Installation manual

Accessories
7.2 Brake chopper (FSGX)
Power Module PM240
106 Hardware Installation Manual, 07/2009, A5E00807525B AD
Threshold switch
The response threshold at which the brake chopper is activated and the DC link voltage
generated during braking are specified in the following table.
WARNING
The threshold switch must only be used when the Power Module is switched off and the DC
link capacitors are discharged.
Table 7- 22 Response thresholds of the brake chopper
Rated voltage Respons
e
threshold
Switch
position
Comments
673 V 1
("top")
3 AC
380 V … 480 V
774 V 2
(bottom
")
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 on 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%.