Compound Braking - Siemens SINAMICS G120 Operating Instructions Manual

Setting functions
8.7 Application-specific functions
8.7.3.3

Compound braking

Typical applications for compound braking include:
● Centrifuges
● Saws
● Grinding machines
● Horizontal conveyors
For these applications, the motor is normally operated with a constant speed, and is only
braked down to standstill after longer periods of time.
Principle of operation
Figure 8-23
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 inverter 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
272
Motor brakes with and without active compound braking
Converter with the CU250S-2 Control Unit (vector)
Operating Instructions, 06/2013, FW V4.6, A5E31759476B AB