Siemens SINAMICS S120 Manual page 245

Only actuate the threshold switch when the device is switched off
The threshold switch must only be switched over when the cabinet unit is disconnected
from the power supply and the DC link capacitors are discharged.
Table 5- 46 Response thresholds of the Braking Module
Rated voltage Response
threshold
380 ... 480 V 774 V
673 V
500 ... 600 V 967 V
841 V
660 ... 690 V 1158 V
1070 V
S3 braking resistor monitoring
Table 5- 47
Function
Braking resistor
monitoring
When monitoring is activated, the switch-on ratio (ratio between ON time and OFF time) set
for the braking resistor on potentiometer "PD" is evaluated electronically.
Cabinet Modules
Manual, 03/2013, A5E03263538A
WARNING
Switch Comments
position
1 774 V is the default factory setting. With line voltages of between 380 V and
400 V, the response threshold can be set to 673 V to reduce the voltage stress
2
on the motor and drive. This does, however, reduce the possible braking
power with the square of the voltage (673/774)² = 0.75.
The maximum possible braking power is, therefore, 75%.
1 967 V is the default factory setting. With a line voltage of 500 V, the response
threshold can be set to 841 V to reduce the voltage stress on the motor and
2
converter. This does, however, reduce the possible braking power with the
square of the voltage (841/967)² = 0.75.
The maximum possible braking power is, therefore, 75%.
1 1158 V is the default factory setting. With a line voltage of 660 V, the response
threshold can be set to 1070 V to reduce the voltage stress on the motor and
2
converter. This does, however, reduce the possible braking power with the
square of the voltage (1070/1158)² = 0.85.
The maximum possible braking power is, therefore, 85%.
Braking resistor monitoring S3
Meaning
0 (open) = Monitoring active
1 (closed) = Monitoring disabled
Cabinet Modules
5.7 Central Braking Modules
243