What this contactor is and where it fits
The Siemens 3RT7025-1AN20 is a 3-pole SIRIUS contactor in the S0 frame size, rated for AC-3 switching duty up to 690 V. It carries three normally-open main contacts and uses screw-type terminals for both the main and auxiliary circuits. The IP20 finger-safe enclosure on the front and terminals suits it for panel-mount installations where personnel touch the front face during commissioning or maintenance.
Mounting and panel integration
Mounts via screw or snap-on onto 35 mm standard mounting rail per DIN EN 50022. The S0 footprint — 45 mm wide, 85.5 mm tall, 91 mm deep — fits a single DIN-rail module pitch, so it lines up cleanly alongside other S0 accessories like overload relays and auxiliary contact blocks. Side-by-side mounting is supported, which simplifies multi-contactor motor starter assemblies in a compact panel.
Electrical ratings and what they mean for your circuit
The AC-3 rated voltage maximum of 690 V covers most 400 V and 690 V motor circuits in industrial distribution. The insulation voltage is also rated at 690 V, and surge voltage resistance is 6 kV, so the contactor holds up against switching transients common on motor lines. For short-circuit protection, Type 1 coordination calls for a 63 A gL/gG fuse (3NA series), while Type 2 coordination requires a 25 A fuse — this matters when you're coordinating with upstream protection devices to minimize downstream damage on a fault.
Coil and switching performance
The DC magnet coil draws 0.72 W during closing and holds at 0.24 W — a low holding power that reduces heat buildup inside the enclosure. Maximum switching frequency is 800 operations per hour under AC-3 duty, dropping to 250 operations per hour for AC-4 (plugging/inching) applications. For vibration environments, the contactor withstands 12.5g for 5 ms and 7.8g for 10 ms sine-pulse shock.
Environmental and wiring specs
Operating temperature range is -10 to +55 °C, with storage from -25 to +70 °C. Pollution degree 3 means it's rated for industrial atmospheres with conductive contamination. Terminals accept solid or stranded wire: 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²), also fine-stranded with ferrule. The mounting position allows ±180° rotation on a vertical surface and ±22.5° tilt forward/backward, giving flexibility in tight enclosures.