The Siemens 3RB1246-1PB30 is an overload relay for full motor protection, rated 1.25-6.3 A and sized for S00 or S0 contactor frames. The Class 5-30 trip curve means you can dial in the thermal protection to match the motor's locked-rotor withstand — Class 10 for standard motors, Class 20 for high-inertia loads, or Class 5 for fast-trip applications like submersible pumps. The DC 24 V control circuit powers the monostable outputs and the integrated ground-fault detection, which trips on residual current without a separate core-balance transformer.
The 1.25-6.3 A setting range covers small motors — think fractional-horsepower pumps, fans, or conveyor drives. The Class 5-30 adjustment lets you match the tripping characteristic to the motor's starting profile: Class 10 for normal starts, Class 20 for high-inertia loads, or Class 5 for fast-trip applications. The integrated ground-fault detection saves panel space and wiring compared to a separate core-balance relay.
Deployment Context
Mounts individually or directly onto the S00/S0 contactor — no separate base required. The screw terminals on the auxiliary circuit accept standard ring or fork lugs; the manual-automatic-remote reset selector lets the control system decide whether to restart after a trip. The DC 24 V coil is common in PLC-driven panels, so it integrates cleanly into a 24 VDC control voltage architecture.