Narrow-Profile Auxiliary Switch for SIRIUS Contactors
The Siemens 3RH2921-2DA11 is a SIRIUS auxiliary switch designed for lateral mounting alongside contactor relays and power contactors in the S00, S0, S2, and S3 frame sizes. At just 10 mm wide, it fits into dense panel layouts where DIN-rail space is at a premium — the snap-on mounting lets you add auxiliary contacts without increasing the contactor's footprint beyond its own width.
Rated Operational Current Across Voltages
The 3RH2921-2DA11 carries a rated operational current of 6 A at 24 V and 230 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V and 250 V, and 3 A at 400 V.
Contact Reliability and Mirror Contact Compliance
The auxiliary contacts are rated for 1 faulty switching per 100 million operations at 17 V, 1 mA — a reliability figure that supports high-cycle applications like safety circuits where missed signals are unacceptable. When paired with the 3RT2 contactor series, the 3RH2921-2DA11 provides a mirror contact per IEC 60947-4-1, meaning the normally closed contact mechanically reflects the main contact position — critical for fail-safe isolation in machinery guarding circuits.
Physical Fit and Wiring
Dimensions are 10 mm wide, 64.8 mm high, and 66 mm deep — the narrow width means you can stack multiple auxiliary switches alongside a contactor without exceeding the standard DIN-rail pitch. Terminals accept 2x (0.5 to 2.5 mm²) solid or stranded wire, or 2x (20 to 14 AWG); finely stranded wire with ferrule is limited to 2x (0.5 to 1.5 mm²). The IP20 front protection keeps fingers away from live terminals inside the enclosure.