The 3RT7045-1AF00 is a Siemens SIRIUS size S3 contactor — three main poles, all normally open, rated for AC-3 switching up to 690 V and 800 operating cycles per hour at that duty. It's an active-production part, so no last-time-buy scramble yet.
Snaps onto 35 mm or 75 mm standard DIN rail, or screws direct to a backplate. The 70 mm width and 139 mm depth mean it fills one standard 8-module slot on a DIN rail — no surprises for panel layout. That covers most cabinet orientations without derating the coil.
AC coil, closing power 0.61 W DC equivalent, holding at 0.26 W. That's a low steady-state draw — the holding power is about what a small indicator LED pulls, so the control transformer can be sized lean.
Auxiliary contacts and PLC compatibility
The contactor accepts add-on auxiliary switch blocks (product extension auxiliary switch: yes). The base contact reliability is rated for PLC-level signals — 17 V, 5 mA — so you can wire the aux directly to a 24 VDC digital input without worrying about contact wetting failure.