The Siemens 3RH2140-1KB40 is a SIRIUS coupling relay designed for switching auxiliary circuits in control panels. It carries 4 NO instantaneous contacts rated at 10 A at 24 V, with a 24 VDC coil that includes an integrated suppressor diode to manage the inductive kickback. The relay is built into the Size S00 contactor footprint, which means it shares the same compact 45 mm width and 57.5 mm height as the smallest SIRIUS contactors — a detail that matters when you're laying out a dense DIN-rail row.
Mounting and integration
Mounts via screw or snap-on onto 35 mm DIN rail. The mounting position is flexible: ±180° rotation on a vertical surface, plus ±22.5° tilt forward/backward. Clearance requirements are tight — 10 mm upward, 10 mm forward, 10 mm downward, and 6 mm at the side (–) — so it fits in a shallow enclosure without forcing a wider panel. Wire termination accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid or stranded conductors.
Electrical ratings and duty
The 24 VDC coil draws 2.8 W closing power. Contact ratings span the full control-voltage range: 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 10 A at 230 V, 3 A at 400 V, 0.5 A at 440 V, 2 A at 500 V, 0.26 A at 600 V, and 1 A at 690 V (–). Mechanical life is rated at 30,000,000 cycles, with a maximum switching frequency of 10,000 operations per hour at AC and an arcing time of 10–15 ms. The degree of pollution is 3, meaning it's rated for conductive pollution environments typical in industrial control panels.