S0 direct starter for 60 mm busbar panels
The Siemens 3RA2120-1GH24-0BB4 is a SIRIUS direct (on-line) starter in Size S0, combining a contactor and overload relay in one assembly that snaps onto 60 mm busbar systems — no separate DIN rail required for the main power connection. The 24 V coil (24... 24 V) is fed via the integrated link module, keeping control wiring to a single voltage rail.
Panel fit and wiring constraints
At 45 mm wide, 165 mm deep, and 260 mm tall, the S0 footprint fits standard motor control center buckets and distribution panels — the 45 mm width matches a 2.5-module DIN-rail slot if busbar-mounted. Clearance requirements: 50 mm upwards, 20 mm forwards, 20 mm at the side, 10 mm downwards, and 0 mm backwards — the rear face sits flush against the busbar or backplate. Mounting position is vertical only; the unit is designed for snapping onto 60 mm busbar systems, not for standalone DIN-rail mounting.
Motor protection and duty ratings
AC-3 rated maximum voltage is 690 V, with the 6.3 A rating at 400 V — the same current holds at 480 V and 600 V (6.3 A at both), indicating the thermal limit, not the contactor's make/break capacity, governs the rating. Operating temperature range is -20 to +60 °C, with storage and transport tolerance from -50 to +80 °C — suitable for unconditioned warehouses and panel interiors near heat-generating equipment.
Sourcing and lifecycle status
The assembly ships with the contactor (3RT2024-2BB40) and link module (3RA2921-2AA00) included — one order code covers the complete starter, not separate components.