What it is and what it does
The Siemens 3RH1344-1AU00 is a SIRIUS auxiliary contactor, size S00, with four instantaneous normally-open contacts. It's the part you add to a contactor or a contactor assembly when you need extra signal feedback or control-circuit isolation — the 4 NO contacts give you four independent dry-contact paths, each rated 10 A at 24 V and 10 A in AC-12 duty, which covers most PLC input and relay-coil switching in a panel.
Mounting and integration
Mounts via screw or snap-on onto a DIN rail, same 45 mm wide footprint as the S00 contactor base. The mounting position is flexible: +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward/backward, so it fits tight enclosures without a special bracket. Front face is IP20 — fine for a closed panel, not for washdown areas. Pollution degree 3 means it's rated for industrial atmospheres with conductive dust or occasional condensation.
Contact ratings — what the numbers mean for your circuit
The 10 A AC-12 rating (resistive load at 24 V) is the headline number, but the real-world switching capability drops as voltage climbs: 6 A at 230 V, 3 A at 400 V, 1 A at 690 V. That's typical for a S00 auxiliary block — the contacts are sized for control-circuit duty, not motor power. At 110 V it's still good for 1 A; at 220 V it's 0.27 A. If you're switching a 24 VDC PLC input, the full 10 A is there. For 400 VAC control transformers, stay under 3 A per contact.
Environmental and mechanical limits
Operates from -25 °C to +60 °C, stores from -55 °C to +80 °C. Shock-rated at 10 g for 5 ms and 5 g for 10 ms — tough enough for most industrial machinery but not for extreme vibration environments. Maximum operating altitude 2 000 m, which covers most plants outside high-altitude mining or mountain installations.
Wiring and termination
Terminals accept solid wire: 2x 0.5...1.5 mm², 2x 0.75...2.5 mm², or 2x 4 mm². That covers standard control wiring from 18 AWG to about 12 AWG. No special tools beyond a screwdriver; the screw terminals are the same as the S00 contactor base.