The 3RT2028-2AC20 is a SIRIUS S0-frame power contactor, 45 mm wide, 102 mm tall, 97 mm deep. Spring-type terminals on the magnet coil and main contacts accept solid or stranded wire from 1 to 10 mm², with double-wire capability up to 2× (0.5 to 2.5 mm²).
Duty cycle and contact ratings
Rated for AC-3e duty at 750 operating cycles per hour maximum, and AC-4 at 250 cycles/h — the AC-4 figure governs reversing or inching applications where the contactor makes and breaks under full motor current. The auxiliary switch is built in, rated at 24 V / 10 A, 48–60 V / 2 A, 110 V / 1 A, 125 V / 0.9 A, 220 V / 0.3 A, 400 V / 3 A, 440 V / 0.6 A. That covers most control-circuit voltages in a 50/60 Hz panel. Arcing time is 10 ms at AC, with a switching frequency of 0.25 at 50 Hz and 0.28 at 60 Hz.