What it is and where it fits
The Siemens 3RH2911-2XA13-0MA0 is a front-mounted auxiliary switch block from the SIRIUS family, designed to snap onto 3RT2 power contactors and 3RH2 contactor relays. It provides one normally-open and three normally-closed auxiliary contacts — terminals labelled 51/52, 61/62, 71/72 (all NC) and 83/84 (NO) — with spring-loaded cage terminals that accept 2x (0.5 to 1.5 mm²) with ferrules or 2x (0.5 to 2.5 mm²) solid, plus 2x AWG 20–14 stranded. Snap-on mounting means it clips directly onto the contactor face without tools, saving DIN-rail space and panel wiring time — a standard fit for any panel using SIRIUS 3RT2 or 3RH2 base units.
Contact ratings and what they mean for your circuit
Each contact is rated for a maximum of 10 A, but the real-world switching capacity depends on voltage and load type. At 24 V DC the contacts handle 6 A; at 60 V DC that drops to 2 A; at 110 V DC it is 1 A. For AC control circuits, the AC-15 rating at 690 V is 1 A — that is the inductive load rating for solenoid valves and contactor coils, which is the typical use case for this block. The DC ratings follow a clear derating curve: 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. If you are switching a DC coil at 110 V, plan for 3 A maximum per contact — not the 10 A headline. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — that is the dry-circuit (low-energy) reliability figure, important for PLC inputs or signal-level loads where oxide films can cause intermittent opens. Mechanical life is 10 million switching cycles typical.
Electrical endurance and isolation
Rated insulation voltage is 690 V AC at pollution degree 3, and surge voltage resistance is 6 kV — that covers the impulse withstand for industrial control panels per IEC 60947-1. The front face carries IP20 protection, meaning finger-safe when installed but not protected against moisture ingress; keep it inside a closed enclosure. Operating temperature range is -25 to +60 °C; storage range is -55 to +80 °C. No special derating is called out for elevated ambient, but standard SIRIUS practice is to stay within the -25 to +60 °C band for full rated current.