Rated current and thermal derating in the panel
The 3RW4028-2BB04: The derating curve matters when the soft starter shares a crowded enclosure with other heat sources — the S0 frame's natural convection relies on the 60 mm upward and 40 mm downward clearance. The integrated bypass contact system switches the thyristors out of the circuit once the motor reaches full speed, cutting heat dissipation during run. This lets the unit handle the rated current without external bypass contactor wiring.
Mounting and wiring for the S0 frame
Screw and snap-on mounting to DIN rail — the snap-on feature lets you seat the unit without tools; the screw secures it against vibration. The S0 frame footprint is 45 mm wide by 150 mm high by 155 mm deep. No screwdriver needed for termination; the spring cage holds the conductor under vibration.
Motor protection and adjustable current limitation
Built-in motor overload protection and intrinsic device protection cover the soft starter's own thyristors against overtemperature and overcurrent. The adjustable current limitation lets you set the start ramp peak current as a percentage of the motor FLA — minimum load is 20 %. An external reset input allows remote fault reset from a PLC or pushbutton panel, keeping the starter in the loop without a manual walk to the cabinet.