SIRIUS 3RT2 contactors/contactor assemblies 
  2.7 Accessories 
SIRIUS Innovations 
System Manual, 01/2011, A8E56203870002-03 
171 
The following surge suppressors are available for the 3RT2/3RH21 contactors: 
Table 2- 28  Overview - Surge suppressors 
With LED  Without LED 
Surge suppressor 
Size S00  Size S0  Size S00  Size S0 
Suppression diode  3RT2916-1L  ---  3RT2916-1DG00  --- 
Diode combination: 
Suppression and 
Zener diode 
---  3RT2926-1M  3RT2916-1E  3RT2926-1E 
Varistor  3RT2916-1J  3RT2926-1J  3RT2916-1B  3RT2926-1B 
RC element  ---  ---  3RT2916-1C  3RT2926-1C 
 
2.7.3.2  Configuration 
Selection aid 
The table below compares the effects of the different surge suppressors and specifies the 
applications to which they are most suited.  
Table 2- 29  Mode of operation and preferred applications of surge suppressors 
Surge suppressor  Suitable for 
Control 
voltage 
Overvoltage
is limited ... 
Effect  Advantages/disadvantages  Preferred 
application 
Advantag
es 
  Simple 
implementation 
  Reliable 
  Non-critical 
dimensioning 
  Low induction 
voltage 
Noise 
suppress
ion/freew
heel 
diode 
 
DC  To 0.7 V 
  OFF-delay 
becomes 
considerably 
longer (6 to 10 
times) 
  With contactors 
of size S0 or 
larger, "2-stage 
drop-out"
1)
 
cannot be 
excluded 
Disadvan
tages 
  Long drop-out delay 
  Only suitable for 
size S00 
Instable control 
commands/con
trol supply 
voltage 
Advantag
es 
  Non-critical 
dimensioning 
Diode 
combi- 
nation: 
Noise 
suppress
ion and 
Zener 
diode 
 
DC  To Zener 
voltage 
  OFF-delay 
becomes 
longer (2 to 6 
times) 
  A 2-stage drop-
out no longer 
occurs 
Disadvan
tages 
  Attenuation only 
above U
ZD
 (10 V) 
EMC-critical 
components in 
the vicinity