The Siemens SIRIUS 3RH2911-4GA04 is a front-mounted auxiliary switch block carrying four normally-closed (NC) contacts — terminals 51/52, 61/62, 71/72, 81/82 — with ring-cable-lug connection and physical coding per EN 50011. It is designed exclusively for use with SIRIUS contactor relays 3RH2140 and 3RH2440; it will not mechanically or electrically mate with other contactor sizes. Rated for a maximum thermal current of 10 A, with AC-15 switching capacity that varies by operating voltage: 10 A at 24 V, 6 A at 125/230/250 V, 4.7 A at 60 V, 3 A at 110/400 V, 1.2 A at 220 V, 0.5 A at 440 V, and 0.26 A at 600 V. The 6 kV surge voltage resistance and 690 V insulation rating (pollution degree 3) suit it for 400 V line-to-line control circuits in industrial panels. The 36 mm width (3 TE) and 43.7 mm depth fit standard enclosure layouts, though the IP00 front protection means the switch block must be housed inside a closed panel or cabinet; it is not rated for exposed or washdown environments.
Switching reliability and mechanical endurance
The typical mechanical service life of 10 million operating cycles means the block outlasts most contactor relays it mounts on.