Siemens SIRIUS 3RT Manual page 177

Characteristic curve: Contact service life of the auxiliary contacts
The contact service life is dependent on the breaking current. This requires operating
mechanisms that switch at random, i.e. not synchronized with the phase angle of the supply
system.
The characteristic curves apply to:
● 3RH1921 auxiliary switch blocks for contactors of sizes S6 to S12
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
Manual, 09/2017, A5E03656507120A/RS-AE/006
6.16 Contact service life of auxiliary and main contacts
Configuration
177