What this contactor is and where it fits
The Siemens 3RT2028-1BF40 is a SIRIUS power contactor in the Size S0 frame, designed for switching motor loads and resistive circuits in industrial control panels. It mounts on a 35 mm DIN rail per DIN EN 60715 via screw or snap-on fastening, and the mounting position allows ±180° rotation on a vertical surface plus ±22.5° tilt forward and backward — useful when panel layout forces an unconventional orientation.
Coil and switching ratings
The coil is rated 110 V AC with screw-type terminals. For DC switching, the contactor handles 10 A at 24 V, 2 A at 48 V, 2 A at 60 V, 1 A at 110 V, 0.9 A at 125 V, and 0.3 A at 220 V — so it covers control-circuit loads across common DC bus voltages. The arcing time sits at 10 ms, and the operate time at DC is 15–18 ms, which matters when coordinating with upstream protection or sequencing multiple contactors.
Mechanical and electrical endurance
Mechanical life is rated at 10,000,000 operations typical. Electrical switching frequency varies by duty: 1,000 ops/h at AC-1 (resistive), 750 ops/h at AC-2 and AC-3 (motor starting/running), and 250 ops/h at AC-4 (plugging/inching). The AC-3e rating also allows 750 ops/h. For a motor-switching application, the 750 ops/h ceiling means it handles frequent starts on a conveyor or pump without exceeding thermal limits.
Termination and wiring
Main contacts accept solid or stranded wire from 1 to 10 mm². Auxiliary contacts use a smaller range: 2x (0.5–1.5 mm²) or 2x (0.75–2.5 mm²). The screw-type terminals are standard for panel wiring — no special tooling needed. Clearance spacing: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the sides, which dictates how tightly you can pack it on the DIN rail alongside other devices.
Sourcing and availability
This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time. No last-time-buy or phase-out notice applies — the lifecycle stage is current.