Rated current and thermal derating
The 3RW4426-1BC35 is rated 133 A at 40 °C ambient. At 50 °C the rating drops to 118 A, and at 60 °C it is 102 A. The derating temperature is 40 °C — above that, the continuous output current must be reduced per the datasheet curve. For a 60 °C panel environment, budget the 102 A figure as the usable ceiling.
Integrated bypass and inside-delta wiring
An integrated bypass contact system is built in — once the motor reaches full speed, the thyristors are shorted, eliminating heat dissipation in the power module during run. The unit also supports inside-delta circuit wiring, which reduces the current through the soft starter to 58% of the line current, effectively extending the motor current range the same hardware can handle.
Mounting dimensions and clearances
The enclosure measures 192 mm high, 170 mm wide, and 270 mm deep. Required clearances: 100 mm above, 75 mm below, and 5 mm at the sides. These gaps are for airflow — the thyristor heatsink needs that volume to stay within the 60 °C operating limit.
Terminal sizes and wire range
Main current circuit terminals are box-type, accepting 2x (4... 50 mm²) stranded or 2x (10... 1/0 AWG) using both clamping points. Maximum wire length from the soft starter to the motor is 500 m — beyond that, voltage drop and cable capacitance may affect thyristor commutation.
Protection and control features
Motor overload protection is built in, along with intrinsic device protection that monitors thyristor temperature and line-side conditions. Adjustable current limitation lets the user set the start current between 8% and 100% of the rated motor current — the minimum load is 8%. An external reset input and a display for fault signals are standard.
Voltage and frequency ratings
Insulation voltage is rated 690 V, and the operating frequency covers 50... 60 Hz.
Storage and operating temperature
During operation the ambient limit is 60 °C; storage range is -25... +80 °C. The unit is designed for a 40 °C derating baseline — above that, the current ratings in the spec table apply.