GE DC 300 Variable Speed Motor Drive

Don't know if this will help, but it might give you a clue where to start...

http://www.practicalmachinist.com/vb/monarch-lathes/ge-dc-drive-99896/

The parameters you are setting are the times for the drive to get to base speed of the motor (acceleration) or from base speed back to zero (deceleration). So what might be happening is that only in forward-low range does the motor actually run at its base speed. In reverse the motor runs slower as well as in high range. Presumable there is a gear box so even though the spindle may be turning faster during high range operation the motor can be turning slower due to the gearing. So then the motor gets to target speed in less time then the accel times because its not accelerating to full speed.

Shawn

Thank you for the reply Shawn.

Yes there is a gear box, the lathe's head stock with the part chuck mounted on it. The top speed for the chuck in low range is 70 rpm & top speed for the chuck in high range is over 200 rpm. The motor's base speed is 850 rpm & the extended speed is 2600 rpm. Usually parts are cut on the operator's side in forward & < 50% of the time they cut on the back side in reverse, but they do run the part being cut in both forward & reverse & there definitly is a difference in accel & decel time in forward & reverse. The spindle is started & stopped frequently for tool insert changes. I wasn't aware the accel & decel time was for the base speed only. I'll need to get over there & look at the time from zero to base speed in both ranges.

Are you very familiar with the DC 300 drives?? If you are there other parameters for accelerating to & decelerating from extended speed??

Thanks again for the information, Jerry.

Hi Jerry,

I am not familiar with the DC 300 drives, just drives in general, mostly VFD but also some DC drives. I would guess the relationship is linear but just a guess. Good Luck!

Shawn