The Siemens 3RH2911-1AA10-ZX90 is a front-mounted auxiliary switch block for the SIRIUS contactor family — specifically the 3RT2 power contactors and 3RH2 contactor relays. It adds one normally-open (NO) auxiliary contact, wired via screw terminals, with cable entry from the top. The part ships in multi-unit packaging (10 pieces per pack). Snap-on mounting means it clips directly onto the contactor or relay front without tools — no extra DIN-rail space needed. The 23.6 mm width keeps the assembly compact inside a panel.
The contact is rated 10 A maximum, but that's at 24 V. For the AC-15 inductive load curve (typical for contactor coils and solenoid valves), the rated current drops with voltage: 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. At 690 V AC-15 it's rated 1 A. These are the numbers that govern whether the contact holds in — not the 10 A headline. DC switching ratings also vary by voltage: 6 A at 24 V, 2 A at 60 V, 1 A at 110 V, 6 A at 125 V, 0.3 A at 220 V, 6 A at 230 V, 6 A at 250 V, and 3 A at 400 V. The 6 A at 125 V and 230 V stands out — that's the DC coil circuit on many North American panels.
Rated for 10 million mechanical switching cycles typical. Front-side protection is IP20 — finger-safe but not washdown-rated. Surge voltage resistance is 6 kV, with insulation rated 690 V at pollution degree 3.
Screw-type terminals accept 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) with core end processing, or 2x (20 to 16) and 2x (18 to 14) AWG. Strip and torque per Siemens standard — no special tooling needed.