Product Description:

The 175G5540 is a soft starter manufactured by Danfoss for the MCD Soft Starters series. Installed between the utility supply and a three-phase motor, it modulates SCR firing angles so the motor accelerates under controlled voltage, limiting inrush current and mechanical stress on couplings, pulleys, and driven equipment. Within automated plants, the device provides a compact alternative to across-the-line contactors when smoother torque transmission and reduced electrical loading are required.

When wired in the conventional in-line configuration, the controller can deliver a continuous motor current of 428 A and can handle short-term bypassed operation at up to 430 A after the motor reaches full speed. The minimum full-load current setting is 86 A, allowing correct adjustment for smaller machines connected to the same frame size. Its rated insulation withstand voltage is 690 V AC, matching common 600 V class distribution systems, and the internal control circuitry endures transient overvoltages up to 4 kV. For branch-circuit protection, a maximum Class J fuse of 450 A may be fitted. The starter operates on three-phase power and carries an open-chassis IP00 protection level, so it must be mounted inside a suitable enclosure with adequate airflow.

Inside-delta wiring increases current capability; in this mode, the unit supports continuous conduction at 643 A and bypassed current of up to 645 A. Its short-circuit current rating reaches 65 kA for three cycles when protected by the required fusing, while its standard fault-current endurance is 30 kA. A relay output rated at 10 A and 250 V AC can signal operating status to a PLC, and a 24 V DC auxiliary source supplies up to 200 mA for external sensors. The SCR thermal limit has an I²t value of 320,000 A²s. The assembly is 689 mm high, weighs 35 kg, and uses bolted bus connections for integration with low-voltage motor control centers.