Panel fit and cooling clearance
The 3RW4466-6BC46 measures 575 mm wide by 780 mm tall by 292 mm deep — a substantial frame that needs a backplate or sub-panel with the screw-fixing pattern laid out before the starter arrives. Siemens calls for 100 mm clearance above, 75 mm below, and 5 mm at the sides for natural convection cooling. Skimp on the vertical gap and the thyristor junction temperature climbs faster than the derating curve accounts for.
Current derating and thermal limits
That 20 % drop from 40 °C to 60 °C is the number to size against if the enclosure runs warm — the derating temperature threshold is 40 °C. Storage range is -25 to +80 °C; operation tops out at 60 °C ambient. Pollution degree 3 per IEC 60947-4-2 means the unit tolerates conductive dust and humidity typical of industrial control rooms — no derating for environment alone.
Wiring and termination
Main circuit power lands on busbar connections accepting 70–240 mm² stranded or 50–240 mm² finely stranded copper, or 2/0–500 kcmil. Maximum motor cable length is 500 m — beyond that, reflected-wave voltage stress on the motor winding becomes a risk even with the integrated bypass closed during run.
Protection and control features
Built-in motor overload protection and intrinsic device protection cover the thyristors and the bypass contactor. Adjustable current limitation lets you cap inrush below the full rated value — useful when starting into a loaded conveyor or pump. Minimum load is 8 % of rated current — below that the starter may not detect the load correctly. The display shows fault signals, and an external reset input allows remote clearing after a trip. The integrated bypass contact system closes after the start ramp, taking the thyristors out of the circuit for the run phase — cuts heat dissipation in the enclosure and improves efficiency. Inside-delta wiring is supported, which reduces the current through each thyristor pair to 58 % of the line current — useful for derating the semiconductor junction temperature on high-duty-cycle starts. A motor brake output component is included on this variant, saving an external contactor for brake control on holding-brake motors.
Supply voltage and lifecycle
Insulation voltage rated 690 V, covering 400 V and 480 V systems with headroom.