The Siemens 3RA1125-0BA23-1AU6 is a nonreversing IEC combination starter in the SIRIUS S0 frame, rated for 0.14–0.2 A with a 277 VAC control voltage. It integrates a motor starter protector (MSP), a contactor, and auxiliary contacts into a single DIN- or panel-mount unit. The UL file E156943, Vol. 1 Sec. 14, covers its listing for North American installations.
The 0.14–0.2 A current range sets the thermal overload protection band for the motor branch. This is the trip class window, not the full-load amp rating of the motor — the starter must be matched to the motor nameplate FLA within that band. The 277 VAC control voltage is the coil rating; it is not the motor supply voltage. The MSP auxiliary provides one SPDT (NO/NC) contact for status feedback, and the front-mount contactor auxiliary adds one normally open contact — both are wired into the control circuit, not the power path.
It serves as a self-contained motor branch for small IEC-frame motors — typically fractional-horsepower pumps, fans, or conveyors — where a nonreversing start/stop function with overload protection is required. The S0 frame size keeps the footprint compact, leaving panel space for additional SIRIUS components on the same rail.