SIRIUS 3RT2 contactors/contactor assemblies 
  2.4 Configuration 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
129 
Design 
The contactors are supplied as complete units with integrated coil electronics and are fitted 
as standard with varistors for damping opening surges in the coil. The opening delay is 
consequently 2 ms to 5 ms longer than for standard contactors. 
 
 
Note 
uxiliary switch blocks are fitted on contactors with an electronic drive in the same way as on 
basic versions. 
 
Mounting instruction  
These contactor versions of size S0 are approved for side-by-side mounting at ambient 
temperatures of up to 70 °C. 
 
Coupling relays for railway applications (sizes S00 and S0) 
These contactors have an extended operating range of 0.7 to 1.25 x U
S
.  
Design 
The magnet coils of the contactor relays and motor contactors with an extended operating 
range in size S00 are connected to suppressor diodes (3RT20..-2K, 3RT2017-2K.4). The 
magnet coils of the motor contactors with an extended operating range in size S0 are 
connected to varistors (3RT202.-2K.40). No additional series resistor is required in either 
case. 
 
 
Note 
Coupling relays for railway applications cannot be expanded by means of auxiliary switch 
blocks. 
 
Mounting instruction  
A clearance of 10 mm must be observed when using side-by-side mounting at an ambient 
temperature > 60 °C < 70 °C.