Siemens SIRIUS 3RW55 - Dynamic DC Braking Without Contactor

Functions
7.3 Run-down
SIRIUS 3RW55 soft starter
104 Manual, 08/2018, A5E35630887002A/RS-AB/002
7.3.6
Dynamic DC braking without contactor
Operating principle
The braking process takes place in two phases. In the first phase, the motor is braked by
controlled DC braking pulses. In the second phase, the motor is brought to a standstill with a
constant DC braking. Use the DC braking function to achieve a uniformly long braking time.
In order to guarantee a secure premature cancelation of the braking process, an external
motor standstill detection can be used to detect the motor standstill before the stopping time
has elapsed. To do this, activate the input action "Motor standstill" or the associated bit in the
process image output "Motor standstill".
Application
● If applications with small mass inertias (centrifugal masses) are to be stopped
(J
load
≤ J
motor
).
● If an electrical braking process without braking contactor is required.
Diagram
①
DC braking torque
②
Dynamic braking torque
t
1
Stop command on soft starter
t
1
... t
2
Stopping time
M
e
Rated torque