The Siemens 3RH2911-4HA13 is a SIRIUS auxiliary switch designed to snap onto the front of contactor relays and power contactors in frame sizes S00, S0, S2, and S3. It adds one instantaneous normally-open contact to the contactor assembly, extending the control circuit without extra panel wiring — the ring terminal lug connection matches the existing contactor termination scheme.
This auxiliary switch carries a 6 A rated operational current at 24 V and 230 V, with a separate 10 A rating at 24 V for AC-12 duty (resistive loads like control transformers and indicator lamps). The AC-15 rating at 690 V is 1 A — that's the inductive load curve for solenoid valves and contactor coils, so it handles the inrush without welding contacts. At 400 V the switch is good for 3 A, enough for most 400 V control circuits in European panels. The 6 kV rated surge voltage means it withstands switching transients on long control cable runs without flashover.
Snaps onto the front of the contactor — no DIN rail or screws needed, which saves panel space and wiring time.
Contact reliability and mirror contact feature
The switch is a mirror contact per IEC 60947-4-1 when paired with a 3RT2 contactor, meaning the NO contact mechanically mirrors the main contact position for safety-related feedback circuits.