The Siemens 3RW5072-2TB04 is a SIRIUS soft starter with a minimum operating current of 90 A, meaning it is sized for motor loads drawing at least that current under normal running conditions — if your motor FLA is below 90 A, this unit will not engage its internal bypass contactor correctly. The trip class is selectable between CLASS 10A, 10E (preset), and 20E per IEC 60947-4-2, which governs how long the starter can sustain the starting current before thermally tripping: CLASS 10A is the tightest (10 seconds at 7.2× Ie) for light-load starts like fans or pumps; 20E gives a longer window for high-inertia loads like centrifuges or conveyors. The rated operating voltage spans 200 to 480 V, covering standard three-phase supplies across 208/230/400/460/480 V grids — confirm your line voltage falls within that window, not just the motor nameplate.
This soft starter mounts via screw fixing on a vertical surface, rotatable ±90°, with ±22.5° tilt forward/backward — flexible for panel layouts where the starter must sit on a sub-panel or backplate. Dimensions are 160 mm wide, 230 mm high, 282 mm deep, with clearances: 100 mm upwards, 75 mm downwards, 10 mm forwards, 0 mm backwards, and 5 mm at the sides. Shock resistance is 15 g / 11 ms, with potential contact lifting starting at 12 g / 11 ms; not a concern for stationary panel mounting but relevant if the panel is on a mobile platform.
Fieldbus and control options
Communication options include PROFIBUS, Modbus RTU, Modbus TCP, EtherNet/IP, and PROFINET (with PROFIenergy support in conjunction with the PROFINET communication module). This makes the 3RW5072-2TB04 integrable into most common industrial networks without a gateway. The starter supports soft torque for gentle starts, voltage ramp, and pump ramp down for reducing water hammer in pumping applications. Remote reset is available by cycling the control supply voltage — no separate reset signal wire needed. An error logbook is available only with special accessories. There is no analog output and no torque control function.