Siemens SINAMICS G120 CU230P-2 HVAC Operating Instructions Manual page 232

Functions
7.9 Application-specific functions
Activating DC braking independent of the speed using a control command
DC braking starts independent of the motor speed, as soon as the control command for
braking (e.g. via DI3: P1230 = 722.3) is issued. If the braking command is revoked, the
inverter returns to normal operation and the motor accelerates to its setpoint.
Note: The value of p1230 is displayed in r1239.11.
DC braking when the motor is switched off
If the motor is switched off with OFF1 or OFF3, the inverter first brakes the motor along the
down ramp until the start speed for DC braking is reached, and then starts DC braking. The
motor is then switched into a torque-free condition (OFF2).
Note
In the following operating modes, it is possible that the motor is still rotating after DC braking.
This is the reason that in these operating modes "Flying restart (Page 237)" must be
activated:
• DC braking when the start speed for DC braking is fallen below
• Activating DC braking independent of the speed using a control command
• DC braking when the motor is switched off
The DC braking function can only be set for induction motors.
DC braking converts some of the kinetic energy of the motor and load into heat in the motor
(temperature rise). The motor will overheat if the braking operation lasts too long or the
motor is braked too often.
230
CAUTION
Frequency inverters with Control Units CU230P-2 HVAC, CU230P-2 DP, CU230P-2 CAN
Operating Instructions, 01/2011, FW 4.4, A5E02430659B AD