National Instruments NI ISM-7401, Руководство пользователя, Страница: 18 / 31

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NI ISM-7401/7402 User Manual
Figure 27. Torque Curve for NI ISM-7402
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 depends on the motor speed and power supply voltage
rather than load. There are certain combinations of speed and voltage at which you can
continuously operate a motor without damage.
The drive electronics of the NI ISM-7401/7402 also dissipate power. The heat produced by the
electronics is dependent on power supply voltage and motor speed.
The following figures show the maximum duty cycle versus speed for the NI ISM-7401/7402 at
commonly used power supply voltages. Refer to these curves when planning your application.
Use the charts depicting typical power dissipation when planning the thermal design of your
application.
A step motor typically reaches maximum temperature after 30 to 45 min of operation. Running
the motor for one minute and then idling for one minute results in a 50% duty cycle. Running
the motor for five minutes on and five minutes off also results in 50% duty. One hour on and one
hour off results in 100% duty because the motor will reach full and possibly excessive
temperature during the first hour of use.
Note
National Instruments tested the NI ISM-7401/7402 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 might vary.
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150
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To
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ISM-7402 Torque at 5A/phase
12V 24V 48V
0
50
0 10 20 30 40 50
Speed (RPS)