Motor starter for 60 mm busbar panels
The 3RA2120-1FD24-0FB4: This is a Siemens SIRIUS direct on-line starter — a pre-assembled combination of a contactor and overload relay in one unit, sized S0 for 60 mm busbar systems. It snaps directly onto the busbars, saving DIN rail space and reducing wiring compared to separate components. Rated 5 A at AC-3 400 V, it switches three-phase motors up to that current in full-voltage starting duty. The 24 V DC coil matches standard PLC control voltages, so no extra transformer or relay interface is needed.
Panel fit and mounting clearances
The starter measures 45 mm wide, 165 mm deep, and 260 mm tall, mounted vertically. For airflow and arc clearance, leave 50 mm above, 20 mm in front, 20 mm to the side, and 10 mm below — no clearance needed behind the unit because it mounts on the busbar face. The main circuit uses screw-type terminals — field-friendly for 5 A motor wiring. The supplied contactor is a 3RT2024-1FB40, and the link module 3RA2921-1BA00 integrates the overload relay; the circuit-breaker section is size S00.
Sourcing and lifecycle — active, quoted to order
Operating temperature range is -20 to +60 °C, storage -50 to +80 °C, making it suitable for most industrial environments without special derating.