What this SIRIUS starter delivers
The 3RA2120-4CD27-0BB4 is a Siemens SIRIUS direct-on-line starter in size S0, combining a contactor and overload relay in one assembly for motor starting and protection.
Mounting and panel fit
Designed specifically for snapping onto 60 mm busbar systems — no DIN rail adapter needed, which saves rail space and speeds assembly in panel builds. Dimensions are 45 mm wide, 260 mm high, and 165 mm deep, with a vertical mounting position required. Clearance needs: 50 mm above, 20 mm below, 20 mm at the sides, and 20 mm forward. Main circuit connections use screw-type terminals — no special tooling needed, but torque to the specified value during commissioning.
What's in the box and sourcing posture
This starter ships with the contactor (3RT2027-1BB40) and link module (3RA2921-1BA00) pre-assembled — it's a matched set, not a field-build kit. RoHS compliance date is 2009-01-10, meaning it meets the EU RoHS directive for restricted substances.