What this block does in the panel
The Siemens 3RH2911-2HA03 is a SIRIUS auxiliary switch block that snaps onto the front of 3RT2 contactors and 3RH2 contactor relays, adding three normally-closed (NC) signal paths to the switching assembly. Each of the three NC current paths is rated for a maximum of 10 A, with specific switching capacities at different control voltages: 6 A at 24 V AC/DC and 230 V, 3 A at 400 V, and 1 A at 110 V — so it handles both low-voltage PLC outputs and higher-voltage motor-control circuits in the same block. The spring-loaded terminals accept 2x (0.5 to 2.5 mm²) stranded without ferrules, or 2x (0.5 to 1.5 mm²) with ferrules — no screwdriver torque check needed, which saves time when you're wiring a row of these on a DIN rail in a crusher panel. Snap-on mounting means it clips directly onto the contactor front without tools; the 36 mm width matches the standard contactor footprint, so it doesn't eat extra rail space.
Rated for the environment it lives in
Insulation voltage is rated 690 V at pollution degree 3, and surge voltage resistance is 6 kV — that's coordination for industrial environments where motor starts and contactor dropout create transients. Mechanical service life is 10 million switching cycles typical, and contact reliability is 1 faulty switching per 100 million operations at 17 V, 1 mA — the block is rated for the long haul on a conveyor or pump starter that cycles daily.
Wiring and fit notes
The block has no leading, lagging, or instantaneous contact timing options — all three NC contacts switch simultaneously when the contactor armature moves. AWG range for the spring terminals is 2x (20 to 14) — standard control wiring sizes are covered without pigtail adapters. Depth is 47.7 mm, height 41.5 mm, width 36 mm.