What it is and what it does
The Siemens 3RH2353-1CL00-0KA0 is a SIRIUS auxiliary contactor — a switching block with 5 instantaneous N/O contacts, designed to extend the control-circuit capacity of a main contactor or to build standalone logic in a panel. It's rated for 10 A at 24 V and carries a rated insulation voltage of 125 V at 50/60 Hz, so it handles typical 24 VDC and 110/125 VAC control signals without derating worries. The 5 contacts give you one spare pole beyond a standard 4-pole auxiliary block, which matters when you need feedback, interlock, and a permissive signal on the same device.
Mounting and panel fit
Mounts via screw or snap-on onto a 35 mm standard mounting rail (DIN rail). The 45 mm width and 57.5 mm height keep it compact for a 5-pole block; the 117 mm depth includes the body and clearance for wiring. Clearance spacings are tight: 10 mm upwards and forwards, 6 mm at the side, 10 mm downwards — so you can pack it next to other S00-sized contactors without leaving a full device gap. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, which helps when the rail is in an awkward corner of the enclosure.
Rated currents and switching capability
The 5 N/O contacts each carry 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, and 1.2 A at 220 V — the current drops as voltage rises, which is typical for DC switching where arc extinction limits the load. For AC loads at 230 V the contactor handles 6 A; at 400 V it's 3 A; at 690 V it's 1 A. That means it's fine for pilot-duty solenoids, contactor coils, and indicator lamps, but not for direct motor starting. The mechanical life is 10 million operations typical, and the arcing time sits at 10–15 ms — a fast break that reduces contact wear in inductive circuits.
Environmental and compliance
Operates from -25 to +60 °C and stores from -55 to +80 °C, so it's comfortable in a non-conditioned panel near a hot drive or outdoors in a temperate climate. Pollution degree 3 means it's rated for conductive pollution environments — typical for industrial control panels where dust and humidity are present. The part is RoHS compliant with a substance prohibition date of 07/01/2006, and the lifecycle status is current production, so it's a standard catalog item, not a phase-out risk.