The Siemens 3RB1246-1EB10 is an overload relay rated 25-100 A for full motor protection, sized for S2/S3 contactor frames. It provides adjustable trip class from 5 to 30, covering fast and slow-start motor loads. The auxiliary circuit uses screw terminals, and the relay accepts DC 24 V control for manual, automatic, or remote reset. Monostable outputs and an overload warning output are standard. The 25-100 A range covers a wide band of motor FLA, but the real decision point is the trip class setting: Class 5 for short acceleration times (pumps, fans), Class 10 for standard induction motors, Class 20 for high-inertia loads (conveyors, crushers), and Class 30 for very long start times. Set it wrong and nuisance tripping — or inadequate protection — follows.
Deployment Context
The S2/S3 footprint mates with the corresponding Siemens contactor range — the relay mounts directly onto the contactor or individually on a DIN rail. The DC 24 V control coil and monostable output make it a clean fit for PLC-controlled motor control centers where the safety circuit expects a normally-open, fail-safe feedback loop.