Current derating and thermal budget
The 3RW4427-3BC36: Minimum load is 8 % of the rated current — below that the soft starter may not trigger the thyristors reliably, so check the motor magnetising current against this floor.
Bypass and protection topology
Integrated bypass contact system means the thyristors are shorted out after start, eliminating continuous conduction losses — the 161 A rating applies to the bypass path, not just the silicon. Built-in motor overload protection and intrinsic device protection reduce external relay count; adjustable current limitation lets you set the start ramp ceiling without a separate current-limiting reactor.
Wiring and panel fit
Envelope is 170 mm wide, 192 mm high, 270 mm deep — screw fixing, not DIN rail. Mounting position allows ±90° rotation and ±22.5° tilt front-to-back, which helps in tight retrofit cabinets. Clearance: 100 mm upward, 75 mm downward, 5 mm at the sides — the side gap is tight; forced airflow or a wider cabinet may be needed above 40 °C.
Inside-delta wiring and motor lead length
Inside-delta circuit configuration is supported — this places the soft starter in the delta legs of a six-lead motor, reducing the current rating needed by about 58 % compared to in-line wiring. Useful for retrofitting a smaller unit onto an existing motor. Maximum motor cable length is 500 m — beyond that, reflected wave voltage spikes at the motor terminals may exceed the thyristor blocking voltage, especially on 690 V systems.
Environmental and compliance
Pollution degree 3 per IEC 60947-4-2 — conductive pollution or dry non-conductive pollution that becomes conductive due to condensation is expected. The enclosure seal and internal creepage distances are designed for this. Storage temperature range -25 to +80 °C; operation up to 60 °C ambient. Insulation voltage rated 690 V, operating frequency 50/60 Hz.