The Siemens 3RB3036-1UD0 is a SIRIUS solid-state overload relay in the S2 frame size, rated for a continuous thermal current of 50 A and a maximum operating voltage of 690 V. The integrated auxiliary switch reports a "tripped" message back to the controller, so the line knows exactly why it stopped.
Mounting and wiring reality
This relay mounts directly onto a contactor — the evidence calls it "contactor mounting" — so it shares the same DIN-rail footprint and bus system as the SIRIUS contactor it pairs with. No separate panel space needed. The main circuit uses screw terminals accepting 2x (10…35 mm²) stranded or a single 50 mm² conductor; the control circuit accepts 2x (0.25…1.5 mm²) solid or stranded. Tightening the M6 main-contact screws with a PZ2 bit at the specified 5–6 mm shaft diameter is standard panel-builder practice.
The 50 A thermal current (Ith) is the continuous rating through the relay's power path — sized for a motor full-load current up to that value. The auxiliary contact ratings (2 A at 24 V, 4 A at 120 V, 3 A at 230 V) are adequate for PLC digital inputs or small contactor coils. Shock resistance to 15g / 11 ms and vibration tested per IEC 60068-2-27 mean it holds calibration on a machine that sees occasional impacts.