Siemens SIRIUS 3RW44 - Coasting down; Stopping Modes

Device Functions
SIRIUS 3RW44 manual
GWA 4NEB 535 2195-02 DS 06
6-11
6.3 Stopping Modes
Different stopping functions can be selected thanks to the large numbers of
applications for which the SIRIUS 3RW44 soft starter can be used. The motor
stop can be set optimally according to application and deployment.
If a start command is output during the stopping procedure, this procedure is
aborted and the motor is started up again using the specified starting mode.
Note
If guided stopping is selected as stopping mode (soft stop, pump stop or
braking), it may be necessary to select a larger dimensioned branch (soft starter,
wiring, branch protection elements and the motor), since the current exceeds the
rated motor current during the stopping procedure.
Figure 6-6: Stopping modes in general
6.3.1 Coasting Down
Coasting down means that when the on command to the soft starter is removed,
the energy feed to the motor via the soft starter is interrupted. The motor will
coast down freely, only driven by the mass reactance (centrifugal mass) of the
rotor and the load. This is also referred to as a natural run-down. A larger
centrifugal mass means a longer coasting-down.
Typical applications for coasting down
Coasting down is used for loads with no special requirements in terms of
stopping behavior, e.g. large fans.
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Motor
speed
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Stop command
at soft starter
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Coasting down
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Torque-controlled
stopping mode
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DC brakin
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Time (t)
s