Siemens SIRIUS 3RW44 User Manual page 106

Device Functions
Stopping time
Stopping mode: DC braking
DC braking torque
6-14
The stopping time determines how long the braking torque should be applied to
the motor. The braking time should be long enough to bring the load to a
complete standstill.
To achieve a sufficient braking effect until standstill, the centrifugal mass (J) of
the load should not exceed that of the motor. The stopping time should be long
enough for the motor to come to a standstill. The soft starter has no standstill
recognition; if required, this must be accomplished using external measures.
Note
The real stopping time can vary during braking processes when the combined
braking function is applied.
Motor
torque
M
M
Nominal operation
DC braking torque
Dynamic
braking torque
Motor
braking torque
Figure 6-8: Combined braking
If the DC braking function is selected, the stopping time and DC braking torque
parameters can be set on the starter. With this braking type, one output of the
soft starter must be switched over to DC braking to control an external braking
contactor. Please refer to Chapter 9 for circuit suggestions.
The optimum parameters must be adjusted on the machine under appropriate
load conditions.
The height of the DC braking torque determines the brake force of the motor.
Stop command
at soft starter
Stopping time
Time (t)
s
SIRIUS 3RW44 manual
GWA 4NEB 535 2195-02 DS 06