Re: Temperature of a brushed servo motor?

Tim,

I'm not sure if there is a universal maximum case temperature for
brush motors. A better way would be to temporarily insert a DC
ammeter in series with the motor. Monitor the motor current under
load and see if it chronically exceeds the maximum rated continuous
current for your motor. That would be the ultimate arbiter for the
maximum case temperature.

Next, you should move the DC ammeter to monitor supply current to the
drive. Note the current draw when the motor stopped. All but 50mA of
that current multiplied by your supply voltage goes up as heat watts
in your motor. Try decreasing GAIN and DAMPING to see if there is a
significant reduction in supply current draw. If there is, your
settings may have been too aggressive.

Mariss

--- In CAD_CAM_EDM_DRO@y..., "Tim Goldstein" <timg@k...> wrote:
> Just got the Z axis of Bridgett running with a permanent magnet
brushed DC
> servo motor and a Gecko G320. So far about 45 ipm on a -Z rapid
(lifting the
> table) without fiddling with the acceleration. A great improvement
over the
> stock 12 ipm and healthy increase over the 24 ipm I was getting
with the
> original stepper motor on a G210a.
>
> Question is, how hot is it acceptable to run a brushed DC servo
motor. I had
> the gain and dampening cranked a little high and the motor got hot
to the
> touch on the outer case (I would guess it was 120 - 130 F). I will
try it
> tomorrow with more appropriate settings, but I am wondering how hot
is it
> normal to run a brushed DC motor. I am guessing that if you keep
them at
> room temperature you are not driving them as hard as they are
designed.
>
> Tim
> [Denver, CO]