The Siemens 3RW4458-2BC34 is a SIRIUS soft starter rated 1680 A at 40 °C, with derated values of 1472 A at 50 °C and 1316 A at 60 °C. That 1680 A figure is the full-load current it can handle in standard duty — sized for large motor loads like pumps, conveyors, or compressors on a 400 V or 690 V line. The 690 V insulation voltage means it's rated for 690 V phase-to-phase systems, common in heavy industrial plants. Operating frequency covers 50 to 60 Hz, so it fits either grid standard without adjustment. The integrated bypass contact system switches the thyristors out of the circuit once the motor is up to speed, eliminating heat dissipation from the semiconductors during run — a key feature for continuous-duty applications where wasted heat would drive up enclosure cooling costs. Adjustable current limitation lets you set the starting current between 8% and 100% of the rated value, giving you control over inrush on weak supply lines or mechanically sensitive loads. The inside-delta circuit capability means this soft starter can be wired in the motor's delta loop rather than in the supply lines, which reduces the current the starter sees by a factor of √3 — useful for squeezing a higher motor rating out of a given starter frame. A display for fault signals and an external reset input simplify troubleshooting and remote restart on a line. The motor brake output is a component-level feature for applications that need a DC injection brake.
Dimensions are 510 mm wide, 640 mm high, 290 mm deep. Clearance requirements: 100 mm above, 75 mm below, and only 5 mm at the sides — the side clearance is tight, so plan for airflow and cable bending radius accordingly. Main current circuit connection is via busbar, accepting stranded wire 70–240 mm² or finely stranded 50–240 mm², and AWG 2/0–500 kcmil. Auxiliary and control circuits use spring-loaded terminals accepting solid 0.25–1.5 mm² or AWG 24–16. Maximum wire length from starter to motor is 500 m — beyond that, voltage drop and cable capacitance may affect performance.