Siemens SIRIUS 3RW44 - Protection of the Soft Starter against Short Circuits

Installation, Connection and Branch Layout
SIRIUS 3RW44 System Manual
GWA 4NEB 535 2195-02 DS 04
3-9
3.3 Protection of the Soft Starter against Short Circuits
(Utilization class 2)
The soft starter has integrated thyristor protection against overloading. In the
event of a short circuit, e.g. due to a defect in the windings of the motor or a
short-circuit via the motor supply cables, this internal thyristor protection function
is not sufficient. Special semiconductor fuses, e.g. SITOR fuses from SIEMENS,
must be used for this purpose.
(Refer to Chapter 10.3 "Technical Data" for the fuse assignment)
Figure 3-7:Block diagram of branch with semiconductor fuses
U1 V1 W1
V2
U2W2
U1 V1 W1
W2 U2
V2
L1
L2
L3
PE
3/N/PE~ 50 Hz 400 V
Q1
G1
M1
F3
012_Standardschaltung und Sitor Zeichnung mit Bildern.vsd
Q11