The Siemens 3RB1246-1EM30 is a SIRIUS solid-state overload relay rated 25-100 A, sized for S2/S3 contactor frames. It provides full motor protection including ground fault detection, with an integrated current transformer on the main circuit and screw terminals on the auxiliary circuit. The relay offers manual, automatic, or remote reset and a monostable overload warning output. Control voltage is AC 220-240 V, 50/60 Hz. Trip class is selectable 5 through 30.
The 25-100 A range covers standard IEC motor ratings from about 7.5 kW up to 45 kW at 400 V. The S2/S3 frame footprint matches Siemens 3RT2 contactors in those sizes — the relay mounts directly to the contactor or individually on a DIN rail. Ground fault detection is built in, so no separate earth-leakage module is needed for the motor circuit. Trip class 5-30 lets you set the overload curve to match the motor's thermal time constant: class 10 for standard motors, class 20 for high-inertia starts, class 30 for very heavy starts.