The Siemens 3RB2016-1PB0 is a SIRIUS solid-state overload relay — a Class 10E device for three-phase motor protection. It is not a bimetallic thermal relay; the solid-state sensing avoids drift from ambient heating and gives a tighter, repeatable trip curve. The relay mounts directly onto a contactor (contactor mounting), saving DIN-rail space. At 45 mm wide, 64 mm tall, and 73 mm deep, it fits a standard contactor footprint. The screw-type terminals accept solid conductors from 0.5 to 4 mm² (or 2× 0.5 to 2.5 mm²), and finely stranded wire with ferrules from 0.5 to 2.5 mm² (2× 0.5 to 1.5 mm²). AWG equivalents are 2× 18 to 14 for the main circuit and 2× 20 to 14 for the auxiliary contacts. The auxiliary contact ratings cover common control voltages: 2 A at 24 V, 4 A at 120 V, and 3 A at 230 V. These are the make/break capacities for the N/O and N/C signaling contacts that feed the PLC or safety circuit. The relay has zero N/O and N/C auxiliary contacts built in — the signaling comes from an external contact block or the contactor's own auxiliaries.
This overload relay is designed for motor control centers and individual motor starters in industrial environments — anywhere a three-phase motor needs protection against overcurrent and phase loss. The ATEX approval (PTB 06 ATEX 3001 Ex II (2) GD) means it can be installed in the safe-area control panel feeding motors in Zone 1 or Zone 2 gas or dust hazardous areas, provided the associated contactor and enclosure meet the installation rules. The shock resistance of 15g / 11 ms covers most industrial vibration from nearby presses or conveyors.
Compliance documentation is in order: the part carries a substance prohibitance date of 01.07.2006, which aligns with RoHS compliance. The ATEX certificate (PTB 06 ATEX 3001) covers the Ex II (2) GD marking. EMC immunity is specified to IEC 61000-4-4 (burst) at severity level 3 — 2 kV on power ports, 1 kV on signal ports — and surge voltage resistance at 6 kV. These are the key compliance documents a sourcing or compliance engineer will need for the file.
Integration notes
The relay fastens directly onto the contactor — no DIN rail required for the overload itself. Clearance: 0 mm upwards, forwards, and backwards; 6 mm at the side. This tight stacking is typical for SIRIUS contactor assemblies in compact motor starter blocks. The 0.02 W power dissipation per pole is negligible for thermal budgeting inside the enclosure.