A Guide to the Application of Surge Arresters for Transformer Protection

With the increasing trend toward electrical power distribution to industrials at primary voltages, it is important to provide proper surge protection for primary stepdown transformers. To provide adequate protective margins for this equipment, it is essential for the application engineer to understand the operation of a surge arrester and how the arrestor provides overvoltage protection. The operation of a surge arrester, arrester protective characteristics, and the establishment of parameters necessary to provide appropriate insulation coordination for surge protection of transformers are discussed.