August 24, 2004

Introducing “KSR” Speed Positrol^® Fuse Links.

S&C is pleased to announce the availability of a new family of high-surge-capacity Positrol Fuse Links designed to fill requirements not presently being served by S&C’s existing offering. They were developed in response to customers’ requests for fuse links having time-current characteristics similar to Kearney Type “KS” Fuse Links, but with the nondamageable performance, enhanced secondary-fault-clearing capability, and tight TCC tolerances for which S&C Positrol Fuse Links are famous. Because these new fuse links are specifically intended as replacements for Kearney Type “KS” Fuse Links, they have been given the speed designation “KSR.” They are interchangeable mechanically — and with respect to time-current characteristics — with Kearney Type “KS” Fuse Links.

Details of the Offering

S&C “KSR” Speed Positrol Fuse Links are available in Universal and Extra-Performance Styles in ratings of 3 KSR through 200 KSR amperes. Like the Kearney Type “KS” Fuse Links they emulate, S&C “KSR” Speed Fuse Links are general purpose, with “extra slow” time-current characteristics. They are slower than “K” Speed Fuse Links, slower than “T” Speed Fuse Links, and even slower than “DR” Speed Fuse Links. See Figure 1 below. “KSR” Speed Fuse Links can be used to protect overhead distribution pole-top transformers and capacitor banks, as well as laterals and taps.

“KSR” Speed Positrol Fuse Links utilize a dual-element design, with upper and lower element wires connected in the center by a solder-filled wire coil; the solder connection causes a purposeful shift — to the left — in the long-time region of the time-current characteristic curve. The ends of the element wires that are inserted into the coil are dimpled to increase the resistance to being pulled apart.

Like all S&C Positrol Fuse Links, “KSR” Speed Fuse Links feature high-melting-temperature element wires and swaged terminal connections for enhanced reliability, and controlled-burst-strength filament-wound fiberglass sheaths for improved secondary-fault clearing performance.

And like Fault Tamer Fuse Limiter cartridges and “DR” Speed Positrol Fuse Links, “KSR” Speed Fuse Links feature higher adiabatic minimum-melting I2t’s than faster-speed links such as “K” Speed, “T” Speed, and “DR” Speed. So the probability of “KSR” Speed Fuse Links operating due to lightning-induced current surges is relatively low, even in high isokeraunic areas. Users can thus mount surge arresters directly on transformer tanks to provide the greatest possible overvoltage protection . . . there’s no need to worry about nuisance fuse link operations.

Figure 1.