What it is — front-mounted auxiliary switch for SIRIUS contactors
The Siemens 3RH2911-1MA02 is a front-mounted auxiliary switch block for the SIRIUS family, designed to snap onto 3RT2 power contactors and 3RH2 contactor relays. It carries two normally-closed (NC) circuits — terminals 71/72 and 81/82 — with cable entry from below. The screw-type terminals accept 2x (0.5...1.5 mm²) or 2x (0.75...2.5 mm²) conductors, or 2x (20...16) or 2x (18...14) AWG.
Rated at 10 A thermal current (Ith), this block handles the full auxiliary contact rating of the contactor frame it mounts to. The AC-15 switching capacity tells you the real-world inductive load it can break: 10 A at 24 V, 6 A at 125/230/250 V, 3 A at 400 V, and 1 A at 690 V. For DC switching, the ratings drop faster — 6 A at 24 V, 2 A at 60 V, 1 A at 110 V, 0.3 A at 220 V — so check your DC control circuit voltage against the curve. The insulation voltage is 690 V at pollution degree 3, with a rated surge voltage resistance of 6 kV, meaning it's suitable for 400/480 VAC panels without additional creepage concerns. Mechanical life is 10 million switching cycles typical, which outlasts most contactor main contacts in cyclic service.
Where it fits — panel integration
Snap-on mounting to the contactor front. Dimensions: 36 mm wide, 37.5 mm high, 43.7 mm deep. IP20 on the front.