The Siemens 3RB1246-1PG40 is an overload relay from the SIRIUS 3RB1 family, sized for full motor protection in S00/S0 frames. It covers a setting range of 1.25 to 6.3 A with adjustable trip Class 5 through 30, letting you match the thermal curve to the motor's starting profile — fast for low-inertia pumps, slow for high-inertia fans. The auxiliary circuit uses screw terminals; the main circuit is straight-through transfer, so wiring passes directly without looping.
The 1.25 to 6.3 A range covers small-to-medium motors — think fractional-horsepower conveyors, small pumps, or fan drives up to roughly 3 kW at 400 V. Class 5 to 30 means you can set the trip delay: Class 5 for short starting times (direct-on-line motors under light load), Class 30 for high-inertia loads like centrifuges that need a longer start without nuisance tripping. The AC 110 to 120 V, 50/60 Hz control supply powers the analog output and ground-fault signaling — the relay can report a fault condition back to the PLC via the monostable output.
This relay mounts on a DIN rail in the S00/S0 footprint, common in Siemens motor starter assemblies. The straight-through main circuit keeps wiring clean — line and load conductors pass straight through the relay body, no bends or loops needed. Screw terminals on the auxiliary side accept standard ferruled conductors; strip length of 8 to 10 mm avoids whiskers under the clamp.