Threshold Switch - Siemens SINAMICS G150 Operating Instructions Manual

Electrical installation
4.11 Other connections
4.11.15.3

Threshold switch

The response threshold at which the braking unit is activated and the DC link voltage
generated during braking are specified in the following table.
The threshold switch must only be used when the cabinet unit is switched off and the DC
link capacitors are discharged.
Table 4- 54 Response thresholds of the braking units
Rated voltage Response
threshold
380 ... 480 V 673 V
774 V
500 ... 600 V 841 V
967 V
660 ... 690 V 1070 V
1158 V
146
WARNING
Switch
position
1 774 V is the delivery condition setting. With line voltages of between 380 V
and 400 V, the response threshold can be set to 673 V to reduce the voltage
2
stress 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 delivery condition setting. With a line voltage of 500 V, the
response threshold can be set to 841 V to reduce the voltage stress on the
2
motor and 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 delivery condition setting. With a line voltage of 660 V, the
response threshold can be set to 1070 V to reduce the voltage stress on the
2
motor and 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%.
Comment
Converter cabinet units
Operating Instructions, 03/2012, A5E03263466A