The Siemens 3RT7045-1AB00 is a Size S3 contactor from the SIRIUS family — three main poles, normally open, rated for AC-3 motor switching up to 690 V. The coil pulls in on 24 V AC and holds at 0.26 W DC holding power, so the control transformer sizing is modest. It lands on a 35 mm or 75 mm standard mounting rail via screw or snap-on fastening; the mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward or backward, which gives panel builders flexibility when laying out a crowded door or sub-panel.
Switching frequency and duty limits
The maximum switching rate is 800 operations per hour under AC-3 duty and 250 operations per hour under AC-4. That 250 ops/h limit under AC-4 (plugging / inching) is the one that governs in high-cycle reversing or jogging applications — exceed it and the contactor overheats. For a standard conveyor start or pump run, the AC-3 figure gives comfortable headroom.
Coordination and environmental fit
With Type 1 coordination the upstream fuse is a 200 A gL/gG NH 3NA. The surge voltage withstand is 6 kV, so it holds up in installations with moderate lightning or switching transients on a 400 V supply. Installation altitude is limited to 2 000 m above sea level without derating.
Auxiliary contacts and PLC compatibility
For DC-13 loads at 220 V the auxiliary circuit carries 0.3 A.