The Siemens 3RH1140-1BP40 is a SIRIUS auxiliary contactor in size S00, carrying 4 normally-open instantaneous contacts rated 10 A in AC-12 duty (resistive loads at 230/400 V). It's the switching block that extends the control-circuit capacity of a main contactor or starter — think signal feedback, PLC inputs, or pilot lights on a motor starter. Rated surge voltage resistance is 6 kV, and the coil draws 3.2 W DC both on pickup and hold.
Screw and snap-on mounting onto a DIN rail. Zero clearance required at the side. IP20 on the front — fine for a closed panel, not for washdown zones. Terminal capacity: accepts 2x 0.5–1.5 mm², 2x 0.75–2.5 mm², or 2x 4 mm² solid.
The 10 A AC-12 rating (resistive) is the headline — it's what you use for control transformers, indicator lamps, and PLC digital inputs. For inductive loads at 230 V, the rated operational current drops to 6 A; at 400 V it's 3 A; at 690 V it's 1 A. That derating curve matters if you're switching contactor coils or small solenoids. Shock resistance is 10g for 5 ms and 5g for 10 ms — typical for industrial panels on conveyors or presses, but not rated for continuous high-G vibration environments without additional damping. Mechanical endurance is 30 million operations typical for the contactor block — that's the relay life, not the contact life under load. Electrical endurance depends on the switched current and voltage.