What it is and what it fits
The Siemens 3RH1122-1BB40-0TK1 is a SIRIUS auxiliary contactor in size S00, meaning it's the compact add-on relay for signaling and interlocking in a motor starter stack or control panel. The 24 V DC coil pulls 3.2 W on close and holds at 3.2 W, so the control transformer or DC supply needs to deliver that continuously — no spike to design around. Two normally-open instantaneous contacts handle the switching; there are no delayed, leading, or lagging contacts on this variant. Rated 10 A at AC-12 (resistive) and 10 A at 24 V, it's a straightforward signal relay for PLC outputs, pilot lights, or contactor coils downstream.
Mounting and wiring in the panel
Mounts via screw or snap-on to DIN rail — the 45 mm width takes one standard slot. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, so it fits odd panel layouts without a special bracket. Wire termination accepts 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid — covers most control wiring from signal loops to motor-circuit interlock runs. Depth of 72 mm keeps it clear of shallow enclosures; height of 57.5 mm stacks neatly with S00 contactors like the 3RT10 series. Pollution degree 3 means it's rated for industrial environments with conductive dust or occasional condensation.
Ratings and what they mean for the circuit
The AC-12 rating of 10 A is the resistive load limit — use that for contactor coils, solenoids, or indicator lamps. For inductive AC loads at higher voltages, the switching capacity drops: 6 A at 230 V, 3 A at 400 V, 2 A at 500 V, 1 A at 690 V. On DC, it's 10 A at 24 V, 1 A at 110 V, and 0.27 A at 220 V — the DC arc extinguishes harder, so stay within those curves. Surge voltage resistance is 6 kV, which covers most 400 V industrial networks without external suppression. Shock resistance tested at 10g / 5 ms and 5g / 10 ms — fine for conveyor and machine-tool vibration. Operating temperature range -25 to +60 °C covers unheated plant floors; storage range -55 to +80 °C.