Bimba STP-10 - Manual (Page 32)

STP-10 Hardware Manual
32
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 curves showing the maximum thrust versus speed for
each motor at commonly used power supply voltages. Please refer to these curves which demonstrate 100% duty cycle 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 measure-
ments 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.