Front-Mounted Auxiliary Block for 3RT2/3RH2
The 3RH2911-1HA30 is a front-mounted auxiliary switch block that snaps onto Siemens 3RT2 contactors and 3RH2 contactor relays, adding three normally-open (NO) instantaneous contacts. It uses screw-type terminals and accepts 2x (0.5...1.5 mm²) or 2x (0.75...2.5 mm²) conductors per clamp, or 2x (20...16) and 2x (18...14) AWG. Part of the SIRIUS product brand, this block is rated for a mechanical service life of 10 million switching cycles typical, with contact reliability specified at 1 faulty switching per 100 million operations at 17 V and 1 mA.
Current Ratings by Duty — AC-15 and DC-13
The auxiliary contacts carry a maximum of 10 A, but the real selection parameter is the rated operational current at the applied voltage and duty. In AC-15 (solenoid/contactor coil switching) at 690 V, the rating is 1 A. In DC-13 (solenoid valve) duty, the current drops with voltage: 10 A at 24 V, 6 A at 125 V, 3 A at 400 V, and 0.26 A at 600 V. For intermediate DC voltages, the rated values are 4.7 A at 60 V, 3 A at 110 V, 1.2 A at 220 V, and 0.5 A at 440 V. These ratings define the maximum continuous current the contacts can make and break under inductive load — exceeding them shortens contact life or causes welding.
Panel Fit and Environmental Limits
The block measures 36 mm wide, 37.5 mm high, and 43.7 mm deep, with snap-on DIN rail mounting for quick panel integration. Front protection class is IP20, suitable for enclosed control panels where accidental finger contact is prevented by the enclosure door. Operating temperature range is -25 to +60 °C, with storage from -55 to +80 °C. Insulation voltage is rated 690 V at pollution degree 3, and surge voltage resistance is 6 kV — sufficient for industrial environments with moderate transient activity.