I agree I thought it also seemed like the problem was with the drive. And I think I've solved it. We bought the machine new and never considered that the manufacturer would have improperly configured the drives, actually not bothered to configure them at all. Upon further inspection I found the drives were improperly configured for both the old and new motors, just that the old motors were more tolerant of it. None of the drives were ever configured for the motors, they were all set to factory defaults. These drives have a parameter setting called "Base Frequency" that should be set to the motors rated frequency. This was the main culprit for the poor performance. The setting for the "Base Frequency" should have been 300Hz and the default on the drive is 1000Hz. Since the drive thought that we were running the motors at 1/3rd their rated speed, they were not giving them full power. This was also causing the old motors to ramp up to speed in about 1/3rd the time that the drive was configured for (about 6 sec insted of 20). Now all of the motors old and new are running much better and are not noticeably slowing during heavy cuts.
----- Original Message ----- From: "Jon Elson" <[email protected]> To: "Enhanced Machine Controller (EMC)" <[email protected]> Sent: Tuesday, March 8, 2016 12:24:59 PM Subject: Re: [Emc-users] Spindle Tourque and VFD Settings On 03/07/2016 04:11 PM, Todd Zuercher wrote: > I'm having a little trouble understanding some things and how they should be > configured. > > I recently purchased a cheapo Chinese spindle to replace another spindle that > failed (small HP high speed for wood carving). > > The old spindle was a 3hp 220v 8.5A 18000 RPM motor. The new one is 18000RPM > 8.6A 220v but is rated for 3kw. When I try to run this new motor with the old > VFD it takes significantly longer to spin up to speed than the old one. It > also seems to bog down more on heavy carving, and if pushed too low may stall > and takes a very long time to recover to full speed. > > Since you still have some of the old drives, check the limit current on them, and compare to the new one. Some drives have fancy stuff, such as reducing frequency when at limit current, thereby slowing the motor. This may either be helpful or hurtful, depending on the cutting action. So, see if the old drives had this feature, or if the new one does. Are you sure the new drive is allowing the full 8.6 A? Maybe the old drives allowed a higher current for a limited time. I know one of my VFDs has "electronic motor protection" which essentially means you can get 125% of rated current for 30 seconds over every 5 minutes or something like that. If the Lenze drive has this option, and it is not turned on, you might look into enabling it. Anyway, it SEEMS like the problem is more likely in the VFD than the motor. Generally, a motor will be able to put out QUITE a bit more torque than its ratings would indicate, until the windings burn out. Since this one has a slightly HIGHER current rating than the old one, it seems almost impossible that it would have less torque than the old one. So, if it bogs down, it seems like the VFD is not delivering enough current to the motor. I'd suggest actually measuring the current, but that could be quite difficult and a bit dangerous. (You'd really have to use a current transformer.) Jon ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://makebettercode.com/inteldaal-eval _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://makebettercode.com/inteldaal-eval _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
