The Siemens 3RB1246-1QB10 is a SIRIUS overload relay covering 6.3...25 A for full motor protection in Size S00/S0 frames. It mounts individually — not on a contactor — so it suits retrofit or standalone thermal protection where the contactor is already panel-mounted or the motor is fed through a separate switching device. The Class 5...30 adjustment range lets you match the trip curve to the motor's thermal time constant: Class 5 for short-time overloads on submersible or high-inertia loads, Class 30 for long acceleration profiles. Set it via the dial on the front face. Auxiliary circuit uses screw terminals, main circuit uses a current transformer (ST transformer). The DC 24 V control supply powers the monostable outputs and the overload warning signal — a separate NO contact that flags a pre-trip condition without dropping the motor. Manual-automatic-remote reset options give the commissioning engineer flexibility: manual for troubleshooting, automatic for unmanned stations, remote for PLC-driven reset logic.
The individual-mount design frees you from pairing it with a specific contactor frame; you can wire it downstream of any contactor or motor starter that can pass the 25 A full-load current. The screw terminals on the aux circuit accept up to 2.5 mm², so keep the control wiring at that cross-section for reliable DC 24 V signaling.