Positrol ® Fuse Links

S&C Positrol Fuse Links, with their precise TCCs, nondamageable fusible elements, and superior fault-interrupting ability, give you the ultimate in fuse-link performance. They eliminate “sneakouts” (uncoordinated blowings due to TCC shifts), and the need to call on upstream protective devices to do the fuse link’s work— thereby saving operating dollars and improving service reliability . . . two factors that are crucial in today’s competitive environment. The exceptional features of Positrol Fuse Links make all of these benefits possible.

Nondamageable and Permanently Accurate
Positrol Fuse Links are not affected by aging, vibration, or surges that heat the element nearly to the severing point. They are nondamageable, so they operate only when they should, not when they shouldn’t; they will not sneak out. To a utility, that’s dollars and cents . . . Positrol Fuse Links eliminate those costly excursions to find and replace needlessly blown fuse links.
And because Positrol Fuse Links are nondamageable, there is no need for “safety zones” or “setback allowances.” Close fusing is achievable without fear that changes in time-current characteristics will occur—causing troublesome departures from your carefully orchestrated protection and coordination plans. The enduring permanency of Positrol TCCs has been repeatedly demonstrated by exhaustive full-scale laboratory testing.

Tight Tolerances
S&C Positrol Fuse Links have exceptionally tight tolerances . . . typically half those of other fuse links . . . which means they can be counted on to clear faults faster. Tight tolerances and nondamageability combine to allow you to choose a minimum-size link for each application, ensuring maximum protection and enhanced coordination. With Positrol Fuse Links you can even coordinate adjacent ampere ratings.

These superb performance characteristics of Positrol Fuse Links are the result of uncompromising design, plus diligent attention to manufacturing details. The fusible elements of silver, silver-copper eutectic, and nickel-chrome (depending on rating) are inherently nondamageable. Wire materials of carefully checked purity and conductivity are drawn through precision dies to exact cross sections confirmed by laser micrometer. And painstaking assembly ensures no nicks, no kinks, no necking down that might compromise TCC accuracy. Elements are swaged to their terminals for permanent, nondamageable connections.

Superior Fault-Interrupting Performance
The fuse link—not the cutout fuse tube—determines the ability of a cutout to interrupt low-magnitude fault currents, particularly transformer secondary-side faults with their severe transient recovery voltages (TRVs). Extensive testing through the full spectrum of secondary faults . . . with realistically severe TRVs . . . has proved the matchless performance of S&C Positrol Fuse Links, whether applied in single-vented or double-vented cutouts. These links, with their controlled-burst-strength filament-wound fiberglass sheaths, reliably interrupt all levels of secondary-fault currents on systems through 27 kV, and in single-phase-to¬neutral applications on systems through 38 kV.

Broad Selection of Speeds
Positrol Fuse Links are available in eight speeds: T, K, QR (interchangeable with “QA” speed offerings), DR (interchangeable with “D” speed offerings), KSR (interchangeable with “KS” speed offerings), N, Standard, and Coordinating.
All these speeds, plus a selection of ampere ratings from 1 through 200 amperes, make optimal coordination and maximum protection a practical reality at every sectionalizing point, riser pole, distribution transformer, and capacitor bank.

Easy to Apply
Easy-to-use application information, developed with the same attention to detail as the Positrol Fuse Links themselves, is available to facilitate selection of S&C Fuse Links. Request S&C Data Bulletin 350-110 for transformer protection, S&C Data Bulletin 350-130 for capacitor protection, or S&C Data Bulletin 350-170 for series coordination. These comprehensive application guides take the work out of selecting the fuse link best suited to each protection requirement.