltage is safe again. So, the resistor will be pulsed on in short bursts as needed during braking. Use a big vitreous enamel resistor, it will only be pulsed during braking, so doesn't need to carry the steady-state wattage of that resistance across 340 V DC. I used a single 25W resistor on my Bridgeport, and a pair of 50 W resistors on my VFDs. The Bridgeport resistor does get hot when rigid tapping many holes, the one on the lathe never does, but it is not CNC'd so no rigid tapping on that machine.
If you can find a chart of braking resistors in the book, use that instead of my scheme. Jon ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785111&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
