What the ratings mean for fit
The 3RB1246-1QG00: The 6.3...25 A setting range covers standard IEC motor sizes from about 1.5 kW to 7.5 kW at 400 V. The Class 5...30 trip class means you can set the thermal memory to match the motor's starting characteristics — Class 10 for standard starts, Class 20 for high-inertia loads like fans or conveyors, Class 30 for very long acceleration times. The S00/S0 frame size tells you the contactor footprint it mates with; verify the mechanical link kit for your specific contactor model. Ground fault signaling is built in, so the relay can indicate a leakage path to earth without a separate module. The AC 110...120 V control supply is common in North American panel designs; for 24 VDC control circuits, a different variant or an interface relay would be needed.