Siemens SIRIUS 3RW40, Manual

Page: 61 / 212

Installation / mounting
8.5 Soft starter assembly with type of coordination 2
SIRIUS 3RW30 / 3RW40
Manual, 01/2010, 535 1995-02 DS01
61
8.5 Soft starter assembly with type of coordination 2
The SIRIUS 3RW40 soft starter has internal protection to prevent overloading of the
thyristors. The SIRIUS 3RW30 soft starter has no internal protection to prevent overloading of
the thyristors. The soft starter must always be dimensioned according to the duration of the
startup process and the desired starting frequency. If the feeder of the SIRIUS 3RW30 or
3RW40 soft starter is assembled accordingly with the feeder components recommended in
chapter Technical data [Page 121] (e.g. motor starter protector or LV HRC fuse), type of
coordination 1 is achieved. In order to achieve type of coordination 2, all thyristors must be
additionally protected against short-circuits by means of special semiconductor fuses (e.g.
SIEMENS SITOR). A short-circuit can occur, for instance, as a result of a defect in the motor
windings or in the motor's power supply cable.
Figure 8-3 Block diagram of a feeder with semiconductor fuses
L2
L1
L3
PE
3/N/PE~ 50 Hz 400 V
4
4
)
0
8
: 8 9
: 9 8
: 8 9
: 9
Note
For the component design, refer to chapter Technical data [Page 121].