What it is and what it does
The Siemens SIRIUS 3RH1131-1MB40-0KT0 is a coupling relay for switching auxiliary circuits — essentially a contactor-style relay that handles control signals, not motor loads. It carries a 24 V DC coil and is rated 10 A at AC-12 (resistive) duty, so it can switch pilot devices, PLC outputs, or signal lamps up to that current. The S00 frame size keeps the footprint tight at 45 mm wide.
Mounting and panel fit
Mounts via screw or snap-on to DIN rail — the snap-on feature speeds panel assembly. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, which helps when routing wires in a crowded enclosure. Dimensions: 45 mm wide, 57.5 mm high, 72 mm deep. Pollution degree 3 means it's rated for industrial environments with conductive contamination.
Coil and contact performance
Pick-up voltage is 85% of rated (20.4 V for the 24 V coil), drop-out is 15% (3.6 V) — standard for industrial relays. Coil holding power is 1.4 W DC, so it won't heat up the panel noticeably. The three normally-open instantaneous contacts handle switching without delay, and the surge voltage resistance is 6 kV, giving decent margin against transients on control transformers.