The Siemens 3RA1120-1EA23-0AT6 is a nonreversing combination starter from the SIRIUS S0 frame family, rated for 2.8-4 A with a 277 VAC control voltage. It integrates a motor starter protector (MSP) and contactor in one DIN-rail or panel-mount package, sized for the S0 frame — the mid-range footprint in the SIRIUS lineup, common in IEC control panels for motor loads up to 4 A.
The 2.8-4 A setting range covers the motor full-load current adjustment band for small IEC motors — typically 0.75 kW to 1.5 kW at 400 V three-phase. The 277 VAC control coil is a North American common voltage for industrial control transformers; verify your panel's control bus matches before wiring. The combination starter ships without auxiliary contacts on either the MSP or contactor side, so if you need status feedback or a holding circuit interlock, plan to add the S0-format auxiliary contact block separately. The S0 frame width (45 mm) fits one 9 mm module per pole — four poles wide — leaving room for adjacent devices on the same rail.
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Listed under UL File E156943 in Volume 1, Section 14 — this is the UL listing for industrial control equipment, meaning the combination starter has passed UL 508 (now UL 60947-4-1) testing for motor-controller duty. That UL file covers the SIRIUS S0 family, so the 3RA1120-1EA23-0AT6 is accepted for North American installations requiring a UL-listed motor starter.