The Siemens 3RB3046-2UX1 is a SIRIUS solid-state overload relay, size S3, with an electronic overload release and an integrated auxiliary switch. It carries a Class 20E trip curve and a thermal current rating of 50 A, sized for straight-through current transformers in the main circuit. The relay provides a dedicated signaling contact for a "tripped" message — that's the Note on the nameplate: the 97/98 auxiliary position reports the overload state, not just the relay's energized status.
Class 20E means the relay allows a 20-second trip delay at 7.2× current setting — standard for medium-inertia loads like fans and screw compressors where nuisance tripping on startup is the real risk. The 50 A thermal current (Ith) is the continuous carry rating through the transformer window; the actual motor FLA setting will be lower, dialed in on the relay's adjustment range. The electronic release gives temperature compensation across -25 to +60 °C ambient, so the trip point stays stable whether the panel is in a conditioned room or a hot plant floor. The auxiliary switch is integrated, so there's no separate add-on block to order; the 97/98 contact handles the tripped signal. Vibration resistance is spec'd at 1–6 Hz, 15 mm amplitude and 6–500 Hz, 20 m/s² over 10 cycles — enough for most industrial machinery but worth checking if the relay is mounted directly on a high-vibration pump skid.
Substance compliance
The relay carries a substance prohibition date of 03/01/2017, aligning with RoHS and REACH compliance milestones for the SIRIUS portfolio. No separate UL or IEC certification numbers appear in the spec record, but the SIRIUS line is typically UL-listed and IEC 60947-rated; verify the specific marking on the unit if a project requires a hard-copy cert.