The Siemens 3RB2016-1SB0 is a SIRIUS solid-state overload relay for three-phase motor circuits, protecting against overload and phase imbalance by monitoring motor current and tripping within CLASS 10E response time. It mounts directly onto a contactor via the contactor mounting fastening method, saving panel space and wiring — no separate DIN-rail footprint needed. Rated for continuous operation from -25 to +60 °C and storage from -40 to +80 °C, with 100 % relative humidity tolerance, so it handles unconditioned enclosures and washdown areas without derating concerns.
The auxiliary contact ratings cover both AC and DC control circuits: 4 A at 120 V AC and 2 A at 24 V DC, so it can switch PLC inputs or contactor coils directly without an interposing relay. Screw-type terminals accept solid conductors from 0.5 to 4 mm² (or 2× 0.5 to 2.5 mm²) and AWG 18 to 14 for main circuits, matching common motor lead sizes in fractional to small integral horsepower ranges. Surge voltage withstand of 6 kV and burst immunity at severity level 3 (2 kV power ports, 1 kV signal ports) per IEC 61000-4-4 means it holds up in industrial environments with contactor switching and VFD noise.
Where it goes and compliance
The ATEX approval PTB 06 ATEX 3001 Ex II (2) GD allows installation in Zone 2 gas and Zone 22 dust hazardous areas when paired with an appropriately rated contactor — common in chemical, grain, and pharmaceutical lines. Shock rated to 15g for 11 ms per the spec, so it survives transport vibration and occasional mechanical impacts on the panel door or machine frame.