The Siemens 3RT2028-1BE40 is a SIRIUS-brand power contactor in Size S0, designed for switching motor and resistive loads in industrial control panels. Its 60 VDC-rated magnet coil draws an initial inrush of 0.8 A and holds at the rated value, with screw-type terminals for the coil connection. Rated for DC-1 and DC-3 duty, it switches 10 A at 24 VDC, 2 A at 48 V and 60 V, 1 A at 110 V, 0.9 A at 125 V, 0.3 A at 220 V, and 3 A at 400 V. For motor loads on single-phase 230 V, it carries a 5 hp rating — the key figure for pump, fan, or compressor duty in North American panels.
Switching Frequency and Duty Cycles
Maximum switching frequency varies by duty class: 1,000 operations per hour at AC-1 (resistive), 750/h at AC-2 and AC-3 (motor starting/running), 750/h at AC-3e (high-efficiency motor), and 250/h at AC-4 (plugging/inching). The AC-4 limit is the one to watch for reversing or jogging applications — exceeding it shortens contact life.
Termination and Wiring
Auxiliary contacts take 2x (0.5 to 1.5 mm²) or 2x (0.75 to 2.5 mm²) — fine for control-circuit daisy chains. The contactor includes an auxiliary switch, so no separate add-on block is needed for basic status feedback.