30
STR2 Hardware Manual
920-0059A
4/20/2012
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 recommended motors in our lab and provided a table and sev-
eral curves showing the maximum duty cycle versus speed for each motor at commonly used
power supply voltages. Please refer to this information 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.
60
80
100
120
140
160
180
200
oz-in
12 VDC
24 VDC
48 VDC
Connection:
series
Drive settings: 2.2A/phase, 20000 steps/rev
HT23
‐
601,
STR2
0
20
40
60
0
10
20
30
40
50
rps
