Siemens 611 configurationmanual Deploying a holding brake

System integration 7.4 Braking concepts

Note

If armature short-circuiting braking is used without braking resistors, special contactors are required because the currents can be very high. - The release timing for the drive system must be taken into account.

3.Mechanical braking via braking elements:

The braking capacity must be dimensioned as highly as possible so that the rotating masses can be reliably braked at maximum kinetic energy.

Drawback: Depending on the speed, the relatively long response time of the brake controller may mean that the rotating mass continues to rotate for a while without being braked.

We recommend that all three measures be implemented together. Measures (2) and (3) are used as an additional protection here in case measure (1) fails: The short-circuiting of the stator works at high speeds to begin with and then the mechanical brake takes effect at lower speeds.

A list of recommended braking element manufacturers is provided in the appendix.

Deploying a holding brake

Due to cogging torques, torque motors can be pulled into a preferable magnetic operating position if the motor is no longer supplied with power from the drive. If the drive is already at a standstill, this can cause unexpected movements in up to a half magnetic pole pitch in both directions. To prevent any damage to the workpiece and/or tool, it may be advisable to use a holding brake.

Due to the lack of a mechanical self-locking system, a holding brake should be installed for inclined or horizontal drives without weight compensation so that the drive can be shut down and de-energized in any position.

WARNING

For inclined and horizontal axes, the load may be reduced in an uncontrolled manner if the center of gravity is outside the rotary axes when the system is disconnected from the power supply.

A holding brake may also be required if:

●The bearing friction does not compensate or exceed the cogging torques and unexpected movements result.

●Unexpected movements of the drive can lead to damage (e.g. a motor with a large mass also generates strong kinetic energy).

●Weight-loaded drives must be shut down and de-energized in any position.

1FW6 Built-in torque motors	113
Configuration Manual, 05/2009, 6SN1197-0AD00-0BP7