Mitigation of electric arc furnace transformer inrush current using soft-starter-based controlled energization

The energization of power transformers is a frequent operation in Electric Arc Furnaces (EAF). Magnetization inrush currents with 10 to 50 times the rated transformer current can flow during several line cycles. The magnitude of the inrush currents depends on parameters like the point on wave of voltage energization, residual flux in the core, transformer size and utility systems characteristics. This momentary high current results in system disturbances and reduction of the transformer life cycle. In this paper a scheme to mitigate the inrush current using controlled voltage ramp soft-starter-based circuit is presented. Simulation and experimental results prove the effectiveness of the soft-starter-based controlled energization.