What it is and what it does
The Siemens SIRIUS 3RH2911-2HA13-0KT1 is an auxiliary switch block that snaps onto a contactor relay or power contactor from the 3RH2 / 3RT2 series. It provides one normally-open and three normally-closed auxiliary contacts, each rated for a maximum of 10 A.
Mounting and wiring
It snaps onto the front of the contactor or relay — no tools needed, no DIN rail space consumed. The spring-loaded terminals accept two conductors per clamp, 0.5 to 2.5 mm² without ferrules, or 0.5 to 1.5 mm² with ferrules. That's a solid 2 x 20 to 14 AWG if you're working in imperial. Strip length and ferrule spec are standard for spring-cage blocks; the clamp holds firm under panel vibration. The block measures 36 mm wide, 47.7 mm deep, and 41.5 mm tall — compact enough that it doesn't crowd adjacent devices.
Environmental and electrical limits
The front face carries IP20 protection — fine inside a closed cabinet, not for washdown or outdoor exposure. Operating temperature spans -25 to +60 °C, storage from -55 to +80 °C. Insulation voltage is rated at 690 V AC with pollution degree 3, and surge voltage resistance is 6 kV. That puts it comfortably inside the typical 400 V / 480 V panel environment with adequate clearance and creepage. Mechanical life is listed at 10 million switching cycles typical, and contact reliability is quoted at one faulty switching per 100 million operations at 17 V, 1 mA — meaning it handles low-energy logic signals as reliably as it handles pilot-duty loads.