What it is and what it does
The Siemens SIRIUS 3RH1344-1BF40-ZX95 is a 4-pole auxiliary contactor in the S00 frame size, designed for control-circuit switching in industrial panels. The coil is rated 110 V DC, pulling 3.2 W for both closing and holding — no power drop once sealed. The four contacts are all normally open (instantaneous, no delayed or lagging switching), rated for 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V, so it handles typical PLC-level loads and small contactor coils without issue.
Mounting and integration
Mounts via screw or snap-on onto a DIN rail, with the S00 footprint (45 mm wide, 57.5 mm tall, 111 mm deep). The mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward — handy when fitting into tight sub-panels or gland-plate areas. Wire termination accepts solid conductors: 2x (0.5...1.5 mm²), 2x (0.75...2.5 mm²), or 2x 4 mm² per terminal; AWG equivalents are 2x (20...16), 2x (18...14), and 1x 12. Pollution degree 3 means it tolerates conductive dust and humidity typical of industrial enclosures. IP20 on the front protects against finger contact, not washdown — keep it inside a sealed cabinet.
Key ratings and what they mean
The 110 V DC coil is rated for continuous duty — the holding power stays at 3.2 W, so no external dropping resistor is needed. The contact reliability spec states one incorrect switching per 100 million operations at 17 V, 1 mA, which means it is dependable for dry-circuit (low-energy) signals as well as power switching. Surge voltage resistance is 6 kV, covering impulse transients in industrial mains. The mechanical life is 10 million operations typical; shock resistance is 10g / 5 ms and 5g / 10 ms, so it holds up on vibrating machinery like conveyors or compressors.