SIRIUS reversing starter for 60 mm busbar panels
The Siemens 3RA2220-4ED27-0BB4 is a SIRIUS reversing starter in size S0, designed for snapping onto 60 mm busbar systems — a common layout in North American and export MCC lineups where the busbars run horizontally behind the starters. It ships with the contactor 3RT2027-1BB40 and the link module 3RA2921-1BA00 already integrated, so the reversing pair arrives as a single assembly with the mechanical interlock in place — one part number covers the build, not three.
Panel envelope and clearances
Dimensions are 260 mm high by 90 mm wide by 165 mm deep, with a vertical mounting position specified — the depth is the key constraint for shallow backpanels or gland-plate clearance. Minimum clearances: 50 mm above, 10 mm below, 32 mm in front, 10 mm at the sides, and 0 mm behind — the zero rear clearance means it can sit flush against the backpanel without a spacer, saving rail space.