What this part is and what it does
The Siemens 3RV5901-1F is a SIRIUS transverse auxiliary switch that mounts on the front of circuit breakers in frame sizes S00, S0, S2, and S3. It provides two normally open (2 NO) instantaneous contacts for signaling or control logic, wired via screw-type terminals. The switch is rated for a maximum continuous current of 2.5 A, with voltage-dependent switching capacity: 1 A at 24 V, 0.5 A at 230 V, 0.3 A at 48 V, and 0.15 A at 60 V.
Fit and integration
The switch plugs into the front of the breaker via a plug-in fixing — no DIN rail or separate mounting required. Its dimensions are 45 mm wide, 12 mm high, and 17 mm deep, matching the breaker's front profile. The front face is IP20 finger-safe per IEC 60529, so it's suitable for panels where accidental contact with live parts must be prevented. Wire termination accepts 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or stranded conductors, or 2x AWG 20–14 with ferrules.