Siemens Sinamics G120 Series Parameter Manual page 145

p1234[0...2] DC braking start frequency / DC brk. start freq
PM240 Access level: 2
Quick comm. NO
Can be changed: C, U, T
Min
0.00 [Hz]
Description: Sets start frequency for DC braking.
When an OFF1 or OFF3 command is received by the drive, the output frequency starts to ramp to 0 Hz.
When the output frequency reaches the value set in start frequency of DC braking P1234, the drive injects a DC
braking current P1232 for the time duration set in P1233.
p1236[0...2] Compound braking current / Compound brk. cur.
PM240 Access level: 2
Quick comm. NO
Can be changed: C, U, T
Min
0 [%]
Description: Defines DC level superimposed on AC waveform after exeeding DC-link voltage threshold of compound braking.
The value is entered in [%] relative to rated motor current (P0305).
If p1254 = 0 :
Compound braking switch-on level
otherwise :
Compound braking switch-on level
The Compound Brake is an overlay of the DC brake function with regenerative braking (effective braking at the
ramp) after OFF1 or OFF3. This enables braking with controlled motor frequency and a minimum of energy
returned to the motor. Through optimization of the ramp-down time and the compound braking an efficient braking
without additional HW components is possible.
Dependency: Compound braking depends on the DC link voltage only (see threshold above).
This will happen on OFF1, OFF3 and any regenerative condition.
It is disabled, when:
• DC braking is active
• Flying start is active
• Vector mode (SLVC, VC) is selected
Notice: Increasing the value will generally improve braking performance; however, if you set the value too high, an overcur-
rent trip may result.
If used with dynamic braking enabled as well compound braking will take priority.
If used with the Vdc max controller enabled the drive behaviour whilst braking may be worsened particularly with
high values of compound braking.
Compound braking does not work when the drive is in vector control.
Note: P1236 = 0 means that compound braking is not activated.
© Siemens AG 2007 All Rights Reserved
SINAMICS G120 Control Units CU240S, Edition 05/2007
P-Group: -
Active: YES
Max
650.00 [Hz]
P-Group: -
Active: YES
Max
250 [%]
= ⋅
U 1.13
DC_Comp
= ⋅
U 0.98 r 1242
DC_Comp
Parameters
List of Parameters
Data type: Floating Point
Data set: DDS
Factory setting
650.00 [Hz]
Data type: Unsigned16
Data set: DDS
Factory setting
0 [%]
⋅ = ⋅ ⋅
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