The Siemens SIRIUS 3RH1344-2BB40-ZX95 is a size S00 auxiliary contactor with four normally open instantaneous contacts and a 24 VDC coil. It's built for control-circuit switching — pilot lights, PLC inputs, contactor coils, that class of load — and carries a 10 A AC-12 rating for resistive loads at 24 V. The 24 VDC coil pulls 3.2 W to close and holds at the same 3.2 W, so there's no inrush spike to size your 24 V supply around. Mounting is screw or snap-on onto DIN rail. The 45 mm wide body fits a standard 45 mm slot in a panel layout, and the 114 mm depth leaves room for wiring gutters. Terminals accept 2x 0.25 to 2.5 mm² solid or stranded wire — fine for most control-circuit runs.
Contact ratings and switching capability
The four NO contacts are rated for AC-12 duty at 10 A maximum, which covers resistive control loads. For inductive or motorized control circuits, the AC-15 ratings tell the real story: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. DC switching is more limited — 10 A at 24 V, but drops to 1 A at 110 V and 0.27 A at 220 V. That DC derating is steep; don't assume the 10 A AC number carries over to a DC solenoid bank. Surge voltage resistance is rated at 6 kV, and the pollution degree is 3 (conductive or dry non-conductive pollution). That's typical for industrial control panels but means the contactor needs reasonable clearance in dirty environments — don't pack it tight against uncoated busbars in a cement plant panel without checking creepage.
Environmental and mechanical limits
Operating temperature range is -25 to +60 °C, storage and transport from -55 to +80 °C. Shock resistance is 10g for 5 ms and 5g for 10 ms — enough for most industrial machinery but not for direct mounting on a large forging press without isolation. Altitude limit is 2,000 m; above that, derate the dielectric withstand. Mounting position is flexible: +/-180° rotation on a vertical surface, and can be tilted forward or backward by +/-22.5°. That helps when you're squeezing it into a tight corner of a retrofit panel. The front face carries an IP20 rating — finger-safe but not washdown-proof.