This 3RB3133-4UB0 is a SIRIUS S2 solid-state overload relay for contactor mounting, sized for motor circuits up to 50 A thermal current and 690 V. Its four adjustable trip classes — 5E, 10E, 20E, and 30E — allow matching the relay's trip curve to the motor's acceleration profile: quick for fast-start fans, slow for high-inertia loads. The trip logic operates when the motor current exceeds the upper current setting multiplied by 3.5, and resets when it drops below the lower setting. That gives a defined window for nuisance-tripping avoidance without relying on a separate time delay. The 'tripped' signal contact (97/98) is rated for 2 A and 4 A. Use it for the external status indication the part's note references.
The relay fastens directly to a contactor — no separate bracket. The S2 frame (55 mm wide, 99 mm high, 104 mm deep) fits standard DIN-rail assemblies when mated to the matching contactor. Control terminals accept 0.5 to 4 mm² solid or 2.5 mm² stranded. Use a PZ2 Pozidriv screwdriver with a 5–6 mm shaft diameter for the main terminal screws (M6).
Storage and transport tolerance extends to -40 to +80 °C. The relay withstands 15g / 11 ms shocks per IEC 60068-2-27 and vibration from 1–6 Hz at 15 mm amplitude, 6–500 Hz at 20 m/s², 10 cycles. That's enough for most industrial machinery but the signaling contact (97/98) in tripped position is limited to 8g / 11 ms — consider that if the panel sees repetitive shock near the limit.