The 3RB1257-0KM10: The 125-500 A range covers large motor loads — think 55-250 kW induction motors at 400 V, depending on service factor. The adjustable class 5-30 lets you match the thermal curve to the motor's starting profile: class 5 for fast-trip on short acceleration times, class 30 for high-inertia loads like centrifuges or crushers. Busbar connection on the main circuit means it's designed for panel-mount busbar systems, not cable lugs — factor that into your enclosure layout.
Panel integration
Mounts in size S10/S12 frames — continuous or individual mounting. The auxiliary circuit uses screw terminals for the reset and warning functions. The monostable overload warning output (AC 220-240 V) provides a normally-open signal that drops on trip, suitable for driving a PLC input or alarm lamp.