SIRIUS 3RT2 contactors/contactor assemblies 
  2.7 Accessories 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
177 
RC circuit with a diode combination 
Equipping the contactor coil with an RC circuit featuring a diode combination, consisting of a 
diode and a Zener diode, also ensures that switching overvoltages will no longer occur; the 
diode combination limits the voltage to 10 V. 
 
 
Note 
The use of a diode combination does, however, extend the switch-off delay (the OFF time) 
by a factor of 2 to 6. 
 
The diagram below shows the voltage characteristic for the contactor relay magnet coil with 
an RC circuit from the graphic named "Disconnection of a contactor coil without RC circuit", 
with an appropriate diode combination. 
8
6S
>9@
W>PV@
 
Figure 2-31  RC circuit with a diode combination