March 8, 2006
Experts from S&C Electric Company to present paper titled, “Nuisance Operations of Distribution Fuse Links Due to Lightning-Induced Current Surges”
IEEE Rural Electric Power Conference 2006
Tuesday, April 11th, 8:30AM - 9:00AM
Albuquerque, New Mexico
Speaker(s): Cameron L. Smallwood, Carey J. Cook, Henrique S. Regina
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 increasing practice of moving the surge arrester to the transformer tank. Historically, the arrester was installed on the cross-arm on the source-side of the fuse cutout. This location protected the fuse link from lightning surges, thereby allowing the selection of the smallest practical fuse-link ampere rating to provide optimal overcurrent protection for the transformer. It has recently been suggested that over voltage protection of the transformer, thought to be adequate by historical standards, could be improved by moving the surge arrester to the transformer tank. One consequence of the practice of moving the arrester to the transformer tank is that the probability of nuisance operation of the fuse link protecting the transformer will increase significantly — from essentially zero when the arrester is mounted on the cross-arm on the source-side of the fuse link, to as high as 5-6% when the arrester is relocated to the transformer tank. This paper will describe a method for determining the probability of nuisance operations of fuse links under various conditions. It will also describe one utility’s experience with moving the arrester to the transformer tank and its success with the “high-surge” fuse links that must be used as a consequence of moving the arrester.