The Siemens SIRIUS 3RH1344-1CB00-0KA0 is a size S00 auxiliary contactor with four normally open (NO) instantaneous contacts, a 24 V 50/60 Hz coil, and a built-in varistor surge suppressor. It is designed for screw and snap-on mounting on a DIN rail, with an IP20 protection rating on the front — standard for enclosed control panels where the front face is the only accessible surface.
Contact ratings and what they mean for your circuit
The 4 NO contacts are rated for switching at various voltages: 10 A at 24 V AC, 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V. The 24 V rating is the highest — typical for control transformers or PLC output circuits. At 690 V the contact can still switch 1 A, which covers motor-circuit signaling or isolation applications. The contact reliability spec — one incorrect switching operation per 100 million operations at 17 V, 1 mA — means this contactor is suitable for low-energy dry circuits (e.g., PLC inputs) where oxide film on the contacts could otherwise cause intermittent faults.
Mounting and integration into a panel
Mounting is screw and snap-on onto a 35 mm DIN rail. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward — useful when the contactor sits on a swing frame or in a tight cabinet where the rail is not perfectly vertical. The width is 45 mm, depth 111 mm, height 57.5 mm — a standard S00 footprint that fits alongside SIRIUS contactors and overload relays in a modular row. The screw terminals accept solid conductors: 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm². Pollution degree 3 means it is rated for industrial environments with conductive dust or occasional condensation.