Lightning protection of pole mounted transformers

The authors present an update on Australian experience with recommended lightning protection of distribution transformers, first implemented in 195/6. It is believed that the major reduction in transformer failure rates is directly attributed to the relocation of HV (high voltage) arresters close to the terminals and to the fitting of LV (low voltage) arresters. The recommended protection has virtually eliminated all transformer fault types other than inter-turn/layer faults on the HV winding, and the rate of occurrence of this type of fault has been greatly reduced. It is concluded that data from over 12 years´ field experience demonstrates the effectiveness of the recommended protection, confirming the laboratory studies conducted in Australia and subsequently in the US and Norway. The results given in the paper should be of value to other electric utilities contemplating measures for reducing transformer failure rates attributable to lightning, particularly the use of LV arresters