Trip class and motor protection
The Siemens 3RW5074-2TB14 is a SIRIUS soft starter rated for a minimum motor current of 135 A, with a rated voltage range of 200 to 480 V. Its trip class is configurable as CLASS 10A, 10E (preset), or 20E per IEC 60947-4-2, which governs how quickly the starter disconnects under overload — 10A is the fastest (for pumps and fans with short acceleration), 20E allows longer start times for high-inertia loads like centrifuges or crushers. The preset 10E is a balanced middle ground for most conveyor and compressor applications. This unit carries ATEX, UKEX, and IECEx certification. The approvals cover the enclosure and internal switching.
The unit measures 160 mm wide, 230 mm high, and 282 mm deep, and is fastened via screw fixing to a back panel. Clearance requirements: 100 mm upward, 10 mm forward, 75 mm downward, 5 mm at the side, and 0 mm backward — so it can sit flush against the backplane. Shock resistance is rated at 15 g for 11 ms, with potential contact lifting above 12 g / 11 ms — this matters for installation on vibrating machinery or near presses. The unit is a hybrid switching device, combining semiconductor and electromechanical paths for reduced heat dissipation during run.