What it is and what it does
The Siemens 3RH1911-1LA11-ZX95 is a SIRIUS auxiliary switch designed to snap onto the front of S00-sized contactors and contactor relays. It adds one normally open (1 NO) instantaneous auxiliary contact to the base device, extending the control circuit's feedback or interlocking capability. Rated for 10 A at AC-12 (resistive load) and 6 A at 24 V, the contact handles typical PLC input and relay coil switching without derating concerns. The mirror contact feature per IEC 60947-4-1 means the NO contact mechanically mirrors the main contactor's welded status — critical for safety circuits where you need positive indication that the power contacts have opened.
Mounting and integration
Snaps onto the front of S00 contactors (e.g., 3RT1 series) without tools — no DIN rail space consumed, no extra wiring trough needed. The 36.5 mm width and 41.5 mm depth keep the assembly within the contactor's own footprint, so panel layout stays tight. Terminals accept 2x (0.5…1.5 mm²) or 2x (0.75…2.5 mm²) solid/stranded, or 2x (20…16) / 2x (18…14) AWG. IP20 on the front means it's protected against finger contact in the enclosure but not washdown — standard for dry indoor control panels.
Ratings and what they mean for your circuit
The AC-15 rating at 690 V (1 A) is the one that governs solenoid and contactor coil switching at higher voltages — the 10 A AC-12 figure applies to resistive loads only. For inductive loads like relay coils, use the AC-15 curve. The 6 kV surge voltage rating (impulse withstand) means the switch can handle transient spikes common on 400 V industrial lines without flashover. Contact reliability is specified at 1 faulty switching per 100 million operations at 17 V, 1 mA — that's dry-circuit capability for low-energy signals (e.g., PLC inputs) without needing gold-plated contacts. Mechanical life is 10 million cycles typical.
Lifecycle and sourcing
RoHS compliance date is listed as 07/01/2006, indicating it meets the EU RoHS directive. The mirror contact certification (IEC 60947-4-1) satisfies most machinery directive requirements for safe isolation monitoring.