Configuration instructions
3.2 Startup class
3RW44 soft starters
Manual, 03/2017, NEB535219502000/RS-AB/008
21
3.2
Startup class
To achieve the optimum soft starter design, it is important to know and take into account the
starting time (startup class) of the application. Long starting times mean a higher thermal
load on the thyristors of the soft starter. 3RW44 soft starters are designed for continuous
operation under normal starting conditions (CLASS 10), an ambient temperature of 40 °C,
and a fixed switching frequency. You will also find these values in chapter Technical data of
the power unit (Page 259). If deviations from this data occurs, the starters may need to be
overdimensioned.
Selection criteria
Note
You must select the size of your SIRIUS 3RW44 soft starters according to the rated motor
current (rated current
soft starter
≥
rated motor current).
Note
For the correct dimensioning of soft starters for motors with high starting current ratios
(typically I/I
e
≥ 8), we recommend our Simulation Tool for Soft Starters (STS) or Siemens
Technical Assistance: Phone: +49 911 895-5900, e-mail: technical-