What This Contactor Is and Where It Fits
The Siemens 3RT2028-2BB44-ZX95 is a SIRIUS power contactor in frame size S0, 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 its spring-type terminals accept solid or stranded conductors from 1 to 10 mm². At 45 mm wide, 102 mm tall, and 154 mm deep, it fits standard panel layouts with clearance requirements: 10 mm upwards, 10 mm forwards, 10 mm downwards, and 6 mm at the side.
Ratings and What They Mean for the Line
The 24 VDC coil draws 6 A at rated voltage, with a pickup/dropout ratio of 0.8 initial to 1.1 full-scale — meaning it holds in reliably down to about 19.2 V and drops out cleanly below that, which matters for brownout ride-through on a mill line. Switching frequency limits are class-typical for this size: 1000 cycles/hour at AC-1 (resistive loads), 750 cycles/hour at AC-3 (standard motor starts), and 250 cycles/hour at AC-4 (plugging/inching duty). The AC-3e rating matches the 750 cycles/hour ceiling, so it handles repetitive conveyor or pump starts without derating. The operating temperature range of -25 to +60 °C and storage range of -55 to +80 °C suit it for unheated electrical rooms or outdoor enclosures in temperate climates — the storage limit governs handling, not running.
Mounting and Wiring Flexibility
Mounting position allows +/-180° rotation on a vertical surface and can be tilted forward/backward by +/-22.5°, which helps when fitting into existing panels where the DIN rail isn't perfectly level. The spring-cage terminals accept 2x (0.5 to 2.5 mm²) for daisy-chaining auxiliary wiring.