Siemens SINAMICS G120 Operating Instructions Manual page 131

DC braking after an OFF1 or OFF3 command has the following timing sequence:
1. Initially, the motor speed is reduced along the down ramp of the ramp-function generator
2. Once the motor speed reaches this threshold, the inverter interrupts the braking operation
3. The inverter then starts the actual DC braking by allowing a DC current to flow through
Parameterizing DC braking
Table 5- 51
Parameter
s
P003= 3
P1230
P1232=
P1233=
P1234=
P0347=
CU240S and CU240E Control Units, FW 3.2
Operating Instructions, 03/2009, A5E02440075B AA
until an adjustable speed threshold is reached.
using an internal OFF2 command until the motor is de-magnetized.
the motor. The magnitude and duration of the DC current can be set.
CAUTION
For DC braking, the kinetic energy of the motor and motor load is partially converted into
thermal energy. The motor can overheat if braking lasts too long or the drive must be
braked too frequently.
Parameters to enable and set DC braking
Description
User access level
3: Expert
Enabling DC braking using an external command
Enables DC braking via a signal that was used by an external source (BICO). The
function remains active as long as the external signal is active.
Current, DC braking (entered as a %)
Defines the strength of the direct current in [%] with respect to the rated motor current
(P0305)
Enable and duration of the DC braking for OFF1 or OFF3 command (entered in s)
Defines the duration of the DC braking in seconds after an OFF1 or OFF3 command.
P1233 = 0 deactivates DC braking for an OFF1 and OFF3 command.
Starting frequency of DC braking (entered in Hz)
Sets the speed threshold for the start of DC braking.
Demagnetizing time of the motor
The inverter calculates this value from the motor data during commissioning. Only
commissioning engineers, who have the appropriate experience, may change the
parameter values. The inverter can trip due to an overcurrent during DC braking if the
demagnetizing time is too short.
Functions
5.10 Technological functions
131