Compound Braking - Siemens SINAMICS G120 Operating Instructions Manual

Functions
8.9 Application-specific functions
8.9.2.3

Compound braking

Compound braking is typically used for applications in which the motor is normally operated
at a constant speed and is only braked down to standstill in longer time intervals, e.g.:
● Centrifuges
● Saws
● Grinding machines
● Horizontal conveyors
Principle of operation
Figure 8-12
Compound braking prevents the DC link voltage increasing above a critical value. The
inverter activates compound braking depending on the DC link voltage. Above a DC link
voltage threshold (r1282), the inverters 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 only active in conjunction with the V/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
208
Motor brakes with and without active compound braking
Operating Instructions, 01/2011, FW 4.4, A5E02999804A AB
SINAMICS G120C Inverter