What it is and where it fits
The 3RH2911-1HA10 is a Siemens SIRIUS auxiliary switch block — one normally open (NO) instantaneous contact that snaps onto the front of a contactor or contactor relay. It's designed for contactor sizes S00, S0, S2, and S3, meaning it covers the small to mid-frame SIRIUS power contactor and relay range. Use it to add a feedback or interlock contact to a 3RT2 contactor (or similar SIRIUS frame) without extra wiring space — the snap-on mount keeps the assembly within the contactor's own footprint. IP20 on the front means it's safe for finger contact inside an enclosure but not for washdown environments.
Rated currents and what they mean for your circuit
The contact carries 10 A at 24 V (rated value) and 6 A at 24 V under the auxiliary contact rating — the 10 A figure is the thermal continuous current, while the 6 A is the switching capacity in AC-15 duty at that voltage. At higher voltages the current drops: 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V. This lets you size the contact for the specific control voltage in your panel. For DC switching, the ratings are lower: 6 A at 24 V, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V and 250 V, and 3 A at 400 V. The DC arc extinction is inherently harder, so these limits are what the contact can reliably break without welding. Contact reliability is rated at 1 faulty switching per 100 million operations at 17 V, 1 mA — this is the low-energy switching spec that matters for PLC inputs or solid-state loads where a dry circuit needs a reliable closure. The surge voltage resistance is 6 kV, giving the insulation system margin against transient spikes on the control bus.
Mounting and wiring in the panel
Snap-on mounting means no screws or tools for installation — the block clips onto the contactor front. The dimensions are compact: 36 mm wide, 43.7 mm deep, 37.5 mm high, so it adds negligible depth to the contactor assembly. This is critical when the panel depth is tight against the backplate or enclosure door. Wiring accepts 2x (0.5... 1.5 mm²) solid or stranded, or 2x (0.75... 2.5 mm²) fine-stranded with ferrules — the dual-wire termination saves a jumper when daisy-chaining the common. AWG equivalents are 2x (20... 16) and 2x (18... 14). Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C.
Lifecycle and compliance
RoHS compliance date is 10/01/2009, so the part meets the EU Restriction of Hazardous Substances directive. No UL/CSA listing is explicitly recorded in the spec data, but the IEC ratings (AC-15 at 690 V rated 1 A) and surge voltage rating (6 kV) indicate compliance with IEC 60947-5-1 for control circuit devices.