S0 feeder — what the dimensions mean for panel layout
The 3RA2120-4CD27-0AP6: This is a Siemens SIRIUS 3RA2 non-fused motor starter, S0 size, direct starter design. The 45 mm width and 155 mm depth are the critical panel clearances — the unit snaps onto a 60 mm busbar system, so the mounting footprint is governed by the busbar pitch, not the enclosure backplate. Vertical mounting is specified; side clearance of 9 mm and 10 mm forward clearance are the minimums for heat dissipation and wiring access. The supplied contactor is a 3RT2027-1AP60, and the link module is 3RA2921-1AA00 — the assembly is pre-coordinated for AC-3 switching up to 690 V.
Rated power and current — matching the motor nameplate
At 400 V, the starter is rated 11,000 W — that's the IEC AC-3 rating for a 15 hp motor at 460/480 V or 20 hp at 575/600 V. The 22 A at 480 V and 21.9 A at 600 V are the continuous current ceilings in those voltage bands. For a 230 V supply, the rating drops to 3 hp; at 200/208 V it's 5 hp.