What it is and what it does
The Siemens 3RT5045-1AG20 is a SIRIUS power contactor in the Size S3 frame, designed for switching motor loads in industrial control panels. It carries screw-type terminals for the main current circuit and mounts via screw or snap-on onto 35 mm or 75 mm DIN rail, with a 70 mm width that fits standard panel layouts. At 60 °C ambient, it is rated for 38 kW at 230 V and 66 kW at 400 V, with a 690 V rating of 114 kW — these are the motor power ratings that govern real-world sizing, not the lower-temperature figures. The contactor handles up to 1 000 switching cycles per hour in AC-3 duty (AC-3e maximum), matching typical conveyor and pump cycling rates. Operating temperature spans -25 to +60 °C, storage -55 to +80 °C, and the insulation voltage is rated 1 000 V. Pollution degree 3 means it tolerates conductive dust and humidity typical of factory-floor enclosures without conformal coating.
Lifecycle and sourcing
RoHS compliance is dated to March 1, 2017, covering the EU substance restrictions. The part carries the SIRIUS brand and is backed by Siemens' standard documentation package (declaration of conformity, UL/CSA/CE certifications available on request).
Panel integration notes
Mounts on 35 mm or 75 mm DIN rail with screw or snap-on fastening. The 70 mm width and 146 mm height leave room for auxiliary contact blocks alongside. Main circuit terminals accept 2x (2.5... 16 mm²) solid or stranded copper, or 2x (10... 1/0) AWG. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt, useful when the gland plate or busbar layout forces an off-angle install.
Coil and auxiliary ratings
The coil draws 6 A at 24 V rated value, 1 A at 110 V, and 0.3 A at 220 V — these are the pick-up/hold currents for the control circuit, not the main contact ratings. At 50/60 Hz the coil impedance is 0.29 per the spec, consistent with a standard AC-operated solenoid. Mechanical endurance is 10 000 000 operating cycles typical, with electrical endurance varying by duty: AC-1 (resistive) up to 900 cycles/hour, AC-3 (motor) up to 1 000 cycles/hour, AC-4 (plugging/inching) up to 300 cycles/hour. The 5 000 cycles/hour figure at AC refers to the no-load mechanical rate.