135 A minimum, 200-480 V — what that means for your motor start
The Siemens 3RW5245-2AC04 is a SIRIUS hybrid soft starter sized for a minimum motor current of 135 A on a 200 to 480 V supply. That 135 A floor is the smallest settable Ie — you cannot dial it lower, so it fits motors that draw at least that much full-load current. The 200-480 V range covers common three-phase industrial voltages (208, 240, 400, 480 V) without an internal tap change. Trip class defaults to Class 10A per IEC 60947-4-2, meaning it clears a stalled rotor in under 10 seconds at 7.2x Ie — fast enough to protect standard squirrel-cage motors. You can also select Class 10E or 20E via parameterization if the load has higher inertia (centrifuges, fans) that needs a longer ramp. Control supply is 24 V DC, which is the standard for modern PLC cabinets. The unit supports remote reset by cycling that control voltage — no need to walk to the panel to clear a trip.
Fieldbus fit: Modbus TCP, EtherNet/IP, PROFIBUS, PROFINET
This variant carries onboard Modbus RTU, Modbus TCP, EtherNet/IP, and PROFIBUS, plus PROFINET with PROFIenergy for coordinated energy management during idle periods. If your site runs a single protocol — say, EtherNet/IP on a Rockwell line — you don't need an extra gateway card. The analog output (4-20 mA default, or 0-10 V with the High Feature HMI) gives a direct speed/fault signal back to the PLC without bus polling.
Mounting and environment — screw-fixed, vertical, derate above 40 °C
Fastening is screw fixing — no DIN-rail clip on this size. Clearances: 100 mm above, 75 mm below, 10 mm front, 5 mm side, 0 mm back. The 393 x 210 x 203 mm envelope (H x W x D) is a substantial panel footprint — plan the backplate layout before drilling. In a warm enclosure near a motor drive or transformer, that derating matters — you may need to reduce the starting duty cycle or add ventilation. Shock resistance is 15 g / 11 ms, with potential contact lifting above 12 g. On a vibrating pump skid or near a large reciprocating compressor, bolt it down securely and consider isolation mounts if you measure sustained vibration above that threshold.