What this part does — and what the ratings mean for fit
The 3RB1246-1QG31 is a current-production solid-state overload relay from the Siemens SIRIUS family, rated 6.3 to 25 A at AC 110 to 120 V, 50/60 Hz. The 6.3-25 A range means it directly protects motor loads within that FLA band — set the dial to the motor nameplate current, and the solid-state sensing tracks true RMS heating without the drift of a bimetal. The 110-120 V control voltage is the coil supply for the relay's internal logic; if your panel runs 24 VDC or 230 VAC, this variant won't pull in. It integrates three protection functions in one housing: overload (standard Class 10/20 trip curve), thermistor motor protection (PTC sensor input for stator winding temperature), and internal earth-fault detection. That means a single DIN-rail device covers motor thermal protection, winding overtemp, and ground-leakage trip — no separate earth-leakage module needed. The output configuration is 1NO/1NC for the combined overload/thermistor/earth-fault signal, plus a separate 1NO/1NC for overload warning only. Both are bistable (latched), so the trip state holds after a fault clears — manual reset required.
Panel integration and wiring
Mounts on standard 35 mm DIN rail per EN 60715. The 45 mm wide housing fits a standard SIRIUS contactor footprint; it can be snapped directly onto a 3RT2 contactor or ganged via the busbar system. The thermistor input (PTC) is a separate two-wire terminal — run a shielded pair from the motor's PTC sensor, no external converter. Earth-fault detection uses a separate toroid or the internal zero-sequence CT; verify the manual for the specific wiring scheme.