The Siemens 3RH2911-2DA02 is a lateral auxiliary switch block from the SIRIUS family, designed specifically to snap onto 3RT2 contactors. It carries two normally-closed (NC) contacts, rated for a maximum thermal current of 10 A, and uses spring-loaded terminals for the wiring connections.
The 10 A maximum thermal current (Ith) is the continuous current the contacts can carry, but the actual switching capacity depends on the voltage and load type. For AC-15 control-circuit duty (solenoids, contactor coils), the rated operational current drops to 1 A at 690 V. At 24 V it handles 10 A, at 110 V it's 3 A, and at 230 V it's 6 A — so at line voltage you've still got solid margin for pilot-duty loads. The 6 kV rated surge voltage resistance and 690 V insulation voltage (pollution degree 3) mean this block is built for the industrial panel environment where transients from motor starting are common.
Snap-on integration with 3RT2 contactors
This block mounts laterally on the left or right side of a 3RT2 contactor via snap-on fastening. The 10 mm width means it adds minimal DIN-rail real estate — about the width of a standard terminal block. Wiring is via spring-loaded terminals accepting 2x (0.5…1.5 mm²) with ferrules or 2x (0.5…2.5 mm²) solid. Strip length for the spring clamp is the usual 8–10 mm; no screwdriver needed for termination.