Elimination of inrush current using a new prefluxing method. Application to a single-phase transformer

The random energization of power transformers may generate high inrush currents. In some cases, the inrush currents reach up to 10 p.u. of the rated current and cause damages mainly to the transformers but also to the power systems and the circuit breakers. For this reason, an efficient and new method of prefluxing has been developed to eliminate inrush currents. This method has been successfully implemented on a 1 kVA laboratory transformer. The prefluxing device consists of a simple source that operates at substantially low power.