99 A at 40 °C — derating drives the real rating
The 3RW4425-3BC45: For a 230 V motor line, this means the continuous current capacity drops by roughly 10 A per 10 °C rise above 40 °C — the derating curve is the number that decides whether this unit holds a given motor FLA in a warm cabinet.
Integrated bypass and inside-delta wiring
An integrated bypass contact system carries the motor current after start-up, removing the thyristors from the power path and eliminating their heat dissipation during run. This keeps the enclosure cooler and lets the soft starter handle longer acceleration times without derating further. Inside-delta circuit wiring is supported — a six-wire motor connection that places the soft starter in the delta legs, reducing the per-phase current the unit must carry by roughly 42 % compared to standard in-line wiring. For a given motor, this can allow a smaller-frame soft starter to do the job.
Termination and mounting
Main power connections use box terminals accepting 2x (4... 50 mm²) stranded or 2x (10... 1/0 AWG) using both clamping points. Screw fixing to the mounting surface. The unit can be mounted with a vertical surface, rotatable ±90°, and tiltable ±22.5° front-to-back — useful when fitting into existing panel layouts where the backplane is not perfectly plumb.
Protection and control features
Motor overload protection and intrinsic device protection are built in — the soft starter monitors both the motor and its own thyristor temperature, reducing nuisance trips from overloads that are actually harmless for the motor but would stress the semiconductors. Adjustable current limitation lets the user set the maximum starting current between 100 % and the unit's rated current (typically 300–400 % of motor FLA in practice), which is the primary tool for limiting line drop during start. Minimum load is 8 % of the rated current — below that the motor may not be reliably detected. External reset input and a display for fault signals are standard — the display shows the last fault code, which cuts troubleshooting time on a line-down call.
Clearance and cable length
Required clearance around the unit: 100 mm above, 75 mm below, 5 mm at the sides. These are the minimum air gaps for natural convection cooling — crowding the top clearance will raise the internal temperature and accelerate derating. Maximum motor cable length is 500 m — beyond that, capacitive charging current from the cable can interfere with the soft starter's current sensing and cause nuisance overcurrent trips.
Environmental and insulation ratings
Rated insulation voltage 690 V, pollution degree 3 per IEC 60947-4-2 — suitable for industrial environments where conductive dust or condensation is present.