What it is and where it fits
The Siemens 3RH2911-2XA11-0MA0 is a SIRIUS auxiliary switch block designed to snap onto the front of a contactor relay or power contactor, adding one normally-open (1 NO) instantaneous auxiliary contact. It is rated for use with the S00, S0, S2, and S3 contactor frame sizes, which covers a broad range of motor starters and switching duties in a control panel.
Switching capacity and what the ratings mean
The contact carries 6 A at 24 V and 6 A at 230 V, with the current dropping as voltage rises — 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. These are the conventional thermal current (Ith) values, meaning the contact can handle that current continuously in a resistive circuit at the stated voltage. For motor or inductive loads, you derate from these figures. The rated operational current tells a different story: 10 A at 24 V, 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V — these are the values for AC-15 (solenoid/contactor coil) duty, which is the real-world load this switch will see in a control circuit. The 6 kV rated surge voltage resistance means it can handle transients typical in industrial panels without flashover.
Integration and mounting
Snap-on mounting onto the front of the contactor — no tools needed. The 36 mm width, 47.7 mm depth, and 41.5 mm height mean it adds minimal footprint to the contactor assembly. Wire termination accepts 2 x (0.5... 2.5 mm²) solid or stranded, 2 x (0.5... 1.5 mm²) finely stranded with ferrule, or 2 x (20... 14) AWG. The IP20 protection class on the front means it is protected against finger contact but not against moisture — keep it inside the panel, away from washdown. Operating temperature range is -25... +60 °C, storage from -55... +80 °C.
Sourcing posture
As an active-production SIRIUS component, this auxiliary switch is sourced through standard Siemens distribution channels. For a BOM line or a line-down replacement, it is a stocked item at most industrial distributors — quoted to order against an RFQ. No second-source or direct cross-reference is listed; the 3RT2 contactor family it mates with is the primary ecosystem.