The Siemens 3RV1901-1D is a transverse auxiliary switch that plugs into the front of SIRIUS 3RV motor starter protectors and circuit breakers in frame sizes S00, S0, S2, and S3. It adds one changeover (CO) contact to signal the breaker's tripped or on/off state back to a PLC or control circuit. The 45 mm width and 12 mm height keep it within the breaker's own envelope — no extra DIN-rail space needed.
The single CO contact is rated 10 A maximum, but that's the thermal current (Ith) — the real switching capacity depends on voltage and load type. At 24 V it handles 1 A; at 110 V it's 0.22 A; at 220 V it drops to 0.1 A. For AC loads at 230 V it's rated 3 A, at 400 V it's 1.5 A, and at 690 V it's 10 A (AC-15 at 690 V is 0.5 A). The AC-15 rating at 690 V (0.5 A) is the one that governs for inductive control-circuit loads at that voltage — don't size off the 10 A thermal figure alone.
Wiring and environmental limits
Terminals are screw-type, accepting 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) solid or ferruled stranded wire. Mounting is plug-in fixing — no tools needed beyond a screwdriver for the terminals.