The Siemens SIRIUS 3RV2901-1E-ZX95 is a transverse auxiliary switch designed to snap onto the front of 3RV2 circuit breakers in sizes S00, S0, S2, and S3. It adds one normally-open and one normally-closed instantaneous contact (1NO+1NC) via screw terminals, giving you a local status signal or control interlock without extra wiring back to the panel door. Rated for a maximum of 2.5 A, the switch carries 1 A at 24 V and derates to 0.15 A at 60 V and 0.3 A at 48 V, so it is sized for control-circuit signalling and low-power auxiliary loads — not motor-current switching. At 230 V it handles 0.5 A, which covers most PLC input and contactor-coil feedback circuits in a standard panel.
The switch measures 45 mm wide, 12 mm tall, and only 17 mm deep — shallow enough to fit behind a cabinet door or inside a shallow enclosure without crowding the main breaker. It plugs into the front of the breaker via the fastening method, so no DIN-rail space is consumed. Terminals accept two conductors per clamp: 2x (0.5... 1.5 mm²) solid or 2x (0.75... 2.5 mm²) solid. For AWG, that is 2x (20... 14). The front is finger-safe, rated IP20.