Siemens SIRIUS 3RW44 - Page 98

Device Functions
SIRIUS 3RW44 System Manual
6-6 GWA 4NEB 535 2195-02 DS 04
Note
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.
Figure 6-3:Function principle of torque control
Typical applications for torque control
Torque control is 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 "Breakaway Pulse in
Combination with the Voltage Ramp or Torque Control Starting Mode". 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 the Voltage Ramp or Torque Control Starting Mode").
5_03_Funktionsprinzip Drehmomentregelung .wmf
Time (t)
s
3
Parameterizable
limiting torque
M
M
Load (e.g. Fan)
1
Parameterizable
ramp time
1
2
Torque-controlled and limited
M
Soft start
2
3
Motor
torque (M)
Nm
Motor has run up and is
in nominal operation (n
Nom
).
The runup is detected and the
bypass contacts close.
Torque-controlled
Soft start
M
Direct on-line starting
(maximum torque
that can be generated)
N
Nom
Parameterizable
start voltage
Acceleration
torque