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6.6.4.2
Compound braking
Function description
Figure 6-68
Compound braking prevents the DC-link voltage increasing above a critical value. The
converter activates compound braking depending on the DC-link voltage. Above a DC-link
voltage threshold (r1282), the converter adds a DC current to the motor current. The DC current
brakes the motor and prevents an excessive increase in the DC-link voltage.
Note
Compound braking is possible only with the U/f control.
Compound braking does not operate in the following cases:
● The "flying restart" function is active
● DC braking is active
● Vector control is selected
NOTICE
Overheating of the motor due to compound braking
The motor will overheat if you use compound braking too frequently or for too long. This may
damage the motor.
● Monitor the motor temperature.
● Allow the motor to adequately cool down between braking operations.
● If necessary, select another motor braking method.
SINAMICS G120XA converter
Operating Instructions, 03/2019, FW V1.0, A5E44751205B AB
Motor brakes with and without active compound braking
Advanced commissioning
6.6 Motor control
299
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