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Speed and Torque
The speed−torque curves for a motor show the safe operating area, speed limit area
and intermittent operating area. These curves are used to determine the maximum
useable speeds with known torque requirements.
If operating within the continuous area, the motor's thermal limit will not be exceeded.
If operated within the intermittent area (extended operation in this area will cause
the motor to overheat), the operating time in this area must be limited to prevent
overheating.
Brushless servo motors are rated at an ambient of 25 degrees C and a temperature
rise of 130 degrees C. For operation at 40 degrees C derate by 8%.
WARNING: Severe burn is possible. The motor winding can reach 155 degrees C during
operation. Do not touch motor without protective clothing or allow sufficient
time for motor to cool to avoid burns.
Peak current
capability of the motor
Intermittent Area
Continuous Area
Continuous current
required by the application
Holding Brake
Holding brakes are offered as options for servo motors. These brakes are designed
to hold the motor shaft at 0 RPM (to rated brake holding torque). The purpose of
the holding brake is to hold the servo axis when power to the machine is turned off.
The holding brake uses the "electric release" principle. Applying 24VDC to the brake
causes the brake to release and lets the motor shaft rotate. Loss of power causes the
brake to hold the motor shaft. The machine controller controls the holding brake. This
ensures correct On and Off switching sequence.
WARNING: The holding brake alone does not guarantee personnel safety. Use structural
measures such as protective fences or a second brake to secure personnel
safety.
Caution:
Do not use the holding brake to stop motion. This will cause premature brake
wear and failure. The brakes are not designed to stop a rotating load. The servo
drive inputs should always be used to stop motor shaft rotation.
2-7
Figure 2-6 Typical Speed−Torque Curve
Continuous Torque at speed
for the application
Required speed for
the application
Maximum Motor Speed Capability
MN1240
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