The 3RW4027-1TB05: It integrates a bypass contact system to remove the thyristors from the circuit after start, reducing heat dissipation during run. Mounting is screw or snap-on to DIN rail; the 45 mm width and 125 mm height fit a standard panel layout. The 155 mm depth leaves clearance for wiring at the side (15 mm) and above (60 mm).
Current ratings and thermal derating
The 32 A rating at 40 °C is the base figure for a 50/60 Hz motor load. Derate to 29 A at 50 °C and 26 A at 60 °C — the temperature rise inside the enclosure must stay below the 40 °C derating threshold or the available current drops. Pollution degree 3 per IEC 60947-4-2 means the unit tolerates conductive deposits in industrial atmospheres. The integrated bypass contact system carries the full motor current after start, so the thyristors only see the start transient. This extends the duty cycle for frequent starts and keeps the enclosure heat load lower than a non-bypassed soft starter.