Inrush current transients during energization of an unloaded trandsformer on the Eskom network

Eskom has experience a high numbers of power transformer failures as from the period of 1996–2004. The high percentage of these power transformer failures are contributed by internal failures. Eskom is busy carrying out research studies on the influence of through faults in the power transformers. This paper concentrates mainly on the inrush currents transients during energization of the unloaded transformers. The field testing was carried out and the data was analysed and presented for debate. A short overview of the simple controlled switching techniques was presented as the solution to reduce inrush currents.