The Siemens 3RH2911-1NF11 is a front-mounted auxiliary switch block for the SIRIUS contactor family, specifically designed to snap onto 3RT2.2/3/4 power contactors and 3RH2 contactor relays. It provides one normally-open and one normally-closed auxiliary contact, both rated for solid-state (low-energy) switching — meaning they reliably switch dry circuits down to 5 V, 1 mA, with a contact reliability of one incorrect operation per 100 million cycles. This makes the block suitable for PLC or logic-level inputs where standard silver contacts might oxide and fail. The contacts are rated 0.3 A at both 24 V and 60 V, reflecting their design for signal-level loads rather than power auxiliary circuits. The insulation voltage is 690 V AC with pollution degree 3, and surge voltage resistance is 6 kV — the same dielectric backbone as the host contactor, so no derating is needed when installed on a 400 V or 690 V motor branch.
Mounting and fit
Snap-on mounting onto the contactor front — no tools, no wiring between block and coil. The block adds 36 mm width, 43.7 mm depth, and 37.5 mm height to the assembly. Screw terminals accept 2x (0.5…1.5 mm²) or 2x (0.75…2.5 mm²) with ferrule, or 2x (20…16) / 2x (18…14) AWG. The compact footprint leaves adjacent DIN-rail space for overload relays or terminal blocks.