Siemens SINAMICS G120C DP

8.21.3 Compound braking
Overview
Compound braking is suitable for applications in which the motor is normally operated at a
constant speed and is only braked down to standstill in longer time intervals.
Typically, the following applications are suitable for compound braking:
• Centrifuges
• Saws
• Grinding machines
• Horizontal conveyors
Compound braking is not permissible for applications with suspended loads, e.g. lifting
equipment/cranes all vertical conveyors.
Function description
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Figure8-65 Motor brakes with and without active compound braking
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 "󹪞ying restart" function is active
• DC braking is active
• Vector control is selected
Advanced commissioning
8.21Electrically braking the motor
SINAMICS G120C Converters
Operating Instructions, 02/2023, FW V4.7 SP14, A5E34263257B AK 331