Nuisance Operations of Distribution Fuse Links Due to Lightning-Induced Current Surges

The probability of nuisance operations of distribution fuse links due to lightning-induced current surges is the subject of much discussion today. This discussion is driven, in part, by the practice of moving the surge arrester to the transformer tank to improve overvoltage protection of the transformer. One consequence of this practice is that the probability of nuisance operation of the fuse link protecting the transformer will increase significantly unless larger fuse-link sizes are employed or unless high-surge-capacity fuse links are used. Section II of this paper describes a method for determining the probability of nuisance operations of fuse links under various conditions. Section III describes one utility´s experience with moving the arrester to the transformer tank and also its success with high-surge-capacity fuse links