Siemens SINAMICS S120 Equipment Manual page 211

Table 5- 58 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
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.
If the set switch-on ratio is exceeded, the "MUL - Overload message" LED will be activated
and at the same time the centralized fault indication will be triggered at terminal -X2:4/5,6.
The fault message can be used by a higher-level controller to ensure timely shutdown,
thereby preventing damage to the connected braking resistor.
Monitoring is carried out solely on the basis of the switch-on ratio that has been set on
potentiometer PD, which means that the actual temperature of the braking resistor is not
monitored.
S120 Cabinet Modules Equipment Manual
Manual, (GH5), 10/2008, A5E00427098A
Switch Comments
position
1 774 V is the default factory setting. With line voltages of between 380 and 400
V, the response threshold can be set to 673 V to reduce the voltage stress on
2
the motor and converter. 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 (1,070/1,158)² = 0.85.
The maximum possible braking power is, therefore, 85%.
Meaning
0 (open) = Monitoring active
1 (closed) = Monitoring disabled
CAUTION
Cabinet Modules
5.7 Central Braking Modules
211