Frequently Asked Questions
What is the Littelfuse KLDR-3?
It is a 3 A Class CC time-delay, current-limiting cartridge fuse from the Littelfuse POWR-GARD KLDR series, designed for compatible control transformer, solenoid and industrial control applications.
What is the manufacturer catalog number?
The manufacturer catalog number is KLDR003. The product marking is KLDR 3A, and KLDR-3 is a corresponding current-rating designation.
What is the current rating?
The fuse is rated for 3 amperes, equivalent to 3000 milliamperes.
What are the AC and DC voltage ratings?
The manufacturer specifies 600 VAC and 300 VDC. The operating circuit voltage must remain within the applicable AC or DC rating.
What are the AC and DC interrupting ratings?
The AC interrupting rating is 200,000 amperes RMS symmetrical at 600 VAC. The DC interrupting rating is 20,000 amperes at 300 VDC and is identified by Littelfuse as self-certified.
Is KLDR-3 a time-delay or fast-acting fuse?
KLDR-3 is a time-delay fuse. The KLDR series is designed to tolerate temporary magnetizing inrush currents associated with control transformers, solenoids and similar inductive equipment.
Does KLDR-3 open in exactly 12 seconds at twice its rated current?
No. The applicable UL requirement specifies an opening time of at least 12 seconds at 200% of rated current. This is a minimum requirement rather than a fixed opening time. Consult the manufacturer's time-current curves for circuit protection analysis.
What are the pre-arcing and total clearing I²t values?
Littelfuse specifies a pre-arcing I²t of 23.21 A²s and a total clearing I²t of 55.99 A²s. The total clearing value is published for the manufacturer's 200 kA test condition. These values apply to KLDR003 and must not be confused with the adjacent 2.8 A or 3.2 A models.
What are the physical dimensions?
The nominal dimensions are 10.3 mm in diameter and 38.1 mm in length, approximately 0.41 inch by 1.50 inches.
What materials and fuse holders are used?
The KLDR series uses a melamine body with nickel-plated bronze caps. Littelfuse identifies compatible holder families including L60030C, LPSC/LFPSC, LEC and 571/572. Confirm the electrical and mechanical compatibility of the specific holder before installation.
Is KLDR-3 UL listed and RoHS compliant?
Littelfuse identifies the KLDR series as UL Listed under file E81895 and CSA Certified under file LR29862 for the applicable AC ratings. The series is RoHS compliant, and the datasheet references a CE declaration. The DC interrupting rating is manufacturer self-certified.
What should be verified before ordering KLDR-3?
Confirm the KLDR-3 or KLDR003 designation, 3 A current rating, applicable 600 VAC or 300 VDC circuit requirement, AC or DC interrupting capacity, time-delay characteristics, Class CC fuse-holder compatibility and purchase quantity. Littelfuse lists KLDR003.TXP for a manufacturer 10-piece pack and KLDR003.HXP for a 100-piece pack; these codes do not determine the quantity supplied by an individual store listing.