SIRIUS 3RT2 contactors/contactor assemblies   
2.7 Accessories 
  SIRIUS Innovations 
180  System Manual, 01/2011, A8E56203870002-03 
Circuit diagram 
The diagram below shows an RC circuit with an RC element on the left, and an RC circuit 
with a varistor on the right. 
/
/
/
5B/
5B/
5B/
&B/
&B/
&B/
8
8
8
0
a
0
a
7 7 7 7 7 7
9B/
9B/
9B/
 
Figure 2-32  EMC suppression module, circuit diagram 
 
2.7.4.2  Configuration 
Selection aid  
When motors or various inductive loads are disconnected, a counter-source voltage is 
generated. This can lead to voltage peaks of up to 4,000 V with a frequency spectrum from 
1 kHz to 10 MHz and a rate of voltage variation from 0.1 to 20 V/ns.  
9
9
9
˩V W
 
Figure 2-33  Counter-source voltage without RC circuit 
Capacitive input to various analog and digital signals makes it necessary to suppress 
interference in the load circuit.