Re: [CAD_CAM_EDM_DRO] max. Servo motor voltage ??

motovidia wrote:

>With steppers your p/s voltage should be between 3 to 25x the rated
>motor voltage. What is the equivalent rating for servo's ?
>
>

There is no simple formula. With a motor rating point, say 24 V at 3600
RPM, you can then
make some calculations. Also, if you are given the motor's Kv (velocity
constant) that is
a rating point of Volts/1000 RPM. First, determine the fastest rapid
feed rate you want, and
figure out what leadscrew RPM you need to get that. Second, convert
that to motor RPM
depending on the belt reduction, if any, that is being used.

Example:

120 IPM feedrate and a 5 TPI screw gives 120 * 5 = 600 RPM. Assuming a
2:1 belt reduction, the
motor would be turning 1200 RPM. With the above motor, it would only
need 24/3 = 8 V
to get 1200 RPM at lo load. Now, if the motor had a peak current rating
of 10 Amps, and
a terminal resistance of 2.5 Ohms (this is a hard thing to measure
accurately on brush motors),
you'd have 25 V of IR drop in the windings, so add that to the 8 V and
you get 33 V at the
motor terminals. You need to add a bit more for drop in the servo amp.
Probably at least
10 V would be a good start. So, now, it looks like you need 43 V
minimum to be sure you
could get your full 120 IPM under load. The servo amp should see to it
that the motor
never gets the full 43 V across it, especially at stall, so it should
not really exceed the
manufacturer's ratings.

Jon