Drive/motor heating, 28 stm17 hardware manual – Applied Motion STM17C-3CE User Manual
Page 28
Drive/Motor Heating
Step motors convert electrical power from the driver into mechanical power to move a load. Because step motors are
not perfectly efficient, some of the electrical power turns into heat on its way through the motor. This heating is not so
much dependent on the load being driven but rather the motor speed and power supply voltage. There are certain
combinations of speed and voltage at which a motor cannot be continuously operated without damage.
We have characterized the STM17 Drive+Motors in our lab and provided curves showing the maximum duty cycle
versus speed for each size at commonly used power supply voltages. Please refer to these curves when planning your
application.
Please also keep in mind that a step motor typically reaches maximum temperature after 30 to 45 minutes of operation.
If you run the motor for one minute then let it sit idle for one minute, that is a 50% duty cycle. Five minutes on and five
minutes off is also 50% duty. However, one hour on and one hour off has the effect of 100% duty because during the
first hour the motor will reach full (and possibly excessive) temperature.
The actual temperature of the motor depends on how much heat is conducted, convected or radiated out of it. Our
measurements were made in a 40°C (104°F) environment with the motor mounted to an aluminum plate sized to provide
a surface area consistent with the motor power dissipation. Your results may vary.
Please use the curves below, which show the motor body temperature, to determine the maximum duty cycle of the
Drive+Motor under various conditions.
STM17S-1AN Max Duty Cycle vs Speed
1.8 Amps @ Ambient of 40°C
80 x 80 x 6(mm) Aluminum Plate
0
20
40
60
80
100
0
10
20
30
40
50
Speed (RPS)
% Duty Cycle
12V Duty Cycle
24V Duty Cycle
48V Duty Cycle
STM17S-1AN Temperature vs. Speed
1.8 Amps @ Ambient of 40°C
80 x 80 x6(mm) Aluminum Plate
0
20
40
60
80
100
120
140
160
0
10
20
30
40
50
Speed (RPS)
Temperature (C)
12V Temp
24V Temp
48V Temp
28
STM17 Hardware Manual
920-0034 rev A
9/30/2010