The Siemens 3RB2016-2NB0 is a SIRIUS solid-state overload relay — a CLASS 20E trip curve device for three-phase motor protection in control panels. It mounts directly onto a contactor (contactor mounting per), saving DIN-rail space and keeping the motor branch circuit compact. The CLASS 20E trip class allows a 20-second thermal overload before tripping.
ATEX and hazardous-area deployment
This relay carries ATEX approval PTB 06 ATEX 3001 Ex II (2) GD.
Termination and wiring constraints
Main current circuit terminals are screw-type, accepting 0.5 to 4 mm² solid (2× 0.5 to 2.5 mm²) or 2× AWG 18 to 14. Auxiliary and control circuit terminals also screw-type, accepting 2× AWG 20 to 14. The solid wire range covers standard panel-building practice — no need for ferrule conversion on solid runs. Finely stranded with core-end processing accepts 0.5 to 2.5 mm² (2× 0.5 to 1.5 mm²). Strip length and torque spec follow the SIRIUS wiring guidelines; verify free-wheel diode polarity on the contactor coil if sharing suppression.
Relative humidity tolerance is 100 % — suitable for condensing environments inside non-heated enclosures. Shock resistance is 15 g for 11 ms, which covers most industrial vibration profiles from conveyor drives and pump skids.
EMC immunity and surge withstand
Surge voltage resistance rated at 6 kV. Burst immunity per IEC 61000-4-4 is 2 kV on power ports, 1 kV on signal ports — severity degree 3. That covers most industrial installations without external surge suppression, though a Type 2 SPD on the panel feeder is still recommended for outdoor or long-cable runs.