Re: [CAD_CAM_EDM_DRO] Re: Power Supply and Capacitor Questions Help!!

Mariss Freimanis wrote:

>Jon,
>
>You might want to check your numbers. Kt is always 1.351 * Kv.
>
>

Right, you showed me that one a while ago. These numbers came right off
the original poster's question, and I didn't check them. And, then,
there is
something VERY wrong with these numbers! I was a bit surprised at
his Kt value, which would give 800 in-Lb at 20 Amps. That is a VERY
high torque motor. So, either his Kv or Kt is wrong.

His original description of the motor is as follows :

40 in/lb DC brush type servo motors that are
rated 40v/K at 2500 rpm 13.7 amps maximum current.

Later, he clarified it a bit as :

40 lb/in per 2500 rpm max and 13.0 continuous amps,
30 amps peak. 40 volts per k of rpm.

I took the 40 Lb/In to be the Kt, and the 2500 RPM as a separate
rating. But, 40 Lb-In/Amp is a huge torque, and clearly incompatible
with the Kv, which seems to be pretty clearly stated as 40 V per K RPM.
So, if the Kv seems like it has to be 40 V/KRPM, which sounds quite
ordinary for mid-size servo motors, then the Kt has to be
54 Oz-In/Amp, a FAR cry from the previous number. Ah, but
54 Oz-In * 13 A is 702 Oz-In, or 43.9 Lb-In. So, the whole line
is really the rating at 13 A. Now it is starting to make sense.

So, his continuous torque is 702 Oz-In, and his peak torque, at
20 A (the Gecko 320's limit) would be 1081 Oz-In, a VERY respectable
output, but not as wild as the numbers that I was coming up with
before.

Thanks for spotting my error in interpreting the somewhat confusing
ratings he gave.

Jon