What this SIRIUS contactor carries
The Siemens 3RT2045-3XJ40-0LA2 is a size S3 SIRIUS contactor rated 77 A at 480 V and 62 A at 600 V in AC-3 duty — those are the motor-switching numbers that govern the BOM line, not the resistive AC-1 curve. The coil is 72 VDC with an extended operating range, meaning it holds in through dips that would drop a standard coil, a real advantage on DC-supplied control buses with voltage sag. Spring-type terminals on both coil and main contacts — no torquing, no re-tightening on a thermal cycle, which saves panel-build time and eliminates a common vibration-loosening failure point.
The 70 mm width and 140 mm height are the S3 frame footprint — same as the rest of the SIRIUS S3 family, so a panel laid out for a 3RT1054 or 3RT1055 accepts this without re-drilling. Depth is 152 mm, which includes the arc chamber and terminal projection.
Listed as current production — no NRND flag, no LTB notice. This is the standard catalogue part, not a phase-out variant.