What it is and where it fits
The Siemens SIRIUS 3RH2911-2HA02-ZW97 is an auxiliary switch block that snaps onto the front of 3RT2 contactors and 3RH2 contactor relays, adding two normally-closed (NC) signal paths for status feedback or interlocking. The spring-loaded terminals accept 2x (0.5... 2.5 mm²) solid or stranded wire without ferrules, or 2x (0.5... 1.5 mm²) with ferrules, and also 2x (20... 14) AWG. It is rated for a maximum of 10 A, with specific switching capacities depending on the control voltage: 6 A at 24 V, 6 A at 125 V, 6 A at 230 V, 6 A at 250 V, 3 A at 400 V, 2 A at 60 V, 1 A at 110 V, and 0.3 A at 220 V. The AC-15 rating at 690 V is 1 A, which governs its use in solenoid and contactor coil circuits at higher voltages. The insulation voltage is 690 V AC at pollution degree 3, with a surge voltage resistance of 6 kV. The front face carries IP20 protection, so it is suitable for enclosed panel environments where accidental finger contact is the main concern.
Contact reliability and service life
The auxiliary contacts are rated for 1 faulty switching per 100 million operations at 17 V, 1 mA, which is a dry-circuit reliability figure — relevant for PLC input signals where the switching energy is low. The mechanical service life is 10 000 000 switching cycles typical, so the block will outlast most contactor main contacts in normal use.
Panel integration
Snap-on mounting to the contactor or relay front face — no tools needed. The block occupies 36 mm width, 41.5 mm height, and 47.7 mm depth, adding minimal footprint to the existing device. The spring-loaded terminals reduce wiring time compared to screw terminals; strip length is 8 mm for a clean connection.