The Siemens 3RA1125-1AA23-1BB4 is a nonreversing combination starter from the SIRIUS S0 frame family, rated 1.1-1.6 A with a 24 VDC control voltage. It integrates a contactor, overload relay, and auxiliary contacts into a single DIN-rail or panel-mount unit, saving panel space versus wiring separate components. The 1.1-1.6 A range covers small motor loads like fractional-horsepower pumps, fans, or conveyors typical in food-and-beverage or packaging lines.
The 1.1-1.6 A current range matches the full-load amps of a small IEC motor. The 24 VDC control coil is standard for PLC-driven panels. The MSP auxiliary provides one SPDT (NO/NC) contact for status feedback to the PLC, and the contactor auxiliary adds one NO front-mount contact for seal-in or pilot light wiring. That gives two independent auxiliary circuits without needing an add-on block — enough for basic interlocking and run indication.
UL File E156943 in Volume 1, Section 14 certifies the starter for North American installations, covering both UL 508 and CSA C22.2 No. 14 requirements. The IEC designation means it also meets EN 60947-4-1 for global machine builds. No separate CE or UKCA marking is listed in the evidence, but the UL file alone clears the part for most US panel shops.
Deployment context
The 24 VDC coil draws steady-state power light enough that a 24 VDC power supply serving a small PLC can also feed a handful of these starters.