The Siemens 3RH2911-4HA11 is a front-mounted auxiliary switch block in the SIRIUS family, designed specifically for 3RT2 power contactors and 3RH2 contactor relays. It provides one normally-open and one normally-closed instantaneous contact, wired via ring cable lug terminals. Snap-on mounting onto the contactor or relay front face means no tools or additional hardware are needed for installation — it clips directly into the designated slot on the device.
The maximum thermal current is 10 A, but the real-world switching capability depends on voltage and load type. At 24 V it switches 6 A; at 110 V it handles 1 A; at 230 V it manages 6 A; at 400 V it drops to 3 A. These are the AC-15 rated values for inductive loads with solenoids and contactor coils — the most common auxiliary circuit duty. For DC switching at 24 V the contact is rated 10 A, at 60 V it handles 4.7 A, at 110 V it manages 3 A, and at 220 V it drops to 1.2 A. The DC ratings follow the expected curve for breaking a DC inductive load without an arc-suppression network. The insulation voltage is rated 690 V at pollution degree 3, with a surge voltage withstand of 6 kV.
The ring cable lug connection is less common than screw-cage terminals on some sibling blocks, so verify your termination preference before committing the BOM line. If your panel standard uses screw terminals, the 3RH2911-4HA11 requires a ring lug crimp tool and appropriate lug size for your wire gauge.
At 36 mm wide, 37.5 mm tall, and 43.7 mm deep, this block adds minimal footprint to the contactor or relay it mounts on. The IP00 front protection means it is intended for enclosed panels only — no exposed live parts in the field. Mechanical service life is 10 million switching cycles typical, matching the base contactor or relay it attaches to.