KLDR fuses are time-delay fuses specifically designed for the protection of control transformers, solenoids and similar inductive components with high magnetizing currents during the first half-cycle.
They closely match most control power transformer characteristics, which permits the fuses to be sized in accordance with the latest revisions of UL 508 (Industrial Control) and UL 845 (Motor Control Centers).
When the time delay of KLDR fuses is adequate to carry motor starting current, they provide excellent protection of motor branch circuits containing IEC or NEMA rated motor controllers or contractors.
Compared to other UL Listed fuses, Class CC fuses are the most current limiting, rating for rating. Because they are physically compact, they provide this superior protection in a fraction of the space required by other fuse classes.
For example, when 600V three-pole, 30 ampere Class R fuse blocks are replaced by Littelfuse Class CC fuse blocks, panel-mounting space is reduced approximately 70%. This is especially important when a panel contains many fuses to protect multiple circuit components.
Three types of Class CC Fuses, specifically designed to protect different types of components:
- Motor protection – CCMR series; dual-element, time-delay fuses specifically designed to protect motor circuits up to 40 HP. Review the motor protection tables in PF101 for more information.
- Small transformer protection (control power transformers) – KLDR series, time-delay fuses designed to withstand the high magnetizing inrush of transformers.
- General purpose protection of equipment requiring fast overload protection – KLKR series, fast-acting fuses used for protection of equipment containing solid-state devices or other electronic components requiring fast response on overloads.
- 200,000 A.I.R. — Reliable interruption of all overcurrents up to 200,000 amperes.
- Extremely current limiting — Reduces damage caused by heating and magnetic effects of short-circuit currents…stops damaging short-circuit faster than any mechanical protective device.
- Class CC fuses are the smallest 600V, 200,000 A.I.R. fuses approved for branch circuit protection.
- Current limiting design often permits use of readily available, less costly equipment.