Panel fit and wiring constraints
The 3RA2120-4EA27-0AP0: The S0 footprint is 45 mm wide, 97 mm deep, and 193 mm tall — the 45 mm width is the DIN-rail pitch, so it occupies one standard 45 mm module position on the rail. Clearance requirements around the unit: 50 mm upwards, 20 mm forwards, 20 mm at the sides, 10 mm downwards, and 0 mm backwards — the zero backward clearance means it can sit flush against a back panel or busbar support without derating. Main circuit wiring uses screw-type terminals — the supplied contactor is 3RT2027-1AP00 and the link module is 3RA2921-1AA00, so the starter arrives as a single assembly ready for line and load connections.