What this reversing starter handles
The Siemens 3RA2220-4NH27-0BB4 is a SIRIUS reversing starter, size S0, designed to reverse a three-phase motor by swapping two phases. It ships with the contactor 3RT2027-2BB40 and the link module 3RA2921-2AA00 already integrated. Trip class is CLASS 10, meaning it disconnects within 10 seconds at locked-rotor current, protecting the motor winding during a stall. The main circuit uses spring-loaded terminals — no screw torque to check, just strip and push. That saves time on a panel build and eliminates a common loose-termination fault.
Mounting on 60 mm busbars — panel fit check
This starter snaps directly onto 60 mm busbar systems — no DIN rail adapter needed. Mounting position is vertical only. Dimensions: 260 mm high, 90 mm wide, 165 mm deep. Clearance requirements: 50 mm above, 32 mm in front, 10 mm below, 10 mm at the sides, zero behind. That 165 mm depth plus 32 mm forwards means the enclosure needs at least 197 mm internal depth from the busbar face to the door.
Active production — sourcing posture
Operating temperature range is -20 to +60 °C; storage and transport range is -50 to +80 °C. The temperature compensation is built into the thermal overload characteristic across the same -20 to +60 °C band.