What this auxiliary switch is and where it fits
The Siemens 3RV6901-1E is a SIRIUS transverse auxiliary switch that mounts on the front of a circuit breaker — it adds one normally-open and one normally-closed contact for status feedback or control interlocking. It fits breaker frames S00, S0, S2, and S3, so it covers the common motor-protective and molded-case sizes in a SIRIUS panel. The switch plugs into the breaker with a plug-in fixing — no tools needed to snap it on, which saves time on a build where you're populating a row of breakers. At 17 mm deep and 45 mm wide it stays inside the breaker's own footprint, so it doesn't eat into DIN-rail clearance for adjacent devices.
Ratings that matter for the control circuit
The contacts are rated for 2.5 A maximum at AC-12 duty — that's the resistive-load rating for control circuits, so it handles pilot lights, PLC inputs, and relay coils within that current. At 24 V it switches 1 A; at 48 V it drops to 0.3 A; at 60 V it's 0.15 A; at 230 V it handles 0.5 A. These are the actual switching limits at those voltages, not just thermal ratings. The screw-type terminals accept two conductors per clamp — 0.5 to 1.5 mm² solid or finely stranded with ferrules, or 0.75 to 2.5 mm². AWG 20 to 14 fits. That's enough for daisy-chaining common and signal wires without extra terminal blocks.
Environmental and compliance
Rated for operation from -20 to +60 °C and storage from -50 to +80 °C, which covers most indoor panel environments and unheated warehouses. RoHS compliance date of May 1, 2012 means it's free of the original six restricted substances; REACH and other EU chemical regulations apply per Siemens standard declarations.