What this part is and where it fits
The Siemens SIRIUS 3RH2140-2XB40-0LA2 is a contactor relay designed for railway applications, carrying four instantaneous NO contacts and a 24-34 VDC coil with an integrated varistor surge suppressor. It mounts via screw or snap-on onto 35 mm DIN rail, occupying the S00 contactor footprint — 45 mm wide, 70 mm tall, 73 mm deep. The mounting position is flexible: ±180° rotation on a vertical surface, ±22.5° tilt forward/backward, or standing on a horizontal surface. Coil inrush peaks at 2.3 A; holding current settles to a mean 40 mA. Arcing time runs 10-15 ms, and the DC operate/release range is 25-45 ms. That 40 mA holding draw matters for a 24 VDC supply budget — it's low enough to daisy-chain multiple relays on one small PSU without voltage drop issues.
Contact ratings — what they mean for the load
The contacts are rated for switching across a wide voltage range, and the duty matters. At 24 V rated value the contacts carry 10 A; at 230 V rated value also 10 A — that's the resistive-load ceiling. At 400 V rated value it's 3 A; at 690 V rated value it's 1 A. The 440 V rated value drops to 0.5 A, and at 600 V rated value it's 0.26 A. These are not motor-starting currents — this is a contactor relay, not a power contactor. Use the 10 A figure for signal-level or resistive loads; derate aggressively for inductive DC loads.
Integration notes
Wire termination accepts 2x 0.5-4 mm² solid or stranded conductors. Side-by-side mounting is permitted — the 6 mm lateral clearance to adjacent devices is the minimum gap. Fastening is screw or snap-on onto 35 mm DIN rail; the S00 size keeps the panel footprint compact. The varistor suppressor is built in, so no external snubber is needed for coil suppression — verify polarity before energizing the DC coil.
Environmental and compliance
Operating temperature range is -40 to +70 °C; storage range is -55 to +80 °C. Relative humidity minimum is 10 %. The substance prohibition date is 10/01/2009, aligning with RoHS/REACH substance restrictions. No specific UL/CSA/CE marks are listed in the spec record, but the railway designation implies compliance with relevant rail standards (EN 50155 family).