Bob Engelhardt wrote:

I'm using a dc motor & a servo amp to run the lead screw on my lathe.
The servo amp is an Advanced Motion Controls model 25A20:
http://www.a-m-c.com/download/datasheet/25a20i.pdf

I'm setting the speed with an analog input on pins 4 & 5 ("REF"). This
is described as "Differential Reference Input (±10 V Operating Range,
±15 V Maximum Input)". My assumption was that this voltage could go to
15v, but beyond 10v there would be no additional effect on the output. I
was wrong. The output continues to increase as REF increases to 15v. I
didn't check if it was linear in the 10 - 15v range.

The question is: is it a bad idea to use it in the 10-15v range? It
might be useful to have the extra output in certain special cases. E.g.
rapid reverse.

Thanks,
Bob

PS - is there another NG that might be better posted to?


The standard control voltage used are +/- 10 vdc. The 15 volt spec. is
the maximum that the servo amp can handle. The input voltage vs. the
speed of the drive is determined by the gain of the drive. The output
of the drive is determined by the hp rating of the drive itself and the
asssociated servo motor. At the full 10 volt +- rating you should be
operating the drive at near the full hp rating of the drive and motor.
This is accomplished by adjusting the gain of the drive and at the same
time measuring the output power to the motor or input current to the
drive and checking it with the mfgr specs.

have fun..


John