Siemens 3RH1921-1DA11 Auxiliary Contacts Terminal Protector

Siemens 3RH1921-1DA11 is a first-lateral auxiliary switch block for Sirius 3RT1 contactors that adds one normally open (NO) and one normally closed (NC) auxiliary contact to expand signaling and control in electrical circuits. The unit uses screw terminal connections for reliable field wiring and mounts laterally on the contactor via a dedicated mounting profile, enabling compact integration with the 3RT1 series. Electrical specifications include an insulation voltage of 500 V and surge voltage resistance up to 6 kV, suitable for standard control-circuit environments with Pollution Degree 3 ratings. The auxiliary contact block is engineered for high reliability, offering a mechanical service life of up to 10,000,000 switching cycles and an electrical endurance of around 200,000 switching cycles at AC-15, 230 V, making it well-suited for signaling, feedback, and interlock applications in motor control and automation systems. In operation, it provides a clear NO/NC signaling path that can be wired to PLC inputs or control relays, helping to verify the contactor’s status and enable safe sequencing in complex control schemes. Compatible with Siemens Sirius 3RT1 contactors, the 3RH1921-1DA11 accessory is commonly used to extend control logic, provide interlocks, or implement simple feedback loops in industrial automation environments where compact, dependable auxiliary contacts are required.