Siemens SINAMICS G120 List Manual page 358

2 Parameters
2.2 List of parameters
p3846[0...n] Friction characteristic record ramp-up/ramp-down time / Frict rec t_RU/RD
Access level: 2
Can be changed: T
Unit group: -
Min
0.000 [s]
Description: Sets the ramp-up/ramp-down time of the ramp-up/ramp-down function generator to automatically record the friction
characteristic.
The drive is accelerated from standstill (setpoint = 0) up to the maximum speed/velocity (p1082) in this time.
Dependency: Refer to: p3845
p3847[0...n] Friction characteristic record warm-up time / Frict rec t_warm
Access level: 2
Can be changed: T
Unit group: -
Min
0.000 [s]
Description: Sets the warm-up time.
For an automatic trace (record) to start, the highest selected speed (p3829) is approached and this time is held. After
this, the measurement is started with the highest speed.
Dependency: Refer to: p3829, p3845
p3856[0...n] Compound braking current / Compound I_brake
PM240 Access level: 3
Can be changed: U, T
Unit group: -
Min
0.00 [%]
Description: Compound braking current is used to define the amount of DC current that is produced on stopping the motor during
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 in the following cases:
- DC braking activated (p1230, r1239).
- motor is still not magnetized (e.g. for flying restart).
- vector control parameterized (p1300 >= 20).
- synchronous motor used (p0300 = 2xx).
Notice: 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 p1280).
Note: The parameter value is entered relative to the rated motor current (p0305).
Compound braking is de-activated with p3856 = 0%.
358
Calculated: -
Scaling: -
Unit selection: -
Max
999999.000 [s]
Calculated: -
Scaling: -
Unit selection: -
Max
3600.000 [s]
Calculated: -
Scaling: PERCENT
Unit selection: -
Max
250.00 [%]
SINAMICS G120 Control Units CU240B-2/CU240E-2
Data type: FloatingPoint32
Dyn. index: DDS, p0180
Func. diagram: 7010
Factory setting
10.000 [s]
Data type: FloatingPoint32
Dyn. index: DDS, p0180
Func. diagram: 7010
Factory setting
0.000 [s]
Data type: FloatingPoint32
Dyn. index: DDS, p0180
Func. diagram: -
Factory setting
0.00 [%]
List Manual (LH11), 01/2016, A5E33839529