What it is and what it does
The Siemens 3RH1140-1BN40 is a SIRIUS auxiliary contactor in Size S00, carrying four normally-open (4 NO) instantaneous contacts. It is designed to switch control circuits — pilot devices, PLC inputs, contactor coils — not motor loads directly. The 45 mm wide housing mounts via screw or snap-on onto a DIN rail, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward/backward, which gives panel builders flexibility in tight enclosures.
What the ratings mean for fit
The headline rating is 10 A at AC-12 (resistive loads and solid-state outputs) per IEC 60947-5-1. That 10 A holds at 24 V and 400 V, but drops to 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, and 1 A at 690 V — the switching capacity follows the voltage curve. For a controls integrator, the AC-12 rating means this contactor is sized for control-circuit duty, not motor switching. The 4 NO configuration gives you four independent signal paths; there are no NC, delayed, or make-before-break contacts on this variant. The coil draws 3.2 W DC both on pickup and hold — no power drop after sealing, so the control transformer or PLC output must sustain that continuously. Ambient range is -25 to +60 °C operating, -55 to +80 °C storage, with a 2000 m altitude limit. Pollution degree 3 means it's rated for industrial environments with conductive pollution; the IP20 front protection keeps fingers out but expects enclosure protection for washdown or dust.
Panel integration notes
At 45 mm wide, 57.5 mm tall, and 72 mm deep, this contactor occupies one standard 45 mm DIN-rail module. Zero clearance required at the sides for heat dissipation — the 0 mm side spacing lets you pack units tight. The screw terminals accept up to 4 mm², which covers most control-circuit wiring in 600 V panels. For a panel OEM wireman, the spring-cage variant (3RH2140-1BP40) is faster for high-volume builds, but the screw terminal on this part is field-serviceable with a standard PZ1 bit.