Applied-motion STM23C-3CE Manual de usuario descargar pdf (Pagina 44)

Drive/Motor Heating

Step motors convert electrical power from the driver into mechanical power to move a load. Because step motors

are not perfectly ecient, some of the electrical power turns into heat on its way through the motor. is heating

is not so much dependent on the load being driven but rather the motor speed and power supply voltage. ere

are certain combinations of speed and voltage at which a motor cannot be continuously operated without damage.

We have characterized the STM23 drive+motors in our lab and provided curves showing the maximum duty cycle

versus speed at commonly used power supply voltages. Please refer to these curves when planning your applica-

tion.

Please also keep in mind that a step motor typically reaches maximum temperature aer 30 to 45 minutes of opera-

tion. 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 ve minutes o is also 50% duty. However, one hour on and one hour o has the eect of 100% duty because

during the rst hour the motor will reach full (and possibly excessive) temperature.

e 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 STM23 drive+motors under various conditions.

STM23-2 Max Duty cycle vs Speed

5 Amps @Ambient of 40°C

Mounted to a 6.4" x 6.4" x .25" Aluminum Plate

100

0 10 20 30 40 50

Speed (RPS)

% Duty Cycle

12V Duty Cycle

24V Duty Cycle

48V Duty Cycle

65V Duty Cycle

Maximum Duty Cycle vs Speed

STM23 Hardware Manual

920-0021F

2/14/2012

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Applied-motion STM23C-3CE Manual de usuario Pagina 44