The Siemens SIRIUS 3RH1911-2HA13 is a 4-pole auxiliary switch block with 1 normally open and 3 normally closed contacts, terminated via spring-loaded terminals. It snaps onto the front of SIRIUS contactor relays and power contactors. The block is rated for a maximum switching current of 10 A, with voltage-dependent ratings from 6 A at 24 V down to 0.3 A at 220 V.
Snap-on mounting means it clips directly onto the contactor without tools — no DIN rail footprint consumed. The spring-loaded terminals accept 2x (0.5 to 1.5 mm²) with ferrule or 2x (0.5 to 2.5 mm²) solid, or 2x AWG 20–14. IP20 on the front keeps fingers out but offers no washdown protection; keep it inside the panel enclosure.
Contact reliability is specified as one incorrect switching operation per 100 million cycles at 17 V, 5 mA and at 17 V, 1 mA for auxiliary contacts. Mechanical service life is 10 million switching cycles typical. Insulation voltage is 690 V at pollution degree 3; surge voltage resistance is 6 kV.