Announcing the New “DR” Speed Fuse Link.

S&C has recently introduced a new family of high-surge-capacity Positrol Fuse Links to fill a market niche not presently being served by S&C’s existing offering. These fuse links were developed in response to customers’ requests for a family of fuse links with time-current characteristics similar to Cooper Power Systems’ Type “D” Fuse Links, but having the nondamageable performance, enhanced secondary-fault-clearing capability, and tight TCC tolerances for which S&C Positrol Fuse Links are renown. Because these new fuse links are specifically intended as replacements for Cooper Type “D” Fuse Links, they have been given the speed designation “DR.” They are directly interchangeable mechanically — and “functionally equivalent” with respect to time-current characteristics — with the Cooper Type “D” offering.

Details of the Offering

S&C “DR” Speed Positrol Fuse Links are available in the Universal Style, as well as the Extra-Performance Style, in ratings of 3DR, 4DR, 5DR, 7DR, 10DR, 15DR, and 20DR amperes. Like the Cooper Type “D” Fuse Links they emulate, S&C “DR” Speed fuse links are intended solely for the protection of overhead distribution pole-top transformers in ratings through 100 kVA single-phase at 15 kV, and through 167 kVA single-phase at 25 kV.

S&C “DR” Speed Positrol Fuse Links feature a high adiabatic minimum-melting I2t — approximately equivalent to that of a 20K fuse link. This means that the probability of “DR” Speed Fuse Links operating due to lightning-induced current surges is low — less than 1% per year — even in high isokeraunic areas. It also means that users can mount the surge arrester directly on the transformer tank, to provide the maximum possible overvoltage protection for the transformer, without the need to worry about nuisance fuse link operations.