What this combination starter does
The Siemens 3RA1120-1GA23-0AK6 is a nonreversing combination starter from the SIRIUS S0 frame, integrating a motor starter protector (MSP) and contactor in one unit for IEC-rated motor circuits. The MSP auxiliary and contactor auxiliary are both none, meaning the starter ships without add-on auxiliary contact blocks — order them separately if your circuit needs feedback or status signaling. A combination starter combines short-circuit protection, overload protection, and switching in a single device, saving panel space and wiring versus separate components. The 4.5-6.3 A range covers small motor loads like fractional-horsepower pumps, fans, or conveyors on 208 VAC systems.
The UL file E156943 in Vol.1 Sec.14 confirms the starter is UL-listed for North American installations, so it meets the same safety standard as a UL 508-listed motor controller. That file covers the SIRIUS S0 family, not just this order code — useful if you are qualifying the whole frame for a panel.
Integration notes
The SIRIUS S0 frame is a compact footprint — roughly 45 mm wide per pole — designed for DIN-rail snap-on mounting inside a control panel. The 208 VAC control coil pulls from the same phase as the motor power, so no separate control transformer is needed if the line voltage matches. Verify the coil pickup and dropout thresholds against your supply: IEC coils hold at 0.8× nominal (166 VAC) and drop out at 0.35× nominal (73 VAC). Because the MSP and contactor auxiliaries are both none, the starter has no built-in auxiliary contacts. If your circuit requires a run-status signal or a fault indication to a PLC input, you will need to add a side-mount auxiliary contact block (SIRIUS S0 series). The terminal layout follows the standard S0 pattern — power terminals on top, load terminals on bottom, coil terminals on the front face.