It uses spring-loaded (cage-clamp) connection technology — no screw-terminal torque checks on the coil leads, which speeds panel wiring and stays tight under vibration. This is a phased-out product; the official successor is the SIRIUS 3RT2 series.
The 400 V AC 50 Hz coil voltage matches standard European 400 V three-phase line-to-line control circuits. The 0.8... 1.1 operating range at 50 Hz means the coil holds in from 320 V to 440 V — a 20 % undervoltage tolerance that keeps it engaged through sags. The spring-loaded connection accepts 0.5... 2.5 mm² stranded or solid, same as the SIRIUS auxiliary contact blocks, so the same ferrule kit and strip length (8 mm) apply across the panel.