What it is and what the ratings mean
The Siemens 3RH1122-2BB40-ZX96 is a SIRIUS auxiliary contactor, size S00, designed to switch control and signal circuits in a panel. Its 24 VDC coil draws 3.2 W both on pickup and hold, meaning the coil circuit sees a constant power load — no inrush peak to size a DC supply against, but the holding power is the same as the closing power, so the supply must sustain that draw continuously. The contact block carries 2 instantaneous NO contacts and 2 NC contacts, rated for AC-12 duty at 10 A maximum — that is the resistive load rating per IEC 60947-5-1, covering solenoid valves, indicator lamps, and PLC digital inputs. For inductive loads like contactor coils, derate to the AC-15 curve: at 230 V the rated value is 6 A, at 400 V it drops to 3 A, and at 690 V it is 1 A. The DC switching capability is present but limited: at 24 V rated value it handles 10 A, at 110 V only 1 A, and at 220 V just 0.27 A — so for DC motor brake or clutch circuits above 24 V, verify the load current against the curve.
Where it fits and how it mounts
The 3RH1122-2BB40-ZX96 mounts via screw or snap-on onto a 35 mm DIN rail, occupying 45 mm width (three 15 mm module spaces). The depth is 73 mm, height 60 mm. The mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward — useful when the panel layout forces a non-standard orientation. Side clearance is 0 mm to adjacent devices, so it can be ganged directly without spacing. The screw terminals accept 2x solid conductors from 0.25 to 2.5 mm² — typical for control wiring in a 600 V panel. The front face carries IP20 finger protection, adequate for enclosed panels but not for open-rack mounting where tools or fingers could contact live parts. Pollution degree 3 means it is rated for conductive pollution environments (condensation, light dust) common in industrial control rooms.