The Siemens 3RH1440-1AN20 is a SIRIUS auxiliary contactor in size S00, carrying 4 normally open instantaneous contacts and no NC or delayed poles.
The contact block is rated for 10 A at 24 V, 6 A at 230 V, 3 A at 400 V, and 1 A at 690 V — these are the thermal continuous currents at those voltages. For a 24 VDC control circuit, the 10 A rating gives you headroom for multiple pilot lights or relay coils. At 400 V, the 3 A rating covers most auxiliary loads in a motor starter bucket. Contact reliability is specified as one incorrect switching operation per 100 million cycles at 17 V, 1 mA — that matters for PLC-level signals where dry switching can cause oxide buildup. The mechanical life is 5 million operations typical for the contactor. The unit handles shock at 10g for 5 ms and 5g for 10 ms, and operates from -25 to +60 °C.
Dimensions are 90 mm wide, 57.5 mm tall, 72 mm deep — the S00 footprint fits alongside a matching contactor on the same DIN rail. Terminals accept solid wire: 2x 0.5 to 1.5 mm², 2x 0.75 to 2.5 mm², or 2x 4 mm². That covers standard control wiring up to 12 AWG. Screw terminals are standard — no spring-cage on this variant.