What this part is and what it does
The Siemens 3RH1371-2FB40 is a SIRIUS auxiliary contactor in size S00, designed to switch control circuits — not motor loads directly. It carries 7 instantaneous normally-open (NO) contacts, each rated 10 A in AC-12 duty (resistive load at 400 V max), and is intended for signaling, interlocking, or extending the contact count on a main contactor or PLC output. The coil is 24 V DC with a built-in diode surge suppressor, so no external flyback diode is needed on the panel wiring.
Mounting and panel fit
Mounts via screw or snap-on onto 35 mm DIN rail. The 45 mm width and 60 mm height match the S00 footprint — same as a 3RT1 contactor of that frame size. Depth is 114 mm including terminals. Clearance at the side is 0 mm, so units can be ganged without spacing. Mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward. Terminal solid capacity is 2x 0.25 to 2.5 mm² per clamp.
Ratings and what they mean for the buyer
The 10 A AC-12 rating is the maximum continuous current per contact for resistive loads at up to 400 V. For inductive or DC switching, derate per the listed values: 6 A at 230 V AC, 3 A at 400 V AC, 1 A at 690 V AC, and 10 A at 24 V DC, 1 A at 110 V DC, 0.27 A at 220 V DC. Coil holding power is a constant 3.2 W DC — no inrush spike to budget for. Pollution degree 3 means it's rated for industrial environments with conductive contamination. IP20 on the front face; the enclosure is open-style for panel mounting, not for wet or dusty locations. Operating temperature range is -25 to +60 °C, storage -55 to +80 °C. Shock resistance is 10g for 5 ms and 5g for 10 ms — sufficient for most machine-mounted panels.