Weeeell, I'm going to take a wild stab.  Given any motor, the power consumed is
proportional to the voltage across it times the current through it (Whew, that
was hard).  The current through it is mainly related directly to the load on
it.  So your analysis has to be performed at max load.  Then the continuous
power must then be limitted in a static sense to heat rise capped by max ambient
temp.  Thus, having figured out what max power is, you divide out the known max
current, leaving you with max V.  BUT you must extend your figure based on a 30
second duty cycle (mor experiments).  On top of all of that, I am sure that
there is a maximum voltage that can be handled by the windings lest you have
insulation breakdown.  Then, we shoudl also take into account that there may be
hot spots in the armature, due to possibly manufacturing imperfections, or then
maybe from geometry.  If geometry contributes hot spots, you could use Finite
Element Analysis to study the heat distribution.

Or you could run it at the voltage you want and see if it quits.
Then run it to a voltage where it does quit.
Presumably an impending failure could be indicated by insulation breakdown, and
thus a change in inductance.  Try dissassembling the motor on occasion through
your tests and measuring the winding impedances.

Good luck (sorry you asked?)
Chris Eddy

"Plunkett, Dennis" wrote:

> 4/4/2000
>
> Simple question,
> what limits the maximum voltage that can be present on a brush type DC
> motor? (Magnet stator)