Siemens CU240B-2 Parameter Manual page 323

p3856[0...n] Compound braking current / Compound I_brake
PM240 Access level: 3
Can be changed: U, T
Units group: -
Min
0.00 [%]
Description: Compound braking current is used to define the amount of DC current that is produced on stopping the motor dur-
ing U/f operation to further increase the DC brake function.
Compound braking is a superimposition of the DC brake function with regenerative braking (net braking along the
ramp) after OFF1 or OFF3. This permits braking with controlled motor frequency and minimum power input into the
motor. Effective braking without using additional hardware components is obtained by optimizing the ramp down
time and compound braking.
Dependency: The compound braking current is only activated if the DC link voltage exceeds the threshold value in r1282.
Compound braking does not operate:
- when DC braking is active (refer to p1230, r1239)
- as long as the motor is not magnetized (e.g. for flying restart)
- for vector control (p1300 >= 20)
- for synchronous motors (p0300 = 2xx)
Caution: Generally, increasing the braking current improves the braking effect when stopping the motor. However, if the
value is set too high, then the drive can be tripped (shut down) as a result of overcurrent or ground fault.
Recommendation: p3856 < 100 % x (r0209 - r0331) / p0305 / 2
Compound braking generates a current in the motor with a ripple manifesting the rotational frequency. The higher
the braking current is set, the higher the resulting ripple, especially when the Vdc(max) control is simultaneously
active (refer to to p1280).
Note: The parameter value is entered relative to the rated motor current (p0305). Compound braking is deactivated with
p3856 = 0%.
r3859.0 CO/BO: Compound braking status word / Compound Br ZSW
PM240 Access level: 3
Can be changed: -
Units group: -
Min
-
Description: Displays the status word of the compound braking.
Bit field: Bit Signal name
00 Compound braking active
Dependency: Refer to: p3856
© Siemens AG 2011 All Rights Reserved
SINAMICS G120 Control Units CU240B/E-2 Parameter Manual (LH11), 01/2011
Calculated: -
Scaling: PERCENT
Unit selection: -
Max
250.00 [%]
Calculated: -
Scaling: -
Unit selection: -
Max
-
1 signal
Yes
Parameters
List of Parameters
Data type: FloatingPoint32
Data set: DDS, p0180
Factory setting
0.00 [%]
Data type: Unsigned32
Data set: -
Factory setting
-
0 signal
No
FP
-
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