Surge Transference Through Transformers

A DISTRIBUTION SYSTEM CAN BE subjected to transient overvoltages due to surges of atmospheric origin transferred through the utility tie transformer, especially if it is of high turns ratio, i.e., the utility system voltage is high. Primary (high-voltage side) surge protection of the utility tie transformers is invariably provided. Secondary (low-voltage side) protection is also gaining momentum, though it may not be always provided in distribution systems. IEEE standard C62.41 [1] details the categories of secondary protection devices and contains recommendations for specific installations. The IEEE standard C62.22 [2] covers the application of metal oxide surge arresters in ac systems.