29 A AC-3 direct starter on a 60 mm busbar
The 3RA2120-4ED27-0BB4 is a SIRIUS direct-on-line starter, Size S0, designed to snap onto 60 mm busbar systems — it's a pre-assembled combination of a contactor and overload relay in one package, saving panel space and wiring time.
The AC-3 rating of 29 A at 400 V is the key figure for motor switching — it's the current the starter can make and break under motor starting conditions. The Class 10 trip characteristic gives you a 10-second window at 600% overload before the relay opens, which suits standard induction motor starts. Mounting is vertical only, fastening by snapping onto 60 mm busbar systems — the clearance dimensions are 50 mm upwards, 20 mm forwards, 10 mm downwards, and 20 mm at the side, with zero backwards clearance needed. The supplied contactor is a 3RT2027-1BB40, and the link module is 3RA2921-1BA00 — so if you're replacing a failed unit, those are the internal components that mate with this assembly.
Lifecycle and sourcing posture
Terminals are screw-type on the main current circuit, which is the standard for panel builders who prefer a proven, torque-controlled connection over spring-clamp alternatives.