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 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. Ambient range is -25 to +60 °C operating, -55 to +80 °C storage, with a 2000 m altitude limit.
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.