What it is and what it does
The Siemens 3RH1344-1DE40-0KA0 is a SIRIUS auxiliary contactor in size S00, designed to switch control circuits in motor starter and contactor assemblies. It provides four normally open instantaneous contacts rated for 10 A at 24 V, with a 24 VDC coil that draws 3.2 W for both closing and holding. The integrated varistor surge suppressor handles coil transients internally, so no external suppression is needed on the control side.
Mounting and panel integration
Mounts via screw or snap-on onto a DIN rail, with a 45 mm width footprint that matches the S00 contactor frame. The mounting position allows +/-180° rotation on a vertical surface and can be tilted forward or backward by +/-22.5°, giving flexibility in dense panel layouts. Front IP20 protection means it's safe for finger contact inside an enclosure but not for washdown environments.
Contact ratings and switching capability
The four NO contacts are rated for switching across a range of control voltages: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V. At 110 V the rating drops to 1 A, and at 220 V it's 0.27 A. The contacts are rated for 10 million mechanical operations typical, with a contact reliability of one incorrect switching per 100 million operations at 17 V, 1 mA. Surge voltage resistance is 6 kV, suitable for industrial environments with pollution degree 3.
Wire termination specs
Terminals accept solid conductors: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², and 2x 4 mm². This covers standard control wiring in panel builds — no special ferrules or crimp tools required beyond what's typical for a 45 mm-wide contactor.