Siemens SINAMICS S120 Function Manual page 194

Basic functions
6.8 Armature short-circuit brake, internal voltage protection, DC brake
Internal armature short-circuit braking (booksize)/DC brake
The "Internal armature short-circuit braking" function short-circuits a half-bridge in the power
unit (Motor Module) to control the motor power consumption, thus braking the motor.
With the "DC brake" function, a DC current is applied after a demagnetization time that
brakes the motor or maintains it at standstill.
The two functions can be initiated either as a "normal" operating mode via BI:p1230 (signal =
1) or as a presettable fault response. The function is initiated when the pulses are canceled.
The fault response is assigned the second-highest priority (second only to OFF2).
Before the function is initiated, a check is made as to whether the following conditions are
met (otherwise fault F7906 is issued):
● Permanent-magnet synchronous motor (internal armature short-circuit)
● Induction motor (DC brake)
When the motor type is changed (in p0300), these prerequisities are also checked, which
may result in the cancellation of all alarms whose parameters have been changed (p2100 /
p2101) and which have this function as a response. In parameter p0491 ("Motor encoder
fault response"), the default response OFF2 is entered again if the response "Encoder fault
results in internal armature short-circuit brake / DC brake" was previously entered there.
Alternatively, all encoder faults 3yxxx, y=1,2,3 as well as F7412 (commutation angle
incorrect (motor model)) provide the option of selecting the function as an alternative fault
response. The user can also use parameter p0491 to select the function as a fault response
for faults of the motor encoder.
The user can use the parameters p2100 and p2101 to set this function as a fault response
for individual alarms.
It may be desired to brake the drive without field/rotor orientation even without the
occurrence of a fault, e.g. to brake in non-regenerative mode.
NOTICE
Especially in servo control mode without an encoder it is not ensured whether the operation
can be continued after the internal armature short-circuit or the DC brake are no longer
applied. This applies both to the DC braking (induction motor) and to the internal armature
short-circuit (synchronous motor). If the motor cannot continue to run after the end of the
internal armature short-circuit or the DC brake, a fault with OFF2 response is issued.
Internal armature short-circuit (synchronous motors)
The internal armature short-circuit is activated via the parameter p1231 = 4. It can be
triggered via an input signal p1230 (signal = 1) or a fault response.
Both types of activation are equivalent and are no longer distinguished during the braking
operation, in contrast to DC brake (see paragraph "DC brake").
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The firmware of the Motor Module supports the internal armature short-circuit (r192.9=1).
If the Motor Module firmware does not support the internal armature short-circuit, any
activation attempt will generate fault 1303 (DRIVE-CLiQ component does not support
requested function) with fault value 101 (Motor Module does not support internal
armature short-circuit).
The parameters of the DC brake must be carefully assigned (p1232, p1233, p1234).
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4
Drive Functions