The Siemens 3RH1131-1BD40 is a SIRIUS auxiliary contactor in the S00 frame size, carrying three normally-open instantaneous contacts and a 42 V DC coil. It is designed for snap-on mounting onto a DIN rail or screw fixing, making it a straightforward addition to a control panel where you need to extend the contact count of a main contactor or signal a PLC input. The 3 NO contacts give you three independent signal paths that close when the coil is energized — no delayed or make-before-break switching here, just clean instantaneous closure.
AC-12 rated current hits 10 A at 24 V, which covers most PLC output and relay-interface loads. At 230 V AC the thermal current is 6 A, and at 400 V it drops to 3 A — that matters if you are switching a contactor coil or a small valve across phases. The DC switching capability is more limited: at 110 V DC the rated current is only 1 A, and at 220 V DC it falls to 0.27 A. For DC loads above a few watts at line voltage, the contactor will need derating or a DC-rated auxiliary block. The coil itself draws a steady 3.2 W holding power, which is low enough to keep the control transformer small.