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4.1.5
Brake concepts
For rotating axes without any restriction on the angle of rotation < 360°, brake concepts are
only available that are individually designed for the drive.
The following aspects are decisive for a brake concept for drive systems based on segment
motors:
● High moment of inertia
● High speeds
● Bearing design
If you need to stop the drive, for example when the power fails, the following
interrelationships make it more difficult to select a suitable brake concept:
Overvoltage protection using the VPM Voltage Protection Module
For a counter EMF Û > 820 V, overvoltage protection can be implemented using VPM
modules. However, the switch-on duration of the VPM is limited to 120 s for the rated and/or
short-circuit current of the VPM.
Generally, drives operating at high speeds and with high moments of inertia cannot be
stopped within 120 s using armature short circuiting of the VPM module.
Switching in short-circuit braking resistors
As a result of the high rated power of the drive, using short-circuit braking resistors requires
a lot of space.
Further, the drive speed range must be carefully coordinated. As a consequence, the braking
characteristic can only be optimized point by point.
Mechanical brake
If braking in the event of a power failure constitutes a critical operating point, then it may
make sense to use a mechanical brake.
Examples of critical operating points for an armature short-circuit include:
● Cooling of the segment motor must be maintained so that it does not overheat.
● For a drive with hydrostatic bearings or air bearings, the bearing fluid must be pumped
until the drive comes to a standstill so that the bearing system is not mechanically
damaged.
Contact the Application and Mechatronic Support group of Siemens to obtain in-depth advice
to obtain a customized, best possible solution for braking your drive system.
1FW68 radial segment motors
Configuration Manual, 04/2017, 6SN1197-0AE02-0BP1
Motor components and options
4.1 Motor components
75
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