Reversing starter for 60 mm busbar panels
The 3RA2220-4EH27-0AP0 is a SIRIUS reversing starter — a pre-assembled combination of two contactors mechanically and electrically interlocked with an overload relay, all in a single S0-sized housing that snaps onto 60 mm busbar systems.
Clearance and mounting for enclosure fit
The unit measures 90 mm wide by 260 mm tall by 165 mm deep — the width is the critical number for spacing on a 60 mm busbar, since it determines how many starters fit per section. Siemens calls for 50 mm clearance above, 32 mm in front, 10 mm below, 10 mm to the side, and zero behind — those gaps are for airflow over the overload relay and to keep the spring terminals accessible for wiring. Mount it vertically only — the thermal bi-metal in the overload relay relies on convection to track motor current correctly; laying it on its side shifts the trip curve.
Duty ratings and motor coordination
At 400 V AC-3 the starter carries 29 A, which translates to roughly 15 kW — that's the motor full-load current it can switch forward and reverse under load without welding the contacts. The supplied contactor is a 3RT2027-2AP00 and the link module is 3RA2921-2AA00 — if you need spares for the contactor or the mechanical interlock, those are the order codes to pull.