Siemens Sirius 3RW44 System Manual page 78

Device functions
Typical applications for torque control
6-6
Notice
The torque generated in the motor and controlled by the soft starter can at no
time be higher than the value of a similar direct start at the same speed.
Motor
torque (M)
Nm
M
Direct on-line starting
(maximum torque
that can be generated)
Parameterizable
limiting torque
M
Nom
Parameterizable
start voltage
M
1
Soft start
Torque-controlled and limitted
M
2
Soft start
Torque-controlled
3 M
Load (e. g. Fan)
Fig. 6-3: Function principle of torque control
Suitable for all applications, especially in cases where a homogeneous and
smooth run-up is required. For machines requiring a breakaway pulse (inverse
load response, e.g. in mills or crushers), the breakaway pulse must be set as
described in chapter 6.2.3. The torque control+current limiting (M+current
limiting) starting mode is recommended for heavy starting (refer to chapter 6.2.4
Current limiting in combination with voltage ramp or torque control starting
mode).
1
Acceleration
2
torque
3
Parameterizable
ramp time
Time (t)
s
Motor has run up and is
in nominal operation (n ).
Nom
The runup is detected and the
bypass contacts close.
SIRIUS 3RW44 manual
GWA 4NEB 535 2195-02 DS 01