What the 16 A AC-3 rating means for your motor feeder
The 3RA2120-4AA26-0FB4 is a SIRIUS direct-on-line starter — a pre-assembled combination of a contactor and overload relay in one Size S0 housing, rated 16 A at AC-3 at 400 V for switching squirrel-cage motors under full-voltage starting.
Panel fit and mounting — Size S0 on DIN rail
Clearance requirements: 50 mm upwards, 20 mm forwards, 10 mm downwards, 20 mm at the side, and 0 mm backwards — the back is flush to the mounting surface, so no rear clearance is needed. Overall dimensions are 107 mm depth × 45 mm width × 193 mm height — the depth is the critical dimension for shallow enclosures, as the starter protrudes 107 mm from the DIN rail face.
Built-in components and wiring
The unit ships with the 3RT2026-1FB40 contactor and the 3RA2921-1BA00 link module pre-assembled — no separate ordering of contactor and overload for this combination. Main circuit connections use screw-type terminals, and the circuit-breaker size matches the S0 feeder frame — the entire power path from breaker to contactor to overload is contained within the 45 mm width. Operating temperature range is -20 to +60 °C with temperature compensation active across the same span — the starter's thermal calibration stays accurate across the full ambient range.
RoHS compliance is indicated by the substance prohibitance date of 10/01/2009 — the starter meets the EU RoHS directive effective from that date.