The Siemens 3RA2145-4FB45-1AK6 is a combination non-reversing motor starter in the S3 frame size, panel-mounted, covering a 28-40 A adjustable overload range. The description reads COMBO NR STR PNL MTD S3 28-40A — that's a compact, self-contained unit integrating a contactor, overload relay, and short-circuit protection into one package for a non-reversing motor load. The S3 frame tells you the physical envelope and the current band it's sized for; this one lands in the upper third of that frame's range.
What the 28-40 A Rating Means for Fit
The 28-40 A range is the adjustable overload setting. Set the overload relay to match the motor's full-load amps within that window.