Armature Short-Circuit Braking For Permanent-Magnet Synchronous Motors; Internal Armature Short-Circuit Braking - Siemens SINAMICS S120 Function Manual

Basic functions
7.12 Armature short-circuit, DC braking
Motor accelerates uncontrollably for pulling loads
For pulling loads, when DC braking is used, during the demagnetization time, the motor can
accelerate uncontrollably. This can result in severe injury or death. An additional supporting
mechanical brake is only closed after the demagnetization time - when the motor is already
rotating - and therefore does not prevent the motor from accelerating uncontrollably.
• Do not use DC braking for pulling loads.
7.12.1

Armature short-circuit braking for permanent-magnet synchronous motors

7.12.1.1

Internal armature short-circuit braking

With the internal armature short-circuit braking, the motor windings are short-circuited using
the Motor Module.
Requirement
● This function has been released for Motor Modules in the booksize and chassis formats.
● Short-circuit-proof motors (p0320 < p0323)
● One of the following motor types is used:
– rotating permanent-magnet synchronous motor (p0300 = 2xx)
– linear permanent-magnet synchronous motor (p0300 = 4xx)
● The maximum current of the Motor Module (r0209.0) must be at least 1.8x the motor
short-circuit current (r0331).
Note
Internal short-circuit braking despite power failure
If armature short-circuit braking should still be maintained despite a power failure, you
must buffer the 24 V power supply for the Motor Module. For this purpose, you can use
for example a dedicated SITOP unit for the Motor Module or a Control Supply Module
(CSM).
Setting
The internal armature short-circuit braking is set with p1231 = 4.
Activation
The function is activated and initiated if the signal source of p1230 is set to a "1".
340
WARNING
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
Drive functions