Startup Class - Siemens SIRIUS 3RW30 Manual

Configuration

11.2 Startup class

11.2 Startup class
To achieve the optimum soft starter design, it is important to know and take into account the
ramp-up time (startup class) of the application. Long ramp-up times mean a higher thermal
load on the thyristors of the soft starter. An appropriately dimensioned SIRIUS 3RW40 or
3RW44 soft starter should be chosen for startup processes with a motor ramp-up time > 20 s.
The maximum permissible ramp-up time for SIRIUS 3RW30 soft starters is 20 seconds.
SIRIUS soft starters are designed for continuous operation with normal starting (CLASS 10),
an ambient temperature of 40 °C, and a defined switching frequency (refer to chapter
Technical data [Page 121]). If other data applies, the starters may need to be calculated with a
size allowance. Using the SIEMENS Win-Soft Starter selection and simulation software, you
can enter your application data and requirements to obtain an optimally dimensioned soft
starter (refer to chapter Win-Soft Starter selection and simulation software [Page 162]).
CAUTION
Risk of property damage
When using the 3RW30: Make sure the selected ramp time is longer than the actual motor
ramp-up time. If not, the SIRIUS 3RW30 may be damaged because the internal bypass
contacts close when the set ramp time elapses. If the motor has not finished starting up, an
AC3 current that could damage the bypass contact system will flow.
When using the 3RW40: The 3RW40 has an integrated ramp-up detection function that
prevents this operating state from occurring.
Selection criteria
Note
You must select the size of your SIRIUS soft starters according to the rated motor current
(rated current
76
>= rated motor current).
soft starter
SIRIUS 3RW30 / 3RW40
Manual, 01/2010, 535 1995-02 DS01