The Siemens 3RT2025-1BF44 is a SIRIUS power contactor in the Size S0 frame, built for switching motor loads in control panels. It carries a 110 V rated coil voltage and uses screw-type terminals for the magnet coil. The 45 mm wide body snaps onto a 35 mm DIN rail per DIN EN 60715, or can be screw-mounted, so it fits standard panel layouts without custom bracketry.
What the ratings mean for fit
The AC-3 switching frequency is rated at 1,000 operations per hour maximum, which covers most conveyor and pump cycling without derating. AC-4 drops to 300 ops/h — that's the inching or plugging duty limit, so if your application reverses the motor under load, stay under that ceiling. The mechanical life is a typical 10,000,000 operations, meaning the contactor itself outlasts most panel refreshes. For DC switching, the contactor is rated at 6 A at 24 V, 2 A at 48 V, and 1 A at 110 V. These are resistive load figures; inductive DC loads need a diode or RC snubber across the coil to avoid contact erosion. The coil pickup is guaranteed at 80% of rated voltage (88 V for this 110 V coil), and withstands 110% continuously — so it holds in during brownout conditions down to about 88 V. Wire range accepts 1 to 10 mm² solid or stranded on the main contacts, and 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) fine-stranded for auxiliaries. That covers most panel wiring up to 6 AWG. The operating temperature range is -25 to +60 °C, so it lives in unventilated enclosures without issue.
Mounting and clearance
The contactor can be mounted in any orientation — +/-180° rotation on a vertical surface, plus +/-22.5° tilt forward or backward. That flexibility helps when the panel layout is tight. Clearance requirements are modest: 10 mm upwards, 10 mm downwards, 10 mm forwards, and only 6 mm to the side. The 85 mm height and 151 mm depth mean it fits in shallow enclosures.