What it is and what it does
The Siemens 3RH1122-1BB40-ZW98 is a SIRIUS auxiliary contactor in the S00 frame size, designed to switch control circuits rather than main motor loads. It carries 2 instantaneous normally-open contacts, rated for 10 A at 24 V, 6 A at 230 V, and 3 A at 400 V — that's the AC-15 / DC-13 control-circuit duty curve, so it handles PLC outputs, relay coils, and signal interlocking in a panel. The coil pulls in at 24 V DC nominal, drawing 3.2 W during both pick-up and hold — no AC hum, no inrush spike to worry about on a 24 VDC power supply. Drop-out is clean below about 18 V, which matters if you're sequencing contactors through a safety relay.
Mounting and integration
Mounts via screw or snap-on onto DIN rail — the S00 footprint is 45 mm wide, 57.5 mm tall, 72 mm deep. The mounting position allows +/-180° rotation on a vertical surface and +/-22.5° tilt forward/backward, so it fits tight enclosures without derating. Terminals accept 2x (0.5 to 1.5 mm²), 2x (0.75 to 2.5 mm²), or 2x 4 mm² solid — AWG equivalents 20-16, 18-14, and 12. Pollution degree 3 means it's rated for industrial environments where conductive dust or condensation is present.
Key ratings at a glance
Surge voltage resistance is 6 kV — that's the impulse withstand for the control circuit, matching IEC 60947-5-1 requirements for isolation in industrial panels. Contact reliability is rated at one incorrect switching operation per 100 million cycles at 17 V, 1 mA, so it's suitable for dry-circuit PLC inputs where low-level switching is the norm. Shock resistance is 10g / 5 ms and 5g / 10 ms — typical for contactors mounted on machine frames or near vibrating conveyor drives. Operating temperature range is -25 to +60 °C, storage and transport from -55 to +80 °C. IP20 on the front means finger-safe terminals when mounted in an enclosure — standard for control panels where the front face is accessible during commissioning.