SIRIUS 3RT2 contactors/contactor assemblies   
2.8 Technical data 
  SIRIUS Innovations 
230  System Manual, 01/2011, A8E56203870002-03 
2.8.1.2  Contact service life of auxiliary and main contacts 
 
Contact service life of auxiliary contacts 
This requires operating mechanisms that switch at 
random, i.e. not synchronized with the phase angle of the 
supply system. 
The contact service life is essentially dependent on the 
breaking current. 
The characteristic curves apply to: 
  Integrated auxiliary contacts on 3RT20 
  Auxiliary switch blocks 3RH2911-., 3RH2921-. for 
contactors size S00 and S0 
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Legend for diagram: 
I
a
 = Breaking current 
I
e
 = Rated operational current 
1) 
  Integrated auxiliary contacts (size S0) and contacts in the auxiliary switch blocks for contactors (size S00 and S0): 6 A 
2) 
  Contacts in auxiliary switch blocks for contactors size S00 and S0:4 A 
 
Contact service life of main contacts   
Size S00 The characteristic curves show the contact service life 
of contactors when switching resistive and inductive 
three-phase loads (AC-1/AC-3) as a function of 
breaking current and rated operational voltage. This 
requires operating mechanisms that switch at 
random, i.e. not synchronized with the phase angle of 
the supply system. 
The rated operational current I
e
 in accordance with 
utilization category AC-4 (breaking of 6 times the 
rated operational current) is specified for a contact 
service life of at least 200,000 operating cycles. 
If a shorter contact service life is sufficient, the rated 
operational current I
e
/AC-4 can be increased. 
In the case of mixed operation, i.e. if normal switching 
operation (breaking of rated operational current in 
accordance with utilization category AC-3) is mixed 
with occasional inching (breaking of the multiple rated 
operational current in accordance with utilization 
category AC-4), the service life of the contacts can be 
calculated approximately using the following formula: 
 
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