What it is and where it fits
The Siemens SIRIUS 3RH1131-1AK20 is a size S00 auxiliary contactor — a 4-pole block with three normally-open and one normally-closed instantaneous contact, designed for switching control and signal circuits in motor starter and contactor assemblies. It mounts via screw or snap-on onto a DIN rail, occupying 45 mm of panel width, and accepts solid conductors up to 4 mm² per terminal.
Contact ratings — what they mean for your circuit
The contact ratings are specified per voltage: 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V. These are thermal current ratings for the auxiliary contacts — they define the continuous current the contacts can carry at each voltage level, not the motor load. For a 24 VDC control loop, the 10 A rating gives ample headroom for pilot devices and PLC inputs; at 690 V, the 1 A limit governs signal isolation in higher-voltage auxiliary circuits.
Mechanical endurance and contact reliability
Rated for 30 million mechanical operations typical, with a contact reliability spec of one incorrect switching per 100 million operations at 17 V, 1 mA — meaning it is suited for low-energy signal switching where oxide film on contacts can cause intermittent failures. The 6 kV rated surge voltage withstand (impulse) ensures the contacts survive transient overvoltages common in industrial control panels.
Mounting and environmental limits
Mounts in any orientation on a vertical surface, with ±180° rotation and ±22.5° tilt permitted. Operating temperature range is -25 to +60 °C; storage and transport extend to -55 to +80 °C. Shock resistance is 10g for 5 ms and 5g for 10 ms. Pollution degree 3 (conductive pollution or dry non-conductive that becomes conductive) — standard for industrial control environments. IP20 on the front means finger-safe but not protected against water ingress; install inside a rated enclosure.